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Scott, T., Russell, P., Masselink, G., Wooler, A. and Short, A., 2007. Beach rescue statistics and their relation to nearshore morphology and hazards: a case study for southwest England. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1 – 6. Gold Coast, Australia, ISSN 0749.0208
The coasts of Devon and Cornwall in the southwest of England experience some of the most energetic wave conditions (Hs,10% = 2–3 m) and largest tide ranges MSR = (4.2–8.6 m) in the UK. They are also a popular tourist destination during the summer months with over 10 million visitors per year. The energetic wave/tide conditions pose a considerable physical risk to beach users and 62 beach environments in this region are therefore patrolled by Royal National Lifeboat Institution (RNLI) lifeguards. Beach rescue statistics collected by the RNLI during spring and summer (1 May to 1 October) were analysed to examine and quantify the risk posed by physical beach hazards to beach users. Rip currents were found to be the main hazard and were responsible for 71% of all recorded incidents. The most hazardous beaches were found on the exposed west coast of the study area. Beaches here can be classified as morphodynamically intermediate and are characterized by low-tide tide bar and rip systems, often topographically-constrained by intertidal geology. The rip currents are generally most active around low tide. Beaches in Devon and Cornwall exhibit morphologies that are significantly different from previously studied beaches in Australia due to the combination of high energy surf zones, large tides and variable coastal geology. This work represents a first step towards the generation of standardized beach risk assessments in the UK.
Short, A D, 2006, Australian Rip Systems – Friend or Foe? Journal of Coastal Research, SI 50, (Proceedings of the 9th International Coastal Symposium), 7 – 11, Gold Coast, Australia, ISSN 0749.0208
Since MCKENZIE'S (1956) classic article on rip currents in the Sydney region, rips have been recognised scientifically as an integral and important component of wave-dominated beaches in Australian and globally. Rips received less formal, but more important, recognition more than 50 years earlier, when Australian's began bathing in large numbers in the surf. The immediate result was a number of drowning owing to bathers being caught in rip currents and carried seaward. In the Sydney region where surf bathing was only legally permitted in 1902, the resulting rash of drowning in 1902 and 1903 lead to the formation of the world's first surf life saving clubs in 1903 and Surfing Life Saving Australia in 1907, an organization which now oversees 305 surf life saving clubs. Since 1949 when recordings begun it is estimated the lifesavers have rescued 300 000 people from the surf in New South Wales alone, the vast majority (∼90%) from rip currents.
This paper will examine the nature of rip currents, including the four types of rips; their role in surf zone morphodynamics; their nature and distribution around the Australian coast; the hazard they pose to swimmers; and ways we can mitigate this risk.
Lazarow, N., 2007. The value of coastal recreational resources: a case study approach to examine the value of recreational surfing to specific locales. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 12 – 20. Gold Coast, Australia, ISSN 0749.0208
Surfing is a major recreational and economic activity involving intimate human interaction with diverse coastal environments and is expanding both in intensity in traditional locations, as well as in reach into new environments often in the developing world. The value of surfing to both Australia's and the global economy has grown significantly over the past three decades. This combined with the significant growth in participation and rising popularity of surfing and surfing culture in many countries, means that the importance of the economic and social value of surfing to various regions cannot be understated.
While there is a growing literature on the value of surfing tourism, especially in the South-East Asian region and of proposed artificial surfing reefs, there is little documented evidence of the value of recreational surfing in more traditional locations such as Australia and the USA, where it has been estimated that over two-million Australians and two-and-a-half million Americans surf on a regular basis.
This paper presents findings from a three-year study using proven economic methodologies as well as those from the other social sciences to collect data on the market and non-market value of surfing at two locations in Australia. The findings demonstrate the significant economic, social and cultural importance of surfing amenity to specific locales, including the need to consider any negative impacts on surf breaks and the environment that may occur as a result of development, coastal planning and protection works.
Williams, P. and Lemckert, C., 2006. Beach Carrying Capacity: Has it been exceeded on the Gold Coast? Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 21 – 24. Gold Coast, Australia, ISSN 0749.0208.
Australia has more than 70,000 kilometres of coastline, 7000 km of those in Queensland. The beach has long occupied a special place in the Australian identity. The beaches are not only important to the Australian people but they are also a highly valuable tourist resource and with the number of tourists visiting the Gold Coast steadily increasing each year, determining their carrying capacity is an essential factor for their effective use and management. This study explored the concept of social carrying capacity, as well as the way Gold Coast beaches are used by locals and visitors. For the social carrying capacity concepts, several user counts using beach web camera images and more than 160 personal interviews were conducted at four different Gold Coast beaches, exploring coastal perception and beach usage. Preliminary results have revealed details including that while the majority of people surveyed thought beach crowds were perfect in their current state, 79% of the remaining respondents indicated carrying capacity had already been exceeded; that is that with Gold Coast beaches were perceived as either over-crowded or that they could do with fewer people. Through the analysis of interviews with beach users during April, 2006 and previously with University students in 2005, this paper explores the perception of beach users, with the aim of creating an understanding of their behaviour and attitudes and liasing with them in future planning and management processes used by local councils.
Hunt, S., Stuart, G., Mcgrath, J. and Hossain, S., 2007. Improvements to Integrated Coastal Zone Management on Australia's Gold Coast. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 25 – 28. Gold Coast, Australia, ISSN 0749.0208
Gold Coast City Council is one of the largest local governments in Australia with a staff of approx 2800. The City includes over 50 km of open coastline and over 600 km of waterways. Given the city's position as an international coastal destination it is important that the values of these environments that attract residents and tourists are managed and protected.
Integrated Coastal Zone Management requires people that can work across many disciplines. Recent projects and roles developed within Gold Coast City Council are presented as an example of ways that one local government is addressing the complexity of ICZM.
Case studies exploring the Gold Coast Ocean Beaches and Foreshores Strategy and the role of the Beaches and Waterways Development Officer describe the ways in which the local coastal management issues are being integrated across a large organisation, across varying disciplines and different levels of government.
Both examples are measured against the barriers to successful coastal policy making as described in a theme report following the Coast to Coast Conference (Australia's national coastal conference) in 2002. The major barriers discussed include; lack of integration, lack of adequate monitoring of policy implementation and review, lack of resources for both policy making and the information base is either inadequate or drawn from a narrow range of sources.
Lawson, S., Hunt, S., Bunt, J. and Waddell, M., 2007. A lesson in managing political will, community pressure and State Government constraints at a local government level - Toogoom Seawall Project. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 29 – 32. Gold Coast, Australia, ISSN 0749.0208
Hervey Bay City Council is a medium sized local government authority with management responsibility over 60km of coastline. At a small coastal village to the north of the main urban area in Hervey Bay, Australia, persistent coastal erosion and poor planning decisions over the past 50 years has left private property at immediate risk of loss. Hervey Bay City Council identified the need to undertake coastal protection works at this location and initiated a project to better understand the physical processes shaping the coastline and to prepare various options to address the conflict between the eroding beach and the developed shoreline. This paper examines the challenges faced by local government in selecting and implementing shoreline protection strategies in Queensland, whilst attempting to manage the diverse pressures from the community, Elected Officials and State Government Agencies. It recommends improved integration and consultation between State Government Agencies and with Local Government to ensure improved delivery and streamlined timelines for coastal protection works for Local Government.
Nogueira, R.X.S. and Dominguez, J.M.L., 2007. Mapping of land cover changes at Conde municipality coastal zone, State of Bahia, Brazil, using medium resolution satellite data. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 33 – 37. Gold Coast, Australia, ISSN 0749.0208
The easier access to medium resolution natural resources satellite data has greatly popularised the use of this type of information in land cover studies and ecosystems management. This paper presents the results of a study of land cover changes in a coastal area located in eastern Brazil (Conde Municipality – State of Bahia). Using a Geographic Information System (GIS), Landsat multi-temporal data (1984, 1995 and 2003) were photo interpreted and converted to raster maps. Overlay operations (map algebra) were then used to assess and quantify land cover changes within the studied area. It was found that the documented changes were mostly related to an increase in tourism and summer resident population, directly related to the construction of the BA-099 highway, also known as Green Line (Linha Verde). In some places, ecosystem degradation arising from these recent occupation patterns could be mapped. Overall however, the ecosystems preservation status between 1984 and 2003 can be considered very good. The methodology used can be easily applied for other sites and proved to be an easy and cheap alternative for environmental institutions interested to quickly evaluate ecosystems preservation status and land use trends during the last few decades. Coastal management initiatives can be better planned and implemented using this kind of spatially geo-referenced data.
Fernandez P.R., 2007. Understanding Relational Politics in MPA Governance in Northeastern Iloilo, Philippines. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium) 38 – 42. Gold Coast, Australia, ISSN 0749.0208
The Philippines archipelago is an important centre of tropical coastal marine biodiversity. Since the 1970s, various national and international actors have popularised marine protected areas (MPAs) as an effective tool for coastal conservation, tourism and even social empowerment. Scholars and practitioners however, overlook the different actors and complex institutions that frame and contest MPA design, implementation and outcomes. Pursuing apolitical perspectives and strategies in MPA governance and management, in turn, lead to continued environmental destruction and impoverished small-scale fishers. This paper describes the resources, power and relationship of key actors in MPA decision-making in four sites in northeastern Iloilo Province, Philippines. The paper explains that state-led, community-based and co-managed MPAs in the case study sites are socially constructed and contested. In such MPA spaces, actors have complex negotiations that have diverse and uncertain socio-political and ecological results. It is argued, however, that unless state and non-state actors link improved coastal ecosystem management, effective MPA governance and opportunities to enhance local livelihoods, then existing institutional arrangements will unlikely promote social justice and equity. In addition the major ecological effects of the Solar 1-Petron oil spill of August, 2006 are described and the potential implications of the disaster to the institutional resilience of MPA management systems are evaluated.
Fernández, P. and Danese, C., 2007. New Planning for Cala Panizo rocky beach. Almeria. Spain. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 43 – 46. Gold Coast, Australia, ISSN 0749.0208
New planning in Cala Panizo Rocky beach in Almeria, south Mediterranean Spanish coast, is presented. This rocky area is the result of an erosion process over a volcanic area on the coast of Almeria in the west Mediterranean sea where the erosive inland process due to a semi-arid region has generated a fine and coarse material from upstream basins, that combined with successive up and down sea level movements has conferred a particular beauty to this coast. In particular, the rocky sea area where Cala Panizo is confined has preserved this area from a more recent inappropriate development. A new project to save and enjoy the beauty of this area has been proposed for the municipality who is in charge and responsible for the future of Cala Panizo. The main proposal of this study is to make the area accessible to public use by building paths on the rock platforms and provide a station which will help visitors understand the evolution of the rocky system and interact with nature without the help of sophisticated equipment. Supplying this plan to Cala Panizo will manifest that development of the area for a tourist purpose can be done in a sustainable manner, enjoyable for tourists, while at the same time generating profit for the local community and creating a new alternative use for the coast. Hopefully this will be an incentive to create similar actions in the surrounding coastal areas.
Espejel, I., A. Espinoza-Tenorio, O. Cervantes-Rosas, I. Popoca, A. Mejia, and S. Delhumeau. 2007. Proposal for an integrated risk index for the planning of recreational beaches: use at seven Mexican arid sites. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 47 – 51. Gold Coast, Australia, ISSN 0749.0208
An integrated risk index has been developed for evaluating tourist and recreational beaches. It includes an index of beach suitability for recreational use, an index measuring the user's perception and an economic index expressing the monetary value of the beaches. The contamination vulnerability was evaluated with one physical attribute that reflects indirectly the cleaning ability of the water body where the beach is located. Seven beaches in north-western Mexico were evaluated with this index. Two beaches have high recreational values but one is located in a semi-enclosed area with the contamination vulnerability causing the risk index to be high. In contrast, the other high-valued beach is on the open sea; therefore the risk index is medium. Three beaches have medium recreational values but only one has a high risk index because it is in the most enclosed area. Two beaches have low recreational values with one having a medium risk index because it is located in a large bay open to the sea. This model, although proved in arid beaches, can be useful for any other beach (temperate or tropical).
Cirella, G.T., Tao, L. and Mohamed, S., 2007. An application of an adaptive quantitative method to measure the sustainability the Gold Coast, Australia. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 52 – 56. Gold Coast, Australia, ISSN 0749.0208
The coastal city of the Gold Coast, Australia is the first of eighteen sub-domain studies within South East Queensland (SEQ) that has been measured using the index of sustainable functionality (ISF). As a quantitative definition of sustainability, the ISF offers an adaptive method of measurement. It does so based on an engineering standpoint that institutes stable energy and mass transfer indicates longevity over spatial and temporal scales. Sustainability trends are measured using adaptive sustainability which incorporates complex interactions by making use of a matrix-based approach. Twenty-three functions were utilised in the study and measured against a total of 53 indicators. The span of the research is between the years 2000 to 2005. The results of the study indicate that the ISF of the Gold Coast can assist in improving the overall sustainability of the region. The overall result shows sustainability trends have slightly improved and are heading toward a sustainable blueprint for rapidly developing regions. Monitoring of trends would reduce future unsustainable action and optimise the ISF to the region and beyond.
Davies, W.R. and Martinez, G., 2007. An integrated observation network for Gippsland Lakes: Balancing the needs of science and management. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 57 – 61. Gold Coast, Australia, ISSN 0749.0208
The Gippsland Lakes region in eastern Victoria is a partially flushed coastal lake system within a diverse catchment of rural and urban communities. Pressure from lakeside developments, re-occurring blue-green algal blooms, declining fisheries, sedimentation and infilling of the ocean entrance, has borne several decades of focussed studies and routine monitoring programs, along with a variety of engineering and management solutions. A recent review recommended that these disparate studies should be enhanced to formulate a coordinated monitoring network that could improve both spatial and temporal coverage, develop a capacity to trigger responsive investigations and was able to serve the needs of system management. Through a series of partnerships an integrated network was developed that comprises event and baseline monitoring of catchment loads, local meteorological forcing and an array of water quality sampling sites within the lakes system. A majority of these sites are incorporated with real-time telemetry that provides up to the minute information to stakeholders via a web-based information management system and vital operational status to technical system management.
Harris, M.S., Tinker, T.P., and Wright, E.E. 2007. Online Beach Profile Management and Analysis System (PMAS). Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 62 – 66. Gold Coast, Australia, ISSN 0749.0208
Long-term beach profile datasets provide coastal communities with information critical to understanding temporal and spatial variability in coastal systems. Given the economic growth in coastal systems, decades of profile data from numerous projects are often needed to conduct accurate analyses for engineering projects, habitat assessment, and scientific study. To make datasets easily accessible, we have developed an SDSFIE compliant relational geodatabase and online beach profile management and analysis system (PMAS) toolset to store, retrieve, view, and analyse beach profile datasets as part of our implementation of the eCoastal and ArcMarine datamodels. Using a combination of HTML, PHP, Java, and Visual Basic with MySQL, MSSQL, ArcGIS™, ArcIMS™ and ArcSDE™, tools are available for logging into the system; loading, viewing, analysing, and managing beach profile data; creating bench marks; and exporting the data (including comma-delimited, RMAP, and ESRI™ Shapefile or Geodatabase format). The system is designed to accommodate additional input and export data formats. Profile analyses currently include cross-sectional area (converted to volume across 1 unit of beach) seaward of a pre-determined or user-defined distance down line, above a certain contour, and/or below a specified contour, and include both beach profile plots and graphical plots of volume and contour through time. Offshore bars are handled automatically or by selecting an offshore intersect. Reports can be saved for later viewing. With contributions from USGS--SC Sea Grant Consortium coastal erosion program, SC-OCRM, and the USACE Charleston District, we have accumulated over nine-thousand wading-depth and long beach profiles collected since 1987 for South Carolina, USA (http://gis.coastal.edu/ or http://www.beachprofiles.com/).
Tejada, M., Malvarez, G.C. and Navas, F., 2007. A New Environmental Indicator for Coastal Artificialisation and Resilience Mapping. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 67 – 71. Gold Coast, Australia, ISSN 0749.0208
Scientists and managers have developed and improved coastal protection and sustainable development measures. However, analysis and diagnostic methods are less than satisfactory when coping with the true complexity of socio economic drivers in coastal areas. Mapping of land use and its temporal variability in the coastal lands enables a first order approximation to the analysis of artificialisation although it shows a snap shot of the situation. An indicator which compares the evolution of land uses over a significant time span in the evolution of a developed coast as well as its spatial behaviour is introduced in this paper. The method, applied on the highly developed coastlines of Torremolinos in Costa del Sol, southern Spain, involves (i) mapping of a series of photo interpreted land use coverage stretching over 40 years; (ii) the implementation of a new algorithm that identifies land use change and calculates distance of change in relation to shoreline across a 1 km. buffer fringe; and (iii) transposing land use variability by qualifying via the concept of resilience onto the mapped shoreline to enable cartographic output of the analysis.
Results of the implementation of the method on the selected pilot site and timeframe illustrate a high capability to interpret resilience (beyond sole scientist's perception). The process of artificialisation is quantified and represented on a map which helps locating areas of potential high and low resilience (as in capacity to recover) given the trends. This is illustrated by mapped results and a final resilience map that could be of use for future decision making in the context of coastal management of developed coasts.
Alves, F. L., Silva, C. P. and Pinto, P., 2007. The Assessment of Coastal Zone Development at a Regional Level – the case study of the Portuguese Central Area. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 72 – 76. Gold Coast, Australia, ISSN 0749.0208
The Portuguese mainland coast is entirely covered by Coastal Zone Management Plans (CZMP). Those plans show that there are great opportunities and strategic values at the Portuguese Coast from the socio-economic and environmental point of view. Therefore, the coast is also under a huge pressure, as result of a fast growing development intensified since the mid 50's of the 20th century.
This situation can be exemplified at the Central Portugal Coastal Zone, classified as a highly vulnerable area to coastal erosion, with a strong demographic pressure and human activities associated. This trend does not show any marks of slowing down, increasing the level of vulnerability for coastal population and settlements. As also the risk, reinforced by sea level rise due to climate change. The methodology used for the assessment of this development was based on a large set of thematic indicators: environment, socioeconomic and governance. The results identify problematic areas and the priority actions to be taken by the central administration towards the application of Sustainable Development principles.
This paper also points out the importance of the establishment of a National Coastal Observatory, for assessing and monitoring the development of the Portuguese Coastal Zone at a regional level. In addition is also enhanced the importance of these regional structures to the national Decision Support System (DSS).
Dolique, F., Jeanson, M. and Besson, J., 2007. A monitoring network for assessing the impact of extreme marine meteorological events on tropical beaches. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 77 – 81. Gold Coast, Australia, ISSN 0749.0208
Since 2003, a monitoring network of the dynamics of sandy beaches has been in operation in three tropical sites: Martinique (French West Indies), Tahiti and Moorea (French Polynesia) and Mayotte (Mozambique Channel). The objective of this network is to measure the impact of extreme weather-related marine events (storms, cyclones, strong swells, surges...) on beaches with varied structural settings and sedimentary environments. The methodology consists in the installation of observatories on the dynamics of sandy beaches in different morphological and sedimentary contexts. A “state zero” is established from a combination of satellite imagery, low altitude digital imagery and topographic and hydrodynamic measurements. These measurements are reiterated after an extreme event in order to apprehend the importance of morphological change, impact dampening and recovery. The monitoring is then continued over regular intervals with the aim of determining rates of morphological and sediment budget recovery until equilibrium is restored.
This experimental network design will subsequently be extended to other tropical beaches located on the propagation paths of cyclones.
Yasumoto, Y., Uda, T., Matsubara, Y. and Hirano, G., 2007. Beach erosion along Tottori coast and comprehensive sediment management. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 82 – 87. Gold Coast, Australia, ISSN 0749.0208
Beach erosion of the Tottori coast, Japan, was investigated based on the long-term shoreline changes using aerial photographs and bathymetric survey data. Excess accretion in the wave-shelter zone and severe erosion simultaneously occurred as a couple. A predictive model for shoreline changes considering grain size changes was applied to the coast. To reduce/control erosion of Tottori coastal dunes, the following regional policies have been developed; 1. No more offshore sand dumping, 2. No more offshore sand dredging for land reclamation, 3. Sand dredged from accretion zones must be dumped near-shore where depth is smaller than the depth of closure. Also, it was found that local control measures (e.g., structures) are not effective in reducing sand lost from the Tottori dunes.
Callaghan, D. P., Nielsen, P. and Ranasinghe, R., 2007. Estimating extreme beach erosion frequency from a Monte Carlo simulation of wave climate. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 88 – 92. Gold Coast, Australia, ISSN 0749.0208
Recent developments in extreme value modelling has been used to develop a robust and defendable framework for determining coastal erosion hazard on sandy coastlines. This framework reproduced well (within factor 2 up to the 15 year return level) the extreme beach erosion volumes obtained from field measurements at Narrabeen Beach, Australia. This encouraging finding was achieved using a simple beach erosion and accretion model following the equilibrium profile approach with exponential response after KRIEBEL and DEAN (1993). The method includes allowances for joint probability between all basic erosion parameters including; wave height, period and direction, event duration, tidal anomalies and event occurrence intensities. This framework includes event grouping where significantly more erosion can occur. This is handled by simulating the event history and estimating the beach accretion between events.
D.L. Revell, J.J. Marra, and G.B. Griggs 2007. Sandshed Management. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 93 – 98. Gold Coast, Australia, ISSN 0749.0208
Sandshed management links the well-known concept of watershed management with a regional approach to shoreline management that emphasises the maintenance of a sandy beach to provide hazard protection while preserving recreational, ecological and economic benefits. Sandshed management planning is described as a three step – inventory, analysis, and implementation process. The inventory is comprised of a collection of cultural characteristics such as economic, social and environmental assets, jurisdictional boundaries, shoreline uses and activities as well as the physical processes that operate across a range of time and space scales to affect shoreline stability. Delineation of the sediment budget, the balance between sources and sinks within a sandshed, is a key part of the physical inventory. The analysis step includes both an assessment of the cause and extent of inundation and erosion-related hazards, and an evaluation of a range of potentially applicable management measures. Describing the positive and negative impacts associated with potential management measures in a way that accounts for community values and priorities is a key part of the analysis process. Once a preferred alternative or suite of alternatives has been identified, a range of implementation mechanisms need to be established. These may include memoranda of understanding or letters of agreement between agencies and organisations or more formal measures such as the adoption of planning and/or zoning code provisions. The comprehensive, regional approach embodied in the concept of sandshed management has significant implications to the management of our coasts worldwide.
Farmer, B. and Short, A.D., 2007. Australian surfing reserves: rationale and process for recognising iconic surfing locations, SI 50, (Proceedings of the 9th International Coastal Symposium, 99 – 103, Gold Coast, Australia, ISSN 0749.0208
Australia has a wide range of world-renowned surfing sites. They are spread around the 13 200 km long southern half of the continent from Fraser Island in the east around to North West Cape in the west. This southern coast has 5700 beaches, which prior to 2006 only one of which had been afforded surfing reserve status, namely Bells Beach in 1973. There are however more than 20 well-recognised iconic surfing sites that also deserve recognition and dedication as a surfing reserve. This paper will address the renewed and to date, very successful process of ensuring the remaining top Australian surfing sites are officially recognised and declared surfing reserves. The declaration of a surfing reserve achieves three purposes: it formally recognises the site as an area of surfing significance and quality surf; it recognises the long and close links between surfers and the surf and it will assist in the long term preservation of the site for future surfers. This paper addresses the following: the nature of and rationale for surfing reserves; the selection process; the reserves dedicated to date and those listed for possible future dedication.
Knight, J. and Burningham, H., 2007. Coastal morphodynamics and prehistoric human occupation, County Donegal, NW Ireland. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 104 – 108. Gold Coast, Australia, ISSN 0749.0208
The complex interrelationship between coastal morphodynamics and prehistoric human occupation of coastal landscapes is explored from two important sand dune sites in County Donegal, NW Ireland. These sites, which are Atlantic-facing and which are morphologically responsive to decadal to millennial-scale climate changes, have a long record of human occupation as evidenced by the presence of Neolithic to Medieval artifacts, occupation horizons, soils and shell middens. Relationships between sand dune development and human activity are identified at these sites through description of archaeological horizons exposed in section, and surrounding dune sands. Results show the role of human-induced land surface changes that impact on succeeding dune sedimentation patterns. Feedback between the physical processes of dune accumulation and human activity within sand dune systems – not previously discussed in the literature – are key to understanding human-landscape relationships over decadal to millennial time scales and can be usefully applied to such relationships in other sensitive geomorphic settings.
Smith, T. F., Brooke, C., Preston, B., Gorddard, R., Abbs, D., Mcinnes, K. Withycombe, G. and Morrison, C., 2007. Managing for Climate Variability in the Sydney Region. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 109 – 113. Gold Coast, Australia, ISSN 0749.0208
Coastal research and management often has an issue-specific focus, with little attention paid to the interdependencies between those issues. Climate variability is one such issue that is impacted by, and impacts on, several other areas (e.g. coastal processes, infrastructure, health and regional economies). These interdependencies create challenges for local governments to scale-up so as to tackle these issues at a regional scale. Critical to this process of scaling-up is the adaptive capacity of local governments. A method to assist local governments deal with climate variability in the Sydney region is being developed by CSIRO and the Sydney Coastal Councils Group through the Australian Greenhouse Office National Climate Change Adaptation Program. The method consists of: (i) creating vulnerability mapping templates; (ii) working with local governments to determine collective and local vulnerabilities; (iii) analysis of local government priorities and capacity for adaptation; and (iv) assessment of transferability of the method to other regions.
Palginõmm, V., Ratas, U. and Kont, A., 2007. Increasing human impact on coastal areas of Estonia in recent decades. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 114 – 119. Gold Coast, Australia, ISSN 0749.0208
The costal zone is a crucial environment that is experiencing pressure from a wide variety of different agents and interests. One key problem in recent decades has been a rapid increase in the number of holiday houses built as close as possible to the seashore. As in the Nordic countries, the historical roots of land use on the Estonian coast go back to ancient society. The original coastal settlements were usually concentrated around naturally suitable harbours. People used the pastures and fishing huts during the summer season. This was an essential part of making an adequate living and was not associated with recreation. The first expansion of villa settlements close to towns took place in the 19th century at Estonia's famous summer resort, Pärnu. Unlike in the Nordic countries where major coastal settlement expansion took place after WWII, almost the entire coast of Estonia was proclaimed the Soviet border zone where people were not allowed to live. Nearly 3,800 km of shoreline, except the coastal cities and a few summer resorts were under the control of Soviet military forces. Revival of coastal land use and a rapid increase of coastal settlements have occurred over the last 10-15 years. This paper focusses on population changes on the coast of Saaremaa Island associated with increasing pressure and conflicts of interests. We also examine the advantages and disadvantages of existing legislation regulating land use within the Estonian coastal zone. The work is based on GIS techniques.
McFadden, L. and Green, C., 2007. Defining ‘vulnerability’: conflicts, complexities and implications for Coastal Zone Management. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 120 – 124. Gold Coast, Australia, ISSN 0749.0208
This paper argues that important insights for improved coastal management can be gained by examining complexities involved in defining vulnerable coastal environments and communities. ‘Vulnerability’ has emerged as an important concept in understanding and managing coastal environments: yet a significant degree of conflict has been associated to the use of the term. Definitions of ‘vulnerability’ have been contested in terms of the nature of, and the driving forcing underpinning, vulnerable environments. However, conflicts also surround the very concept itself, in particular efforts towards identifying a ‘true’ definition of the term. The paper suggests that such conflicts highlight the fact that the definition of a coast as vulnerable is not a neutral act. Conceptualising ‘vulnerability’ must be considered not only as a technical matter but in terms of social relationships between those involved in coastal management. This necessitates that scientists, policy-makers and other stakeholders involved in managing the coast, consider vulnerability analysis a comprehensive systems assessment of coastal environments and communities. The learning process, through which such a comprehensive assessment is achieved, is critical to creating new and more useful insights into the behaviour of the total coastal system. Simplifying vulnerability for coastal management has occurred at the cost of the essential complexity of coastal systems. If vulnerability analysis is to make a significant contribution to sustainable management of 21st Century coasts, we must be certain to retain this complexity in our approaches to understanding the term.
Calado, H., Quintela, A. and Porteiro, J., 2007.Integrated Coastal Zone Management Strategies on Small Islands. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 125 - 129. Gold Coast, Australia, ISSN 0749.0208
In 2002 the European Parliament and Council indicated the general principles and options for an Integrated Coastal Management Strategy for Europe (Recommendation 2002/413/CE). In 2005, due to the lack of contributions by each State member, the European Council invited all the EU countries to establish the ground rules for that strategy by presenting the national efforts on the field and by establishing their one Integrated Coastal Zone Management Strategies (ICZMS). The document had a deadline of February 2006. The National Strategies then presented are now being evaluated.
What is proposed in this paper is not a quantitative structured analysis but a comprehensive one applied to small islands. For sure we know that small islands problems and needs are different from the mainland countries. So, is there a true need for ICZM guidelines with a scale and operational contexts often applied to larger territories? Are there specific features to small island ICZM Strategies? Based on the analysis of the Macaronesian Archipelagos of Azores, Madeira and Canary Islands the discussion is presented and some conclusions are drawn.
Symonds, A. and Collins, M., 2007. The development of artificially created breaches in an embankment as part of a managed realignment, Freiston Shore, UK. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 130 – 134. Gold Coast, Australia, ISSN 0749.0208
Recently there has been an increase in managed realignment, despite the lack of a complete understanding of the possible impacts it may cause. Therefore, it is essential to highlight impacts from past schemes and use this experience to help select and design future sites. The channels within the breaches created for a managed realignment at Freiston Shore were subject to enhanced erosion. Hydrodynamic data were recorded within a channel in a breach and inside the managed realignment site. In addition, RTK-GPS and aerial photography were used to calculate the change in plan view area of the channels in the breaches. In the first 1 to 2 months following the breaching of the embankment the channels eroded rapidly, increasing their plan view areas by 5 to 10 times. Initially, after becoming inundated during a high water, the site continued draining until the subsequent high water; however, owing to the erosion of the channels in the breaches, the flooding and draining of the site became more rapid. After 14 months, the tidal curve inside the site was similar to that over the saltmarsh. The erosion of the channels in the breaches was a result of the saltmarsh being at a higher elevation than the managed realignment site. The findings from this study demonstrate the importance of the site elevation relative to the adjacent intertidal zone.
