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Murdukhayeva, A.; August, P.; Bradley, M.; LaBash, C., and Shaw, N., 2013. Assessment of inundation risk from sea level rise and storm surge in northeastern coastal national parks.
Sea level rise and an increase in storm frequency and intensity are two major impacts expected to result from climate change in coastal ecosystems. Coastal national parks have many low-lying areas that are at risk from inundation resulting from these impacts. To help park managers meet their goal of preserving resources, we developed a methodology to evaluate risk of inundation from sea level rise and storm surge at sentinel sites, areas of importance for natural, cultural, and infrastructural resources. We selected the most recent, readily available, and appropriate geospatial tools, models, and data sets to conduct case studies of our coastal inundation risk assessments in two northeastern coastal national parks—Cape Cod National Seashore, MA, and Assateague Island National Seashore, MD/VA. We collected elevation data at sentinel sites using real-time kinematic global positioning system (RTK GPS) technology. We used three modeling approaches: modified bathtub modeling; the Sea Level Affecting Marshes Model (SLAMM); and the Sea, Lake, and Overland Surges from Hurricanes (SLOSH) model to assess the likelihood of inundation at sentinel sites. Cape Cod's sentinel sites, which in many cases occurred in high-elevation settings, were found to be less vulnerable to inundation than were Assateague Island's sentinel sites, which were distributed in low-lying areas along the barrier beach island. This inundation risk assessment methodology can be applied to other coastal areas and to the same coastal parks at different times as more accurate elevation data sets and updated sea level rise projections become available.
Peek, K.M. and Young, R.S., 2013. Understanding the controls on storm surge through the building of a national storm surge database.
The Program for the Study of Developed Shorelines at Western Carolina University (WCU) is using relational tools (Microsoft Access) and a geographic information system (ArcGIS) to build a national storm surge database. The database is comprehensive, queriable, and will provide one central location for coastal scientists, engineers, and the general public to access storm surge and high water-mark data. The national database currently contains over 5800 storm surge data points from 42 hurricanes. Detailed geo-referenced storm characteristics from the National Ocean and Atmospheric Administration's International Best Track Archive for Climate Stewardship are also part of the database and include storm track, wind speed, central pressure, and storm diameter. This allows the database to be queried to match storm characteristics with the surge generated. Analysis of the database was performed to examine the relationship between storm surge and a variety of storm characteristics. Results show no significant relationship between surge height and the widely used Saffir-Simpson scale, which is based solely on wind speed. In fact, of all the storm track characteristic data analyzed, only pressure at landfall had a significant relationship with surge height, indicating that multiple factors likely control surge heights during a storm. An important aspect of this project is distributing this storm surge information to the public. A user-friendly website and mobile application are being developed from the database for simple lay-person access to storm surge data for all localities. The database and public access tools will assist in educating coastal residents, emergency planners, and developers about past storm surge flood levels. The database can also be used by scientists and engineers to verify storm surge models and to examine the controls on storm surge variability.
Duclos, P.-A.; Lafite, R.; Le Bot, S.; Rivoalen, E., and Cuvilliez, A., 2013. Dynamics of turbid plumes generated by marine aggregate dredging: an example of a macrotidal environment (the Bay of Seine, France).
On the French marine shelf, marine aggregates are currently dredged by trailing suction hopper dredgers (TSHD), without screening, with an overflow process, with or against currents. In the framework of the Groupement d'Interét Scientifique (GIS) Suivi des Impacts de l'Extraction de Granulats Marins (SIEGMA), the dynamics of the turbid plume formed by the overflow was studied at an experimental dredging site (0.6 km2), located in the Bay of Seine (eastern English Channel), a macrotidal environment where the seabed is composed of sandy gravel. An original field strategy based on Lagrangian monitoring, using the back-scattered signal of an Acoustic Doppler Current Profiler (ADCP), Laser In Situ Scattering and Transmissometry (LISST) measurements, water samples, and aerial photographs, has shown good results in describing suspended sediment concentration (SSC) dynamics from a turbid plume. The behaviour of suspended sediment has been studied, for the first time, to our knowledge, from their release at the dredger overflow to their deposition on the seabed. A fluid mixture, overflowed from the TSHD, with a mean concentration of 6 g L−1 of mineral and organic silty sands, induces the formation of a turbid plume at the rear of the TSHD, with an immediate dilution effect about 10–100 on SSC. Then, the SSC decreases through the process of lateral dispersion and sedimentation until the plume disappear in 2 hours. Evolution of the plume characteristics (SSC, particle size and nature, geometry) makes it possible to quantify the processes involved: dilution, advection, dispersion, and settling. The passive and dynamic behaviours of the plume are analysed. Extensions of deposits are calculated for spring tide conditions: 800 m for sand and 6.5 km for silt. This study has been conducted in macrotidal and specific dredging conditions (orientation of the dredging tracks against currents, dredger speed, loading capacity, overflow type), whose effects on plume dispersion have been quantified. Indicators relative to the effect of the plume on the water column (I/R) and to the plume duration (T1.25SSC) are proposed.
O'Shea, M. and Murphy, J., 2013. Predicting and monitoring the evolution of a coastal barrier dune system postbreaching.
A study of the morphodynamic evolution of a midbay barrier beach system of Inner Dingle Bay, County Kerry, Ireland is presented. The system has been under observation by the Hydraulics and Maritime Research Centre (HMRC) of University College Cork since 2008 when the Rossbeigh barrier breached. This event had been the culmination of 10 years of intensive erosion. Since breaching occurred, erosion rates have continued to increase on Rossbeigh, while offshore an ebb tidal delta continues to grow. Similar barrier inlet systems are examined in order to identify trends and features that might provide an insight into the future morphology of Dingle Bay. The study utilises field data collection sediment transport analysis and remote sensing to understand the coastal processes driving the systems evolution. The changing orientation of Rossbeigh, the relative stability of the Inch barrier beach, and the variability in ebb tidal delta were the findings of the long-term morphological part of the study. The influence of the ebb tidal delta on wave refraction, emergence of a vegetated gravel ridge in the breach zone, and the role of tidal currents in sediment transport along Rossbeigh are significant findings of the monitoring campaign. These results provide indicators of future evolution of the system. The study concludes that the realignment of the beach will continue on Rossbeigh beach while alongshore tidal currents dominate sediment transport in the breached area.
Hosseinyar, G.; Behbahani, R.; Chaychizadeh, S.; Lak, R., and Chakeri, M., 2013. High-resolution seismic stratigraphy and current-induced bed forms in the Khoran Strait, south of Iran.
The distribution of current-induced bed forms, shallow sub-seabed architecture, and geological development of the Khoran Strait, south of Iran, were investigated using subbottom profiler and side-scan sonar data. Current-induced bed forms in this area include a variety of dunes, such as simple large flood-dominated, composite medium to very large flood-dominated to simple-composite large to very large ebb-dominated, simple medium to very large ebb-dominated, and large symmetrical dunes. High-resolution shallow seismic profiling reveals two depositional sequences. The lower sedimentary sequence, which displays channel infills in the southern part of the study area, provides evidence of sea-level changes having resulted in the formation of four different units (A, B, C, and D). After deposition of unit D, sea-level fall led to erosion of the lower sequence. Further evolution of the basin and subsequent sea-level rise resulted in renewed inundation and formation of the upper sequence. The general seismic architecture of the area reveals both deposition and erosion along the margin of the strait, while sediment starvation prevails in the inner part of central areas.
Simeone, S.; Palombo, L., and De Falco, G., 2013. Morphodynamics of a nontidal embayed beach: the case study of Is Arutas (western Mediterranean).
This study evaluates the reliability of the Short morphodynamic model by using experimental data on the wave climate, sediment budget, and topographic beach profiles of an embayed beach located in western Sardinia, Mediterranean Sea. Wave parameters, measured by an offshore buoy located to the NW of Sardinia were downloaded daily, from the Rete Ondamentrica Nazionale Web site. Beach elevation data were collected in 2005 and 2010, using a Differential Global Positioning System, to determine the volume of beach sediments. Three beach profiles were measured in the northern, central, and southern areas of the beach from September 2010 to May 2011 to investigate morphological variability. Grain-size and composition of beach sediments were determined.
From 2005 to 2010, the sediment volume did not show any significant changes (14,200 m3 and 13,800 m3, respectively). Sediments were sandy to gravelly, whereas the composition was siliciclastic. Morphological variability occurred in the swash zone, where the northern and southern profiles showed an opposite trend, in terms of changes in elevation. This was related to the longshore redistribution of sediments and occurred mainly during the autumn–winter season. The Short model revealed that, for 98% of the available data, Is Arutas assumed a “normal” or “transitional” morphodynamic state. The sediment remained constrained between the headlands, in accordance with the results of the Short model, which showed the assumed morphodynamic states did not implicate the transport of sediment outside the system.