Silva, C. P., Alves, F. and Rocha, R.,, 2007. The Management of Beach Carrying Capacity: The case of northern Portugal. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 135 – 139. Gold Coast, Australia, ISSN 0749.0208
The rapid growth of coastal tourism that has been seen in the last 40 years is frequently described as one of the major reasons for the development of these areas and also as responsible for many current coastal problems. The beaches perform, in this context, a fundamental role where the issues related to planning and management are increasingly more important when it comes to an implementation of a sustainable development philosophy. In these circumstances, concepts such as carrying capacity need to be used in a careful way.
In Portugal, where coastal tourism plays a major part for the national economy, the management of beaches is crucial for maintaining their quality and therefore continuing to attract tourists. Since the 1990s, with the application of Coastal Zone Management Plans to the whole Portuguese coast, beach plans are now required. In those plans various parameters are considered, from the type and location of equipment and parking lots, to the definition of beach carrying capacity.
This paper explores the results of the implementation of these plans to the beaches of northern Portugal. This part of the coast is very dynamic with high erosion rates. Some of the interventions from the Plans changed part of the characteristics of the beaches making it necessary, in some cases, to re-calculate the carrying capacities that were initially proposed, bringing new challenges to their management. This paper aims to stress the validity of the carrying capacity concept as applied to beaches, taking into account the need to use the concept in a flexible and dynamic way.
Uda, T., Hoshigami, S., Seino, S., and Ozawa, H., 2007. Increase in disaster potential caused by excess use of land in coastal zone. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 140 – 146. Gold Coast, Australia, ISSN 0749.0208
Relationship between long-term change in land use and increase in disaster potential of a coast was investigated through the comparison of past photographs, taking the Tojo and Maebara coasts as the example. In 1950s, there was a wide sandy beach at the Tojo coast but the coastal forest was artificially expanded very close to the shoreline as well as the construction of the Kamogawa Sea World, resulting in narrowing the natural sand dune area. On the Maebara coast, located southwest of the Tojo coast, a seawall was constructed very close to the shoreline, resulting in the expansion of the residential area. Then, detached breakwaters were built to protect this area and the fishing port breakwaters were also built, resulting in significant shoreline recession on the Tojo coast. These case studies clearly show that these coasts became vulnerable against coastal disaster due to the man-made activities. This is of concern in coping with expecting sea level rise.
Patterson, D.C. Sand Transport and Shoreline Evolution, Northern Gold Coast, Australia. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 147 – 151. Gold Coast, Australia, ISSN 0749.0208
A net onshore supply of sand appears to exist along the northern Gold Coast beaches, resulting from an offshore profile shape at depths between 12-20 m that is flatter than that expected for dynamic equilibrium, a residual feature from past northward migration of the Nerang River mouth. Analysis of survey data over the period 1966 to 2002 shows progressive depletion of the lower profile (depths > 7.5 m out to 20 m) due to onshore supply and a substantial gain in the sand volume in the upper part of the nearshore and beach profile (depths < 7.5 m). Additionally, this section of shoreline has been nourished with about 3.7 million cubic metres of sand over the period 1974 to 2000, including an estimated 0.75 million placed from building sites.
However, despite the beach nourishment undertaken, the total volume of sand in the profile along the 10km section of beach analysed is only about 0.3 million cubic metres greater in 2002 than in 1966, indicating a corresponding local increase in the alongshore loss of sand. The reported historical changes and analysis of the longshore sand transport regime suggests that the evolution of the alignment of shoreline of the Spit has been commensurate with such a local increase of about 80,000 m3/yr in the longshore transport rate north of Narrowneck, increasing to about 90,000 to 100,000 m3/yr due to more recent beach nourishment works. This was matched initially by equivalent losses into the Broadwater and, following Seaway development, by a ‘leakage’ of sand past the bypass system and growth of the river entrance bar.
Beach management considerations need to account for these processes. The assessment undertaken supports the strategy of back-passing sand from the Seaway to the beaches to overcome future depletion of the onshore supply and associated recession of the shoreline alignment.
Vespremeanu-Stroe, A.,Constantinescu, Ş., Tătui, F. and Giosan, L., 2007. Multi-decadal Evolution and North Atlantic Oscillation Influences on the Dynamics of the Danube Delta Shoreline. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 157 – 162. Gold Coast, Australia, ISSN 0749.0208
A comprehensive analysis of data collected over the last five decades on the Danube delta coast (topographic maps, satellite imagery, GPS surveys and beach profiles) revealed two different shoreline dynamics patterns: (1) high mobility during 1961-1979 interval with high retreating and; (2) advancing rates and low mobility afterwards (1979-2006). The divergence zones in the longshore sediment transport system experienced the highest rates of retreat (∼20 m/yr and ∼10 m/yr in the first/second time interval), whereas the shoreline advanced fastest along the coast of active lobes (i.e., Chilia and Sf. Gheorghe lobes). During the second interval the decrease of shoreline changes rates was similar for the erosive beaches (with 55-66%) and non-uniform for the accretionary coasts (20-61% for open beaches and 80% for the sheltered secondary deltas). Wind data analysis reveals a good connection between multi-decadal winter storm frequency along the Danube delta coast and negative NAO phases (r = -0.76). The results of the present study clearly show that shoreline changes at decadal time scales are also ultimately driven by the NAO which controls the storminess on the Danube delta coast.
Pérez-Arlucea, M., Álvarez-Iglesias, P. and Rubio, B., 2007. Holocene Evolution of Estuarine and Tidal-flat Sediments in San Simón Bay, Galicia, NW Spain. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 163 – 167. Gold Coast, Australia, ISSN 0749.0208
San Simón Bay is located in the inner part of a Galician ría. Three rivers enter the bay from the north, forming shallow estuaries. Tidal range is mesotidal (2 to 4 m with an average of 2.2 m). High productivity ecosystems develop due to upwelling processes, which are common in all the Galician rías. The aim of this paper is the study of fluvial and tidal interactions giving rise to distinctive facies architecture in the context of the Holocene transgression. Vertical facies distributions and architecture show alternating units of well-defined estuarine channel-fill and tidal flat deposits. Two millennial-scale, fining-upward sequences show an initial incision evolving into channel fill and tidal flat deposits. An age model has been developed based on AMS 14C and 210Pb and 137Cs dating to put them in the context of the established climatic and sea-level changes. Older dated deposits give an age of 5.9 ky cal BP close to the last Holocene eustatic maximum. Millennial-scale sedimentation rates are about 1.0-1.6 mm y-1, whereas the last few decades show values 5 to 6 times higher. Differences in sedimentation rates are attributed to increasing human influence over recent decades. Incision stages at the base of the sequences (5.1 to 4.8 cal. ka BP and 2.3 to 2.0 cal. ka BP) followed by aggradation are interpreted in terms of high frequency climatic oscillations and related changes in sediment supply and river activity (incision taking place with a decrease in sediment supply). Meter-scale sequences are developed in channel-fill units, indicating superimposed minor, centennial-scale, climatic instabilities giving way to changes in channel activity.
Houghton, A., Whitehouse, R. Calkoen, C. and Wouters, F., 2007. The application of satellite derived bathymetric data to the coastal zone management market. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 168 – 172. Gold Coast, Australia, ISSN 0749.0208
The uptake of novel coastal management tools is often restricted by a lack of interaction between service providers who develop the techniques and Market Player organisations providing services to end users. HR Wallingford (UK), ARGOSS (NL) and Geoserve (NL) have undertaken a collaborative study to determine how an Earth Observation based bathymetric charting technique could be integrated into existing coastal engineering and management services, thereby providing added value to end users. During the initial phase of the study a number of trial cases were carried out to identify sectors of the Coastal Zone Management market where the Special purpose Large Area Bathymetry (SLAB) service could be used in favour of traditional bathymetric charts or surveys. The performance of the SLAB service was evaluated against a set of predetermined demand criteria and although a range of potential applications were identified, there were also a number of blockages that would prevent commercial uptake of the service. To combat these blockages, a Value Adding Market Player Integrated Information Service (VAMPIIS) supply chain has been defined comprising Geoserve and ARGOSS as service providers and HR Wallingford as Market Players. The framework of the supply chain will facilitate delivery of a range of bathymetric products based on both Earth Observation and traditional techniques combined with data analysis and numerical modelling. Typical applications include long term assessment of seabed and sandbank mobility for the marine construction industry, coastal impact studies, navigation risk assessments and wave/current transformation studies.
Longdill, P.C., Healy, T.R., Black, K.P., and Mead, S.T.,, 2007. Integrated sediment habitat mapping for aquaculture zoning. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 173 – 179. Gold Coast, Australia, ISSN 0749-0208
The benthic environment of the nearshore to inner-shelf within the Bay of Plenty, New Zealand, was sampled and surveyed to classify sedimentary environments and benthic habitats. Reef and soft sediment habitats are characterised, delineated, and the potential impacts of suspended bivalve aquaculture considered. An integrated approach is used, utilizing a GIS database to combine remote sensing techniques such as multi-beam sonar and underwater video capture, with physical sampling of the soft sediments using sediment grab samples and in-faunal organism identification. Soft sediment habitats, comprised of fine silty and muddy sediments with low organic contents, are determined to be the most suitable benthic environments above which to site suspended bivalve aquaculture. Transfer of knowledge from the study is maximised through the creation of a CD-ROM complete with hyper-linked analysed data and video files, thematic data layers and a freely available, query-able GIS viewer package.
Kutser, T., Metsamaa, L., Vahtmäe, E. and Aps, R., 2007. Operative monitoring of the extent of dredging plumes in coastal ecosystems using MODIS satellite imagery. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 180 – 184. Gold Coast, Australia, ISSN 0749.0208
MODIS band 1 imagery is the only satellite data with acceptable spatial resolution (250 m) and sufficient revisit times (up to 4 times a day) potentially available for monitoring dredging plumes. The aim of this study was to determine the potential use of MODIS band 1 imagery in an optically sophisticated environment such as the Baltic Sea coastal waters for monitoring of total suspended matter in natural conditions and near dredging activities. It was found that there is linear correlation between MODIS band 1 (620-670 nm) reflectance and the total suspended matter concentration measured from water samples. The regression algorithm was used to produce suspended matter concentration maps and monitor dredging activities. The results showed that in such shallow water environments as the Estonian Coast resuspension caused by strong wind may increase the suspended matter concentration to the levels similar to those occurring during dredging. Areas affected by wind resuspension are much larger than the areas affected by dredging plumes. Therefore, the natural variability of suspended matter concentration has to be taken into account when estimating environmental impact of dredging activities on local ecosystems.
Vahtmäe, E., Kutser, T., 2007. Mapping bottom type and water depth in shallow coastal waters with satellite remote sensing. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 185 – 189. Gold Coast, Australia, ISSN 0749.0208
Species composition of benthic macroalgal cover and the changes therein are indicators of the trophic state of aquatic ecosystems. On the other hand, mapping and knowledge of water depth in shallow water areas, not accessible by hydrographical ships, is important for several reasons. This study assessed the suitability of high spatial resolution multispectral and medium spatial resolution hyperspectral data for mapping water depth and benthic macroalgal cover in shallow coastal waters of the Baltic Sea. Results of this study indicate that use of multispectral satellite data with high spatial resolution is preferable to using hyperspectral medium resolution data in mapping benthic macroalgal cover in areas where the spatial heterogeneity is very high. In case of a single image and availability of in situ data, multispectral high spatial resolution (2.4 m) satellite QuickBird can provide more detailed information about benthic cover than was assumed based on the shape of reflectance spectra of different bottom types and spectral resolution of the sensor. Depth maps of shallow (less than 3 metres) waters proved to be reliable except in turbid water areas with no bottom visibility.
Ozden, U.A. and Topal, T., 2007. Quality assessment of the armourstones for some Black Sea rubble mound breakwaters, Turkey. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 190 – 194. Gold Coast, Australia, ISSN 0749.0208
The Black Sea coastline is a hazardous region in Turkey, especially in winter, due to the dominant wave action. Therefore, rubble mound breakwaters used as ship shelters are vital structures, especially for the fishermen. Construction of the breakwater requires good quality, durable armourstones. Due to the nature of the rubble mound breakwaters, armourstones of various sizes and types are used in the construction of these structures. The deterioration of these armourstones with time may result in the failure of the breakwater. In this study, the quality and durability of the armourstones (mainly limestone, andesite and sandstone) used or to be used in three rubble mound breakwaters are investigated through field and laboratory studies. Among the studied armourstones, the three limestones are found to be good in long-term quality and durability. However, the sandstone displays poor performance, whereas the andesite is marginal. Both static durability index and CIRIA/CUR evaluation successfully predict the long-term durability of the armourstones.
Al-Banaa, K., and Liu, P., 2007. Numerical Study on the Hydraulic Performance of Submerged Porous Breakwater under Solitary Wave Attack. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 201 – 205. Gold Coast, Australia, ISSN 0749.0208
The hydraulic performance of horizontally slotted submerged porous breakwater under solitary wave attack is investigated with the use of a well-validated two-dimensional model based on solving the Reynolds-Averaged Navier-Stokes (RANS) equations. A set of numerical experiments with various porosity, P, values are performed to evaluate the hydraulic performance of submerged breakwater in terms of the wave reflection, transmission, and dissipation coefficients. A comparison between the different methods for calculating the coefficients is also presented. The effect of porosity, P, values on the wave characteristics for an engineering application are calculated and discussed. For the sets of numerical experiments, only the weakly nonlinear solitary waves H/h=0.10 are considered. The solitary waves can be considered good representations of tsunami, storm surge and nonlinear shallow water waves.
Tsujimoto, G., Kakinoki, T., Hamaura Y., Shigematsu T. and Uno K., 2007. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 206 – 210. Gold Coast, Australia, ISSN 0749.0208
Sediment transport inside and outside a permeable submerged breakwater was examined in a laboratory experiment and a numerical calculation. The Macroscopic turbulence model, which has been applied for the thermal conduction in porous media, was used for the theoretical approach. A two- equation model for inside regions and 0- equation model was used for the outside region. Suspended sediment could be transported toward the onshore side due to two effects; vortex over sand ripples and the slope of a permeable breakwater. The amount of sediment deposited in the breakwater decreased gradually from the offshore to the onshore side during the experiment, while on the other hand decreasing rapidly in the numerical calculation. The surface profile over the submerged breakwaters could be reproduced excellently.
Salmon, S. A., Bryan, K. R and Coco, G., 2007. The use of video systems to measure run-up on beaches. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 211 – 215. Gold Coast, Australia, ISSN 0749.0208
Wave run-up on beaches is a major driver of dune erosion and flooding during storm events on beaches. Using video imagery time-series collected over 2 field experiments, a new technique for measuring extreme run-up has been developed for use on natural beaches over a wide range of spatial and temporal scales. Waterline variations over 2 storm events were measured by collecting pixels from the video images along a cross-shore transect (timestack). The maximum swash excursions were digitized from the time-stacks, and rectified to provide a runup time series with a duration of 20 minutes. In order to rectify run-up observations an estimate of the run-up elevation is needed. This was supplied using video measurements of the beachface morphology (e.g. beach slope). This was estimated by measuring the variation of the waterline over a tidal cycle from time-averaged video images taken during a storm event. This technique was tested against run-up measurements calculated using a standard empirical run-up equation and provides reliable estimates of run-up from video observations.
J. Vidinha, F. Rocha, C. and rade, C. Gomes and C. Freitas, 2007. Clay minerals – a mineralogical tool to distinguish beach from dune sediments. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 216 – 220. Gold Coast, Australia, ISSN 0749.0208
The usually textural parameters of sand sediments employed in order to distinguish present-day beach and dune deposits has been a matter of discussion in coastal studies. The results of these studies suggest that it may not be efficient to discriminate when the referred deposits exhibit well-sorted coastal sands, as was observed in limited coastal sections of the Portuguese coast. An innovative mineralogical approach based upon the study of the fine-grained fraction trapped in coastal sands, supported on univariate and multivariate statistical analysis, has been previously applied to a test area in the western Portuguese coast. This paper presents results from the mineralogical study of the clay fraction entrapped in coastal sand samples from the Espinho - Mondego Cape coastal sector in the north of the country following the same methodology. In 45 cross-shore profiles, spaced 2000 m, 130 samples were collected. Three sand samples were taken from each profile, at the beachface, berm and foredune. The mineralogical composition of the clay fraction was analyzed by XRD. Distinct clay mineral associations were identified expressing the relative importance of terrigenous contributions to the beach and dune sediments, stressed by a number of content differences between beachface (illite>> kaolinite, random mixed layers>chlorite), berm (illite>> random mixed layers, kaolinite>chlorite) and foredune deposits (illite>> kaolinite>random mixed layers, chlorite) with significant statistical results. The environmental contrasts exhibited along this coastal sector suggest that this ability might be related with functional factors and not just a product of local constraints.
Michallet, H., Grasso, F. and Barthélemy, E., 2007. Long waves and beach profiles evolutions. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 221 – 225. Gold Coast, Australia, ISSN 0749.0208
Experiments were carried out in a flume 36 m long and 55 cm wide equipped with a piston wave generator. The sloping bottom consists of a loose material of low density (1190 kg m-3) with a median diameter d50=0.6 mm in order that Shields and Rouse numbers are of the same magnitude as those of natural environments. Time and length scales ratios are roughly 1/3 and 1/10. Irregular waves were generated according to a JONSWAP spectrum. The waves were measured along the flume and bottom profiles were recorded in between repeated wave sequences. A wave climate (characterized by its peak frequency and root mean square wave height) was run for several tens of hours, so as to reach bottom equilibrium conditions. Hrms and infragravity mode amplitudes along the flume were obtained for transient and equilibrium bottom profiles. The long waves node positions and structure conform to model solutions of the linearized Saint-Venant equations. On the equilibrium bottom profile they are more energetic and the correlation between infragravity waves and the incident short wave envelope clearly indicate that they conform on both breaking point and bound long wave release mechanisms.
Buynevich, I., Bitinas, A. and Pupienis, D., 2007. Reactivation of coastal dunes documented by subsurface imaging of the Great Dune Ridge, Lithuania. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 226 – 230. Gold Coast, Australia, ISSN 0749.0208
Large coastal and inland dunefields often consist of multiple generations defined by periods of stability and reactivation. Where earlier phases of aeolian activity are masked by subsequent deposition, continuous high-resolution geophysical images help to reconstruct the history of landscape change. Ground-penetrating radar (GPR) profiles from relict Holocene dunes on the northern Curonian Spit, Lithuania reveal distinct contacts between older deposits (barrier-spit facies, older aeolian strata, paleosols) and overlying dune sands. Early stages of dune migration began prior to 6,000 years B.P. followed by several periods of stabilisation and subsequent reactivation. Parabolic and transverse dunes, some attaining heights of 40-60 m, have migrated to the east in response to westerly winds from the Baltic Sea. In several places, similar to a number of sites in Northern Europe, the upper sections of large dunes have been deflated leaving near-horizontal exposures where subsurface imaging extends the continuity of key stratigraphic horizons. Within dune sequences, oblique lateral accretion surfaces indicate the direction of earlier migration phases and exhibit distinct meso-scale geometries. In GPR images and shallow trenches, buried slipfaces have dip angles varying from 10-15°to 31-34°, the latter being similar to the angle of repose maintained by modern unvegetated dunes. A series of cores taken through sequences of stacked buried slipfaces show little visible variation in sediment properties with depth, suggesting that minor changes in texture, mineralogy and grain packing may be responsible for individual reflections in geophysical records. Occasionally, laterally extensive horizons enriched in heavy minerals produce prominent subsurface reflections and are indicative of periods of increased wind activity.
Freitas, M. C., Andrade, C., Ferreira, T., Cruces, A. and Araújo, M. F. 2007. Wet dune slacks, sea-level and coastal evolution in the south-western Portuguese façade. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 231 – 236. Gold Coast, Australia, ISSN 0749.0208
Dune slacks are peculiar features of the Portuguese coast with evident scenic, ecological and geological value and yet the existing knowledge on their origin, evolution and dynamics is poor. A number of wet dune slacks in the South-western Iberian coast (Poços do Barbaroxa and Lagoa da Sancha) have been studied using sedimentological and geochemical proxies which, coupled with radiocarbon dating, were allowed to establish major steps of coastal evolution, environmental changes and relations with sea-level throughout the Holocene. The Barbaroxas basins are blind freshwater lakes while Lagoa da Sancha is, at present, connected with a small rivulet. The size and shape of interdune depressions reflect a palaeotopography inherited from a ridge and swale complex that accreted seaward in the Pleistocene. The interdune infill consists essentially of peat resting upon dune sand; accumulation of organic material initiated diachronically in the different slacks, between circa 7700 and 4160 cal BP, in dependence of piezometric level. At Barbaroxas this organic facies persisted until present, whereas at Lagoa da Sancha it was replaced circa 670 cal BP by minerogenic sedimentation. At the present state of knowledge it is unclear if this change represents a capture of the tributary stream, either natural or man-induced, or a massive release of top soil due to contrasting land-use in the watershed. At present, the peat surface in Barbaroxas stands 1 to 2 m above mean sea level and is fairly horizontal. Assuming similar relation in the past, then sea level should have been positioned at -3/-4 m and -0.5/-1.5 m by 7400 and 4100 cal BP, respectively. These figures are consistent with the most recent sea-level data published for the Portuguese coast.
Udo, K. and Yamawaki, S., 2007. Short-term backshore processes under wave and wind actions. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 237 – 241. Gold Coast, Australia, ISSN 0749.0208
Wave and wind impacts on short-term backshore processes were investigated through field observations of daily bed elevation, sand grain size, and wave, tide, and wind conditions at an open-ocean dissipative beach in Japan from September 2004 to March 2005. Indices of wave and wind impacts were defined by wave run-up level and wind-driven sand transport rate, respectively. The results show that waves have larger effects than winds on backshore sedimentation. Furthermore, both waves and winds cause sand coarsening in the backshore. Run-up waves are the external force with the greatest impact on backshore processes, followed by landward strong winds, and mild winds.
Haines, P.E. and Thom, B.G., 2007. Climate change impacts on entrance processes of intermittently open/closed coastal lagoons in New South Wales, Australia. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 242 – 246. Gold Coast, Australia, ISSN 0749.0208.
Intermittently open/closed coastal lagoons are a relatively unique feature of the south-east Australian coastline, and NSW in particular. Future climate change is expected to modify a number of climate variables that define the physical and chemical structure and ecological behaviour of the NSW coastal lagoons. These climate variables include mean sea level, wave climate and rainfall behaviour (total depth and storm intensity). Entrance morphodynamic processes are particularly vulnerable to climate change. These processes, which describe the opening and closing cycle of these lagoons, are controlled by dominant coastal (wave and sea level) conditions and episodic catchment runoff events. The magnitude of entrance impacts will depend on the particular characteristics and location of individual lagoons. An increase in mean sea level is likely to move the entrance sand berm upward and landward. An increase in south-easterly waves will cause minor rotations in beach planform alignments with expected net erosion from southern ends of beaches and net accretion at northern ends. For lagoon entrances at the southern end of beaches, this will result in a net loss of sand from the entrance and a shortening of the entrance channel. For lagoon entrances at the northern end of beaches, this will result in a net growth of the entrance berm, possibly offsetting the recession resulting from mean sea level rise. Increased typical lagoon water levels behind the berm are also expected. Marine flood tide deltas may accrete vertically and more landward. A decrease in total rainfall depth is likely to retard the cycle of filling and draining, and reducing the frequency of entrance breakout for mostly closed lagoons. For mostly open lagoons, however, an increase in rainfall storm intensity may actually increase scour through the entrance, thus increasing the longevity of ocean connections.
Al-Nassar, W., Neelamani, S.; Al-Banaa, K., Al-Ragum, A., and Ljubic, J., 2007. Wave action on a mild sloped offshore breakwater for protection of a promenade. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 195 – 200. Gold Coast, Australia, ISSN 0749.0208
Physical model study on a 1:25 scale model of an offshore rubble mound breakwater is carried out. The breakwater is to protect an artificially built sandy promenade in Al-Khiran, South of Kuwait in the Arabian Gulf. The wave transmission, reflection, energy dissipation, wave climate on the crest and seaside toe velocities were assessed based on measurements. Random waves of JONSWAP spectrum were used. The sea side slope of the breakwater is 1:4.9 and the lee side slope is 1:2. The physical model tests were carried out for different water levels to cover a wide range of astronomical tide, i.e. Low (LAT), High (HAT), Highest high (HHWL) and water level at the crest of the breakwater (CAT). The results indicate that at CAT condition the transmission coefficients can be on the order of 0.5. The water particle velocity at the seaside toe can reach a design value of about 2.5 m/sec. In general it has noted that normalised value of the significant wave height at the crest of the breakwater can be in the order of 5% to 18% when the incident wave height is increased from 80% to 120% of the design value without considering the CAT level. The range of average reflection coefficient is between 0.22-0.49 and the dissipation coefficients are well above 0.8.
Martins, V., Sequeira, C., Jouanneau, J., Weber, O. and Rocha, F. 2007. Multiproxy study of Ria de Vigo sedimentation during the late Holocene (last 2600 years). Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 258 – 262. Gold Coast, Australia, ISSN 0749.0208
The main aim of this work is to identify changing and characterise the hydrographical regime in the outer sector of the Ria de Vigo during the late Holocene. Sediment samples were collected every centimetre along the core KSGX 24 and used for textural, mineralogical and microfaunal studies (benthic foraminifera). The age model was based on four AMS radiocarbon dating. This sedimentary sequence recording the last ∼3 ka cal BP has a mean grain size varying between 13-26 µm. Fine fractions represent 76-92 % of the bulk sediment. Detrital minerals are the main constituents of the sediments (55-85 %). A total of 202 benthic foraminiferal taxa were identified. A significant amount of tests belongs to exotic species. Two finer sections were identified between 175-75 cm and 35-0 cm. These sections are characterised by the slight increase of detrital minerals and by the decline of carbonated minerals. In the first section the percentage of benthic foraminifera tests supplied from deeper waters and the percentage of the species related with high flux of organic matter, increased. These results suggest the occurrence of a higher oceanic influence in the Ria de Vigo, between ∼2.2-1.2 ka cal BP, probably induced by stronger up-welling events followed by periods of relaxation which were followed by weaker events of downwelling. During the later period between ∼0.5-0 ka cal BP it is possible that stronger up-welling events may have occurred, followed by stronger down-welling events which have probably enhanced the vertical water mixing and caused lower retention of sediments inside the outer sector of the Ria.
Silva, R., Coelho, C., Veloso-Gomes, F. and Taveira-Pinto, F., 2007. Dynamic numerical simulation of medium term coastal evolution of the West Coast of Portugal. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 263 – 267. Gold Coast, Australia, ISSN 0749.0208
Coastal erosion is a common problem within Europe. The main causes of this phenomenon are the generalised sea-level rise, the coastal interventions (defence and harbour structures), which cause serious perturbations in the littoral drift system, the littoral occupation and the river sediment supply reduction caused by dams, dredging and fluvial regularisation. Numerical models are helpful tools in future planning and management of coastal policies, by allowing the projection and analysis of different scenarios of medium term coastal evolution. A numerical coastline evolution model (LTC – Long Term Configuration) is being developed to support coastal zone planning and management in relation to erosion problems. The model simulates the dynamic variability of sandy beaches, where the alongshore sediment transport is controlled by waves, currents, wind, water level, sediments' sources and sinks and sediments' properties. The model also simulates different coastal interventions (groins and breakwaters, longitudinal revetments, artificial nourishments, river sediments supply). It may be applied to extensive coastal areas up to one hundred years time scale. In this paper, LTC will be used in the evaluation of the relative importance of each of the identified causes of coastal erosion at the Northwest Portuguese coast at a medium term horizon. Special attention will be given to the discussion of common coastal defence interventions influence in the littoral drift system and impact in what concerns erosion.
Nguyen, T.V. and Tanaka, H., 2007. Study on the Effect of Morphology Change on Salinity Distribution in the Dinh An Estuary, Lower Mekong River of Vietnam. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 268 – 273. Gold Coast, Australia, ISSN 0749.0208
Salinity intrusion into estuaries, in general, is mostly affected by river discharge and tidal level. Additionally, the change of salinity can also be attributed to other external forces such as wave height and river mouth morphology. However, there has been very few investigations conducted so far, taking into account these kind of aspects. Therefore, the present paper focused on examining the influence of morphology change on salinity concentration. The question that should be paid attention here is: how is the interaction between morphology change and salinity distribution in the Dinh An estuary, Vietnam? In this research, a three-dimensional model has been used to figure out the effects of morphology change on salinity distribution. The drawn conclusion is that the change of salinity is influenced by not only usual parameters as river discharge and tidal level but also another external force such as changes in the estuarine morphology. Furthermore, river mouth width is found to be directly proportional to the averaged salinity concentration. Therefore, the influence of morphology changes on salinity distribution should not be ignored when simulating salinity.
Zheng, J.-H., Zhou J., Liang J.-Y., and Lin, J.-Y., 2007. Hydrodynamic impact assessment of coastal reclamation project in semi-enclosed bay. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 273 – 276. Gold Coast, Australia, ISBN 0749.0208
A two-dimensional numerical model of depth-integrated tidal motion in an orthogonal boundary-fitting curvilinear coordinate was developed and the engineering sedimentation method was used to study the possible impact of the coastal reclamation project of Mazucheng in the Meizhou Bay upon the tidal motion and the sediment siltation intensity in the vicinal sea area. The momentum equations were rewritten in the Lagrangian form and the convection term in the momentum equations was discretised by the Eulerian-Lagrangian method instead of the explicit upwind finite differences. The improved Double-Sweep-Implicit method was used to improve the computational stability and accuracy. Three comparative cases were studied on the basis of the satisfactory model verifications with field data. Computations show that the maximum change of tidal discharge would be smaller than 0.8% of that of the whole Meizhou Bay, indicating that the change of the situation of shoals and channels in the Meizhou Bay would be small. Based on numerical computations an optimum layout of the coastal reclamation project was recommended. For the recommended scheme, comparisons of the velocity field before and after the project revealed that there were a bit of changes in the vicinity of the project; the annual siltation intensity was smaller than 0.08m nearby the project site while that was smaller than 0.003m at the locations of main harbours and the navigation channel.
Mirfenderesk, H. and Tomlinson, R., 2007. Numerical Modelling of Tidal Dynamic and Water Circulation at the Gold Coast Broadwater, Australia. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 277 – 281. Gold Coast, Australia, ISSN 0749.0208
The development of a vertically averaged numerical model of an estuary in the coastal region of the Pacific Ocean on the east coast of Australia is described. The primary objective of the study is to provide a detailed picture of the tidal characteristics in the study area to enable the simulation of the whole water circulation within the water body. A comprehensive data set is collected as part of this study to understand local dynamics and to calibrate and validate the model. Calibration and validation have been achieved through a comparison of computed tidal harmonics against those derived from harmonic analysis of the measured water level variations. Also a comparison was made between the measured discharges across seven cross sections at critical locations in the study area with the discharge obtained through modelling. Calculations show that tides become mixed, mainly semidiurnal in the estuary. The study shows that for lunar constituents (M2 and S2) dissipation mechanisms are dominant and their amplitudes decrease along the estuary. Solar constituents (O1 and K1) experience an increase in amplitude. However, the net result is a reduction of tidal amplitude, indicating the dominance of dissipation mechanisms.
Stamou, A.I., Memos, C. and Spanoudaki, K., 2007. Estimating water renewal time in semi-enclosed coastal areas of complicated geometry using a hydrodynamic model. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 282 – 286. Gold Coast, Australia, ISSN 0749.0208
A methodology is presented to determine water renewal time in semi-enclosed coastal areas with artificial peninsulas or islands of complicated geometry. The methodology is applied in Durrat Alkhobar development in Saudi Arabia. The coastal area consists of the inner and the outer region. The inner region will be dredged and a fingerlike alignment will emerge. A hydrodynamic model was applied to illustrate the future conditions of the Bay regarding water circulation and renewal due to wind and tidal forcing. The model employs the fundamental hydrodynamic equations of continuity and momentum. The inner region of the coastal area was divided into 21 compartments. The communication of the inner region with the outer region is performed via two openings. Calculations showed that average renewal times ranged from 2.3 to 10.1 days for the wind conditions tested; in 12 compartments renewal times were less than 10 days. Furthermore, tide contributed significantly to the renewal of waters. Renewal time decreased with increasing wind velocity; southerly winds were beneficial for water renewal, because they created flow fields with relatively high exchange of flow via the openings.
Joorabchi, A. Zhang, H. and Blumenstein, M, 2007. Application of artificial neural networks in flow discharge prediction for the Fitzroy River, Australia. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 287 – 291. Gold Coast, Australia, ISSN 0749.0208
Prediction of flow discharge, and in particular floods, in rivers is one of the basic and key information in regards to operation and management of the river systems. The Fitzroy River, one of the largest Australian river systems, has a historical recording of heavy floods and there is a concern for the people of that area to have a clear prediction of the stream discharge to avoid damages. In this paper a feed-forward artificial neural network (ANN) model has been used to forecast the daily flow discharge of the Fitzroy River up to four days ahead. The feed-forward neural network uses error Back-propagation learning algorithm. A cross validation method is applied to prevent the over-fitting problem. The network uses multiple inputs including the daily values of discharge. The network output consists of four neurons in respect to the number of forecasted days. A suitable number of inputs for time-series data were selected by trial and error. Two different multi-layer networks were compared to find the optimised network. The results show an accurate forecasting of flow discharge during flood events. However, the neural network overestimates during low discharge with a mean value of 80 (m3/s).
Song, H. and Tao, L., 2007. Homotopy analysis of 1D unsteady, nonlinear groundwater flow through porous media. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 292 – 296. Gold Coast, Australia, ISSN 0749.0208
In this paper, the 1D unsteady, nonlinear groundwater flow through porous media, corresponding to flood in an aquifer between two reservoirs, is studied by mass conservation equation and Forchheimer equation instead of Darcy's law. The coupling nonlinear equations are solved by homotopy analysis method (HAM), an analytic, totally explicit mathematic method. The method uses a mapping technique to transfer the original nonlinear differential equations to a number of linear differential equations, which does not depend on any small parameters and is convenient to control the convergence region. Comparisons between the present HAM solution and the numerical results demonstrate the validity of the HAM solution. It is further revealed the strong nonlinear effects in the HAM solution at the transitional stage.
Hurther, D., Michallet, H. and Gondran, X., 2007. Turbulent measurements in the surf zone suspension. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 297 – 301. Gold Coast, Australia, ISSN 0749.0208
An irregular wave field experiment over a mobile bed is performed in a laboratory channel. The surf zone measurements are collected at the average breaking point after the formation of a stable, non-progressing beach profile (Michallet et al. 2007). The use of a wave averaging technique allows the decomposition of the velocity into mean, orbital and turbulent components for the representation of all ensemble averaged quantities as a function of wave period normalised time. As a result, we present fields of wave velocity, TKE, TKE production, TKE dissipation rate and sediment concentration (only two points in the outer region), below the trough of the waves. Nearbed and outer region processes are both seen in the TKE production and dissipation fields. In particular, the cross-shore velocity lead due to bed friction effects shown in Shin and Cox (2006) is observed in the wave velocity and TKE fields. Although the phase lead zone is seen in the velocity and TKE fields, no corresponding production or dissipation zones could be observed. Furthermore, the zone of high TKE is much more uniformly distributed over the water column than the zones of TKE production and dissipation that are clearly separated between the nearbed and the outer regions. In the outer region, the sediment concentration (orbital component) is seen to be well correlated to the TKE and TKE dissipation zones. Finally, we detect a low frequency correlation at 0.025Hz between the velocity and sediment concentration. This frequency corresponds well to the first mode of the infra-gravity wave released at the average breaking point (Michallet et al. 2007).
Kato, S., Aoki, S., and Torii, H., 2007. Temporal Variation of Graded Suspended Sediment Concentration in the Surf Zone. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 302 – 306. Gold Coast, Australia, ISSN 0749.0208
Some studies have demonstrated that the relationship between suspended sediment concentration and turbidity changes according to the grain size distribution. However, to obtain a more accurate estimation of the suspended sediment concentration (SSC) and associated transport rate by surrogate measurements, such as turbidity and acoustic backscatter, a better understanding of the characteristics of the grain size distribution of the suspended sediment and its variation is necessary. In this research, a sediment size distribution sensor (LISST-100) was employed to perform field measurement of graded grain size (2.5∼500 µm by 32 log-scaled size bins) in suspended sediment and its volume concentration under storm conditions. Thirty measured particle sizes were classified into three groups, SSC1 (2.5∼100 µm), SSC2 (100∼200 µm) and SSC3 (200∼300 µm), to grasp easily the characteristics of the SSC temporal variation and its relationship with the sea surface fluctuation, η. The results obtained for each group show the following: (1) The correlation coefficient between SSC3 (given in percentage with respect to the total SSC) and the total SSC is 0.75. The grain sizes larger than 200 µm (SSC3) are the more significant component in larger amounts of total SSC. (2) SSCs of the grain sizes smaller than 200 µm have almost constant energy of temporal fluctuation in the frequencies higher than 0.005 Hz, and this tendency is also found in the power spectral density of ηrms. On the other hand, the power spectral density of SSC of the grain sizes larger than 200 µm increases as the frequency becomes lower. This gradient of spectral shape is almost the same as that of ηrms for frequencies lower than 0.005 Hz.
Lekshmi G.R. and Sannasiraj S.A., 2007. Correlation of Breaking Wave Characteristics with Energy Dissipation. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 307 – 311. Gold Coast, Australia, ISSN 0749.0208
It is well accepted that wave breaking has a dominant role on the dynamics of upper layers of the ocean. While a lot has been learnt about wave breaking including the kinematics and dynamics of mixing, wave energy losses and ambient noise, there are many issues that are yet to be resolved These include the issue relating the energy dissipation with the wave spectral characteristics. In the present paper, the dependence of intensity of wave breaking on the energy dissipation has been studied. The simulation of wave breaking has been carried using constructive wave-wave interaction approach. The various intensities of breaking ranging from plunging to spilling have been generated in the controlled laboratory wave flume. The energy dissipation has been measured by tracing the water surface from pre-breaking to post-breaking zone. The results showed a noted difference in the amount of energy dissipation with the intensity of breaking. The study also reveals that wave breaking results in redistribution of spectral energy. Energy loss is found to be more towards the high frequency end.
Strauss, D., Mirferendesk, H. and Tomlinson, R., 2007. Comparison of two wave models for Gold Coast, Australia. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 312 – 316. Gold Coast, Australia, ISBN 0749.0208
Managing hazards associated with shoreline responses to extreme events and the provision of safe boating access is an ongoing concern for coastal authorities. The open sandy coastline of Gold Coast city is a wave dominated coast with a highly variable wave climate and a narrow continental shelf thus experiencing substantial variations in long-shore transport rates. Detailed wave transformation information is central to further investigations of sediment transport processes as complex bathymetry associated with trained river entrances and rocky headlands causes localised interruptions to the overall northward littoral drift. Temporal variations in wave energy are driven by a wide range of swell direction and size while spatial variations occur as a result of the strong refraction during particular swell events. This paper presents a comparison of two near shore wave models of the region using MIKE 21 and SWAN. The transformation of waves arriving from offshore is simulated using the models for selected time series of wave parameters. The parameterized boundary conditions are derived from NOAA Wave Watch III global wave model data. Model output is compared with observed data from existing wave recording buoys at Gold Coast Seaway and Point Lookout. The inclusion of wind in the modelling undertaken did not improve the models' accuracy and winds in excess of 10 ms-1 led to an over-estimation of significant wave height while increasing the processing time. Sheltering of the near-shore site during southerly swell conditions was well-represented by the modelling.
Kazeminezhad, M. H., Etemad-Shahidi, A. and MousavI, S. J., 2007. Evaluation of neuro fuzzy and numerical wave prediction models in Lake Ontario. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 317 – 321. Gold Coast, Australia, ISSN 0749.0208
For planning or designing maritime structures, wave observation with a long-term history is generally necessary. However, we may often encounter the problems that only short-term observed data were available or the records are incomplete in a station. In this study, the performances of a new generation spectral wind-wave model based on unstructured meshes and a neuro fuzzy model for predicting wave parameters are investigated. The data set used in this study comprises of wave data and over water wind data gathered from deep water location in Lake Ontario. The data set was divided into two groups. The first one that comprises of 26 days wind and wave measurement was used as training and checking data to develop neuro fuzzy models and also to calibrate the numerical model. The second one that comprises of 14 days wind and wave measurement was used to verify the neuro fuzzy and numerical models. Wind field was specified as constant in space and variable in time. Results show that whitecapping factor is the most important calibration factor in this case and satisfactory results can be obtained by tuning this factor. Results also indicate that the errors of proposed neuro fuzzy models in predicting wave parameters are more than those of on the numerical model.
Neelamani, S.; Al-Salem, K. and Rakha, K., 2007. Extreme waves in the Arabian Gulf. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 322 – 328. Gold Coast, Australia, ISSN 0749.0208
The extreme significant wave heights were predicted for return periods of 12, 25, 50, 100 and 200 years for 38 different locations in the territorial and offshore locations of various countries in the Arabian Gulf (Kuwait, Saudi Arabia, Bahrain, Qatar, UAE and Iran). The input wave data for the work was obtained by hindcasting of waves, using a WAM model. Wave data was hindcasted for a total period of 12 years, starting from 1st Jan, 1993 to 31st Dec, 2004. The peak over threshold method, with 1.0 m as threshold value was used for selecting the data for the extreme wave analysis. In general, Weibull distribution is found to fit the data well compared to the Gumbel distribution for all these locations. It is found that the significant wave heights for 100 year return period varies from 3.0 to 4.5 for water depths of 9 to 16 m, whereas in the offshore sites it is found to vary from 5.0 to 7.0 m, where the water depth varies from 30 to 60 m. A large number of coastal projects are in progress in the Arabian Gulf and many new projects are being planned in this region for the future. The results presented in this paper will be useful for optimal design of the ocean structures in the Arabian Gulf region.
CaÑellas, B., Orfila, A., Méndez, F.J., Menéndez, M., GÓmez-pujol, L. and Tintoré, J., 2007. Application of a POT model to estimate the extreme significant wave height levels around the Balearic Sea (Western Mediterranean). Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 329 – 333. Gold Coast, Australia, ISSN 0749.0208
Extreme value wave climate analysis at a particular site requires predicting long-term wave height levels from short duration records. In the present work we used the Peak Over Threshold (POT) model, assuming the frequency as a Poisson process and the intensity to be Pareto distributed, to characterise the spatial variability of the long-term extreme value wave climate along the Balearic Sea. Wave data used is part of the HIPOCAS database, a 44-years high resolution, spatial and temporal, wave hindcast covering an area between 38°N-42°N and 1°W-6°E, of the western Mediterranean Sea. The use of data from a homogeneous grid, instead of a single location wave data record, allows describing the spatial variability of the long-term extreme wave height levels over the whole Balearic basin. Results show that extreme values for a 50-year return period level around 11 m are found in the north sector of the Balearic Islands while in the southern part much lower extreme values are found, due to the shadow effect of the islands under severe north-eastern storms.
Zheng, J.-H., Jeng, D.-S. and Mase, H., 2007. Sandy beach profile response to sloping seawalls: an experimental study. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 334 – 337. Gold Coast, Australia, ISSN 0749.0208.
Seawalls are commonly used as a tool for coastal defence worldwide. Most previous studies have considered the case of vertical seawalls and descriptions of existing seawalls, rather than the influence of different designs of sloping seawalls on beach erosion. In this study, laboratory investigations of an undistorted moveable bed model were conducted to determine the resulting beach profile of artificial sandy beaches. In the experiments, three different sloping seawalls were considered under erosive wave conditions with a 50-year return period. The coast of Northern Jiangsu Province, China, is used as a case study. To simulate natural conditions, similarity criteria are developed assuming that the energy dissipation per unit volume along the beach profile is uniform and that the wave properties can be properly scaled by Froude criteria. Field surveys of beach profile changes due to the storm surge induced by Typhoon 9711 were taken to validate the experimental model and good agreements were attained. Spatial profile configurations were studied by examining dominant profile features such as the break point bar and the scour trough on the seawall-backed profiles. Experimental results provided a reference for the maintenance of artificial sandy beaches and the design of seawalls on the coast of Northern Jiangsu Province, China.
Williams, S.J., and Jeng, D.-S., 2007. Viscous attenuation of interfacial waves over a porous seabed. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 338 – 342. Gold Coast, Australia, ISSN 0749.0208
In this paper, we study the viscous damping of waves on a stably stratified fluid over a porous elastic seabed. Using the linearised Navier-Stokes equations as the governing equations of motion, the newly derived solution describes the attenuation of a progressive surface wave on a two-layer stratification due to damping caused by interfacial shear and from the wave interaction with a porous elastic seabed. The analytical results are discussed in the light of experimental observations and the viscous effects are considered by comparison with the previous solution for a rigid impermeable seabed. It is shown that the overall decay scale for viscous attenuation is determined by the relative wavelength and the non-dimensional depth of the lower fluid layer. Wave attenuation due to the porous bed is at a maximum when the lower overlying fluid layer is approximately 50% thicker than its Stokes boundary layer.
Achiari, H., and Sasaki, J., 2007. Numerical analysis of wind-wave climate change and spatial distribution of bottom sediment properties in Sanbanze Shallows of Tokyo Bay. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 343 – 347. Gold Coast, Australia, ISSN 0749.0208
An integrated model for the prediction of waves and currents as well as bed shear stresses was developed and applied to Sanbanze Shallows of Tokyo Bay. The wave model consists of a wave hindcasting sub-model for the whole of the bay and a wave propagation sub-model for detailed wave computation in Sanbanze Shallows. The wave hindcasting model follows the Shore Protection Manual (SPM) formulas for both shallow and deep-water cases with modification in fetch calculation. A random wave propagation model based on a modified energy balance equation by Mase (2001) is adopted for the computation of the detailed wave field in the shallow waters. The radiation stress gradient was estimated based on the spatial variation in waves considering the vertical profile of the stress after Xiaet al. (2004). The radiation stress terms were incorporated into the momentum equations of the coastal circulation model developed by Sasaki and Isobe (1999). The model was validated through comparison between numerical results and time variation in wave and current at two stations in Sanbanze Shallows in September of 1999. The computational results show that the present model can reproduce the trend of time variation in wave and current successfully. The computed bed shear stress distribution, which is dominated by waves rather than currents, correlates with the bottom sediment grain size distribution in the field collected by Chiba Prefecture (1998).
Ha, T.-M., Cho, Y.-S., Choi, M.-K., and Jeong, W.-C., 2007. Run-up heights of Tsunami along the eastern coast of the Korean Peninsula. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 348 – 352. Gold Coast, Australia, ISSN 0749.0208
Most of finite difference numerical models developed for simulation of tsunami propagation are based on the shallow-water equations. If spatial and temporal grid sizes are properly selected, the leap-frog finite difference scheme gives correct dispersion effects for a constant water depth. If a water depth changes, however, dispersion effects of tsunami can not be accurately considered at every grid point in the whole computational domain. In this study, new dispersion-correction terms are added to the leap-frog scheme with a purpose of considering dispersion effects as a water depth changes on a real topography. To verify the practicality of the improved numerical model, the propagation across the East Sea of the Central East Sea Tsunami occurred on 26th May, 1983 is simulated. Maximum run-up heights are then predicted at several locations. The predicted run-up heights are compared with available field observed data. A very reasonable agreement is observed.
Spiers, K.C. and Healy, T.R., 2007. Investigation of Sorted Bedforms, Tauranga Harbour, New Zealand. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 353 – 357. Gold Coast, Australia, ISSN 0749.0208
Elongated bands of coarse grained ripples (sorted bedforms) are common in the nearshore swell wave environment and have been identified by numerous researchers. Although there is a general concurrence regarding the maintenance of these features, the mechanism controlling their formation and positional stability is still under discussion. In 2004-5 the current study was conducted to investigate sorted bedforms on the inner shelf off Mt Maunganui beach, which is located on the north-eastern coast of New Zealand. The morphology and evolution of these features was examined by 4 side-scan sonar surveys, spanning 9 months. The influence of wave convergence on the formation and positional stability of the sorted bedforms was investigated via a calibrated numerical wave model (Mike21-NSW). Transects from multibeam bathymetry were used to assess the influence of alongshore flow. Results from the side-scan sonar surveys indicate an alternating pattern of degradation and restoration during the monitoring period. Based upon numerical model simulations it seems likely that the positional stability of the elongated sorted bedforms at Mt Maunganui is primarily determined by localised wave height reinforcement, resulting from the focussing of wave energy by two offshore spoil mounds. Cross-sections indicate that the maintenance of these features is likely to be assisted by increased near-bottom turbulence over the coarse bedformed areas and removal of fine suspended load by superimposed alongshore currents.
Yoon, H.S., Yoo, C.I., Na, W.B., Lee, I.C. and Ryu, C.R., 2007. Geomorphologic evolution and mobility of sand barriers in the Nakdong estuary, South Korea. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 358 – 363. Gold Coast, Australia, ISSN 0749.0208
This study discusses the characteristics of the spatiotemporal changes of the sand barriers in the Nakdong estuary for the last century, focussing on geomorphologic evolution and mobility of the sand barriers in the view of coastal engineering. The Nakdong estuary, the research subject, has a complexly changing natural environment by interaction between ground and marine elements such as water wave, tidal current, sediment, etc. Moreover, recently, unnatural geomorphologic changes have been radically increased in the area possibly due to rapid coastal developments such as reclamation, new harbour construction, etc. Because of those matters above, its sand barriers have developed a quite unstable condition. Therefore, to identify the development process of geomorphologic changes, a close examination on historical spatiotemporal changes of the sand barriers is required. This study, based on six marine charts published between 1927 and 1995, analyses the lengths and areas of the sand barriers for the last hundred years and studies the cause of the changes by investigating the changes of water depths for the last two years and doing ocean-physical on-the-spot observations. In conclusion, the sand barriers of the Nakdong estuary grow towards the open sea by 7.4 to 26 m in annual average, maintaining a fixed distance between 1,241 and 1,279 m and their areas are expected to increase about 28,800 m2 annually. It is believed that the causes of the spatiotemporal changes are the waves from the open sea and the discharge of the Nakdong River, which is mainly affected by the Nakdong estuarine bank.
Sierra, J. P., Gironella, X., Sánchez-Arcilla, A., Sospedra, J. and Alsina, J. M., 2007.Hybrid modelling of scouring – deposition in front of a coastal structure. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 364 – 368. Gold Coast, Australia, ISSN 0749.0208
Wave-structure interactions in the presence of a sand bottom constitute a complex problem, which is not yet satisfactorily solved. The process of erosion/deposition at the front toe of the structure, in particular, is only crudely defined up to the point that its quantitative dependence on wave conditions, structural permeability or sediment characteristics is poorly known. This paper analyses the scouring/deposition at the toe of detached breakwaters using large scale data from the CIEM wave flume in Barcelona and the simulations from a numerical wave-current-sediment transport model. The LIMORPH code has been developed and tested in a number of European Union research projects. The large scale wave flume data come from past (SCARCOST) and present (HYDRALAB III) European Union research projects. The paper discusses the relative merits of numerical/physical models and the gain in understanding for the underlying hydro/morphodynamic processes when a combination of both types of models is used. This is illustrated by the influence of wave characteristics and freeboard in erosion/deposition patterns.
Zhang, H., Jeng, D-S., Cha, D. and Blumenstein, M., 2007. Parametric study on the Prediction of Wave-induced Liquefaction using an Artificial Neural Network Model. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 374 – 378. Gold Coast, Australia, ISSN 0749.0208
The prediction of the wave-induced liquefaction potential is particularly important for coastal engineers involved in the design of marine structures. An artificial neural network (ANN) model is used to estimate the wave-induced liquefaction in terms of wave and seabed sediment conditions. The sensitivity of wave and seabed sediment parameters is extensively investigated to get the most accurate results. The deterministic wave and liquefaction models are used to explain the parameter features physically. Numerical examples demonstrate the capacity of the ANN modelling approach in simulating complex mechanisms such as wave-induced liquefaction with adequate information.
Alsina, J.M., Sánchez-Arcilla, A., Gironella, X. and Baldock, T.E., 2007. Design of scaled movable bed experiments using numerical models. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 379 – 383. Gold Coast, Australia, ISSN 0749.0208
Scaling designs for mobile bed short wave experiments have been analysed using a suite of numerical models to test different sediment scaling configurations. The numerical simulations have revealed that geometrical sediment scaling gives similarity in the boundary layer flow but the sediment transport mode switches from bed-load in the prototype to suspended-load in the model. This is due to the high relation of prototype to model sediment sizes. However, scaling to maintain the relative fall speed allows smaller sediment size relations and closer similarity in the dominant transport processes. A set of corrections have been proposed to minimise the scaling effects in sediment transport rates and bottom evolution.
Kuo, C.A., Lai, J.W., Kuo, C.T. and Chien, C.H. 2007. Maximum run-up on the movable bed of uniform materials. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 384 – 388. Gold Coast, Australia, ISSN 0749.0208
The characteristics of maximum run-up on the movable bed of various medium materials were investigated in this study. Six different medium diameters of uniform materials (D50= 0.15, 0.54, 1.02, 1.39, 2.68 and 4.84mm respectively) were used to construct the movable bed with a slope of 1/15 within the wave flume. In these experiments the topographical profile, wave shoaling and run-up were measured over various durations by generating irregular waves over 20 types of wave conditions. The effects of wave duration and medium diameter on the maximum run-up were initially analysed, with the results showing that under the same wave conditions the foreshore slope and maximum run-up on the movable bed would become steeper and higher with increasing wave duration before the topographical profile tended to stabilise. Hence, the varied profile of the movable bed should be measured at the various wave durations and used to estimate the height of maximum run-up. It is shown that the relative maximum run-up Rmax/Hs,o decreased as the medium diameter of the movable bed increased. Furthermore, considering the influence of roughness factor on the movable bed, a modified factor was led to MASE's empirical formula (1989) and was used to effectively estimate the maximum run-up on the movable bed.
Lu, J.-F. and Jeng, D.-S., 2007. A coupled model for an offshore pile, seabed and seawater interaction. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 389 – 393. Gold Coast, Australia, ISSN 0749.0208
A coupled model is developed to investigate the dynamic interaction between an offshore pile, poroelastic seabed and sea water. The pile and the seabed are treated as saturated porous media described by Biot's dynamic theory. The sea water is regarded as an acoustic medium which is characterised by the Helmholtz equation. Three boundary element formulations are constructed for the pile, the seabed and the sea water, respectively. The three boundary element method formulations and the continuity conditions (stress and displacement) between the pile, the seabed and the sea water are used to formulate the coupled model for the system. Airy linear wave theory is used to evaluate the external force applied on the pile and the seabed due to the incident and the scattered water waves. The dynamic response of the system is calculated by the coupled boundary element method formulation. A numerical example is used to demonstrate the capacity of the coupled model.
Sriram, V., Sannasiraj, S.A., and Sundar, V., 2007. 2D Nonlinear wave body interaction using Semi-ALE. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 394 – 399. Gold Coast, Australia, ISSN 0749.0208
The present study aims at generating the fully nonlinear waves based on Finite Element method (FEM) used by SRIRAM et al. (2006). The author simulated the nonlinear waves based on structured mesh by regenerating the mesh at each and every time step using the Mixed Eulerian and Lagrangian (MEL) scheme. In this paper, it has been extended to unstructured mesh. The mesh is adapted at each and every time step by using the spring analogy method instead of regenerating at every time step which makes the above method called as Semi-Arbitary Lagrangian and Eulerian (Semi-ALE/SALE). The simulation has been carried out in a numerical wave tank (NWT) with a surface piercing rectangular object. For such a situation, the diffraction by a surface piercing object becomes relevant in connection to breakwater studies where the primary interest is wave reflection and wave transmission. Regular waves and solitary waves are generated from one end of the tank. The nonlinear wave reflection and transmission characteristics reveals that the transmission is less for regular waves, while in the case of solitary waves the reflected energy is very small and the transmission is more.
E. Pranzini, 2007. Airborne LIDAR survey applied to the analysis of historical evolution at the Arno River delta (Italy). Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 400 – 409. Gold Coast, Australia, ISSN 0749.0208
The study of river delta evolution allows reconstruction of the land-use changes that occur within a sediment supplying watershed zone. The Arno River delta formed during the past 2500 years as river input of sediment increased due to the deforestation of the watershed from Etruscan times. Aerial photographs and satellite image interpretation allowed reconstruction of the main phases of accretion and erosion of this landform. The oldest erosional phases are related to a number of demographic events that led to the reduction of the cultivated surface, e.g. those produced by the fall of the Roman Empire and by the Black Death. The present delta erosion (1300 m since the mid 19th century) is caused by reforestation, river damming and river bed quarrying.
The almost continuous vegetation cover of the delta area prevented any high resolution analysis to be performed using remotely sensed data. However, last-pulse processing of altimetric airborne LIDAR data recently acquired on the delta area proved to be a useful ‘defoliant’ technique producing a Digital Terrain Model of 15 cm accuracy in elevation. This allowed each accretion and erosion event responsible for the present morphology of the delta to be highlighted.
The general scheme of evolution, previously produced through high resolution satellite image analysis, was confirmed, but the actual delta structure proved to be more complex: during each fast progradation phase, several low ridges formed (even one every four years), whereas during slow progradation phases few higher dunes formed. A beach ridge pattern classification is proposed based on the geometrical relationship among the ridges.
Morris, B.D., Coco, G., Bryan, K.R. and Turner, I.L., 2007. Video-derived mapping of estuarine evolution. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 410 – 414. Gold Coast, Australia, ISSN 0749.0208
Coastal changes are being monitored around Australia and New Zealand using a network of state-of-the-art coastal imaging stations. These systems are being used to build a database of frequent, long-term, spatially-extensive observations of coastal behaviour across a diverse range of coastal environments. The focus of the research detailed herein is the application of this technology to the investigation of estuarine systems. Boat-based surveying of estuaries is generally both difficult (e.g. shallow mudflats) and time-consuming. The ability to complete regular and repeated surveys within highly dynamic and fast-changing systems is usually limited. In contrast, image-derived methods provide a practical solution. Digital images are analysed to detect successive (hourly) waterlines at measured water levels through a single tidal cycle and then processed to generate intertidal bathymetries. Repeating these ‘virtual’ surveys enables the quantification of key processes such as channel infilling, growth of intertidal mudflats and response of the estuary to extreme forcing events. A particular advantage of this approach is that archived images may be used to complete ‘surveys’ retrospectively. Application of these research techniques are illustrated at two contrasting field sites in Australia and New Zealand. The first is a dynamic and small-scale inlet system dominated by the ingress of beach sediment (Narrabeen Lagoon, Australia) and the second is a large-scale and more slowly evolving mudflat system (Raglan Estuary, New Zealand). Results presented illustrate the practical application of video-derived methods to the monitoring and quantification of estuarine processes and evolution, and provide a unique dataset that can now be used for comparison with model simulations.
Liu, C. and Tao, L., 2007. Two-dimensional digital particle tracking velocimetry algorithm based on the image of particle trace. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 415 – 419. Gold Coast, Australia, ISSN 0749.0208
A digital method is developed to judge the instantaneous flow velocity by the image of the moving tracer particle formed during the exposure time. The grey-scale image of the particle trace is changed into the binary image and the pixels included in the particle trace image are marked. The length of the particle trace is obtained by determining the central principal axis of the particle trace image. The direction of the particle moving is determined by the fact that the flow velocities in a small local domain are almost the same. The instantaneous flow velocity field in the channel is measured by the method presented in this paper. The mean flow velocities along the vertical direction obtained by averaging the instantaneous velocities agree well with the logarithmic law.
Reichert, K. and Lund, B., 2007. Ground based remote sensing as a tool to measure spatial wave field variations in coastal approaches. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 427 – 431. Gold Coast, Australia, ISSN 0749.0208
Wave data are needed in coastal areas to help increase safety of ship navigation and improve coastal protection strategies. In recent years, remote sensing of surface waves and currents became a powerful tool, especially in areas with high spatial and temporal variability. The data discussed in this paper was measured with the wave monitoring system WaMoS II. This system is based on a standard marine X-band radar and can be operated from platforms, coastal buildings and from moving vessels. In contrast to wave buoys, this kind of data covers a rather large area with high temporal and spatial resolution. This paper presents data obtained from the island of Sylt, Germany and from the entrance to Port Phillip Bay, Melbourne, Australia. Both regions are characterised by a complex bottom topography that leads to a highly spatially variable wave field. For the Sylt data, examples of wave transformation such as refraction, shoaling and dissipation are described and quantified. The Melbourne data is described qualitatively showing the abilities of area covering wave measurements over such a complex topography.
Hemer, M.A.; Church, J.A. and Hunter, J.R., 2007. Waves and climate change on the Australian coast, SI 50 (Proceedings of the 9th International Coastal Symposium), 432 – 437. Gold Coast, Australia, ISSN 0749.0208.