Experimental data confirmed that the Short morphodynamic model can be applied to studies on sediment exchange on embayed Mediterranean beaches.
Diez, J.J.; Esteban, M.D.; López-Gutiérrez, J.S., and Negro, V., 2013. Meteocean influence on inland and coastal floods in the east of Spain.
The Santa Irene flood, at the end of October 1982, is one of the most dramatically and widely reported flood events in Spain. Its renown is mainly attributable to the collapse of the Tous dam, but its main message is to be the paradigm of the incidence of the maritime/littoral weather and its temporal sea-level rise on the coastal plains inland floods. The Santa Irene flood was attributable to a meteorological phenomenon known as gota fría (cold drop), a relatively frequent and intense rainy phenomenon on the Iberian Peninsula, particularly on the Spanish E to SE inlands and coasts. There are some circumstances that can easily come together to unleash the cold drop there: cold and dry polar air masses coming onto the whole Iberian Peninsula and the north of Africa, high sea-water temperatures, and low atmospheric pressure (cyclone) areas in the western Mediterranean basin; these circumstances are quite common during the autumn and, as it happens, in other places around the world (E/SE Africa). Their occurrence, however, shows a great space-temporal variability (in a similar way to hurricanes on Caribbean and western North Atlantic areas or also in a similar way to typhoons). In fact, all of these are equivalent, although different, phenomena, able to have a different magnitude each time. This paper describes the results of a detailed analysis and reflection about this cold drop phenomenon as a whole, on the generation of its rains, and on the different natures and consequences of its flood. This paper also explains the ways in which the nearby maritime weather and the consequential sea level govern floods on different zones of any hydrographical basin. The Santa Irene case can be considered as a paradigm to explain the influence of nearby maritime climatic conditions on flooding phenomena not only in coastal but also in upward inland areas.
Badescu, V.; Ciocanea, A.; Cathcart, R.B., and Finkl, C.W., 2013. Desalination brine disposal by submerged pipes in Red Sea.
Seawater desalination plants, especially those in Saudi Arabia, require the disposal of useless posttreatment brine—generally about 50% of the volume of seawater processed by such plants designed to make freshwater. This article focuses on the sustainability of the brine disposal process. A proper decision about the brine disposal method must take into account technical, environmental, and economic constraints. Brine disposal by submerged pipes is considered here; the case of desalination plants in Saudi Arabia on the Red Sea shore is considered as an example. The central concept is the available head at the discharge point. Higher values of the available head ensure larger jet dispersion lengths and better conditions for submarine brine dilution. We assessed the quality of the dilution process by calculating the Froude number of the brine discharge jet, whose optimum values are between 20 to 25. Using the Froude number allows us to find the optimum pipe length and the optimum depth of the discharge point for a sustainable brine disposal. Comments concerning the cost of the submerged pipes are presented.
Smith, S. and Medeiros, K., 2013. Manipulation of water levels to facilitate vegetation change in a coastal lagoon undergoing partial tidal restoration (Cape Cod, Massachusetts)
East Harbor is a back-barrier coastal lagoon and salt marsh within Cape Cod National Seashore (Massachusetts), which has been undergoing partial tidal restoration since 2002. The current tidal exchange has been sufficient to elevate salinities in the open lagoon but is still too constrained by the present infrastructure to create high tides sufficient to flood the peripheral marsh areas. Consequently, an adaptive management strategy using a one-way tide gate was implemented in 2011 that let high tides into the system while blocking their escape. The increased flooding of the marsh, above and beyond what the current engineering of the system could provide by opening the restrictive culvert, raised porewater salinities in many areas and resulted in decreases in the cover of freshwater and brackish-water plant taxa—a necessary precursor for the establishment and expansion of native halophytes. This kind of adaptive-management tool can be used to enhance salt marsh restoration in systems that can only be partially restored tidally.
Cox, D.; Kämpf, J., and Fernandes, M., 2013. Dispersion and connectivity of land-based discharges near the mouth of a coastal inlet.