There is a need to plan for the impacts of coastal erosion in response to climate change Australia-wide. A deep-water wave climatology of the Australian region is determined, which is required as boundary conditions for coastal wave models. Available wave data for the Australian region has been analysed to determine the mean climatology and interannual variability of mean significant wave height. Available data includes global wave model output from the ECMWF 45-yr re-analysis, ERA-40; corrected ERA-40 wave heights and the NOAA WaveWatch III operational wave model; satellite altimetry measurements; and data from a network of 30 waverider buoys surrounding the Australian coast located on the inner-mid continental shelf and some short-term deep-water wave-rider buoy deployments. These data have been analysed to determine the long-term mean, annual cycle and interannual variability of the mean Australian wave climate. Correlation with a number of climate indices in the Australian region indicate that southern ocean wind anomalies are a dominant mechanism responsible for variability of wave climate in the region. Correlation between monthly mean significant wave heights and the Southern Oscillation Index is significant along Australia's eastern margin.
Lahijani, H., Tavakoli, V., and Hosseindoost, M., 2007. History of Caspian environmental changes by molluscan stable isotope records. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 438 – 442. Gold Coast, Australia, ISSN 0749.0208.
The Caspian Sea, as a land-locked basin, is more sensitive to environmental changes compared with world oceans. The Pliocene to the present sediments of the Caspian coast recorded repeated seawater fluctuations. The South Caspian coast surrounding the main water body of the sea (i.e. South Caspian sub-basin), has recorded basin-wide environmental changes, rather than local oscillations.
An outcrop of the Holocene sediments in the South Caspian coast, Iran, provided new palaeoenvironmental records for this region. Field study (along with mollusc content, shell mineralogy, oxygen and carbon isotopic composition of the shells) was used to constrain the main changes in the Caspian environment during the Late Holocene. This molluscan-rich lagoonal sediment is located around four metres above the present Caspian sea-level and distanced 2 km from the present shoreline. Oxygen and carbon stable isotope data retrieved from diagenetically unaltered shells show mean values of -2.87‰ and -1.64‰, respectively. General trend of δ18O and δ13C are similar through the sedimentary sequence, except for minor changes in the mid-section. These well-preserved isotopic records demonstrate cyclic variations along the outcrop that reflect past environmental changes. The paleotempreture curve calculated by δ18O shows that the range of seawater temperature variations was similar to last century's instrumental records.
Mallman, E.P. and Zoback, M.D., 2007. Subsidence in the Louisiana Coastal Zone due to Hydrocarbon Production. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 443 – 449. Gold Coast, Australia, ISSN 0749.0208
Coastal wetland loss in southern Louisiana poses a great threat to the region's ecologic and economic stability. Wetland loss in the Louisiana Coastal Zone is caused by the interactions of multiple natural and human induced mechanisms, and it has been suggested that subsurface oil and gas production may be a large contributing factor. We model the effect of oil and gas production in Lafourche Parrish, Louisiana on surface subsidence using a first-order leveling line along highway Louisiana 1 to constrain our model. Using geologic and pressure data, we estimate the amount of compaction in modeled reservoirs. We find the subsidence predicted from reservoir compaction is consistent with observations of localized subsidence between 1982 and 1993. Both modeling and observations show that subsidence due to reservoir compaction is a highly localized signal that is not consistent with observations of regional subsidence. Interestingly, while predictions of subsidence from compaction of the reservoir sands fit the observed subsidence in one time epoch, the leveling data shows an increasing rate of subsidence from the 1965-1982 to 1982-1993 epoch – a time when production rates decreased. This indicates the potential for a time-dependent mechanism for production-induced subsidence. This work is a critical part in the development of an integrated model of subsidence and wetland loss in southern Louisiana.
Volkmer-Ribeiro, C, Ezcurra De Drago and Parolin, M., 2007. Spicules of the freshwater sponge Ephydatia facunda indicate lagoonal paleoenvironment at the Pampas of Buenos Aires Province, Argentina. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 449 – 452. Gold Coast, Australia, ISSN 0749.0208
Sediments dredged at the site Puente de la Tropa by the banks along the middle reach of River Luján (34°34´40"S-59°08´14"W), northeastern Pampas of Buenos Aires Province, Argentina, were 14C dated as 4,000 (80 cm) and 11,000 (222cm) yr B.P. Abundant gemmular spicules of the freshwater sponge Ephydatia facunda (Weltner, 1895), were seen in the samples dated 11,060 and 10,420 yr B.P. The spicules were associated with diatoms together with a rich gastropod and ostracod fauna, silicophytoliths and fish bones. Hyalodiscus subtilis (Bailey) a brackish, benthic diatom dominated the diatom flora. The detected taxocene indicates the existence of a lagoonal environment in this area during the Pleistocene. The remarkable presence of E. facunda lends weight to this interpretation as the species has been proven to presently thrive in coastal lagoonal brackish to fresh water rivers and swampy areas along the Brazilian and Argentinean ocean border. A strong relationship was seen between the species and the enrichment by floating meadows that occurs in such areas, the corresponding organic enrichment of the waters and sediments and the reduction of the free water column.
Williams, A.T., Sellers, V., and Philips, M.R. 2007. An Assessment of UK Heritage Coasts in South Wales: J A Steers revisited. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 453 – 458. Gold Coast, Australia, ISBN 0749.0208
Much of the South Wales, UK coastline is designated as Heritage Coasts, based upon coastal scenic evaluations conducted in 1944-46, by Professor J. A. STEERS. He utilised a four category scale: ‘Exceptional', ‘Very Good’, ‘Good’ and ‘Undeveloped’ (called ‘Poor’). Stretches of coastline rated in the top two categories subsequently became the first 27 Heritage Coasts. The boundary for Heritage/non-Heritage status lies between the ‘Good’ and ‘Very Good’ categories, i.e. the median of this scale. The methodology relied on subjective judgment and did not relate to scenic preferences of actual coastal users. At 14 locations, the current study compared Steers’ evaluations with a new scenic assessment technique using fuzzy logic based on a checklist of the main scenic coastal parameters deemed important by beach users. Results can be differentiated into 5 Classes by a dimensionless Decision parameter (D) value, calculated from checklist assessment attributes, which are weighted and subjected to fuzzy logic analysis. The checklist median was Class 3, with a D midpoint value of 0.53. If the Steers’ scenic assessment was accurate, all Heritage Coast areas should have a D value >0.53. Only three anomalies were found. Furthermore, Heritage Coast beach D values, were significantly higher than that for non-Heritage Coast beaches (t = 4.559; df = 12; p < 0.01).
Pais-barbosa, J., Veloso-gomes, F., and Taveira-pinto, F, 2007. Coastal features in the energetic and mesotidal west coast of Portugal, SI 50 (Proceedings of the 9th International Coastal Symposium), 459 – 463. Gold Coast, Australia, ISSN 0749.0208
The Portuguese west coast can be classified in three morphological groups: sandy coast, low rocky coast and cliff coast. This coastal zone is very energetic (wave-dominated) and is undergoing severe erosion, especially on the sandy coast. The study area is characterised by an extensive sandy flat area, very dynamic and environmentally fragile, under a mesotidal regime. The main objective of this paper is to identify and classify morphologically (e.g. megacusps, bars, cuspate shorelines, beach cusps) and hydrodynamically (wave breaking, surf-zone processes, rip currents, littoral drift) coastal patterns, based on the analysis of aerial photographs datasets. The identified features and coastal patterns will be compared with the existent morphological beach models and classifications. The preliminary analyses allow the identification of several morphological features such as megacusps; shore attached oblique bars, crescentic bars, cuspate shorelines and beach cusps, as well as the associated hydrodynamic currents. A certain similarity with other tidal regimes (microtidal) was found but in some cases with different spatial scales.
Woodroffe, C.D. 2007. Critical thresholds and the vulnerability of Australian tropical coastal ecosystems to the impacts of climate change. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 464 – 468. Gold Coast, Australia, ISSN 0749.0208
Paleoenvironmental studies of tropical coastal ecosystems in northern Australia indicate past responses to sea-level changes, implying geomorphological resilience in the face of future sea-level rise. However, there are several critical thresholds beyond which abrupt change appears inevitable. Elevated temperatures have recently caused extensive coral bleaching and reefs appear threatened if the thermal tolerance of corals is exceeded. Many reef islands have accumulated on reef platforms under stable or falling sea level. Continued accretion seems likely under gradual sea-level rise, but may no longer be sustainable if the sea drowns the reef platform on which they have formed. Similarly, broad mangrove-fringed plains have prograded under stable sea level, predisposing them to inundation if sea level continues to rise rapidly. The resilience of coastal ecosystems is also threatened by the synergistic interaction with several other pressures.
Hanes, D.M. and Barnard, P.L., 2007. Morphological Evolution in the San Francisco Bight. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 469 – 473. Gold Coast, Australia, ISSN 0749.0208
San Francisco Bight, located near the coast of San Francisco, USA, is an extremely dynamic tidal inlet environment subject to large waves and strong currents. Wave heights coming from the Pacific Ocean commonly exceed 5 m during winter storms. During peak flow tidal currents approach 3 m/s at the Golden Gate, a 1 km wide entrance that connects San Francisco Bay to the Pacific Ocean. Flow structure in this region varies markedly spatially and temporally due to the complex interaction by wind, waves and tidal currents. A multibeam sonar survey was recently completed that mapped in high resolution, for the first time, the bottom morphology in the region of the ebb tidal delta. This data set includes a giant sand wave field covering an area of approximately 4 square kilometres. The new survey enables the calculation of seabed change that has occurred in the past 50 years, since the last comprehensive survey of the area was completed. This comparison indicates an average erosion of 60 centimetres which equates to a total volume change of approximately 9.2 x 107 m3. Morphologic change also indicates that flood channels have filled and that the entire ebb delta is contracting radially.
Cronin, K.M.; Devoy, R.J.N., and Gault, J., 2007. Modelling estuarine morphodynamics on the south coast of Ireland, Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 474 – 479. Gold Coast, Australia, ISSN 0749.0208
Several important studies of coastal processes in Ireland exist, establishing the patterns of sea-level change, the impacts of storminess, erosion and sedimentation rates. Approximately half of Ireland's coastline is deemed sensitive to erosion under climate change. This paper presents work on the collection of field data and the setting up of a process-based model (Delft3D) to study morphological change in Courtmacsherry estuary on the south-coast of Ireland. Bathymetric and topographic surveys have been carried out and monitoring of the hydrodynamic and sediment transport regimes is being undertaken to validate and calibrate the models. Results from the hydrodynamic model simulations agree well with field measurements. The outputs from this modelling work shall be used to run an abstracted model (Asmita). Results from this study will be used to examine the drivers and processes responsible for changes occurring in Courtmacsherry and as example of estuarine-bay functioning in the region.
Khalil, S.M. and Finkl, C.W., 2007. Submarine geomorphology and coastal process zones: Morphodynamics of the inner continental shelf off southeast Florida. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 480 – 485. Gold Coast, Australia, ISSN 0749.0208
The subtropical southeast coast of Florida is a mixed siliciclastic-carbonate shore that contains sandy beaches, marshes, estuaries, rock reefs and barrier coral reef systems that make up the Florida Reef Tract (FRT). Detailed study of coastal morphologies in a 45-km2 study area to an offshore depth of about 25 m, identified numerous morphostructures including dune, beach, shoreface and bar systems, sand waves, hardground, zetaform bays, patch reefs, barrier reefs, inter-reefal sand flats and reef gaps. The morphostructures were used to interpret spatial distributions of processes related to their development. Morphology and genesis were thus classified in terms of ten coastal process zones. Mapping coastal morphostructures gives new insight into the topologies of coasts that affords better understanding of form-process relationships. The value of mapping coastal process zones lies in the ability to interpret the spatial distribution of morphostructures for large-scale investigation of coastal areas subject to shore erosion, protection and investigation of sand resource potentials.
Fortunato, A.B. and Oliveira, A., 2007. Improving the Stability of a Morphodynamic Modeling System. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 486 – 490. Gold Coast, Australia, ISSN 0749.0208
Coastal area morphodynamic modeling systems couple modules for tidal hydrodynamics, wave propagation, sediment transport and bottom update. The non-linear coupling between these modules generates spurious oscillations and stability problems that are still poorly understood. This paper assesses and compares various methods to avoid the oscillations and improve the stability of a coastal area morphodynamic modeling system (MORSYS2D). The model is assessed with a simple case, the propagation of a sinusoidal bedform, and a complex natural system (Óbidos Lagoon, Portugal), whose exceptional dynamics enhances numerical problems in the morphodynamic models. The best results are obtained with a combination of methods: a predictor-corrector method to improve the implicitness of the solution, along-flux diffusion in the Exner equation to control oscillations, and a morphological factor below unity to reduce the Courant number. With these methods, the modeling system can be used with Courant numbers well above unity.
Taylor D, Hall K and Macdonald N, J., 2007. Investigations into ship induced hydrodynamics and scour in confined shipping channels. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 491 – 496. Gold Coast, Australia, ISSN 0749.0208
Deep draft ships transiting through confined channels can significantly alter surrounding hydrodynamic conditions. Drawdown is a long-period motion, in the order of 30 to 150s, caused by the ship displacing water from the channel. The long-period character of the drawdown wave causes relatively large near-bed currents which are capable of inducing significant rates of sediment transport.
The Burlington Shipping Channel is a confined channel, 88m wide and 800m long, which connects Hamilton Harbour to Lake Ontario. Significant scour levels have been observed near the entrances to the channel and along the nearby sheet-pile channel piers. A series of investigations have been undertaken to determine the extent of scour and the magnitude of the forces causing scour. Investigations discussed in this paper include bathymetric and hydrodynamic data collection and numerical modelling using the ship wake and drawdown model SGH (Ship-Generated Hydrodynamics).
Hydrodynamic data was collected for seven ship movements to investigate hydrodynamic forces contributing to the scour. The applicability of simulating drawdown using a two-dimensional depth-averaged ship drawdown model such as SGH has been investigated. The model achieved a good level of calibration, particularly in the mid-sections of the channel and near the western entrance. The investigations have confirmed the validity of using sophisticated ship models such as SGH to investigate complex hydrodynamic and scour processes associated with deep draft ships transiting through confined channels. These models are capable of realistically simulating the spatial variation in sediment transport potential in confined channels and could be used to assist in the design of appropriate channel protection.
Parnell, K.E, Mcdonald, S.C. and Burke, A.E., 2007. Shoreline effects of vessel wakes, Marlborough Sounds, New Zealand. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 502 – 506. Gold Coast, Australia, ISSN 0749.0208
The science of vessel wake generation and propagation is well advanced, but the environmental effects of wakes are less well understood. The introduction of large vehicle and passenger-carrying fast ferries (HSC) in the 1990s resulted in numerous reports of environmental damage worldwide. In the Marlborough Sounds, New Zealand, regulatory agencies have struggled with the management of vessel wakes from both HSC and conventional vessels operating between the North Island and South Island. Gravel beaches along the route responded very quickly to the higher energy levels associated with the introduction of HSC, and there has been little change since that time, except in situations associated with geological instability. There has been no recovery of beaches towards pre high-energy conditions following HSC speed restrictions in 2000. Evidence of wake influences on very low-energy beaches in the far-field, over 7 km from the vessel path shows that long wave lengths associated with HSC can result in geomorphically significant waves and sediment transport. These findings are in accordance with other recently published results resported by other authors in the Baltic Sea.
Kim, Chang S. and Lim, H. S., 2007. Safety criteria on water depth, offshore distance and dredging volume in marine sand mining operation in Kyunggi Bay, Korea. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 507 – 510. Gold Coast, Australia, ISSN 0749.0208
A model study to investigate the sediment transport and cross-shore sediment flux near the shoreline is conducted for a marine sand mining operation in Kyunggi Bay, Korea. A modelling effort using a 3-dimensional model, a wave model and a wave-current sediment flux model has been applied to the study area. The ROMS (Regional Ocean Modelling System), SWAN and the HARRIS and WIBERG (2001) model represent the basic modules of the 3-dimensional hydrodynamics, wave transformation in shallow water and sediment transport respectively. The goal of the current study is to estimate the cross-shore sediment flux to quantify the erosion vulnerability of the shoreline by imposing various dredging intensity as in real situation. Being the wave and current interaction considered, the sediment transport model adopts the outputs of ROMS and SWAN for any designated time and space in the computation field. The realistic hydrodynamic conditions and wave field obtained from 20-year wave statistics enhance the prediction of the erosion process according to the water depth, offshore distance from the shoreline and dredging intensity (volume and frequency etc).
Shibutani, Y., Kuroiwa, M. and Matsubara, Y., 2007. One-line Model for Predicting Shoreline Changes due to Beach Nourishments, SI 50 (Proceedings of the 9th International Coastal Symposium), 511 – 515. Gold Coast, Australia, ISSN 0749.0208
This study is concerned with a new one-line model that takes account of the shoreline changes after beach nourishments. The behaviour of the injected materials is represented using one-dimensional convection diffusion equation in the alongshore direction. The shoreline changes are calculated by solving the fundamental equation for the conservation of bed material, combined with the advection diffusion equation. In this paper, first, the proposed model was applied to the tombolo formation behind offshore structures in the field. Secondly, the performance of the model was investigated by a model test. Finally, the presented model was applied to the sand recycle project at Yumigahama Coast, Japan in order to investigate the applicability of the model. The computed results showed that the new model could qualitatively predict shoreline changes due to beach nourishments.
Kakinoki, T., Tsujimoto, G. and Uno, K., 2007. Morphodynamics of artificial beach fronts on straits. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 516 – 519. Gold Coast, Australia, ISSN 0749.0208
The resistance of an artificial beach installation against ocean waves has been considered but tidal current has not. This study sought to clarify the relationship between morphological changes of an artificial beach installed in a strait with a strong tidal current. The results of a field survey and numerical analysis are described. Akashi-Strait is a narrow water channel of about 3.6 km width and 100m depth connecting two neighboring open seas, the Harima-Sea and Osaka-Bay. Strong tidal currents run through the strait with a maximum running speed of 4.5m per second. An artificial beach, Maiko beach, has been constructed in the strait. The beach has two detached breakwaters built to protect the 0.8 km of artificial beach shoreline. The distance of the 180m long breakwaters from the shoreline is 60m, the gap distance between adjacent breakwater segments is 80m, and the depth of the breakwater structure below mean water level is 5m. There are two well-developed salient formations behind the structures. The main conclusions from this study were: a) Tidal current fluctuates in a semidiurnal period, but sea level fluctuates semidiurnally or diurnally. b) Ebb and flood currents had different maximum running speeds. c) Spatially asymmetric patterns of ebb and flood may cause mass transport of both water and sediment in this area.
Donnelly, C. Morphologic Change by Overwash – Establishing and Evaluating Predictors. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 520 – 526. Gold Coast, Australia, ISSN 0749.0208
The ability to predict cross-shore profile response to coastal overwash is important for both understanding how barrier islands respond to overwash and for disaster management on developed coastlines. This study establishes morphologic and hydrodynamic parameters for predicting the type of cross-shore profile response following overwash for given pre-storm profile and storm conditions. More than 50 data sets were categorised into 7 different types of cross-shore profile response to overwash. These responses are: 1) crest accumulation 2) landward translation of dunes/berms 3) dune lowering 4) dune destruction 5) barrier accretion 6) barrier rollover (short-term),and 7) barrier disintegration. Dimensionless parameters describing the pre-storm morphology and storm characteristics for these data sets were then plotted in two-dimensional space and trends for the different response types identified. For some responses it was possible to define criteria for their occurrence and for the others an approximate trend could be identified. Maximum surge level, maximum run-up level, storm overtopping duration, beach crest height, dune width and dune volume proved some of the most important parameters to distinguish responses. The criteria that are established and trends identified should allow the user to qualitatively predict the overwash response of a given cross-shore beach profile to a given set of storm conditions, using readily available data.
Hu, K., Ding, P. and Ge, J., 2007. Modelling of storm surge in the coastal waters of Yangtze Estuary and Hangzhou Bay, China. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 527 – 533. Gold Coast, Australia, ISSN 0749.0208
The region of Yangtze Estuary and Hangzhou Bay (YE-HB) is subjected to tropical cyclone (TC) impacts during summer almost every year, resulting in extensive loss of life and property. An integrated model system which includes a storm-induced wind model, wave model and hydrodynamic model was developed for storm surge simulation in this area. Nesting computation was adopted for considering the effect of a remote wind field. Wave effects were included by considering radiation stress and enhanced bottom shear stress. Taking Typhoons Agnes (8114) and Matsa (0509) as examples, the model system was applied to the waters of the YE-HB. The calculated results of winds, waves and storm surges agree well with the observed data, which means there is good applicability of the model system for the study area. The distributions of the surge setup were analysed. Finally, the effects of waves and remote winds on storm surge were probed by numerical experiments.
Castelle, B., Turner, I.L., Ruessink, B.G., and Tomlinson, R.B., 2007. Impact of storms on beach erosion: Broadbeach (Gold Coast, Australia). Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 534 – 539. Gold Coast, Australia, ISSN 0749.0208
The 70 km long Queensland Gold Coast has been one of Australia's premier coastal holiday resort destinations for more than 40 years. Extreme events, particularly tropical cyclones approaching the area, can generate storm waves and surges which have caused widespread episodic damage to the local economy. Broadbeach, located on the Gold Coast, is a double-barred beach which is representative of most of the Gold Coast beaches. The present study aims to quantify Broadbeach response to storm events in order to assess the ability of this beach to withstand extreme events and to recover during periods of lower wave energy. From the 1st of March to the 10th of July, 2006, 35 accurate subaerial beach surveys were undertaken. ARGUS images were used to estimate the location of the nearshore bars. During this period, Broadbeach experienced three storm erosion events. Offshore buoy measurements are used to estimate wave conditions that occurred. The first storm (from the 2nd to the 6th of March) was a hybrid-cyclone which generated one of the most energetic wave conditions on the Gold Coast of the past 30 years, with measured offshore significant wave height reaching 5.3 m, and maximum wave height 10.7 m at the Gold Coast Seaway buoy. During the two other storm wave events, wave conditions were much less energetic than during the first storm, with significant wave heights ranging from 2 to 3 m. The early March extreme event resulted in a 48m3/m erosion of the subaerial beach and a 70 m seaward migration of the outer bar in just a few days. Abnormally high erosion rates were measured during both the second and third storm wave events. This may be explained by the outer bar decay following the early March extreme event, which did not provide any significant protection during the subsequent two storm wave events. The severe erosion measured in this study suggests that the current average beach width may be too narrow to withstand an extreme event succession similar to the conditions that occurred in 1967.
Ciavola P., Armaroli C., Chiggiato J., Valentini A., Deserti M., Perini L. and Luciani P., 2007. Impact of storms along the coastline of Emilia-Romagna: the morphological signature on the Ravenna coastline (Italy). Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 540 – 544. Gold Coast, Australia, ISSN 0749.0208
The coastal zone of the Emilia-Romagna region in Italy is exposed to risk from coastal flooding and erosion during storms. The vulnerability of this coastline is a topic of interest for future planning as this area provides large revenue for coastal communities and the whole region. An assessment of the historical record of storm events for the period 2000-2004 was carried out using a wave prediction model, forced by archived atmospheric circulation data. High-resolution air-borne laser detection technology (LIDAR) and video-monitoring (ARGUS) were used to undertake a feasibility study for the assessment of coastal erosion and flooding patterns along one of the best-preserved dune systems of the area. The object of the work was the comparison between two LIDAR flights at an interval of one year (July, 2003-September, 2004) with the second flight carried out after a major storm occurred in September, 2004. Following this event the whole coastal system was severely eroded. The study presented in this paper suggests that for the coast of the Emilia-Romagna region the critical factor that controls dune destruction and inland flooding is the joint occurrence of storm waves and surges. Beach slope is the main morphological control on wave run-up and the impact evaluation for the exceptional event has proved that a wide beach can provide a factor of safety. A small beach replenishment (33,000 m3) was undertaken on the test site but this resulted to be ineffective because of the small volume. Larger-scale beach recharge schemes should be undertaken at the site on a regular basis to provide wider beaches at the dune toe.
Lee, J.L. and Lee, D.Y., 2007. A fast forecasting system of typhoon-generated waves. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 545 – 549. Gold Coast, Australia, ISSN 0749.0208
This study presents an efficient operational model that can be used by civil defence agencies for real-time prediction and fast warnings on typhoon-generated wind wave and storm surge. The wind waves are simulated by the hyperbolic wave model of the mild-slope equation type, instead of using wave models such as WAM or SWAN, which are most widely used in the world. A new concept of wave length modulation is used to apply the MSE model of phase-resolving type to broader ocean areas. The results show reasonable agreement with the wind waves recorded by Pacific Hawaii Island buoy data for Hurricane Iniki (1992) and at the Korean coasts during Typhoon Nabi (2005).
Rakha, K., Al-Salem K. and Neelamani, S., 2007. Hydrodynamic Atlas for the Arabian Gulf. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 550 – 554. Gold Coast, Australia, ISSN 0749.0208
Long term wave data is important for the design of coastal structures and for the calculation of sediment transport rates. Such data is usually obtained by hindcasting waves from wind data. The use of simplistic hindcasting formulas will not provide realistic data. In this study a third-generation wind driven wave model WAM is used to generate 12 years of wave data for the Arabian Gulf. The WAM model is a two dimensional model that uses non-stationary and non-homogeneous wind fields in predicting wind waves. The RMA-10 hydrodynamic model was also used to generate data on tidal currents and water levels in the Gulf for a period of 13 months. All the data produced was stored in a digital geographic data base that was developed to provide a user friendly environment for data visualisation and extraction. The data showed that the maximum significant wave height in the Gulf is 5.5 m for data covering a period of 12 years and the maximum tidal water level fluctuations are of the order of 4.0 m.
Jing, Z. Y., Hua, Z. L., Qi, Y. Q. and Cheng, X. H., 2007. Coastal processes on a low energy beach. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 555 – 563. Gold Coast, Australia, ISSN 0749.0208
The upwelling structure and its seasonal variation along Zhejiang and Fujian coast of the East China Sea are studied using a three-dimensional baroclinic nonlinear numerical model forced by QuikSCAT winds over 2000-2004, in which other important factors such as realistic topography, boundary currents (Taiwan Warm Current, Kuroshio and Changjiang Discharge) and heat flux are all included. Numerical model results indicate that there exist obvious upwellings in the coastal area along Zhejiang and Fujian coast during every season and their intensity and spatial distribution have distinct seasonal variability. The stronger upwelling centres are mostly located in the vicinity of Zhoushan Islands and Yushan Archipelago of Zhejiang coast, Haitan Island and Mazu Archipelago of Fujian coast. In addition, the mean upwelling velocity is about 0.3×10-3cm/s and the magnitude of upwelling intensity is 10-3cm/s in winter, while in summer they are about 0.3×10-2cm/s and 10-2cm/s, respectively. The modelling results also show that the change rate of upwelling intensity is less in wintertime with the weaker coastal upwelling but quite to the contrary in summertime.
Nasser H. Zaker, P. Ghaffari and S. Jamshidi, 2007. Physical Study of the Southern Coastal Waters of the Caspian Sea, off Babolsar, Mazandaran in Iran. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 564 – 569. Gold Coast, Australia, ISSN 0749.0208
Temperature, salinity and density field observations over the period of summer to autumn of 2003 in the eastern part of the southern coast of the Caspian Sea are presented. Field investigations were carried out by CTD profiling and RCM9 time series recording across the southern continental shelf of the Caspian Sea off Babolsar, Mazandaran in Iran. These seasonal scale measurements were conducted for the first time in the southern Caspian Sea adjacent to Iran. The results showed a strong thermocline located between 20m and 50m depths in summer with 15 oC temperature decrease across it. In the beginning of autumn, the thickness of the thermocline reduced to 15 m and thermocline was located between 30m and 45m depths. The daily temperature in the surface mixed layer ranged between 25 to 30 oC in summer and smoothly decreased to 20 oC in late autumn. Below thermocline the temperature ranged between 10.5 oC to 7.5 oC at 110m depth with small seasonal variation. In summer, outside of the continental shelf, an average salinity of 12.2 and 12.3 was observed above and below the thermocline, respectively. The salinity variation from the sea surface to 110 m depth was less than 0.25. Over the continental shelf salinity ranged between 12.05-12.10 and it was slightly less than that in the similar depth outside of the continental shelf. Vertical density variation, considering small vertical salinity variations, was highly correlated with vertical temperature variations.
Carbonel C. and Galeão A., 2007. Modelling the Circulation and Transport Processes in a Coastal Area where Bays interact with an Upwelling Centre. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 570 – 575. Gold Coast, Australia, ISSN 0749.0208
This paper deals with transport processes and circulation patterns in a coastal area where bays interact with an upwelling centre. We focus on the coastal water along the meridional coastline of the Rio de Janeiro state, where the spatial variability of hydrodynamics characteristics is considerably greater than in open sea. Particular emphasis is given on the physical processes related to countercurrent flows. To study those processes an extended gravity reduced model for open marine regions is used taking into account the hydrodynamic and thermodynamic of coastal zone waters. To solve the non-permanent hydro-thermodynamic governing equations, a Petrov-Galerkin (PG) finite element model for open-area domain is proposed. Using a set of idealised wind field patterns, some numerical experiments are performed showing typical hydrodynamical features of that coastal area, such as: upwelling plumes, warming influences of the bays in the surrounding sectors and the coastal countercurrent flows.
Lee, R.S., Pritchard, T.R., Ajani, P.A. and Black, K.P., 2007. The influence of the East Australian Current eddy field on phytoplankton dynamics in the coastal zone. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 576 – 584. Gold Coast, Australia, ISSN 0749.0208
Phytoplankton blooms are often studied too late in their development when the surface expression of predominantly senescent cells triggers an investigation. As a result studies typically depict an environment exhausted of nutrients and provide limited information on the mechanisms that caused the bloom. The purpose of the study reported here is to quantify the oceanographic and meteorological conditions leading to nutrient enrichment and subsequent phytoplankton responses (blooms) through a series of cross-shelf flux studies undertaken over spring/summer seasons in the 1990's along Australia's east-coast. The region is impacted by western boundary current encroachments of the East Australian Current (EAC), and anthropogenic inputs from the Newcastle-Sydney-Wollongong conurbation. Synoptically triggered responsive sampling transects along a 300km section of the shelf, identified coherent diatom - dinoflagellate successions over several weeks after oceanic nutrient enrichment of shelf waters. Concurrent physical observations identified perturbations of the East Australian Current into meanders, eddies and back-eddies by coastal and shelf topography as a key influence in determining the local nutrient budget and phytoplankton distributions. Response of the heterotrophic dinoflagellate Noctiluca scintillans (Macartney) occurred after sufficient critical prey mass of diatoms was achieved and overwhelmed zooplankton communities. The extent and duration of these blooms were unprecedented in these coastal waters, and were mitigated by local prevailing circulation patterns. Suggestions that preferential diatom feeding by Noctiluca may control its abundance, and that climatic variance may determine the dominant diatom population, indicate these events fluctuate inter-annually rather than seasonally.
Pilkey, O.H. and Cooper, J.A.G., 2007. Lifting up the flap or why quantitative beach behaviour predictive modelling can't work. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 585 – 587. Gold Coast, Australia, ISSN 0749.0208
Quantitative mathematical modelling of beach behaviour with sufficient accuracy for engineering purposes is not possible. Success in “prediction” by hindcasting does not indicate a model works. Probabilistic modelling of beach processes is not possible either because accurate determinations of error bars is impossible. One measure of the problem with quantitative modelling is the nature of model simplifications. In qualitative models where the how, why and what if answers sought are directional, or order of magnitude, simplifications are often quite useful and valid. But a quantitative model can have no simplifications of important processes. All important processes along with their interactions and feedbacks must be represented in the models. Even if all parameters in the models are perfectly understood, one never knows their intensity, frequency, direction or duration. Some widely used models such as the Bruun Rule use virtually none of the critical processes in the model (except sea level rise) that cause shoreline retreat. The CERC equation and its many variants uses only a few of what are likely to be the important parameters effecting sand transport.
Hanslow, D. J., 2007. Beach Erosion Trend Measurement: A Comparison of Trend Indicators, SI 50 (Proceedings of the 9th International Coastal Symposium), 588 – 593. Gold Coast, Australia, ISSN 0749.0208
The measurement of longer-term trends in coastal erosion is of particular importance for the management of the world's coastlines. Methods commonly used for trend determination involve measurement of the shoreline or high water mark using aerial photography. For more dynamic coasts however, longer term trends in these features may be obscured by short-term fluctuations. In the present study, several different methods of quantifying beach recession and accretion are compared. In addition to the shoreline and the high water mark, these include the use of position indicators such as the vegetation line and the bluff or scarp location, as well as various volumetric measures. Comparison of the various methods is made with reference to MacMasters Beach, south-east Australia. The results show that the use of different indicators may result in significantly different trend estimates and that great caution needs to be exercised in the selection of appropriate indicators. For highly dynamic beaches, like MacMasters Beach, the less variable indicators like the scarp location and the dune volume may provide a better indication of underlying trends in beach erosion than the shoreline or high water mark.
Backstrom, J.T., Jackson, D.W.T. and Cooper, J.A.G., 2007. Shoreface Dynamics of Two High-Energy Beaches in Northern Ireland. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 594 – 598. Gold Coast, Australia, ISSN 0749.0208
The morphological response of shorefaces to fair-weather and storm forcing on two geologically distinct beaches on the north coast of Northern Ireland is under investigation. Measurements of shoreface morphology and related wave forcing at the adjacent beaches of Portrush West Strand and Portstewart reveal important differences in form and behaviour at seasonal and monthly timescales. The shoreface at Portrush has a high degree of geological constraint – it is located in a headland-embayment cell and is backed by an intermediate beach and a seawall. A thin veneer of sand on the beach is underlain by peat that crops out periodically. Portstewart is a long, sandy dissipative beach backed by a vegetated dune system and contains abundant sand on the shoreface and inner shelf. The shoreface at Portrush is steep and concave and highly responsive to storm events while that of Portstewart is convex in profile and largely stable, except along the very upper shoreface. The differences between the beaches and the behaviour predicted by existing conceptual models may be related to sediment abundance.
Brunel, C. and Sabatier, F., 2007. Pocket beach vulnerability to sea-level rise. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 604 – 609. Gold Coast, Australia, ISSN 0749.0208
The objective of this paper is to quantify the role of relative sea-level rise in the retreat of the shoreline and to evaluate this retreat in terms of future sea-level rise on 23 pocket beaches in Provence (France). Between 1896 and 1998, all of the investigated pocket beaches underwent erosion, with an average retreat of 12.1 (± 3.5) m. Making use of the flooding principle, and assuming a relative sea-level rise of +11 cm between 1896 and 1998, we obtain an average shoreline retreat of 5.8 (± 3.5) m. A comparison between measured average retreat and calculated average retreat suggests that sea-level rise is one of the main factors influencing shoreline retreat (50% of shoreline retreat can be explained by sea-level rise). The position of the shoreline for 2100 is evaluated not only by using the historical shoreline trend and the flooding method but also by adding the historical shoreline trend and the flooding concept in the case of an increase in sea-level of about +44 cm (for 2100). On the investigated pocket beaches, the presence of a cliff ‘blocking’ the landward migration of the profile will lead to a significant reduction in beach width. Thus, we envisage that the pocket beaches will lose 75 % to 97 % of their present surface area. In other words, we predict the eventual disappearance of the pocket beaches in Provence.
Figueiredp S. A., Cowell P. and Short A. D., 2007. Intermittent backbeach discharge to the surfzone: modes and geomorphologic implications. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 610 – 614. Gold Coast, Australia, ISSN 0749.0208
The exchange of sediment between dune-beach and surfzone is influenced by the elevation of the water table relative to the surface. Locations where the discharge of water from the backbeach to the surf zone is established, in the form of seepage, washouts and lagoons openings are associated with seaward transport of sediment. The generation and maintenance of washouts at the beach are mainly related to water table levels, sediment characteristics and frequency of precipitation. Their source area is chiefly the water table and swamp areas behind foredunes; in contrast, the pocket lagoons openings and intermittently open lagoon (ICOLL) breaching are due to high beach water tables and lagoons level immediately landward of the berm. The locations of surface discharge points may be preferential places for the establishment of subsequent coastal processes, as a consequence of a lower beach and dune line. This may influence the longer term-large scale coastal evolution of the dune, back beach and sediment budget.
Esteves, L.S., Williams, J.J., Lisniowski, M.A. and Perotto, H., 2007. Measured Cross-Shore and Vertical Variations in Grain Size, Sorting and Composition in Suspended Sediments Transported by Longshore Currents. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 615 – 619. Gold Coast, Australia, ISSN 0749.0208
Data defining the grain size and composition of suspended sediment transported by longshore currents is scarce. Present data was obtained on six dissipative to reflective, micro-tidal, wave-dominated beaches composed of fine to very fine sand along the southern coast of Brazil. At each site, samples of suspended sediment were collected at equally spaced heights above the bed over a 10-min period using streamer traps placed at accessible locations along the cross-shore profile. To define the relevant hydrodynamic conditions, measurements were obtained of the beach profile, longshore current speed, wave breaker height, wave period and the breaker angle relative to the shoreline. Suspended sediment samples were weighed, sieved and analysed for carbonate content. The carbonate content is highly variable and does not show any trend of changes across the surf zone or in the water column, although generally lower concentrations were found in bed than in suspended sediments, except at shallower locations. Changes in the characteristics of suspended sediments are not considerable across the surf zone. Vertical differences are more apparent in the troughs than in shallower areas across the surf zone where sediment properties are more homogeneous due to wave-generated turbulence. The median grain size of suspended sediments was up to 64% smaller than the median grain size of bed samples. Cross-shore and vertical variations in sediment grain size should be accounted for to improve results obtained by models used to quantify concentration profiles or longshore sediment transport rates.
Souza, C.R De G., 2007. Determination of net shore-drift cells based on textural and morphological gradations along foreshore of sandy beaches. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 620 – 625. Gold Coast, Australia, ISSN 0749.0208
Longshore currents have two components driving towards the same point: longshore drift (surf zone) and beach drift (foreshore). Both develop drift cells, which are current segments with the same direction ranging from a few metres up to kilometres. Three zones form each drift cell: erosion (updrift), transport and accumulation (downdrift). Sedimentary processes occur along each drift cell imprinting special characteristics on beach sediments and morphology, as per the following statement: from updrift zone towards downdrift, sediments become finer and better sorted, wave energy decreases, beach slope decreases and beach width increases. However, in some beaches special processes may change one or more of these trends, which could lead up to misinterpretations on drift direction assessment. This paper proposes a method to determine net shore-drift cells based on three textural parameters of foreshore sediments (mean diameter, sorting and kurtosis) and two geomorphologic properties (foreshore slope and beach width). Studies have been developed on beaches of different morphodynamic states along the 500 km length shoreline of the State of São Paulo (Brazil). This simple method proved to be sensitive for homogeneous and very heterogeneous beaches, as well as very efficient in beaches under those particular processes mentioned.
O' Connor, M., Cooper, J. A. G., and Jackson, D. W. T., 2007. Morphological behaviour of headland-embayment and inlet-associated beaches, northwest Ireland. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 626 – 630. Gold Coast, Australia, ISSN 0749.0208
Both static and dynamic environmental conditions contribute to the behaviour of coastal sedimentary systems. Sand beaches on the bedrock-framed northwest coast of Ireland exist in two distinct planform settings that offer the opportunity to examine their varying behaviour. Beaches in this region are either located in coastal re-entrants between rocky headlands and backed by vegetated sand dunes or adjacent to the inlets of large sandy estuaries that are themselves located in bedrock valleys. They all have a finite sediment volume due to the deeply embayed coastal morphology and lack of contemporary sediment input. The behaviour of these types of systems over the past 170 years is recorded in historical maps, air photographs and morphological measurements. Preliminary results show that the beaches of inlet-associated systems involve complex exchanges between beach, dunes and tidal delta while headland-embayment beaches cycle sediment between beach and dunes. The inlet-associated beaches are typically more dynamic than the headland-associated beaches, although both are subject to the same range of wave forcing. Inlet-associated beaches appear to show cyclicity in their behaviour that alternates between rapid erosion and accretion at horizontal scales of decametres and timescales of decades. Headland-embayment beaches show relative stability or slow progressive erosion. High magnitude storms, long term patterns of ‘storminess’ and morphological feedback all offer potential explanations for the behaviour identified.
Baldock, T. E., Manoonvoravong, P. and Pham K. S.., 2007. Beach face morphology and surf beat sediment transport. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 631 – 635. Gold Coast, Australia, ISSN 0749.0208
Predicting the evolution of the beachface is important in terms of coastal protection, recreation and environmental sustainability. Swash zone sediment transport plays a major role in this morphological response. However, despite recent advances in swash zone modelling and data collection, specific details are lacking, notably the cross-shore variation in net transport rates, the influence of surf beat and wave groups on swash sediment transport and the effects of the feedback between the surf and swash zones. This paper provides novel data from carefully controlled small-scale laboratory experiments investigating surf beat sediment transport. The data include very detailed observations of the cross-shore distribution of net sediment transport in the surf and swash zones for both eroding and accreting beaches. Further, these distributions are contrasted for monochromatic waves, monochromatic waves with surf beat and bichromatic wave groups with surf beat. In this case, free surf beat is shown to reduce nearshore wave heights and reduce short wave velocity amplitudes. Free surf beat is found to promote onshore sediment transport under accretionary conditions and reduce offshore transport under erosive conditions. Hence, the free surf beat tends to transform the beach toward a reflective state and possibly protects the beach. However, a bichromatic wave group shows the opposite effect. Additional data show the influence of the beach face evolution on the onshore migration of longshore bars, illustrating coupling between swash and surf zone morphology.
Butt, T., Russell, P., Miles, J. and Turner, I., 2007. Sediment Transport Processes in the Swash Zone of Sandy Beaches. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 636 – 640. Gold Coast, Australia, ISSN 0749.0208
In recent years, there has been a general resurgence of interest in the swash zone. However, it still remains one of the least well understood parts of the coastal zone. The sediment transport and resulting morphological changes in the swash zone are notoriously difficult to predict. Energetics-type formulations are less useful for predicting sediment transport in the swash zone than further seaward, particularly as conditions become more reflective. One reason for this is the existence of processes in the swash zone such as bore turbulence, inexfiltration and sediment advection. This paper presents an overview of the findings from a recent 3-year UK swash-zone field study with particular focus on these processes and the way their influence varies according to the prevalent hydrodynamic and morphological conditions. There is now evidence that (a) the influence of bore turbulence decreases with increasing dissipativeness, (b) in-exfiltration biases the transport onshore or offshore above and below a particular grain size respectively and (c) sediment advection may bias the transport onshore in reflective conditions and offshore in high-energy dissipative conditions.
Barnes, M.P. and Baldock, T.E., 2007. Direct Bed Shear Stress Measurements in Laboratory Swash. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 641 – 645. Gold Coast, Australia, ISSN 0749.0208
Knowledge of the boundary shear stress in the swash zone is essential for the accurate prediction of sediment transport rates and beach morphology. The variation of bed shear stress over the swash cycle has been investigated directly using a novel shear plate instrument. Laboratory measurements of bed shear stress, flow depth, and fluid velocity were obtained for dam break waves and bore generated swash. For dam break and swash uprush, a large positive (landward) spike in bed shear stress has been measured at the fluid tip followed by a rapid decay throughout the flow interior. The maximum measured negative (seaward) bed shear stress occurring in the swash backwash flow interior is several times smaller than the measured peak uprush bed shear stress. Surface elevation measurements indicate a virtually zero gradient at the uprush tip, a predominately adverse gradient throughout the decelerating uprush interior, and a weakening favourable gradient throughout the entire accelerating backwash. Measured pressure gradients indicate negative (seaward) total acceleration for the majority of the swash cycle. Considering that fluid velocity and total acceleration favours seaward sediment transport for a single swash event, the positive peak in bed shear stress at the uprush tip may in fact be a significant contributor towards the observed uprush sediment transport efficiency.
Benfer, N.P., King, B.A. and Lemckert, C.J., 2007. Salinity observations in a subtropical estuarine system on the Gold Coast, Australia. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 646 – 651. Gold Coast, Australia, ISSN 0749.0208
Saltwater Creek and Coombabah Creek are branches of the Coomera River estuary situated within the subtropical Gold Coast City region, Australia, where fresh water flushing occurs during the wet season. The two creek systems are physically adjacent to each other and join at a confluence before connecting to the lower Coomera River. Saltwater Creek is 17 km long and is joined again halfway up its tidal section, via an anabranch, to Coomera River. Coombabah Creek leads upstream to Coombabah Lake, a large shallow lake ringed by mangrove swamps. In order to develop an understanding of how these systems interact with each other, in particular their salinity dynamics, at time scales ranging from tidal to annual, three field studies were undertaken.
Field measurements confirmed that the salinity dynamics of these systems were dominated by rainfall and tidal events, typical of estuaries during the ‘wet season’ in subtropical environments. In contrast, the studies found that hypersaline conditions (salinity as high as 42 psu) developed upstream during the ‘dry season’ within Coombabah Lake due to the evaporative effects of its large shallow area and adjoining mangrove swamps. Further, the data also revealed that during the dry season, Saltwater Creek’s high frequency salinity fluctuations were in-phase with tidal oscillations while Coombabah Creeks’ were out-of-phase despite their close proximity. The mechanism for this was attributed to ebb tidal currents in Coombabah Creek which flushed hypersaline water out of the lake past the confluence, and the following flood tidal currents bringing that water into Saltwater Creek. The studies also identified a low frequency oscillation in Coombabah Creeks’ salinity which was caused by the diurnal inequality in the tides.
Ou, Su-Ying., Zhang, Hong., Wang, Dong-Xiao. and He, Jie., 2007. Horizontal characteristics of buoyant plume off the Pearl River Estuary during summer. SI 50 (Proceedings of the 9th International Coastal Symposium), 652 – 657. Gold Coast, Australia, ISSN 0749.0208
Field measurements of salinity from 1978 to 1984 are used to investigate the horizontal structure of the Pearl River buoyant plume during high river discharge. According to the characteristics of horizontal salinity
distribution in summer, buoyant plumes are classified into four types - offshore bugle spreading (TypeⅠ), west alongshore spreading (TypeⅡ), East offshore spreading (Type Ⅲ), western and eastern alongshore spreading (Type Ⅳ). It is found that the plume shapes vary with time, presenting obvious monthly and annual variations and TypeⅡalways occur in June, while in July the plume type has very high probability belong to Type Ⅲ which controlled by river discharge and local wind.
Etemad-Shahidi, A. and Azimi, A.H. 2007. Simulation of thermal discharges using two mixing zone models. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 663 – 667. Gold Coast, Australia,, ISSN 0749.0208
In this paper, dilution obtained from two laboratory data sets were simulated with a length scale model (CORMIX) and an integral type model (VISJET). In the weak ambient current regime the results predicted by CORMIX and VISJET models were relatively in good agreement with the laboratory data. Comparison between these two mathematical models shows that CORMIX model over-predicted the observed dilutions but remained within the model's stipulated error whereas VISJET predicted the dilution more accurately. It is also shown that the behaviour of the plume depends on a dimensionless parameter called Rv, which is relative depth multiplied by the ratio of the ambient current velocity to the discharge velocity. The observed dilution and Rv plotted in a log-log scale indicated a linear relationship. Empirical equations are obtained to aid the preliminary estimation of jet shape outfalls dilution.
Bryan, K. R. Tay, H. W, Pilditch, C. A., Lundquist, C. J. and Hunt H. L. 2007. The Effects of Seagrass (Zostera muelleri) on Boundary-Layer Hydrodynamics in Whangapoua Estuary, New Zealand. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 668 – 672. Gold Coast, Australia, ISSN 0749.0208
Seagrass beds (Zostera muelleri) form extensive (> 10 Ha) intertidal beds in New Zealand estuaries potentially altering particle and nutrient fluxes to sediments. The effects of seagrass (blade length 5-8 cm, shoot density ∼60/0.01m2) on boundary layer dynamics were investigated at a site exposed to both tidal currents (∼20 cm/s) and small wind waves (significant height 2-10 cm) over four days providing a variety of wave-current combinations. Flow characteristics were determined using two ADVs: one fixed at 15 cm above the bed and the other at varying heights within and above the canopy. The vertical variation of currents in and at the edge of the patch and on bare sediment during different tidal stages was measured. The inertial dissipation method was used to characterise changes to dissipation rate caused by varying bed character and hydrodynamic conditions. Results show that Z. muelleri altered the shape of the current profile by extending the boundary layer upward. The presence of waves caused substantial differences within the patch, appearing to increase the bed roughness. Dissipation rates outside the patch increased with proximity to the bed, whereas within the patch, they increased with distance from the bed. Dissipation rates were also observed to be greater on the incoming tide, even when differences in mean current speeds between flood and ebb tide were accounted for. Although the sudden transition at the edges of the Z. muelleri canopy caused more variable boundary profiles, the shape of the current profiles at the edge of the patch were clearly different on the ebb and the flood tides.
Williams J. J; Carling P. A. and Bell, P. S., 2007. Dynamics of Intertidal Gravel Dunes. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 673 – 677. Gold Coast, Australia, ISSN 0749.0208
The paper examines the dynamics of intertidal gravel dunes located at Hills Flat in the Severn Estuary, UK. Here a veneer of shale gravel (D50 = 4 mm) is locally deformed by strong tidal currents to form a series of flow transverse dunes with average heights and wavelengths of 0.6 m and 7.0 m, respectively. Incipient threshold values were much higher than expected owing to a coarse armor layer with D50 = 9 mm on the surface of the dune. More than 80 % of dune migration occurred during the first three days of the spring flows tide. During mobilisation and translation of the dune fine suspended sediment were released and concentrations were approximately one order of magnitude greater than the background level for this site. In a narrow range of hydraulic conditions highly localised and ephemeral secondary dunes were observed. Migration of the primary dune was accomplished without a measurable change in the dune volume supporting the view that the bedforms exist in quasi-equilibrium.
Soomere, T. and Quak, E., 2007. On the potential of reducing coastal pollution by a proper choice of the fairway. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 678 – 682. Gold Coast, Australia, ISSN 0749.0208
Sea coasts located adjacent to fairways hosting intense ship traffic are frequently subject to major oil pollutions. Since (i) the coastal areas are generally the major life reproduction areas and (ii) combating oil pollution on open sea is generally much more effective and less expensive than at the coasts, keeping the oil spill in the open sea area usually causes the least damage. We discuss the possibilities of the choice of the fairway (or smart rerouting of the ship traffic) so that a potential oil spill will stay in the open sea area as long as possible. In certain cases a reduction of the probability of coastal pollution may be achieved with the use of intrinsic properties of dynamics of water masses. As an example of this approach, the potential use of the patterns of currents in the Gulf of Finland, as part of the Baltic Sea, is analysed. Surface currents in this area are non-persistent. Numerical experiments suggest that there is a quasi-persistent subsurface flow at the depths of about 2.5–7.5 m. The current is able to carry the pollution out of the gulf before it reaches the coasts. Outside the stream, water motion usually forms circular current cells that periodically carry the water masses close to the coast. The experience of two pollution events in 2006 suggests that the propagation pattern of the pollution qualitatively matches the estimated current patterns. Perspectives and consequences connected with solutions of this type are discussed.
Narayana, A.C., 2007. Peat deposits of the west coast of India: implications for environmental and climate changes during late quaternary. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 683 – 687. Gold Coast, Australia, ISSN 0749.0208
Two boreholes (viz., one in a lagoon and the other in a paleo-delta), drilled in the coastal land of south-western India penetrated layers of peat. Radiocarbon ages and pollen analysis of these deposits were carried out. Radiocarbon dating of samples of peat suggested ages as 8,460 yr and >40,000 yr B.P. Pollen analysis of peat samples of BH-1 yielded pollen assemblages belonging to the family Rhizophoraceae and Mallotus. Peat samples of BH-2 with C-14 age of 8460 yr B.P. reveal the presence of mangrove forest comprising Avicennia and Kandalia. The evidences strongly suggest possible existence of various mangrove forests under different environmental conditions.
Panayotou, K., Woodroffe, C.D., Jones, B.G., Chenhall, B., Mclean, E. and Heijnis, H., 2007. Patterns and rates of sedimentary infill in the Minnamurra River estuary, south-eastern Australia. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 688 – 692. Gold Coast, Australia, ISSN 0749.0208
This paper presents a revised process-based model that explores aspects of estuarine geomorphology and the rates and patterns of sedimentary infill based upon the Minnamurra River estuary, a mature barrier estuary in south-eastern Australia. The Minnamurra River is located on the south coast of New South Wales and is characterised by three main facies: a marine flood tide delta/barrier, a central lagoon/estuary and a fluvial delta. The sedimentary record in this system was examined in detail to quantify the rate of estuarine infill. This predominantly infilled mature barrier estuary is now largely dominated by river influence. In the early stages of evolution this wave-dominated estuary was characterised by a central mud basin which trapped sediment supplied from the catchment. In the latter stages of evolution, decreased accommodation space restricted sediment retention within the basin, enabling the river to potentially contribute sediment directly to the coast. . The record of sediment retention for this wave-dominated estuary demonstrates that the rate and pattern of infill has changed with time as this system has become increasingly dominated by river influence.
Yuhi, M. and Hayakawa, K., 2007. Long-term field observation on sand bar migration near Tedori River mouth, Japan. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 693 – 699. Gold Coast, Australia, ISSN 0749.0208
Long-term variations of seabed elevation near Tedori River mouth, Japan, have been investigated using a set of field surveys collected over 40 years. The focus is placed on the formation and migration of nearshore bars. The typical seabed profile configurations vary from multiple barred to nearly unbarred. The height of offshore bars evolves as high as 5 m at its maximum. The variation of the cross-shore bar location is examined in detail. For the time variation it is shown that the cross-shore periodic movements have been repeated several times with about 10-year cycles. Superimposed on periodical migration, the outer bar position has a clear onshore trend in longer time scale of several decades. This is considered to be related with the construction of coastal structures as well as the significant coastal erosion accelerated by the recent reduction of sand discharge from the River by damming and sand mining. These onshore trends of the offshore limit of bar-migration zone are asymmetric with respect to the River mouth. In the west side of the River mouth, which corresponds to the downdrift side of littoral sediment transport, the retreating features are more significant while the trend is relatively weak in the east side. An attempt has been made to separate the general eroding trend and periodic migration of bars by using a time-varying standard profile. On the basis of the separated results, real type empirical orthogonal function analysis is conducted to effectively capture the characteristics of sand bar migrations.
H. Takebayashi, S. Egashira, H.S. Jin† and T. Sasaki, 2007. Water Surface Elevation at the Upstream Side of a River Mouth Sandbar during Floods. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 700 – 704. Gold Coast, Australia, ISSN 0749.0208
Temporal change of water level at the upstream side of a river mouth sandbar during floods is discussed by means of a depth-integrated two dimensional numerical model based on the boundary fitted orthogonal curvilinear coordinates. The results suggest that the highest water level during floods at the upstream side of a sandbar is significantly affected well by bar height but rather by unsteadiness of water discharge. On the other hand, both bar height and unsteadiness of water discharge significantly affect the continuous time of high water level at the upstream side of the sandbar. Low height bars suppress the highest water level during floods but lengthen the continuous time of high water level. This result implies that low height sandbars do not always have an advantage for flood control under all hydraulic conditions.
Vila-Concejo, A., Short, A.D., Hughes, M.G. and Ranasinghe, R., 2007. Flood-tide Delta Morphodynamics and Management Implications, Port Stephens, Australia. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 705 – 709. Gold Coast, Australia, ISSN 0749.0208
Port Stephens is a drowned river valley estuary located in SE Australia. Its flood-tide delta is part of the morphological transition between the wave-dominated open coast and the tide-dominated estuarine environment. The sand surface of the flood-tide delta is subject to episodic disturbance by large ocean waves that penetrate into Port Stephens. Moreover, the flood-tide delta is a dynamic feature that responds to variations in the forcing mechanisms. Shoal Bay, Nelson Bay and Jimmy's Beach located on both sides of the entrance have experienced severe erosion for the last 40 years, resulting in expensive shoreline management controls. The evolution of these beaches has been linked to the flood-tide delta morphodynamics. Most of the morphologic features in outer Port Stephens have undergone erosion processes during at least the last 40 years. Yacaaba Head seems to be the only morphologic unit that has undergone sedimentary accretion. Results from numerical models obtained by other authors found eastward directed sediment transport occurring on the eroding beaches. Field measurements and observations show westward sediment transport. Further studies to identify the sediment exchange mechanisms and controls are needed to clarify the morphodynamics of the outer part of Port Stephens.
Burningham, H. and French, J. R., 2007. Morphodynamics and sedimentology of mixed-sediment inlets. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 710 – 715. Gold Coast, Australia, ISSN 0749.0208
Inlet research has a long history dominated by sandy systems: mixed sediment (sand-gravel) inlets have only recently been scientifically described, and as such remain an emerging research area. Inlet hydro- and morphodynamics are currently considered within the context of relative importance of wave and tidal processes, which is thought to account for geographical variation in their character and behaviour. Although wave-tide processes are principal forcing factors, sedimentological character is an important variable that can directly influence the efficacy of transporting mechanisms and the morphology of inlet shoals. Here, two sand-gravel inlets on the southeast coast of England are examined to evaluate the relative importance of sedimentology on inlet and ebb-tidal delta morphometry, and system behaviour. Woodbridge Haven at the mouth of the Deben estuary maintains a fixed inlet position 8 km to the south of Orford Haven, the more mobile mouth of the Alde/Ore estuary. Woodbridge Haven bypasses sediment through ebb-tidal breaching, whilst bypassing at Orford Haven occurs through a combination of long-term alongshore inlet migration and spit breaching with short-term ebb-tidal breaching. Both systems comprise sand and gravel sized sediment and are subject to a similar coastal climate (North Sea storm climate, meso-tidal regime). Whilst these inlets can be conceptualised in a similar way to their sand-dominated counterparts, their morphometry and periodicity are not directly comparable: they are smaller and bypass sediment more slowly than expected. This is thought to be a direct consequence of their sedimentological character.
Steeghs, L. and Healy, T., 2007. Tidal inlet configuration and bathymetric changes resulting from active sedimentation, Buffalo Bay, New Zealand. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 716 – 720. Gold Coast, Australia, ISSN 0749.0208
The Whitianga tidal inlet lies within Mercury Bay, on the northeast coast of New Zealand. The Whitianga Estuary harbours many recreational and commercial vessels. Terrestrial sediment inputs into the Whitianga Estuary catchment are high, due to the erodible tertiary sediments and the steep nature of the catchment, which suffers intense rainfall that results in high sediment influxes, much of which becomes deposited within the estuary. In recent years active shoals have appeared in Buffalo Bay and the inlet channel has noticeably shallowed, both of which inhibit the use of the inlet by boat traffic. The past and present bathymetry of Buffalo Bay is compared to establish changes in morphology and zones of accretion and erosion within Buffalo Bay. The outcomes of this research contribute to a larger research programme which aims to use numerical model simulations to identify sediment transport pathways and patterns within Buffalo Bay. This research will particularly provide information which can be used to calibrate a sediment transport model. Comparison of the Buffalo Bay bathymetries over the 38 year period from 1938 to 1979 and Whitianga inlet bathymetries between 1979 and 1995, show extensive accretion in the ebb discharge channel which is predominantly associated with the migration of the tidal inlet channel and growth of the ebb delta, and within the inner inlet area which are attributed to the growth of the flood delta system.
Shand, R.D., 2007. Bar splitting: system attributes and sediment budget implications for a net offshore migrating bar system. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 721 – 730. Gold Coast, Australia, ISSN 0749.0208
Net offshore bar migration or NOM, refers to the systematic seaward migration of longshore (primary) sand-bars across the surf zone. NOM appears to be the product of storm-induced seaward bar migration (sediment transport) exceeding landward bar migration (sediment transport) during intervening fair weather periods. NOM also appears to involve the cross-shore redistribution of sediment rather than the continual loss of sediment to the shoreface. While ‘grain by grain’ return processes appear to predominate within the outer surf zone, alternative return mechanisms may exist within the inner surf zone. The aim of this paper is to assess whether sediment travelling landward within inner bifurcates formed during the process of bar splitting can offset a NOM-induced cross-shore sediment imbalance. Bar splitting has been observed on several NOM coasts and involves a longshore bar bifurcating, with the inner bifurcate detaching, moving landward, and in some cases welding to the foreshore. Analysis of several years of morphological data from Wanganui, on the west coast of New Zealand’s North Island, found that the sediment gained by the foreshore from inner bifurcate welding amounted to approximately half the sediment lost from the foreshore by newly generated sand-bars which subsequently underwent NOM. In addition, during the study, several other types of 3D morphological behaviour were identified which are also capable transporting sediment shoreward across the inner surf zone as a coherent sand body. Landward migrating secondary bars therefore appear to play a significant role in returning sediment to the inter-tidal beach. Finally, a conceptual morphodynamic model of the NOM system at Wanganui is presented which incorporates 3D morphological behaviour in contrast with existing models which are entirely 2D.