This work investigates the physical marine connectivity between Adelaide's Barker Inlet and Port River system with discharges from a wastewater treatment plant that is located just outside the inlet. Cluster deployments of Lagrangian global positioning system drifters were used to determine the pathways and dispersive properties of currents in the region. We derived a lateral dispersivity of a mean value of 0.157 m2/s, ranging from 0.053 to 0.240 m2/s. Hydrodynamic modelling (calibrated with the dispersion data) indicates that, during winter months and neap tides, nutrients from the nearshore wastewater discharge intrude directly into the inlet. Modelling further indicates that this connectivity can be substantially reduced in the case of an offshore discharge ∼3 km offshore in a water depth of ∼5 m.
Ghandour, I.M.; Al-Washmi, H.A., and Haredy, R.A., 2013. Gravel-sized mud clasts on an arid microtidal sandy beach: example from the northeastern Red Sea, South Al-Wajh, Saudi Arabia.
Gravel-sized mud clasts (GMCs) of clay-grade material are abnormally documented from the microtidal Red Sea sandy beach at the mouth of Wadi Al-Hamd some 55 km S of Al-Wajh, Saudi Arabia. The area of study represents an asymmetric delta flanked to the N by a sandy linear shoreline and to the S by a heterolithic muddy tidal flat. Shape, roundness, and mineralogical composition of 200 randomly collected grains were determined to infer their source and depositional mechanism. The diameters of GMCs vary from 1.25 to 6.7 cm (long axis), with a mean diameter of 2.89 cm. The clasts are mostly rounded to well rounded, and the bladed forms are the most dominant shape, followed by elongated, platy, compact platy, and very rare compact bladed shapes. The GMCs are mostly unarmoured; however, large elongated forms have single-grain thick external armour of sands, shell fragments, or both. The mineralogical composition consists mainly of quartz, halite, plagioclase, and calcite, along with traces of phyllosilicates, feldspars, hornblende, mica, gypsum, anhydrite, pyrite, and dolomite. The documented GMCs are the end product of various processes that started with deposition of muddy source materials within shallow and small pools on the lower tidal flat. This muddy source was then subjected to desiccation, cracking, and detachment by repeated dryness and inundation during summer and winter, respectively. The detached clay-rich mud clasts were submerged during winter sea level rise and then transported to the beach either as bedload or lifted in the water column by high-energy waves and currents during times of sea breeze, some clasts being differentially armoured by adhering loose sand grains to the surface. The findings of this study will help to understand the environmental and climatic conditions required for the formation of GMCs on microtidal coasts in arid regions.
Talke, S.A. and Jay, D.A., 2013. Nineteenth century North American and Pacific tidal data: lost or just forgotten?
Tide data are the oldest and longest oceanographic records and comprise one of the few tools for understanding, quantifying, and separating century-scale human and climate impacts on the coastal zone. Our archival research indicates that continuous measurements of tides began in 1844 in the western Atlantic, 1853 in the Eastern Pacific, and 1858 in the Western Pacific. At least 50 multiyear tide series existed by the year 1900. With few exceptions, however, these 19th and early 20th century measurements have not been analyzed in more than a century and have been forgotten and neglected by the scientific community. This article describes historical tide measurements in the Pacific Ocean and North America, their current status, and ongoing efforts to recover the data. Possible uses of the data include assessing trends in sea level, tidal properties, and river flow, and reanalyzing extreme events such as historical storms and floods. More than 600 years of station data are confirmed to still exist in paper form, out of approximately 1900 years total.
Kuang, C.P.; Huang, J.; Lee, J.H.W., and Gu, J. 2013. Impact of large-scale reclamation on hydrodynamics and flushing in Victoria Harbour, Hong Kong.
A three-dimensional (3D) hydrodynamic model for the Pearl River Estuary based on Delft3D is established and calibrated to study the changes in tidal circulation and flushing in Victoria Harbour. The tidal circulation and flushing were simulated by this 3D model under the existing reclamation conditions, including Central Reclamation Phases I, II, and III (CRI, CRII, and CRIII), and Wan Chai Reclamation Phase I (WRI). The model is also applied to predict the hydrodynamic changes after the reclamation of proposed Wan Chai Development Phase II (WDII) to be constructed in 2017. Compared to the coastline in 1975 (before large-scale reclamation), the numerical results show that the following changes have taken place after the existing reclamation: (1) The peak flow at all cross sections along Victoria Harbour decreases by about 9–25%, with an average value of about 15% for the existing reclamation; (2) the peak velocity in the eastern harbour near Lei Yue Mun decreases after the existing reclamation because of the reduction of flow, but it increases in the central and western harbour due to the significant narrowing in harbour width; (3) flushing time in Victoria Harbour increases by about 25–40% in the wet season and increases by almost 15–30% in the dry season as a result of the changes of the flow discharge and tidal range. After the reclamation of WDII, the flushing rate and flow discharge in Victoria Harbour only change slightly compared with that under the existing reclamation condition. Another finding is that for the present coastline, the flushing time ranges about 1.5–2.5 days in the wet season and 5–7 days in the dry season.