Jackson, D. W. T., Anfuso, G. and Lynch, K., 2007. Swash bar dynamics on a high-energy mesotidal beach. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 738 – 745. Gold Coast, Australia, ISSN 0749.0208
Swash bar dynamics can be an important constituent of beach dynamics, playing a significant role in post storm recovery of displaced beach systems. However, their low amplitude and dynamic nature make them difficult to monitor and thus challenging in terms of unravelling their evolutionary patterns. This study makes use of sensitive measurement techniques to measure fine scale (vertical) changes of an advancing swash bar over several tidal cycles. The coincidence of moving from neaps to springs in this period, alongside a relatively steady set of wave conditions, highlighted the high importance of tidal stage level in controlling swash bar dynamics. A high resolution shallow water wave model (SWAN) was also run with the empirical measurements of wave and beach response to produce wave force (on seabed) predictions over the swash and trough zones of the beach. The latter showed a close correlation between model results and bed response.
Uno, K. and Nakano, S., 2007. Effect of Tidal Current on Sediment Transport at the Tidal Flats. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 746 – 750. Gold Coast, Australia, ISSN 0749.0208
To study the sediment transport at the tidal flat and the bar of the river mouth, it is useful to clarify the mechanism of colonization of vegetation or the settlement of benthic animals. This paper focuses specifically on the transport of the sediment to which the diameter is 2,000 µm or less, according to tidal current. The study site is located at the mouth of the Yoshino River, Shikoku Island, Japan. In this study, field observations were carried out to measure the sediment accumulation in a period between two successive low tides. Secondly, time variation of friction velocity on a tidal flat with uniform slope was calculated to examine the relationship between the sediment transport and tide level. Thirdly, 2-D FEM tidal current simulations were conducted to clarify time series behaviour of friction velocity on the tidal flat and the river mouth bar. Finally, the amount of sediment transportation was estimated. This resulted in: 1) The results of field observation coincide approximately with that of theoretical analysis using a tidal flat with uniform slope; 2) The value of friction velocity becomes greater just before dry up and just after submerged; and 3) The amount of sediment transport was generally estimated by bed load theory.
Coughlan, C., Vincent, C.E., Dolphin, T.J. and Rees, J.M., 2007. Effects of tidal stage on the wave climate inshore of a sandbank. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 751 – 756. Gold Coast, Australia, ISSN 0749.0208
Modelling of the processes that link the movements of offshore sandbanks to erosion and accretion of neighbouring beaches was undertaken to improve understanding of the links between sandbanks and beaches in order to inform coastal management. The effect of varying tidal stage on the wave climate inshore of a sandbank was examined using the TELEMAC suite of numerical models. Longshore sediment transport was calculated using the CERC formula to investigate changes to the magnitude and pattern of coastal erosion/accretion according to tidal stage using waves from two of the most frequent directions. Tidal stage has a significant impact on the inshore wave climate, varying wave heights by up to 0.5 m and increasing tenfold the magnitude of the longshore sediment transport. Tidal elevation appears to play a more important role than the tidal currents, with wave heights and longshore sediment transport maximum at high water. The pattern of alongshore erosion and accretion varies more strongly with wave direction than tidal stage.
Jose, F., Kobashi, D. and Stone, G.W., 2007. Spectral Wave Transformation over an Elongated Sand Shoal off South-central Louisiana, U.S.A. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 757 – 761. Gold Coast, Australia, ISSN 0749.0208
Ship Shoal is an elongated sand shoal located along the 10 m isobath in south-central Louisiana adjacent to a rapidly eroding barrier island complex, Isles Dernieres. High quality sand resources from this shoal are considered as a viable source for the long term maintenance of the adjacent barrier islands. Previous wave modelling studies suggest that the shoal acts as a submerged barrier and mitigates storm waves. The present investigation employs a fully spectral finite element model to estimate the wave transformation over the shoal during a cold front generated storm event in April, 2005. MIKE 21, a spectral wave model, was implemented for the eastern Ship Shoal area at a high resolution scale, to estimate wave attenuation over the shoal and to better understand the directional spectrum when the storm–generated waves cross the shoal. The fine resolution coastal model was nested within a regional wave model for the Gulf of Mexico. NCEP re-analysed wind data were used as input and the spatial distribution of bottom sediments were also included in the model to select an appropriate friction factor. It was found that southerly storm waves could lose as much as 22% of their offshore wave height while propagating over the shoal. This level of wave energy reduction also points to the effectiveness of the shoal in shielding the already vulnerable coast against the frequent cold fronts and hurricanes. The model results were validated with time series data collected from in situ measurements on the shoal as well as using data from an observation site CSI 6. The dissipating wave energy over the shoal helps in resuspension and transport of shoal material during storm events.
Shand, T.D., Peirson, W.L. and Cox, R.J., 2007. Wave group effects on breaker height on a uniform slope. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 767 – 772. Gold Coast, Australia, ISSN 0749.0208
The maximum wave height that can be achieved during shoaling is of key importance in the design of coastal structures and the assessment of near shore currents and water levels. Previous investigations, upon which current design guidelines are based, have tended to focus on regular, monochromatic waves thereby neglecting group effects. Studies incorporating random wave testing include these group effects but may require prolonged testing periods to achieve the design condition. The shoaling transformations of wave groups as they progress into shallow water and break has been investigated in laboratory wave flume experiments. The water surface elevations were recorded by capacitance type wave probes. The type and position of breaking was recorded and video imaging used to observe wave kinematics during shoaling and breaking. Results show that the interaction of horizontal (intra-group) and vertical (depth-induced) energy fluxes plays a key role in the shoaling and breaking processes of the wave group. Notably, the evolutional stage of the wave group as it approaches a critical threshold depth facilitates the emergence of two distinct shoaling cases – an early shoaling case and a delayed shoaling case. These distinctive shoaling cases appear to cause significant variation in the wave breaking properties (breaker type and breaking position) and in the maximum depth limited wave heights (Hb/d) observed. In particular, the delayed shoaling case appeared to stabilise the wave groups, delaying breaking and yielding Hb/d ratios in excess of current design guidelines. These preliminary results indicate that current design guidelines based on monochromatic waves may underestimate the ‘worst case’ scenarios associated with wave groupiness with consequent implications for engineering design, coastal modelling and hazard mapping and planning.
Newell, C. and Mullarkey, T., 2007. Wave-Current Interaction Involving Iteration between Finite Element Wave and Current Models. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 773 – 777. Gold Coast, Australia, ISSN 0749.0208
A wave-current interaction model has been developed by the authors. The wave sub-model uses the elliptic form of the mild slope wave equation in the domain and the parabolic form of the mild slope equation as an absorbing boundary condition. A set-up/set-down and current sub-model uses radiation stress values as a driving force. These are obtained from the velocity potential results, including breaking, of the wave sub-model. The wave sub-model includes wave-current interaction and hence an iterative solution scheme can be carried out between the two sub-models to achieve accurate results of wave behaviour in the coastal zone. The results of this paper show that wave-current interaction is accurately modelled by the wave sub-model and that the overall iterative solution scheme provides accurate results for wave behaviour in the coastal zone.
Graham, G.W., Bass, S.J., Nimmo Smith, W.A.M., and Manning, A.J., 2007. Exploring Marsh Surface Canopy Dynamics – A Discussion of Laboratory Methods. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 778 – 783. Gold Coast, Australia, ISSN 0749.0208
The complex interactions between marsh surface vegetation, hydrodynamics and the settling of suspended sediments in marsh surface waters are poorly understood. An improved understanding of the role of vegetation in modulating marsh surface hydrodynamics and mass settling fluxes, at the canopy scale, may improve current abilities to explain spatio-temporal variations in erosion/deposition and may be of benefit to morphodynamic prediction. In this paper, an experimental methodology is discussed which uses a large annular flume and Doppler Velocimetery to addresses the influence that a dense Spartina anglica canopy (1000 stems m-2) has on time-averaged hydrodynamics and suspended sediment dynamics. The construction of artificial S.anglica mimics, which have geometric and dynamic similarity with prototypical vegetation, is outlined and illustrative velocity profiles measured in laboratory flows through this mimic canopy are presented. The flow response is shown to be produce vertical profiles of velocity statistics that are similar to a number of previously published studies which use real or artificial vegetation. The implications of flow modification by submerged S.anglica on the flocculation and settling of Suspended Particulate Matter is discussed as the basis of further research.
Yuk, J.H. and Aoki, S., 2007. Impact of Jetty Construction on the Current and Ecological Systems in an Estuary with a Narrow Inlet. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 784 – 788. Gold Coast, Australia, ISSN 0749.0208
The influences of the construction of five jetties at the inlet of Hamana Lake on the tidal response and the associated currents, between 1965 and 2000, were investigated using the field data and numerical simulation. Hamana Lake is one of the semi-enclosed and highly eutrophicated estuaries in Japan. Using the old topographic and bathymetric data a hydrodynamic and ecological model was developed. The model reproduced the tidal current, temperature and salinity for the physical system and chlorophyll concentration (Chl-a), dissolved oxygen concentration (DO) and the chemical oxygen demand (COD) for three different years: 1965, 1984 and 2000. The results were compared with each other. The changes to the inlet from 1965 to 1984 controlled the environment of Hamana Lake for 35 years. Therefore the extension of the inside-west jetty and the construction of the inside-east jetty since 1984 did not contribute to the inflow propagation through the narrow inlet and the improvement of the marine environment.
Shiau, B.S., Yang, C.L. and Tsai, B.J., 2007. Experimental Observations on the Submerged Discharge of Brine into Coastal Water in Flowing Current. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 789 – 793. Gold Coast, Australia, ISSN 0749.0208
In assessing the coastal environment impact effect, experimental observations were conducted in the towing water flume to investigate the effect of flowing current speed on brine water from desalination plant discharging into homogeneous, two-layer, and linear density stratification coastal waters. The submerged discharge of brine water forming the negative buoyant jet, were observed by applying the Charged Coupled Detector to grab the laser light sheet illuminated image of the brine jet. Runs for different discharging densimetric Froude numbers and ambient water current flow speeds were executed. Proper scale variables are found and used as characteristic parameters. For still or flowing homogeneous ambient water, the scaled terminal height of the submerged brine discharge grows as increasing the discharging densimetric Froude number. Increase of the flowing current speed reduces the submerged brine discharge terminal height. The density interface between two layers of ambient water inhibits the terminal height growth of the brine discharge. And the flowing current advects the brine discharge in downstream along the density interface. In the linearly stratified ambient water, the log function form of scaled inverse of flowing current speeds is found in proportional to the log function forms of scaled submerged brine discharge terminal height and attached length, respectively.
Maraqa, M. A., Ali, A. and Khan, N., 2007. Modelling Selected Water Quality Parameters at Jebel Ali Harbour, Dubai-UAE. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 794 – 799. Gold Coast, Australia, ISSN 0749.0208
Jebel Ali Free Zone in Dubai has the largest man-made harbour in the world. Several factors may affect water quality in the harbour, including discharge of treated wastewater, navigational activities, and nearby projects in the Arabian Gulf. The main objective of this study was to simulate the level of BOD and some nutrients in the harbour water under existing and potential future conditions. Modeling of water quality was carried out using the ECO Lab coupled with the advection-dispersion modules in the MIKE21 modeling system. The results showed that the input rates of BOD, ammonia, nitrate and phosphate associated with the discharged treated wastewater are not sufficient to simulate the observed levels of these parameters in the harbour water. Additional input rates of 600 times for BOD and 144 times for nitrate are needed to adequately describe the observed levels of these parameters. An assimilation capacity analysis of BOD in the harbour water revealed that the BOD starts to build up when the BOD loading rate reaches 2.88 g/m2/d, which is about 20% higher than the estimated loading rate under the current conditions. Simulations further showed that increasing the organic loading into the harbour will reduce DO and increase ammonia, but will not significantly affect nitrate and phosphate levels in the harbour water.
Minh Hang, N. T., Araki, H., Cao Don, N., Yamanishi, H. and KOGA, K., 2007. Hydrodynamics and Water Quality Modeling for the Ecosystem of the Ariake Sea, Kyushu, Japan. Journal of Coastal Research, SI 50, 800 – 804. Gold Coast, Australia, ISSN 0749.0208
In this study, a water quality model was developed to model the ecosystem in the Ariake Sea in Kyushu, Japan. The model simulates the dynamic of phytoplankton, zooplankton, nutrients, organic detritus and dissolved oxygen. Through the observed data and the simulated results, the characteristics of the sea were examined. We found that the concentrations of nutrients and other water quality constituents were high in summers, where as, dissolved oxygen concentration was low during the summer months, then elevated during the winter months. Moreover, high concentrations of nutrients and Chlorophyll-a were found in the inner part of the sea during the summer periods, when high discharge loadings from rivers and high release and resuspension from the bottom mud were predominant. Sensitivity analysis shows that the increase of nutrient loads would significantly result in the increase of phytoplankton biomass, especially during summer to early winter. The effects of loads reductions will be most pronounced in the river mouth areas.
Miner, M. D., Kulp, M. A. and Fitzgerald, D. M., 2007. Tidal Versus Shoreface Ravinement Surfaces and Tidal Inlet Fill Preservation Potential, Mississippi River Delta Plain, U.S.A. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 805 – 809. Gold Coast, Australia, ISSN 0749.0208
Barrier island and tidal inlet systems along the Mississippi River Delta Plain are undergoing rapid morphological change due to shoreface retreat and increasing bay tidal prism, driven by high rates of relative sea-level rise (RSLR) (1 cm/yr) and interior wetland loss, respectively. Two adjacent tidal inlets, Little Pass Timbalier and Raccoon Pass, exhibit contrasting morphology and sediment regimes. Little Pass Timbalier is ebb-dominated with a deep main channel (10 m), enlarging ebb-tidal delta, and negligible flood tidal delta. Contrastingly, Raccoon Pass is flood-dominated with a shallow main channel (4 m), negligible ebb-tidal delta, and enlarging flood-tidal delta.
Sediment cores, shallow subbottom profiles, and comparisons of historic bathymetric maps (since the 1800's) and recent bathymetric data allowed a determination of the depth of shoreface ravinement and the geometry and extent of tidal inlet fill deposits preserved by retreating tidal inlets. Results show that the depth of shoreface ravinement in this area is greater than 10 m, which exceeds the deepest tidal ravinement depths. Raccoon Pass has a low preservation potential due to its shallow depth and small sized ebb delta. In contrast, the prograding ebb delta at Little Pass Timbalier protects and stabilizes its deep ebb channel, which will allow backfilling of the channel to occur before complete excavation during shoreface retreat. The subsidence driven RSLR coupled with ebb-tidal delta progradation increases the potential of tidal inlet fill preservation because the distance between the tidal ravinement and shoreface ravinement surfaces is continually increasing with time.
Kulp, M. A., Miner, M. D. and Fitzgerald, D. M., 2007. Subsurface Controls on Transgressive Tidal Inlet Retreat Pathways, Mississippi River Delta Plain. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 816 – 820. Gold Coast, Australia, ISSN 0749.0208
Tidal inlets and associated barriers along the Mississippi River delta plain are migrating landward in response to rapid relative sea-level rise, backbarrier land loss, and tidal prism increases. Bathymetric data, vibracores, and high-resolution subbottom profiles are used to construct a stratigraphic model of the modern Timbalier Islands including Little Pass Timbalier and Raccoon Pass tidal inlets as well as the relict, landward Terrebonne barrier island trend. Large sand deposits comprising relict ebb deltas are associated with the Terrebonne paleo-barrier trend. Modern inlets are aligned with relict inlets. Moreover, modern inlets have migrated approximately 3 km in a landward direction during the past 100 years with little lateral migration, indicating a tendency of retreating inlets to remain fixed in former inlet channels. Cores from Little Pass Timbalier show that tidal currents are presently scouring into underlying relict Terrebonne ebb tidal delta deposits and introducing this sand into the modern littoral system. Stratigraphic data from modern inlet systems show that tidal inlet retreat paths may also coincide with former distributary channels. Finally, during periods of delta reoccupation and progradation, it appears that relict tidal inlet channels may control the pathway of advancing distributaries. Collectively, these processes lead to an amalgamation of deltaic coastal sand deposits.
Dickson, M.E, Hicks, D.M., and Coco, G. 2007. A Holocene-Scale Numerical Model of Shore Profile Evolution on an Eroding Alluvial Fan Coast, JCR SI 50 (Proceedings of the 9th International Coastal Symposium), 821 – 826. Gold Coast, Australia, ISSN 0749.0208
The Holocene evolution of beach, cliff and substrate on an idealized sand/gravel shoreface is investigated using a newly developed numerical model. The model describes a geomorphic system in which a gently sloping alluvial fan composed of sand and gravel is eroded by wave action under stable relative sea level. In this system landward erosion into the sloping surface produces cliffs that increase in height with time. Beneath water level, wave orbital motions impart stress on the seabed, which gradually lowers as a result. Excavation of the alluvial fan, both at the shoreline and in the nearshore, releases sediment that is transported onshore by wave asymmetry, building beaches. With no abrasion of the beach sediment, the beaches build to an elevation and volume that prevents erosion of the backshore, and the system progresses to a steady state where the nearshore has been excavated to closure depth. By contrast, with abrasion of the beach sediment (producing fine material that is assumed to be transported offshore and lost from the system), the beach volume reduces until the beach only provides intermittent protection against backshore erosion, leading to the formation of cliffs which, when they erode during storms, recharge the beach with sediment. In this situation, a translating shoreline develops. Depending on the various rates assumed for abrasion, seafloor lowering and cliff recession, beaches of various sizes and shapes emerge, and these provide a feedback in terms of the frequency of erosion events.
Manning, A.J.; Martens, C.; De Mulder, T.; Vanlede, J.; Winterwerp, J. C.; Ganderton, P. and Graham G. W., 2007. Mud Floc Observations in the Turbidity Maximum Zone of the Scheldt Estuary During Neap Tides. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 832 – 836. Gold Coast, Australia, ISSN 0749.0208
Significant changes of sediment concentration and shear stress can occur within an estuarine turbidity maximum. Prediction of mud transport depends on a good specification of the settling velocity and the mass settling flux. This can only be achieved by using field measurements of floc settling dynamics that can be implemented in sediment transport models. This paper describes flocculation observations conducted during a neap tide in the Lower Scheldt Estuary. The data forms part of the Deurganckdok tidal dock field survey commissioned by the Flemish government. The findings showed that within the turbidity maximum zone the suspended sediment concentration reached 277 mg l-1 and the floc mass distribution was bi-modal, with 46% of the population comprising macroflocs up to 507 µm in diameter. These macroflocs had individual settling velocities ranging from 1 to 11 mm s-1. In the turbidity maximum the macroflocs represented 88% of the floc mass, had a Wsmacro = 3.9 mm s-1 and contributed to 97% to the total settling flux. In contrast, at peak turbulence, the floc mass distribution was now weighted 58%:42% in favor of the smaller microflocs.
Cao Don, N., Araki, H., Yamanishi, H., Ohgushi, K. Minh Hang, N. T., and Tokunaga, T., 2007. Sediment transport and short-term sedimentation processes in the tidal flats of the Ariake Sea, west coast of Kyushu, Japan. Journal of Coastal Research, SI 50, 837 – 841. Gold Coast, Australia, ISSN 0749.0208
Predicting suspended sediment transport in coastal waters is an important task in coastal engineering and related areas, not only to dredging but also to living systems due to the ability of fine particles to adsorb nutrients and contaminants. In this study, the hydrodynamic characteristics of water flow and suspended sediment transport in the tidal flat of the Ariake Sea were studied using a numerical hydrodynamic mud transport model. The model was calibrated with observed water level, current, salinity and suspended solid concentration data in 2004. The model could reproduce the dynamic processes of water flow, current velocity, salinity and suspended solid concentration over the simulation period. It was found that the tidal currents play an important role in the sediment resuspension in the tidal flat area and the majority of the released sediment during both the ebb and flood tides will deposit on the tidal flats. Most of the sediment delivered by inland rivers surrounding the tidal flat is deposited in the western part of the sea.
Hanamgond P. T. and Mitra D., 2007. Dynamics of the Karwar Coast, India, with special reference to study of Tectonics and Coastal Evolution using Remote Sensing Data. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 842 – 847. Gold Coast, Australia, ISSN 0749.0208
Multi-temporal satellite data has been used for change detection (coastal erosion/accretion), identifying beach ridges and tectonic influence at Karwar coast, Central West Coast of India. The change detection study shows that the coast has experienced net erosion during the 13 years of observation. It has experienced a net erosion of 661.86 and 924 hectares during 1989-2000 and 2000-2003 respectively. This observation indicates that the erosion of land was dominant during 2000-2003. It can be noted that the amount of erosion during 2000-2003 (3 years) is 1 ½ times more than the net erosion during 1989-2000 (11 years). This could be mainly due to human interference in the form of expansion of settlements, development of industries, mining activity, establishment of Konkan railway, construction of naval base, influence of dams built across Kali River and much other interference apart from the changing weather and coastal processes that happened during the period. It is observed that the beach ridges are slowly vanishing along the coast especially at Karwar and Majali, owing to urbanisation and other developmental activities. The beach ridges at Majali are formed owing to the presence of Kangiguda Island and to some extent by Kurmagad Island, which is supporting the formation of spit at the southern end of Majali beach (northern portion of Kali River mouth) owing to tombolo effect. The entire city of Karwar has been built on numerous beach ridges. Many lineaments traversing and criss-crossing the area have been mapped which have variable extent and different azimuthal orientation as obtained by visual interpretation. The lineaments have been identified along the river course, creeks, hill ridges and they are linear and continuous. It is evident from the study of lineaments that the coast is structurally controlled. The present paper is the outcome of a study of satellite data of this coast with the available literature as supporting or ground truth input.
Pritchard, T.R., Holden, C, Lee, R.S., Black, K.P. and Healy, T. 2007. Dynamics and Dispersion in the Coastal Boundary Layer off Coffs Harbour in Eastern Australia. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 848 – 857. Gold Coast, Australia, ISSN 0749.0208
Time series analysis and model simulations defined dynamics of coastal boundary layer formation off Coffs Harbour based on four deployed acoustic Doppler current (ADCP) meters and wind data from Coffs Harbour airport. Variance preserving spectra revealed peak energies at 7.8, 3.9 and 2.5 days plus ∼24 and ∼12 hours consistent with dominant forcing by winds. At inshore sites the highest energy levels occurred at the surface and decrease uniformly with depth at all frequencies with local peaks centred at exactly 24 hours, corresponding to peak local wind energy. In contrast, offshore sites showed depth dependency in the peak spectral energy with evidence of regional influences and wave-guide effects due to density stratification. Hydrodynamic simulations using the 3-dimensional explicit finite difference model 3DD revealed local bathymetric controls on circulation. A coastal boundary layer, delineated by a shear zone ∼2km offshore in the lee of Corambirra Point, south of Coffs Harbour, was associated with formation of transient eddies. Model simulations and independent ADCP data identified 3 dimensional flow structures typified by clockwise rotation of flows down through the water column at all sites except for the quiescent, shallow water site in the headland wake south of Corambirra Point. The area south of Corambirra Point was predisposed to clockwise eddy rotation while offshore flows were generally shore-parallel. Pollutant dispersal was shown to be significantly less within this coastal boundary layer thus highlighting the need to consider effects of coastal boundary layers when locating discharges such as ocean outfalls.
Hein, C.J., Fitzgerald, D.M., and Barnhardt, W., 2007. Holocene Reworking of a Sand Sheet in the Merrimack Embayment, Western Gulf of Maine. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 863 – 867. Gold Coast, Australia, ISSN 0749.0208
Recent bathymetric, backscatter, and seafloor sediment samples demonstrate that a large sand sheet was formed in the inner shelf by the reworking of the Merrimack River lowstand delta (deposited 12 kya; currently at 45 m depth) and braid plain during the Holocene transgression. Asymmetric bedforms and distinct grain size distributions suggest the sand sheet is actively being reworked by inner-shelf processes.
Bottom sediments range from silty sand at the submerged delta to coarse sand and fine gravel in the innermost shelf (depth: 10-50 m). Coarse-grained sand comprises an expansive (32 km2) featureless sand sheet centered off the Merrimack River. Fine-grained sand discontinuously overlies this sand sheet in many locations and forms long wavelength (100 – 800 m), low amplitude (1-2 m), asymmetrical bedforms. Sets of these bedforms are oriented from slightly oblique offshore to onshore; several bedform sets are located within 1 km and oriented orthogonally to one another. Along the paleo-delta front north-northwest oriented bedforms are dominant. Inshore of these features, the bedforms become more closely spaced and have orientations to the west and west-southwest. Preliminary data suggest that the combined forces of instantaneous storm-wave generated shear stress and storm-induced currents associated with high energy northeast storm events may be responsible for sand sheet reworking and bedform development.
Park. H.-B. and Vincent, C. E., 2007. Evolution of Scroby Sands in the East Anglian coast, UK. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 868 – 873. Gold Coast, Australia, ISSN 0749.0208
Scroby Sands, a major nearshore sandbank on the East Anglian coast of the U.K., is constantly changing its configuration and alignment with the surrounding sandbanks. Analysis of sixteen charts between 1846 and 1992 shows that the area of shallowest part of Scroby (above the -5 m depth contour) has steadily increased over this period with significant movements in the north-south direction by either accumulating or redistributing sand. Numerical modelling using the TELEMAC finite element system was used to investigate the importance of hydrodynamic conditions in modifying this sandbank by simulating waves, tidal currents and sand transport over this complex region, and to suggest the future long-term morphological evolution of Scroby Sands. Waves around, and inshore of, Scroby are strongly influenced by the water depth over this sandbank; North Scroby, which is a relatively low part of Scroby, allows offshore waves to penetrate to the shore with strong refraction and energy dissipation due to the bottom friction and depth-induced breaking, while South Scroby, the highest part of Scroby, protects the shore by providing direct shelter. The spatial distribution of residual tidal currents demonstrates that the local flood-ebb asymmetry is strongly influenced by the local water depth. The sand transport/morphodynamic model suggests that Scroby evolves slowly under the action of tidal currents alone, but migration is significantly accelerated under the combined wave-tidal current action, especially with northerly storms. The bed evolution, under a variety of hydrodynamic conditions, implies that shallower part of Scroby (less than 10 m water depth) will gradually migrate to the N-NE, joining with Caister Shoal and Caister Ness through Cockle Shoal, while Caister Shoal and North Cross Sand will move to the N-NW.
Truong, T.K. and Tanaka, H., 2007. Effects of a river mouth terrace to longshore sediment transport. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 874 – 878. Gold Coast, Australia, ISSN 0749.0208
Recently, beach erosion has become a concern in Japan. Much research has studied the balance of sediment transport and influencing factors, but the influence of river mouths has rarely been of concern. For a coast including an estuary, river mouths can be seen as a source of sediment supply. However, for the case where a consolidated river mouth terrace exists, the longshore sediment transport can be intercepted, as well as the effect of jetty. Therefore, the existence of a river mouth terrace is not only the source of sediment but also intercepts the longshore sediment transport. To estimate these problems, a wide data of the river mouth and surrounding coast was used. The study area includes the Nanakita River mouth, located in the northern part of the Sendai coast, northeast Japan. Aerial photographs, taken every two months from 1990 to 2005, were used to analyze the shoreline changes and the effect of the Nanakita river mouth on longshore sediment transport. The results show that after 1998, the Nanakita river mouth terrace had no further effect of blocking the longshore sediment transport.
T. Tokunaga, N. Matsunaga and A. Takahashi, 2007. NH4+ adsorption characteristics of tidal flats along the Kumamoto coast of Ariake Sea. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 879 – 883. Gold Coast, Australia, ISSN 0749.0208
The NH4+ adsorption characteristics of sediments were investigated in sandy tidal flats along the Kumamoto coast of Ariake Sea, Kyushu Island, Japan. The vertical distributions of NH4-N and PO4-P concentrations of pore water showed that the organic substances in the seabed were actively decomposed. The values of NH4+ adsorbed to mud were evaluated by means of the extraction method using 2 mol/l KCl solutions, and they increased monotonically with the increases of the mud content and the NH4+ concentration in the pore water. It was found that in the sandy tidal flats along the Kumamoto coast of the Ariake Sea, the amount of adsorbed NH4+ to the mud was much larger than that included in the pore water and most of the NH4+ in the seabed was adsorbed to the mud, i.e., clay and silt particles.
Gibbes, B., Robinson, C., Li, L., and Lockington, D., 2007. Measurement of hydrodynamics and pore water chemistry in intertidal groundwater systems, SI 50 (Proceedings of the 9th International Coastal Symposium), 884 – 894. Gold Coast, Australia, ISSN 0749.0208
Oceanic forcing due to tides and waves results in complex and dynamic pore water flows in intertidal groundwater systems. In the presence of fresh groundwater discharge these flows are further complicated by variable density effects. The recirculation of seawater through these systems significantly influences the fate and fluxes of subsurface terrestrial contaminants discharging to coastal waters. As a result, understanding the dynamics and variability of the flow, transport and reaction processes in intertidal groundwater systems is crucial for accurate predictions of chemical loading to the receiving coastal ecosystem. Measurements of pore water flows and chemistry in the intertidal region are difficult due to the various forces acting on the system, each of which operate over a wide range of spatial and temporal scales. In this paper we provide a review of monitoring techniques that are applicable to sandy intertidal groundwater systems. In particular we focus on relatively inexpensive equipment, based on commercially available pressure transducers and water quality probes, which have been successfully employed to collect simultaneous hydrodynamic and chemical data. Results from two recent field investigations are presented to illustrate the range of measurements which can be obtained.
Bonardi, M.; Ravagnan, G.; Stirling, J.A.R.; Morucchio, C. and De Sanctis, S., 2007. Innovative treatment by bioremediation of contaminated sediments from the Venice Lagoon, Italy: the Arsenale Vecchio case study. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 895 – 899. Gold Coast, Australia, ISSN 0749.0208
Sediments in industrialized and/or urbanized coastal shallow waters have reached an alarming and harmful level of contamination that requires the development of new cost effective technologies. We report on the in situ forced aeration experiment in the Arsenale shipyard dock basin of the Venice Lagoon, Italy.
This study follows the promising results obtained by similar experiment carried out in the Industrial Harbor of Marghera, where sediment reworking and mixing are strong. The study site of the Arsenale shipyard was chosen in order to test a new forced aeration system aimed at oxygenating the surficial sediments with a minimum of reworking and mixing.
The aeration technique, chosen for the oxygenation of the highly polluted bottom sediments, is unique due to its innovative use of a system of porous pipes laid on the bottom sediments, therefore it is non intrusive and does not obstruct harbor activities.
Forced aeration consists in the introduction of a great quantitative of oxygen at the surficial sediment-water column interface with the aim of stimulating aerobic bacterial communities to create an adapt environment for the biodegradation of organic and inorganic pollutants. The general reduction of organic pollutants and heavy metals in the surficial sediments resulted in the documented return of small fish to the area as an indication of a less polluted environment. The experiment has indicated that tangential forced aeration could represent a non intrusive and cost effective way for reducing organic and heavy metal pollutants in coastal environments where other techniques may not be environmentally and/or economically feasible.
Saeedpanah, I. and Jabbari, E., 2007. Simulation of water pollution in coastal areas using combination of the Meshless Local Petrov-Galerkin scheme with radial basis functions and the fuzzy parameters. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 900 – 906. Gold Coast, Australia, ISSN 0749.0208
Randomly-changing values in time and space of different parameters such as pollutant load sources and physico-chemical coefficients is the difficulty in water with space and time is a basic problem in modeling water pollution modeling. Deterministic modeling is not adequate because it introduces crisp values of these parameters. To tackle the problem, fuzzy set theory is applied to define imprecise parameters which are used in a water pollution model. Physico-chemical coefficients and pollutant load sources are expressed in the form of fuzzy numbers. A two dimensional Meshless Local Petrov-Galerkin (MLPG) with multiquadric radial basis function (MQ-RBF) as the interpolation method combined with fuzzy arithmetic is used for the solution of the advection-diffusion equation for BOD (Biochemical Oxygen Demand) parameter. An upwind scheme is also used in order to reduce the numerical diffusion due to the convective term. The advantage of this method to the common methods in this field is that with the minimum amount of input data, one would be able to produce the necessary output due to the possibility of inputting the implicit and indefinite data in the form of fuzzy values and receiving the output in the same form, this method could replace the statistical methods. Another advantage of this method is that less input data and consequently less computation is needed. So the use of this method, in the cases that the data is not sufficient for statistical methods, could be very much successful so that the ambiguous and accidental parameters could be defined and described in the form of fuzzy data and relations.
Cooper, J.A.G., Pilkey, O.H., and Lewis, D.A. 2007. Islands behind islands: an unappreciated coastal landform category. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 907 – 911. Gold Coast, Australia, ISSN 0749-0208
The 15,000 plus barrier islands in sheltered or fetch-limited, nearshore marine waters have not achieved recognition as a distinct and important landform. As a consequence, these abundant islands have never been counted, described, measured or otherwise examined in any systematic way. About half of these islands are actively eroding, accreting or migrating in response to modern oceanographic processes, and these are the subject of this study. The other half are inactive islands enclosed by salt marsh or mangroves which are shorter than ocean barriers (average 1 km), but evolve via the same processes. Overwash is almost always the dominant process, while dune building is only important locally.
More than 70% of fetch-limited barrier islands are found on trailing edge coasts where conditions are favourable for formation of sheltered waters under a rising sea level. Active fetch-limited barrier islands are found in estuaries and bays (Chesapeake Bay, USA); behind ocean barriers (Pamlico Sound USA); adjacent to inlets (Tapora Bank New Zealand); rimming deltas (Menderes River, Turkey); eroding thermokarst (Yensei Bay, Russia); and glacial outwash fans (Canal Baker, Chile). Understanding the highly variable processes of evolution of these islands should be a high priority, because sheltered barriers are becoming the next frontier of coastal development. The aim of this paper is to describe the geomorphology of islands within the sheltered settings produced in barrier lagoons, and to discuss the management issues associated with their human occupation and use. Examples from lagoons of the eastern United States and the Gulf coast of Mexico are discussed.
Lewis, D.A., Cooper, J.A.G., Pilkey, O.H., and Short, A.D 2007. Fetch-limited barrier islands of Spencer Gulf, South Australia. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 912 – 916. Gold Coast, Australia, ISSN 0749-0208
Islands that form in fetch-limited coastal environments are widely distributed but poorly documented and seldom recognised as a distinctive landform type. They occur in a variety of sheltered coastal environments worldwide. In the upper Spencer Gulf, South Australia abundant barrier islands (numbering around 340) are arranged in shore-parallel lines associated with Holocene sea-level fall. They occur on the upper sheltered gulf shoreline, and also within adjacent embayments (Cowell Bay), but are absent from higher energy stretches of the lower gulf. The islands average 400m long and just a few tens of metres wide. Mangroves grow on some of the wide accretionary platforms seaward of the islands. Barrier islands exist both in front of and behind mangroves, and are composed of mainly sand-sized skeletal carbonate debris. Landward of the actively forming islands are several earlier islands that are separated by supratidal flats that are periodically active when flooded by spring high tides. A variety of plan form morphologies are identified, and there is a strong vegetational control on island geomorphology. Most island modification is ascribed to storms which are effective despite fringing mangroves.
Fontolan, G., Pillon, S., Delli Quadri, F., and Bezzi, A., 2007. Sediment storage in the northern Adriatic ebb-tidal deltas, Italy: sand use potential and GIS database. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 917 – 921. Gold Coast, Australia, ISSN 0749-0208.
Tidal inlet morphodynamics have often resulted in conflicting situations with the navigation and maritime uses of the lagoon areas in the northern Adriatic Sea, Italy, where important industries and harbours are located. Many of the inlets are now rigidly stabilised by jetties; others are managed through periodic excavations. A new automatic geostatistical procedure has been developed for the ebb-tidal delta volume calculation and applied on five relatively natural inlets. Sand storage potential varies considerably, as a function of the tidal prism, from ca. 0.27 · 106 to 11· 106 m3. Our results compare well with the volumes obtained from the application of the Hicks and Hume (1987) relationship. Spatial queries from GIS emphasise that a significant amount of the ebb delta material consists of more than 1-m-thick sand deposits, thus suitable for dredging and re-use. A GIS catalogue of the different lithologies, obtained through specified inquiry about mean grain-size and sorting, may be a useful tool for a beach nourishment plan for the neighbouring erosional beaches.
Dougherty, A.J. and Nichol, S.L., 2007. 3-D Stratigraphic models of a composite barrier system, northern New Zealand. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 922 – 926. Gold Coast, Australia, ISSN 0749-0208
This paper presents for the first time, detailed three-dimensional stratigraphic models of both the Holocene and Pleistocene components of a double barrier using ground-penetrating radar. The study focuses on a composite Quaternary barrier system located in Bream Bay, north-east North Island, New Zealand. This coastal compartment maintains a mesotidal environment with low to moderate wave energy. The Holocene barrier has prograded over the last 6500 years during a relative sea-level still stand, or at most 2 metre fall, resulting in a hummocky dune morphology. In contrast, the Pleistocene barrier was formed during rapid sea-level fall towards the end of the Last Interglacial (oxygen isotope 5e to 5a), which resulted in a forced regression producing linear beach ridges. The sublithified nature of these barrier sediments is conducive to utilising both coring and ground-penetrating radar techniques. This study uses standard sedimentological analysis to ground-truth multiple GPR transects collected over the width of both barriers. This method was employed in order to reconstruct the subsurface stratigraphy in detail and to compare barrier structure over the timescale of successive sea-level highstands. The resulting two- and three-dimensional GPR records all show detailed stratigraphy of a regressive facies succession with similar architecture. However, slight differences in spacing and geometry between beach facies were detected in association with the different dune morphologies from each timeframe. While both beach facies are laterally continuous and dipping in a seaward direction, the Holocene stratigraphy exhibits a more closely-spaced, curvilinear cross-sectional geometry consisting of medium sand and shells; whereas the Pleistocene barrier beachface is highlighted by heavy mineral-rich, fine-grained sands showing a similar concave shape in the large scale, but at a more regularly-spaced interval associated with individual beach ridges. The replication of this stratigraphic form at successive sea-level highstands within the beachface indicates that present-day intermediate nearshore conditions are similar to those of the last interglacial highstand. The overall evolutionary sequence for each barrier differs in width, morphology and stratigraphy due to a combination of factors, including variations in sediment supply, accommodation space, and relative sea level within successive highstands.
Hart, D.E., 2007. River mouth lagoon dynamics on mixed sand and gravel barrier coasts. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 927 – 931. Gold Coast, Australia, ISSN 0749.0208
This paper examines the dynamics of river-mouth lagoons on mixed sand and gravel coasts receiving high wave energy. The role played by rivers in these non-estuarine systems is recognised as essential for carving out space for the coast-parallel waterbody, defining its physical scale, and for driving cycles of lagoon behaviour from closure to breaching. The role played by waves, by contrast, is not fully recognised in that it is limited to barrier building across river mouths and gradual lagoon-outlet offsetting along the shore. Field observations and water-level records were used in combination with river-flow, wave, and hourly-camera records at the Ashburton river mouth, New Zealand, to establish the importance of wave versus river forcings of lagoon dynamics. Several new behaviours were identified, including storm-induced lagoon breaching, rapid longshore migrations in outlet position and outlet channel truncations in response to storm-wave overtopping. Similar dynamics forced by combined river-flood and storm events were also common. Despite the observed complexity of river, wave and lagoon processes, characteristic morphologies and equilibrium states were apparent, with the lagoon appearing to be dominated by wave processes at all but the highest river-flow stages. Analysis of the frequency of the observed events is used as the basis of a new understanding of lagoon behaviour, from which management implications are drawn.
Bruneau, N.; Bonneton, P.; Pedreros, R.; Dumas, F. and Idier, D., 2007. A New Morphodynamic Modelling Platform: Application to Characteristic Sandy systems of the Aquitanian Coast, France. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 932 – 936. Gold Coast, Australia, ISSN 0749.0208
Along coasts, waves and wave-induced currents are the main factors of morphological evolution. A morphodynamic model is constructed to take into account tide changes, wind conditions and waves in the computation of the induced currents and morphological evolution. The spectral wave model SWAN, the shallow-water model MARS and a sedimentary module are coupled to create the morphodynamic model. First, we validate the hydrodynamics of the model on two characteristic complex bathymetries: an idealised subtidal crescentic bar and an intertidal ridge and runnel system. The crescentic bar induces wave energy focalisation zones which could give rise to transverse bars. Thus, we investigate the morphology evolution of the intertidal area. Simulations appear to show the formation of inner bars that connect the subtidal bar with the intertidal area.
Guard, P., Teakle, I., Nielsen, P. and Baldock, T.E., 2007. Modelling Sheet Flow Sediment Transport Using Convolution Integrals. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 937 – 942. Gold Coast, Australia, ISSN 0749.0208
A new method for the prediction of instantaneous sediment transport rates is presented based on the use of convolution integrals. The convolution integral technique allows solution of the governing differential equations in the time domain while accurately representing important unsteady flow effects. This technique overcomes many of the limitations of simple quasi-steady sediment transport models and does not require the computational effort of more detailed process-based models. The present model has been parameterised using results from a more detailed process-based two-phase model. Preliminary results indicate that the technique is successful in predicting net transport rates in oscillatory flow tunnel experiments in the sheet flow regime. Extension of the model to other sediment transport regimes and incorporation of real-wave effects such as boundary layer streaming is possible.
Jabbari, E. and Saeedpanah, I., 2007 Simulation of sediment transport in coastal areas with Meshless Local Petrov-Galerkin scheme. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 943 – 948. Gold Coast, Australia, ISSN 0749.0208
The phenomenon of sediment transport plays an important role in the design of coastal structures. Lack of enough attention to the sediment transport process at coastal areas would cause considerable problems distribution such as filling the ports basins by sediment in a short time. In this paper, the truly Meshless Local Petrov-Galerkin (MLPG) scheme is extended for computation of concentration distribution of suspended sediment in depth and at different distances from a coast line, governed by the time-averaged advection-diffusion equation. The present method is a truly meshless method based only on a number of randomly located nodes. The meshless method is based on a local weighted residual method with the Heaviside step function and quartic spline as the test functions respectively over a local subdomain. Moving Least Square approximation (MLS) is employed in shape function construction for approximation of a gauss point. Due to dissatisfaction of kronecker delta property in MLS approximation, the penalty method is employed to enforce the essential boundary conditions. The results of the simulations were compared with the results of the simulations done by van Rijn. The comparison of computational results shows that the developed method is capable of accurate resolution of concentration distribution of suspended sediment at depth and in different distances from the coast line.
Ceyan, E., Basuchowdhuri, P., Judeh, T., Ou, S., Estrade, B., and Kosar, T., 2007. Towards a faster and improved ADCIRC (Advanced Multi-Dimensional CIRCulation) model. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 949 – 954. Gold Coast, Australia, ISSN 0749.0208
Given the aftermaths of Hurricane Katrina in New Orleans and the surrounding parishes, the need to predict tropical storms and hurricanes has increased multifold. Accurate predictions may assist decision makers to implement appropriate evacuation plans necessary for the wellbeing of citizens. Coastal modelling is a key tool used to foresee hurricanes, storm surge and flooding. Of the many models implemented, ADCIRC, a project of the University of North Carolina, seems to hold much promise. Our objectives in this study were multifold. First, we ascertained the current limitations of the ADCIRC model. We achieved this goal through a variety of means including ADCIRC benchmarks on single and multiple clusters as well as a gprof profile of ADCIRC on a single cluster. Then, based on the information obtained from these efforts, we suggested appropriate improvements to optimise ADCIRC. With the achievement of these objectives, we hope ADCIRC will become a vital tool in developing accurate evacuation plans under duress that will aid in saving a countless number of lives.
Mackey, R., 2007. Rhodes Fairbridge and the idea that the solar system regulates the Earth's climate. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 955 – 968. Gold Coast, Australia, ISSN 0749.0208
Rhodes Fairbridge died on 8th November, 2006. He was one of Australia's most accomplished scientists and has a special connection with Australia. In July, 1912 his father Kingsley established Fairbridge Village near Perth. It contains a chapel of elegant simplicity designed by one of the world's most famous architects of the time, Sir Herbert Baker, as a labour of love to commemorate Kingsley. Rhodes is one of the few scientists to research the sun/climate relationship in terms of the totality of the sun's impact on the earth (i.e. gravity, the electromagnetic force and output and their interaction). When the totality of the sun's impact is considered, having regard to the relevant research published over the last two decades, the influence of solar variability on the earth's climate is very strongly non-linear and stochastic. Rhodes also researched the idea that the planets might have a role in producing the sun's variable activity. If they do and if the sun's variable activity regulates climate, then ultimately the planets may regulate it. Recent research about the sun/climate relationship and the solar inertial motion (sim) hypothesis shows a large body of circumstantial evidence and several working hypotheses but no satisfactory account of a physical sim process. In 2007 Ulysses will send information about the solar poles. This could be decisive regarding the predictions about emergent Sunspot Cycle No 24, including the sim hypothesis. According to the sim hypothesis, this cycle should be like Sunspot Cycle No 14, and be followed by two that will create a brief ice age. During the 1920s and ‘30s Australia’s Bureau of Meteorology published research about the sun/climate relationship, especially Sunspot Cycle No 14, showing that it probably caused the worst drought then on record.
Pranzini, E. and Rosas, V., 2007. Pocket beach response to high magnitude – low frequency floods (Elba Island, Italy). Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 969 – 977. Gold Coast, Australia, ISSN 0749.0208
A megaflood, with an estimated recurrence time of approximately 200 yr, affected the Elba Island in September, 2002. In several pocket beaches, active and reactivated creeks discharged a huge volume of unsorted sediments to the coast. Since the morphological and sedimentological conditions of one of these bays (Gulf of Procchio) was known due to topographic and sedimentologic studies performed in 1999, the impact of this event was easily evaluated through a survey performed a few days after the flood. The main beach responses were the formation of ring deltas, the increase of the fine fraction in the nearshore sediments and the coarsening of those in the swash zone.
A further survey in 2004 allowed monitoring the recovery of the beach, which is still returning to the pre-event conditions, at a slow rate. Although only the widest delta among those formed is still identifiable on the shoreline, and in spite of the nearshore sediments having lost all the fines, gravel and cobbles are still present from the step to the berm crest in the sectors adjacent to the old outlets and gravel is moving alongshore. The erosion that affected some pocket beaches at Elba during the second half of the 20th century, firstly attributed to the agriculture abandonment and to the consequent forest recovering, now has a new or additional cause: the return of the bay to pre-flood conditions within cycles of catastrophic accretion followed by mild erosion.
Yamada, F., Uehara, K., Hokamure, T. and Yamabe, T., 2007. Morphology and seasonal evolution of intertidal multiple sand bars in low wave environment. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 978 – 984. Gold Coast, Australia, ISSN 0749.0208
The morphology of intertidal multiple sand bars of Okoshiki Beach in Ariake Bay, Japan is examined to provide insight into the factors controlling the bar characteristics in the low wave environment. Cross-shore profiles of intertidal multiple sand bars were measured monthly for 2 years from July, 2003 to July, 2005. Each measured profile is separated into a mean profile and a bar geometry using quadratic polynomial fitting. Superimposed on the mild foreshore (1/250) are at least seven low height (0.1-0.6m) ridges with an average wavelength of 40 m. The sand bar morphology appears to be a permanent feature in both form and position. Probability density functions of bar height and length have indicated that their distributions can be approximated well using standard normal distributions. These results may suggest that the genesis of multiple sand bars has a different mechanism comparing to that of wave-generated ripples. The bars occur approximately between the mean high and low water levels during neap tides. This bar zone is related to the zone where the tidal shoreline velocity is largest in the cross-shore.
Jesus, C.C., Miranda, P., Rocha, F. and Oliveira, A., 2007. Fine-fraction mineralogy and geochemistry of beach sediments of SW Portugal as markers of sedimentary dynamics. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 990 – 994. Gold Coast, Australia, ISSN 0749.0208
Mineralogy and geochemistry of fine-grained sediment fractions have been used since the 1960-ies to identify sediment source. Along the Tróia-Sines littoral-arc (SW Portugal) 126 beach-dune profiles have been sampled as well as sea-cliffs and watercourses located close to the study area. Mineralogical analysis of the fine sediment fraction was carried out by XRD, and multi-elemental analysis by ICP-MS was used to determine total Fe, Al, Mg, Ca, K, Sr and Mn. For all fine-fractions only eight different minerals were identified. Their percentages vary significantly: quartz (8-85%), phyllosilicates (1-68%), K-feldspars (2-32%), plagioclases (0-21%), magnesium enriched calcite (0-28%), calcite (0-46%), aragonite (0-32%) and goethite (0-18%). On the basis of mineralogy and geochemistry the studied area can be subdivided into three sectors: 1) northern sector between Tróia and the Carvalhal beach where the Sado estuary, benthic macrofauna communities and the littoral drift constitute the main sediment sources; 2) central sector between Carvalhal and the Melides beach where sea-cliffs are the only identified sediment source; 3) southern sector from Melides to Cape Sines where the volcanic massif and the sea-cliffs were identified as the main sediment sources to the beach system. We conclude that the mineralogical and geochemical composition of the fine sediment fraction provides provenance information for beach and dune sediments, complementing traditional provenance studies with coarser fractions.
Plecha, S., Sancho, F., Silva, P. and Dias, J.M., 2007. Representative waves for morphological simulations. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 995 – 999. Gold Coast, Australia, ISSN 0749.0208
In the present study, a set of representative waves is derived for the coast adjacent to the Ria de Aveiro, such that it is morphologically equivalent to the complete wave regime. Different schematising methodologies are presented, based on the principles of conservation of wave energy and equivalent longshore sediment transport capacity over the beach profile. Firstly, the sediment transport capacities due to the whole set of waves is computed and then various sets of representative waves are proposed based on the principles above. The most suitable set is selected by taking into account the dominant sediment transport processes at the selected site. The representative waves can be used to significantly reduce computational time in morphological models, by reducing the number of different sea states that characterise the annual wave climate. This simplified nearshore wave regime shall provide the wave effects into the sediment transport formulae and the hydrodynamical model.
Vaz, N., Leitão, P.C. and Dias, J.M., 2007. Channel-ocean exchange driven by tides and river flow: Espinheiro Channel (Portugal). Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1000 – 1004. Gold Coast, Australia, ISSN 0749.0208
A 3D baroclinic model (Mohid) was used to perform hindcast simulations in a tidal channel – Espinheiro Channel (located within Ria de Aveiro, north coast of Portugal) – in order to study its hydrography. The simulations were conducted for four distinct periods where markedly different river discharge and tides occurred and the outputs are compared with synoptic thermohaline data. The model qualitatively reproduces along-channel thermohaline distributions at three different vertical levels during low-to-medium river inflow, underestimating the salinity stratification under high river inflow (higher than 100 m3s-1). Once the numerical model is fully implemented, the hydrography of the channel was analysed in terms of two main forcing factors: river discharge and tide. Tidal currents and thermohaline data were analysed at the channel's inlet and at a mid channel station during two tidal cycles. The stratification and water column stability were found to vary in these stations as a function of the estuarine Richardson number and the buoyancy frequency. Well mixed conditions were found at the lower and mid channel area when the river flow is weak (independently of the tidal regime), turning to highly stratified when the river flow is very high (during neap tide). The residual currents were also analysed revealing an ebb-dominated channel, with a more intense seaward current near the surface due to the freshwater inflow.
Abrantes, I. and Rocha, F., 2007. Sedimentary dynamics of the Aveiro shelf (Portugal). Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1005 – 1009. Gold Coast, Australia, ISSN 0749.0208
Clay mineralogy of 95 surface sediments samples of Aveiro shelf (covering the continental shelf and upper slope from Espinho to Aveiro) have been analysed in order to determine sediment provenance, dispersion and deposition of fine-grained sediments. A semi-quantitative X-ray diffraction study of the clay fraction (<2 µm) has been carried out, using peak areas. Illite (average 59%), kaolinite (average 30%), chlorite (average 5%) and smectites (average 5%) are the major clay mineral groups identified. A terrigenous origin of these clay minerals can be supported by their presence in the bottom and suspended sediments of Douro river and Ria de Aveiro lagoon and in the adjacent continental masses. However, the smectites minerals found near Aveiro Canyon may be of an authigenic origin. The main source of fine sediments to the studied area is Douro River discharge through along-shore currents. Other supply processes are coastal erosion and Ria de Aveiro lagoon discharge. The occurrence of kaolinite in coarse-grained deposits is probably related with relict supply processes. The patterns of mineral distribution in the studied clay fraction suggest preferential offshore transport and deposition in lower energy environment of outer shelf and upper slope.
González-Villanueva, R., Costas, S. Alejo, I. and Pérez-Arlucea, M., 2007. Morphological changes forced by the tidal cycle in a low estuarine beach. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1010 – 1014. Gold Coast, Australia, ISSN 0749.0208
The aim of this study is to analyse the morphological variations of a low energy estuarine beach during a tidal cycle. Following this purpose, two surveys were deployed under contrasted hydrodynamic conditions at the beach face of Ladeira Beach (NW Spain). Data and field observations provided an elaborate two-phase sequence to explain the evolution of the morphological changes occurred during a tidal cycle. The first phase is characterised by a minor accretion landward and seaward from the breaking zone. The second phase is characterised by erosion seaward from the breaking zone. The balance between both phases determines the cross shore sediment transference and therefore, morphological changes along the beach face. This behaviour may be altered by the presence of fixed structures truncating the foreshore or by the fluctuations of the water table. Simultaneously, measurements of activity depth were carried out, suggesting that this parameter mainly depends on the ratio between sea level and water table level position.
Choi, K. H.; Yoon, K. S.; Choi, J. H.; Shin, Y. K.; Lee, J. C.; Suh, M. H.; Munyikwa, K., and Oh, K.H., 2007. Anthropogenic geomorphological changes during the last century in the Kangneung area along the east coast of Korea, Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1015 – 1022. Gold Coast, Australia, ISSN 0749.0208
Geomorphological changes in the Kangneung area along the east coast of Korea were studied through analysis of topographic maps, aerial photographs and sedimentological characteristics of the coastal deposits. Luminescence dating techniques were used to provide depositional chronologies of the sediments. The study area can be classified into various landforms that include beaches, dunes, lakes, rivers, flood plain, coastal terraces and wetlands. Over the last century, among these landforms, Lake Poongho was most seriously damaged and the dune structures were also affected by human interferences. Anthropogenic activities ranging from agriculture to land reclamation and urbanization are the main causes for these changes. In particular, rapid changes were observed in the area in the 1970s with the construction of a huge, coal-fired power plant and the erection of a groyne. Lake Poongho had initially formed at least 2 ka ago when an estuary of the Shidong Stream was blocked by the growth of barriers. At the turn of the century, the dune field was twice its present size, and the foredune was higher than at present. Over the last 90 years, however, the lagoon diminished in size as a result of agricultural activities in the hinterland. During the last 30 years, it almost disappeared completely when coal ashes from the coal fired power plant filled it up. The beach-dune interactions and their landforms have also been affected by other human activities including sand mining, planting of trees, and construction of buildings and groynes. As a result, many slacks and swamps have disappeared and the grain size distributions of the beach and dune sediments are also changing. The results of this study highlight the loss of natural coastal landscapes that date from two thousand years ago as a result of anthropogenic activities which have occurred over the last few decades.
Y. Sakuno, 2007. Anoxic water distribution in Hiroshima Bay. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1023 – 1028. Gold Coast, Australia, ISSN 0749.0208
The objective of this research is to estimate the summertime distribution of anoxic water in the northern part of Hiroshima Bay using thermal infrared (TIR) sensor images captured by the ASTER (90-m resolution) and MODIS (1-km resolution) sensors aboard the Terra and Aqua satellites (launched in 1999 and 2002, respectively). The known strong correlation between (i) the difference (dT) in surface water temperature (Ts) and water temperature at the sea bottom (Tb) (index of stratification) and (ii) the summertime dissolved oxygen at a sea bottom (DOb) was used to estimate the distribution of anoxic water from the satellite/TIR images. This relationship was also verified from field data obtained in August from 1994 to 2003 (10 years). In addition, Ts can now be estimated from satellite/TIR data because of the strong correlation between Ts and dT. The relationship between the radiance of these satellites/TIR data and Ts showed a very strong correlation. The DOb distributions estimated from ASTER and MODIS data using these relations was mostly in agreement with observed distributions. These results demonstrate that satellite TIR data are an effective tool in estimating the distribution of anoxic water.
Kim, Y.T., Lee, J.I. and Heo, J.W., 2007. Stability of armour block at Starting Part of Seawall. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1029 – 1033. Gold Coast, Australia, ISSN 0749.0208
The purpose of the research is to investigate hydraulic stability of the seawall at Jungjuk Island, which is a part of the Busan-Geoje Fixed Link Project in Korea. Jungjuk Island is exposed to extreme waves and high water levels during typhoons from southerly directions. The main function of the seawall is to protect immersed tunnels and tunnel portal structures from the heavy wave impacts and flooding. In this study, a series of experiments were performed to investigate stability of various designs for the seawall and an optimum cross section among the proposals was suggested.
Hudson formula or van der Meer formula (CIR/CUR, 1991) is normally used to assess weight of armour blocks for perpendicularly incident waves. The experiments showed that the design of the seawall based on the formulas were comparatively stable enough to satisfy the design condition for the trunk part where waves propagated almost perpendicularly. However, the design was found to be not stable enough for the starting part where strong wave breaking induced currents and big waves due to the geomorphologic characteristics occurred and impacted the seawall. For usual breakwater designs, the weight of an armour block used at a head part is 1.5 times that at a trunk part, whereas there are no regulations for a starting part. From the laboratory study, this research suggests there is a need to consider the area (starting part).
Dias, J.M., Abrantes, I. and Rocha, F., 2007. Suspended Particulate Matter Sources and Residence Time in a Mesotidal Lagoon. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1034 – 1039. Gold Coast, Australia, ISSN 0749.0208
In the frame of this work the suspended particulate matter (SPM) concentration was measured in February 2002 in seven sites of Ria de Aveiro (located in its four main channels) during one tidal cycle of a neap tide event (at approximately 2-hour intervals, including high tide and low tide measurements) and its mineralogical composition was identified.
The purposes of this work are to identify the main sources of sediments for these locations (ocean or rivers), as well as to determine the sediments residence time for this locations and their paths along the channels. The methodology adopted consisted in applying a lagrangian model coupled to a previously calibrated hydrodynamic model of Ria de Aveiro to study the dispersion and mixing processes of passive particles during the sampling period. Considering the sediments represented as passive particles, lagrangian models allow the simulation of sediments transport paths and the computation of residence times. Several simulations were performed in order to simulate the surveys conditions and understand the dynamics and origin of measured SPM.
The model results are supported by textural, mineralogical and concentrations field data, revealing that it may constitute an important tool to study the lagoon sediments dynamics and origin.
Machado, A., Rocha, F., Gomes, C. and Dias, A., 2007. Distribution and Composition of Suspended Particulate Matter in Guadiana Estuary (Southwestern Iberian Peninsula). Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1040 – 1045. Gold Coast, Australia, ISSN 0749.0208
The construction of the Alqueva Dam may have a significant impact on the suspended sediment concentration (SSC) of the Guadiana River, its estuary and coastal zone. Suspended particulate matter (SPM) was collected along the Guadiana Estuary at distinct river flow and tidal conditions. 84 samples of SPM were collected during low and high spring tides, in November 2000 and February 2001, respectively. During November 2000, in low-runoff conditions, the mean SSC value was 32.45 mg/l and the highest values were found at 20-30 km, upstream of the river mouth. However, after short periods of heavy rain, the SSC increased in the water column and the highest values (501.6 mg/l) were found near the river mouth. In what concerns the mineralogical composition, the main minerals in SPM are phyllosilicates, quartz, plagioclases. Illite, kaolinite, chlorite, smectite and irregular illite-smectite mixed-layers are the main clay minerals. In low-runoff, the increment of quartz and illite concentrations seems to be associated to the entrance of saline water in the estuary and, consequently, to flood-tide flows. Kaolinite relatively to illite, exhibits an opposite behavior, indicating that its source is largely continental. The total contents of phyllosilicates and, particularly, chlorite enrichment during the flood-situation seems to be associated to low-tide flows being exported to the adjacent shelf. This study confirms the importance of energetic events, in transferring particles to deeper domains, while during low runoff the main trend is the import from the adjacent ocean.
Kim, I.H and Lee, J.L., 2007. Changes in the sediment transport pattern after breakwater extension at Anmok Port, Korea. Journal of Coastal Research, SI 50, 1046 – 1050. Gold Coast, Australia, ISSN 0749.0208
The breakwater extension at Anmok Port has resulted in erosional stresses along the shoreline immediately south of the port. In this study, the downdrift affects caused by the breakwater extension are investigated through both analytical and numerical model approaches. The analytical approach is accomplished through littoral drift vectors which are estimated in this study from measured volumetric changes by using an inverse matrix. The model has five components including a parabolic equation for wave transformation from the deep ocean to the coastal region, depth-integrated shallow water equations for calculating coastal current, diffusion-advection equations for sediment transport and a mass conservation equation of bottom-layered sediments for predicting depth changes. Analyses of sand transport processes in the vicinity of Anmok Port resulted in the conclusion that a heavy eddy generated in a sheltered zone is the predominant erosion mechanics at the site and therefore, the bypassing system is considered as a necessary device in order to basically solve the concurrent problem such as heavy accumulation of sediments in a port entrance and the closure of a stream mouth in the east coast as well as the eroding problem.
Al Hulail, F. and Al-Salem K., 2007. Laboratory verification of a numerical model of wave diffraction and refraction around islands and shoals. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1051 – 1055. Gold Coast, Australia, ISSN 0749.0208.
A combined wave refraction and diffraction numerical model for predicting the wave conditions around the presence of an island was evaluated in the present study with various laboratory test conditions. The model was developed by LO (1991) for predicting wave conditions for large coastal areas. Two sets of laboratory data (ITO AND TANIMOTO, 1972; BERKHOFF et al., 1982) were selected for comparison with the prediction of LO'S model; however, the two data sets are for cases of submerged shoals and not for an island's conditions. Therefore, a laboratory study to simulate the wave characteristics around an island with a mildly sloping shoreline has been completed in the Hydraulics lab at Kuwait Institute for Scientific Research (KISR) to validate the assumption used in LO'S wave refraction and diffraction numerical model for an island.
After comparing the laboratory test results with the numerical model predictions, the following conclusions and recommendations are made: for submerged shoal conditions, the laboratory test results and the numerical model's predictions compare in both wave height and wave direction; while for island condition, there is good agreement in both wave height and wave direction in most measured locations, although near the centre area, the predicted wave height is much higher than that measured. Based on the present study, the numerical model can be applied to predict wave conditions around an island but the predictions near the centre area are questionable.
Wang, X.C., and Zhao, H.M., 2007. Uptake and Biodegradation of Polycyclic Aromatic Hydrocarbons by Marine Seaweed. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1056 – 1061. Gold Coast, Australia, ISSN 0749.0208
The distribution and fate of polycyclic aromatic hydrocarbons (PAHs) in coastal waters are of global environmental concern due to their mutagenic and carcinogenic effects within ecosystems. In this study, we investigated the uptake and biodegradation of two PAHs (phenanthrene and pyrene) by a brown seaweed Laminaria joapnica, a common macrophytic plant grown in the near shore waters along the East China coast. In laboratory culture, the seaweed showed great ability to take up and metabolise phenanthrene and pyrene. The uptake and degradation appeared to be rapid processes and concentration-dependent. At a PAH concentration level of 0.1mg/l, Laminaria joapnica tolerated and survived well for up to two weeks and > 90% phenanthrene and pyrene were removed and subsequently degraded. The metabolism of phenanthrene and pyrene in seaweed tissues was carried mainly by the enzyme-oxidation process converting PAHs to less or non-toxic forms of compounds. At high concentration levels (> 0.2 mg/l), however, the toxic nature of PAHs to the seaweed was significant, and resulted in serious damage and destruction to tissue. Our study suggests that in natural PAH contamination levels found in coastal waters, Laminaria joapnica could play an important role in removing PAHs and possibly other organic pollutants from sea water, thus serving as an ‘environmentally-friendly’ bioremediation system protecting ecological health and marine life.
Chen, H.B., Tsai, C.P. and Jeng, C.C., 2007. Wave transformation between submerged breakwater and seawall. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1069 – 1074. Gold Coast, Australia, ISSN 0749.0208
This paper presents the experimental results of wave transformation between a submerged permeable breakwater and a seawall including variations of the wave profile, the piling-up of water and the wave run-up. The results show that the wave height transformation behind the submerged breakwater varies in spatial due to the transmitted wave being reflected from the seawall. The energy transfer from the fundamental harmonic to higher frequencies due to the submerged breakwater was also investigated. The piling-up of water behind the submerged breakwater also varies spatially, where the maximum occurs about in the middle area of these two structures. The height of piling-up decreases as the freeboard of the breakwater increases, from which the empirical equation is presented in this paper. As comparing to the case of no submerged structure in front of a seawall, the result shows that the installation of the submerged permeable breakwater is capable of reducing the wave run-up on the seawall efficiently.
Sousa, M. C. and Dias, J. M., 2007. Hydrodynamic model calibration for a mesotidal lagoon: the case of Ria de Aveiro (Portugal). Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1075 – 1080. Gold Coast, Australia, ISSN 0749.0208
Ria de Aveiro is a shallow vertically homogeneous mesotidal lagoon, located in the Northwest of Portugal. It has a very intricate morphology and large tidal flats areas that cover and uncover along the tidal cycle. A two-dimensional vertically integrated hydrodynamic model was considered to be adequate to simulate its hydrodynamics and a model developed from the SIMSYS2D model was applied. The purpose of this study is to describe the implementation and calibration of this model which is able to predict tide-induced water level and depth integrated velocity for the entire lagoon. The numerical bathymetry used was developed from data concerning depth obtained from a general survey carried out in 1987/88 and actualised for several channels in the last years. The Monte Carlo method was used to generate the rectangular computational grid, which has 409 cells in the eastward direction and 966 cells in the northward direction (dimensions of 40×40 m). The model calibration was performed adjusting the bottom friction coefficient for the entire lagoon, through the comparison between measured and predicted time series of sea surface elevation (SSE) for a large number of stations distributed along the main channels of the lagoon. The relative mean absolute error, the root-mean square and a skill assessment of the difference between those SSE values were determined to quantify the models performance. Harmonic analysis was also performed in order to evaluate the model accuracy. According to the results the hydrodynamic model was successfully calibrated, reproducing accurately the barotropic flows in this complex lagoon.
Kang, J.W., Moon, S.R and Lim, H.S. and Lee, J.L., 2007. Surge-wave combined inundation at Mokpo North Harbour, Korea. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1081 – 1085. Gold Coast, Australia, ISSN 0749.0208
Tidal amplification by construction of the sea-dike and sea-walls had been detected not only near Mokpo North Harbour but also at Chungkye Bay which is connected with Mokpo North Harbour by a narrow channel. This brings about increase of tidal flat area and in particular increase of run-up height and inundation area during storms. In this study, the simulation process is composed of wind wave generation model for large area and wave inundation model for small coastal area. The nonlinear version of mild-slope equation is modified for simulating the wind-driven surge and wave inundation at a small area. The models are applied to Chungkye Bay and possible inundation features at Mokpo North Harbour are investigated.
Sennes, G., Castelle, B., Bertin, X., Mirfenderesk, H. and Tomlinson, R.B., 2007. Modelling of the Gold Coast Seaway tidal inlet, Australia. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1086 – 1091. Gold Coast, Australia, ISSN 0749.0208
The Seaway entrance is a tidal inlet located on the Gold Coast (Queensland, Australia). Before the 80s, the entrance was highly variable in terms of inlet location and sand bar characteristics. The Seaway stabilisation with two training walls combined with an artificial sand bypassing system were completed in 1986 with the aims of fixing the entrance, maintaining a safe navigable channel, preventing shoreline erosion to the north and a buildup of sand to the south. Despite these training works, the dynamics of the Seaway is still poorly understood: channel infilling problems and navigation issues remain. For these reasons, the present study aims to develop a comprehensive model of the entrance to be used for further dredging and training work issues. The present investigation is carried out in two stages. The first stage is based on historic aerial photograph analysis of the Seaway before training works. It shows that the mouth was periodically driven northward by the longshore drift, with an average cycle time of 10 years. The second stage is based on numerical modelling after training works. Refined Delft3D modelling is undertaken with a 2DH approach on the Seaway area, taking into account the training walls and the sand bypassing system. This local model is coupled with MIKE21 implemented on a regional scale to provide accurate tide and flow forcing at the boundaries. After calibration, the analysis of flow patterns shows that the Gold Coast Seaway is ebb-dominated and that the more intense flow velocities are observed in the northern channel. Morphological evolution of the inlet is also investigated with a qualitative approach. Results indicate the pathways and rate of the sand movement within the tidal inlet in its current configuration and provide information about a planned 400 m extension of the southern training wall. A significant calibration work, involving sediment transport and bathymetry measurement, is required for the model to be used as a comprehensive tool for further dredging and dumping strategies within the entrance.
Bernardes, C. and Rocha, F., 2007. Temporal evolution of the sand-spit between Torreira and Furadouro (NW Portugal). Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1092 – 1096. Gold Coast, Australia, ISSN 0749.0208
Dune systems comprise about 60% of the Portuguese coast but they are best developed in northern areas, where they form an extensive sand plain. The dunes display several stratigraphic evidences for a long period of sand accumulation during the Holocene, related with sea level rise. Morphological aspects have shown that coastal systems progradated to the shelf but it is not clear if they migrated great distances prior to doing so. Between Torreira and Furadouro beach, three main genetic units have been recognised which are separated by major surfaces. The first unit, unit A, defines the top of a depositional cycle that marks a period of estuarine lagoonal condition stabilities and the inversion of the depositional trend. Radiocarbon data suggests that the lagoon was formed before 1997 years BP (calibrated ages). The sedimentation of unit B favoured the development of sand ridge systems. Unit C marks a new period that leads to the reworking of coastal sediments by wave and wind action in a landward direction. The evolution of this sector may be attributed to sea level fluctuations induced by local factors such as periods of intense supply of sediments to the shelf.
Pereira, S.D., Chaves, H.A.F., and Dos Santos, S.B., 2007. Evidence of sea level change at Guaratiba Mangrove, Sepetiba Bay, Brazil. (Proceedings of the 9th International Coastal Symposium), 1097 – 1100. Gold Coast, Australia, ISSN 0749.0208
Any change in sea level would lead to a migration from mangrove areas. In order to identify this migration, seven cores have been taken along a profile (SW-NE) in Guaratiba mangrove (Rio de Janeiro – Brazil) for sedimentological, biological and geochemical characterisation of the sedimentary sequence. Studies have shown the development of typical bottom bay sedimentation that corresponds to a transgressive event, consisting of muddy sediments and aged 6130 years B.P. at depth of 5.20 metres. According to bibliographical sources, this event reached its highest about 5100 years B.P., with the sea level reaching about 4.8 metres above present level. The area that corresponds to the regressive event is comprised predominantly of sand and silt. Bibliographical sources indicate this gradual rising of the sea level beginning about 4900 years B.P. When a new transgressive event begins, the layer of muddy sediment begins. Bibliographical sources indicate the occurrence of a transgressive event, over a shorter period (ca 3800 years B.P.) when the sea level rose about 3.0 metres. Since then, beginning a regressive event, characteristic sedimentation of lagunar and mangrove areas have been occurring. This last event might have occurred about 2400 years B.P. Considering transgressive and regressive periods, observed in the Guaratiba mangrove, in the Quaternary evolution of the Brazilian coast, it is possible to estimate that these periods are relayed to the last events of the Quaternary, corresponding to the Holocenic Highstand or Santos Transgression.
Lee, J.I., and Kim, Y.T. 2007. Numerical analysis of stem waves along a vertical wall. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1101 – 1105. Gold Coast, Australia, ISSN 0749.0208
This study presents investigation about the characteristics of stem waves along a vertical wall generated by obliquely incident monochromatic waves through numerical simulations and laboratory experiments. The present study focusses on the nonlinear effect of the incident waves on the propagation characteristics of the stem waves. The numerical simulations are performed using parabolic approximation equations and are compared with the laboratory measurements conducted in a wave basin. Comparisons are in good agreements. The main results of this study show that the normalised stem wave height along the wall decreases and the stem width increases as the angle of the incident waves decreases or the nonlinearity of the incident waves increases.
Yoon, H.S., Kang, T.S., Nam, S.Y., Kim, J.T., and Park, J.H., 2007. Measuring coastline morphodynamics using video-based techniques at Haeundae Beach, South Korea. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1106 – 1111. Gold Coast, Australia, ISSN 0749.0208
In this study, video-based monitoring systems were installed at three locations on high-rise buildings in Haeundae, Busan, South Korea and beach image data were obtained from September, 2003 to December, 2005. Through quantitative analyses (statistical and time-series analyses) of the observed video image data, areal changes in Haeundae Beach and the shoreline were identified and summarised as follows. 1) Shoreline changes varied according to season and could be divided into four sections (east side section I: 250 m; II: 350 m; III: 300 m; west side section IV: 250 m). The biggest change in beach width occurred in section III; the change pattern at section IV differed from that at the other sections. The shoreline usually regressed (eroded) during the typhoon period (summer) but progressed (by sedimentation) during other seasons. 2) The overall change in beach width was correlated with the frequency of typhoons during the same period with abrupt beach erosion occurring between July and September, when typhoons struck. However, beach erosion and sedimentation at both ends of the beach during winter and summer were opposite of that at the centre of the beach. 3) During the video-monitoring period the maximum beach area was approximately 42,689 m2 and the minimum area was approximately 36,100 m2. The beach area was reduced due to typhoons and high waves by about 15.4%. 4) The beach area decreased by 6,400 m2 in summer during the typhoon period but rose by 5,300 m2 through winter resulting in an 82.8% recovery. As a result, the total beach area declined by approximately 17.2% during the observation period.
Choi, J.Y. and Lim, D.I., 2007. Morphological change of Byunsan Beach, mid west coast of Korea – 14 year monitoring during the Saemangum Reclamation Project. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1112 – 1115. Gold Coast, Australia, ISSN 0749.0208
Changes in beach morphology have been monitored at macro-tidal Byunsan Beach on the west coast of Korea over 14 years from 1992 to 2005. The primary purpose of the study is to find out any side-effects of Saemangum sea dike, constructed 4 km north off Byunsan Beach. Saemangum Project is a large scale tideland reclamation project involving construction of a 33 km sea dike impounding an area of over 40,000 ha. Construction began in 1991 and was completed in March, 2006. During the early phase of the dike construction from 1992 to 1997, deposition occurred rapidly on Byunsan Beach, with net accumulation rates over 4 cm/yr. Construction of the sea dike during this phase likely decreased the hydrodynamic energy level of tide and wave, hindering the offshore return of sediment materials that resulted in the cumulative accumulations. Byunsan Beach however, shifted toward the significant erosion phase from 1997 to present, with net erosion rates of about 2 cm/yr. Erosion took place along the coast at the mid- to low-tidal zone whereas net cumulative deposition continued at the zone of high-tidal level, resulting in the steeper gradient of the slope of shoreface. As the dike was constructed seaward, most of the water masses were concentrated through the narrow Gap area. Tidal flow during the ebb-period through the Gap makes counter-clockwise residual circulation, with net northward current field along Byunsan Beach. Materials eroded from the sub-tidal zone by waves and currents are thought to be transported northward and also shoreward by the residual currents.
Pereira, L.C.C., Guimarães, D.O., Ribeiro, M.J.S., Costa, R.M. and Souza Filho, P.W.M., 2007. Use and Occupation in Bragança Littoral, Brazilian Amazon. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1116 – 1120. Gold Coast, Australia, ISSN 0749.0208
This work focusses on the Bragantinian Coastal Plain, which is located in the northeastern littoral of Pará State, presenting an approximately 15 km waterfront. This area is situated in a macrotidal zone strongly affected by natural processes and human activities. The environmental and social aspects of five beaches in the Bragantinian littoral are described taking into account the several natural and human impacts that these beaches have been suffering along the last years. The methodology adopted in this study was based on interviews with inhabitants, direct observations and the monitoring of physical and human components. The obtained results showed that these beaches present several erosive problems, lack of adequate services and infrastructure, land use occupation disorder and lack of governmental incentive to support the sustainable development in the region. In addition, this coastal zone is one of the most frequented areas of the state, and it is considered of good quality by beach users, who pointed out its natural beauty, tranquility and fish abundance. On the other hand, the natural erosive process, intensified by the disordered occupation, is responsible for the destruction of their natural ecosystems and buildings located along the waterfront, mainly during the equinoctial spring tides. Due to importance that the Amazon littoral represents to the world, an urgent action plan is necessary to minimise the social and environmental problems observed in Bragança beaches, promoting a sustainable development of local natural resources.
Costas, S. and Alejo, I., 2007. Local and Global Influences on the Evolution of a Transgressive Sand Barrier: Cies Barrier, Northwest Spain. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1121 – 1125. Gold Coast, Australia, ISSN 0749.0208
The decadal evolution and the factors that control the variability of a recent welded barrier located in the northwest of Spain have been investigated. Analysis of the morphological changes and the evolution of the shoreline were carried out using georectified aerial photographs spanning from 1949 to 2003. The barrier shows a complex temporal and spatial behavior. Erosive and constructive, or accretionary stages, alternate over time giving rise to a cyclical evolution. Shoreline behavior differed according to geomorphic setting. In regards to the spatial behavior, the shoreline presented different response patterns depending on the presence of dunes, cliffs or an inlet.
The evolution of the sand barrier was related to the effect and variability of global (sea level and climate change) and local factors (storm regime or sediment input). Despite some cyclic behavior between 1949 and 2003, the net shoreline position moved landward approximately 24 m. This was associated with inlet relocation and lagoon infilling. Despite the episodic behavior of the shoreline from 1949 to 2003, the barrier receded around 24 m causing important morphological changes such as the adjacent lagoon infilling or inlet relocation. The evolution of the sand barrier seems to result from the combined effect of different factors such as sediment scarcity, wave exposure, climate oscillation or mean sea level rise. These factors interact so that their combined effect is greater than the sum of their individual effects.
Hashimura, R., 2007. Using the magnitude method to forecast damage to maritime structures caused by Typhoon 9918. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1126 – 1131. Gold Coast, Australia, ISSN 0749.0208
In 1999 Typhoon 9918 struck Kyushu Island, which is located in Western Japan. During the strongest stage of the typhoon the central pressure was 930 hPa and the maximum wind speed was 45 m/s near the center of the typhoon. The maximum storm tide was over 2 m along the coast of Kumamoto Prefecture on Kyushu Island. Due to the storm surge and wind waves the typhoon caused enormous damage to maritime structures, including breakwaters, sea walls, sea dikes, jetties, and wharves. In this paper, the Magnitude Method is used to estimate the number of damaged maritime structures along the coast caused by Typhoon 9918. Based on 43 previous typhoons the Magnitude Method creates an index that determines the vulnerability of the coast to a typhoon with a specified path. This index is estimated using the path of Typhoon 9918 as determined from the location and the direction of the typhoon at a latitude of 30° N. The vulnerability index of maritime structures is calculated based on the path of the typhoon and coastline. The number of damage cases is estimated using the vulnerability index and the magnitude of the typhoon at a latitude of 30° N. Based on the results the Magnitude Method can be used to estimate the damage level of maritime structures that will occur along the coast before a typhoon strikes.
You, Z.J. and Yin, B.S., 2007. Direct measurement of bottom shear stress under waves. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1132 – 1136. Gold Coast, Australia, ISSN 0749.0208
Wave-induced bottom shear stress is one of the most important parameters in modelling of wave hydrodynamics and coastal sediment transport. A new type of shear plate has been successfully developed to measure instantaneous wave bottom shear stress in a laboratory wave flume. The shear plate measures instantaneous horizontal force by applying the Wheatstone half bridge circuit to detect a tiny horizontal movement of the shear plate. There are about 280 individual test runs carried out over one smooth bed and two roughened beds, respectively. In each test run, instantaneous bottom shear stress was measured at a sampling rate of 10 Hz for about 10 minutes. The measured total horizontal force, which consists of wave-induced bottom shear stress and hydrodynamic pressure, is found linearly proportional to wave height in both laminar and turbulent flows. The wave friction factors measured on the smooth bed are shown to agree excellently with the theoretical values derived in laminar boundary layer flow, but those on the rough beds are affected by the bed roughness length estimated. An empirical formula is also proposed to compute the wave bottom shear stress.
Barrera-Alba, J.J., Gianesella S.M.F., Saldanha-Correa F.M.P., and Moser G.A.O., 2007. Influence of an Artificial Channel in a Well-Preserved Sub-Tropical Estuary. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1137 – 1141. Gold Coast, Australia, ISSN 0749.0208
The Estuarine-Lagoon System of Cananéia-Iguape is located on the southeast coast of Brazil, with an extension of 10000 ha. It is a complex and naturally eutrophicated ecosystem associated to a broad and relatively well-protected mangrove forest. The system is formed by channels and small islands separated from the sea by a 74 km barrier island, with two main connections to the Atlantic Ocean. Suspended matter, dissolved inorganic nutrients, chlorophyll a and phytoplankton density were studied over complete tidal cycles during a period of five years. Surveys were conducted during dry and rainy seasons in order to investigate the influence of Valo Grande, an artificial channel, onto the estuarine dynamics. This channel is the main freshwater input for the northern portion of this ecosystem, having an annual mean runoff of 435 m3 s-1. Since 2002 a dramatic increase in dissolved inorganic phosphate concentrations (DIP) has been observed in estuarine waters. The recommended range of total phosphorus concentration in estuaries and coastal ecosystems to prevent algal blooms is 0.01 to 0.1 mg L-1, according to the Brazilian Environmental Legislation. In the present study, DIP concentrations as high as 2.90 and 1.07 mg L-1 were observed during July 2005 and January 2006, respectively. Suspended matter concentrations higher than 1.0 g L-1 and changes in phytoplankton community were also observed. Present study points out the necessity of driving research efforts to identify the potential pollution sources in the drainage basins of the Ribeira de Iguape River and in the estuarine-lagoon system of Cananéia-Iguape. The increase in phosphorous concentrations is leading the estuary to anthropogenic eutrophication processes, as revealed by the decrease in oxygen levels and macrophytes proliferation. So, a monitoring program and public management policies are necessary to improve an environmental conservation plan to control the anthropogenic eutrophication over this preserved area.
Gratiot, N. and Manning, A. J., 2007. A Laboratory Study of Dilute Suspension Mud Floc Characteristics in an Oscillatory Diffusive Turbulent Flow, SI 50 (Proceedings of the 9th International Coastal Symposium), 1142 – 1146. Gold Coast, Australia, ISSN 0749.0208
To further the understanding of mud flocculation the COSINUS project funded a series of laboratory experiments whereby dilute mud suspensions were sheared (between 3.7 s-1 - about 20 s-1) with nominal concentrations ranging from 200-600 mg l-1, within a Plexiglas tank, using an oscillating grid. The floc properties were then examined using the LabSFLOC instrument. Results showed that for low concentrations of natural Tamar estuary (UK) mud exposed to high shear, the largest flocs were slightly less than the Kolmogorov eddy size of about 220 µm. The high shear resulted in all flocs having settling velocities of only 0.6 mm s-1. Lowering the shear for the same mud improved flocculation, and raised the macrofloc settling velocity to 1.8 mm s-1. This translated into macroflocs constituting 64% of the floc mass, and 80% of the mass settling flux. In contrast, low concentrations of natural Gironde mud displayed significantly faster settling macroflocs at each shear increment than Tamar mud, but the largest flocs were of the same order as the Tamar mud flocs. The suspended matter distribution showed the macroflocs only constituted 20-30% of the particulate mass. However, their faster settling rate transformed the low macrofloc mass into 62% of the settling flux. The removal of organic matter from the Gironde mud resulted in few flocs exceeding 125 µm in diameter.
Lee, J.Y and Lee, J.L., 2007. An analytical study on heavy siltation in the Keum River Estuary after the construction of a dyke. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1147 – 1151. Gold Coast, Australia, ISSN 0749.0208
The effects of a dyke construction on morphological changes in the Keum River Estuary were analytically investigated. Based on data measured during the last 20 years, this paper presents a theoretical model for understanding the morphological changes in the estuary and concluded that the reduction of tidal prism after a dyke construction caused the heavy deposit of fine-grained sediments in the Keum River Estuary. A noteworthy result from this study is that the overall rate of sedimentation depends on the difference in the suspended sediment concentration between the estuary and surrounding area. Field measurements show that the estuary did not allow the deposition of fine sediments under concentrations more than 100mg/l, but it appears to allow the heavy deposition under about 50mg/l. Therefore, the equilibrium concentration seems to exist between 50mg/l and 100mg/l.
Lee, R.S., Wallace, S.L., Holden, C. and Black, K.P., 2007. Scaling coastal upwelling features of the East Australian Current. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1152 – 1162. Gold Coast, Australia, ISSN 0749.0208
The coastal waters of eastern Australia are frequently influenced by eddies driven by the East Australian Current stream. Topographic steering and bottom shear associated with western boundary flows are considered responsible for localised coastal upwelling. A 300km array of temperature and current meter moorings (1996-2000) assessed the spatial and temporal variability of upwelling. Long-term records indicated the highest frequency of upwelling occurs in austral spring and late summer. Temperature records were analysed for coherence and phase, power spectra, and wavelet analysis provided an instantaneous and localised estimate of the temperature signal components. Coherent across the array were energy peaks associated with typical weather-band periods of 7-10 days. Regional events (length scales of 100 -150 km) were mostly coherent and in-phase for periods greater than 5 days. Localised upwelling events occurring at the two ends of the study region were generally incoherent throughout the frequency spectrum. Embedded within a southward cooling gradient of 0.5oC per 100 km were long-shore variations in upwelling frequency. The local anomalies were related to topographically-induced upwelling around changing shoreline orientations. Alongshore regions prone to upwelling were related to sharp positive rotations in shoreline orientation, having scales in accordance with the local Rossby radius. The current deployments indicated that strong upwelling at the most pronounced location (in the lee of Port Stephens promontory) was associated with back-eddy formation. This eddy formation represented the peak variance/energy at that location, and was out of phase with ambient forcing experienced at the remaining mooring locations in the array.
Bezerra, M.O., Pinheiro, L. and Morais, J.O. 2007. Shoreline Change of the Mucuripe Harbour Zones (Fortaleza-Ceará, Northeast of Brazil) 1972 - 2003. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1163 – 1167. Gold Coast, Australia, ISSN 0749.0208
This study analyses the space-time evolution along the Fortaleza coast over the past 31 years (1972-2003) with a special emphasis on the Mucuripe port area (Fortaleza, Ceará, Brazil) examining changes in the coastal dynamics produced by the building of the city's port. The construction of the port's jetty interrupted the natural feeding process of the beaches with sediment moving east to west. Sediment was blocked east of this structure leading to an erosion process to the west. This multi-temporal study is based on the analysis of aerial photographs and images from the Quickbird satellite. The objective is to determine the recent evolution of this coastline through calculation of the variation in retrograding and prograding areas. The variation of the city of Fortaleza's dune-beach interface shoreline, which concerns an extension of approximately 30 km of shoreline, revealed a prograding rate of 0.8284 km2/31 years (1972/2003) and a retrograding rate of 0.0701 km2/31 years (1972/2003). Analysis of images of Mansa Beach, located in the Mucuripe port basin, showed that in 1972 Mansa Beach had an area of 0.13843 km2, in 1998 it increased to 0.15307 km2 and in 2003 it reached 0.15455 km2. The analysis revealed that the changes in the shoreline are more subject to shoreline accretion. The analysed period shows a 92% accretion rate and an 8% erosion rate. The results contribute to the improved management of the Fortaleza coast.
Park, D, Cho, Y.-S., and Kim, S.-M., 2007. Simulation of Inundation at Imwon port during 1983 Central East Sea Tsunami. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1168 – 1172. Gold Coast, Australia, ISSN 0749.0208
The Central East Sea Tsunami which occurred on 26th May, 1983 had attacked the eastern coast of the Korean Peninsula and caused considerable damage at coastal communities including Imwon, a small fishery port. The tsunami has been recorded as the most destructive tsunami during the last century in Korea. The observed average run-up height of the tsunami at the Imwon port was approximately 4.0 m. A numerical model, which consists of the propagation and the inundation models, is used to simulate inundation at the Imwon port. The numerically predicted maximum inundation area is in excellent agreement with the observed data and correctly simulates the vortex that occurred within the port and significantly damaged the anchored ships.
Winter, C.; Becker, M.; Ernstsen, V.B.; Hebbeln, D.; Port, A.; Bartholomä, A.; Flemming, B. and Lunau, M. 2007. In-situ observation of aggregate dynamics in a tidal channel using acoustics, laser diffraction and optics. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1173 – 1177. Gold Coast, Australia, ISSN 0749.0208
To describe the dynamics of aggregates in a tidal channel, in situ measurements of current velocity, turbulence, backscatter intensity, particle size distribution and suspended matter concentration have been carried out throughout half a tidal cycle. The dynamics of suspended particle matter are shown: distinct turbidity clouds due to temporal increases in total concentration are detected by all sensors but acoustic methods seem to underestimate the amount of SPM when large aggregates are present. This study compares two different approaches for the in-situ analysis of particle size distributions: a laser diffraction method (Sequoia LISST 100) and image analysis of in-situ photography. Both instruments are limited due to their resolution and technical properties. Applied in combination, the two methods reveal the broad range of particle sizes ranging from a few microns to millimetre size.
Sartor, S.M., Hans, M.F.P., Palm, L., Sartor, L.M., Leão, A.L., 2007. Coastal Marine Mapping as an Ecosystem Based Management – the case study of the Baixada Santista Region – São Paulo, Brazil. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1178 – 1182. Gold Coast, Australia, ISSN 0749.0208
Despite the enormous environmental impact occurring in the study area and the relevant scientific studies ongoing, the decision-making processes of management and enforcement activities are still restricted. It happens mainly due to the inexistence of data integration of the available information. The development of integrating maps that summarize the information on geomorphology, biological processes, ecology, biodiversity, sociology and economic data, is therefore strategic. So with this purpose, a multidisciplinary team developed a data bank gathering the previously existing information with documented visits to all the area under study. These included interviews about socio-economic uses, biological occurrences and pollution impacts.
The study demonstrated that spite of being important fishes´, birds´ and invertebrates´ matting areas; there are important ecosystems like mangroves and estuaries that suffer many deleterious impacts. The study also determined the number of species present in the area: 216 marine fish species, 77 estuarine fish-, 454 bird-, 174 terrestrial mammal- and 22 marine mammal species. Beaches, rock shores and mangrove areas were also fully mapped. On the long run this study will help to define new areas to be protected and to establish a better policy management. Another aim of this study is to shorten time to analyse and understand the ecosystem, allowing the promotion of new studies in observed gaps.
Ataie-Ashtiani, B. and Najafi-Jilani, A., 2007. A Higher-order Two-dimensional Boussinesq Wave Model. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 1183 – 1187. Gold Coast, Australia, ISSN 0749.0208
A two-dimensional Boussinesq-type model is presented accurate to O(µ)6 , µ = h0/l0, in dispersion and all consequential order for non-linearity with arbitrary bottom boundary, where h0 is the water depth and l0 is the characteristic wave length. The mathematical formulation is an extension of (4,4) the Padé approximant to include varying bottom boundary in two horizontal dimensions. A higher order perturbation method is used for mathematical derivation of the presented model. A two horizontal dimension numerical model is developed based on derived equations using the Finite Difference Method in higher-order scheme for time and space. The numerical wave model is verified successfully in several checks such as wave transition over an arbitrary bottom and the accuracy of numerical results in all cases are acceptable.
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