Wang, P. and Roberts, T.M., 2013. Distribution of surficial and buried oil contaminants across sandy beaches along NW Florida and Alabama coasts following the deepwater horizon oil spill in 2010.
The failed Deepwater Horizon (DWH) well released approximately 7.0 × 105 m3 of oil into the northern Gulf of Mexico during an 84-day period from 20 April 2010 to 15 July 2010. This study examined the beach oiling that resulted from the DWH spill, specifically the cross-shore distribution of both surface and buried oil, based on a series of field investigations and transport mechanisms following principles of beach morphodynamics. Five types of oil contamination were distinguished, including tar balls, tar patties, tar cakes, oil sheet, and stained sand. All five types were identified both on the beach surface and buried underneath contaminated and clean sand. The cross-shore distribution of surface oil was bound landward by the maximum high-tide wave run-up, which was, in turn, controlled by the incident wave condition. Concentrated surface oil contaminants were often found along the maximum high-tide wave run-up and in the trough landward of the berm crest. The foreshore, with dynamic and constant swash motion, was not conducive for preservation of surface oil deposition. The burial of oil contaminants occurred at similar temporal scales and was driven by the same processes as the initial surface deposition. The buried layers of oil contaminants were documented in varying thicknesses (up to 15 cm) and depths (up to 50 cm) below the surface. The deepest buried oil was found beneath the active (or storm) berm crest and decreased in depth both landward and seaward. Buried oil contaminants can resurface as the beach erodes. Buried oil can be removed through mechanical excavation. Detailed description of cross-shore distribution of oil contaminants relating to beach morphodynamic terminology may help optimizing beach cleanup planning.
Dunn, R.J.K.; Lemckert, C.J.; Teasdale, P.R., and Welsh, D.T., 2013. Macroinfauna dynamics and sediment parameters of a subtropical estuarine lake—Coombabah Lake (Southern Moreton Bay, Australia).
The distribution, composition, density, and biomass of benthic macrofauna within estuarine environments typically exhibit significant variations attributable to heterogeneity in and interactions between physical, biological, and chemical processes. The spatial and temporal dynamics of benthic macroinfauna assemblages and physicochemical sediment parameters within the intertidal mudflats of a subtropical estuarine lake (Coombabah Lake, Southern Moreton Bay) were studied at four sites from August 2006 to April 2007. No significant seasonal changes were observed at any site for all physical sediment parameters. The northern sample sites were characterised by fine- to medium-grained to moderately to poorly sorted sediments and the southern sample sites by fine-grained to moderately well to well-sorted. A total of 1029 individuals representing species from three orders, including deposit feeding and filter feeding macroinfaunal groups, were collected. The highest combined species densities occurred in the fine-grained southern sites, with the greatest combined species density occurring at Site 4 during winter. Amphipods (Victoriopisa australiensis) and polychaete worms (Simplisetia aequisetis) dominated the lake-wide faunal community with V. australiensis, representing 49% of the total retrieved macroinfauna. Significant correlations between mean macroinfauna densities, biomassDW, sediment parameters, and seasonal maximum monthly temperatures were identified during the study. Seasonal trends in combined site densities were observed at each of the lake sites, with the highest combined density occurring during winter. Spatial and temporal variations might also be partially explained by the predation pressures of fish and migratory wading birds within the lake, with the seasonal presence of migratory wading birds coinciding with the minimum observed macroinfauna densities at each sample site.
Gontz, A.M.; Maio, C.V., and Rueda, L., 2013. The Duxbury sunken forest—constraints for local, late Holocene environmental changes resulting from marine transgression, Duxbury Bay, Eastern Massachusetts, U.S.A.
The present marine transgression has forced geological and ecological zones vertically higher and landward since the late Pleistocene. A recent investigation in Duxbury Bay, Massachusetts, identified 18 Juniperus virginiana tree stumps emergent on an intertidal flat immediately seaward of a small marsh and pond situated between two eroding drumlins. The position of each stump was mapped with global positioning system (GPS), and its elevation with respect to mean lower low water was surveyed. Samples were selected from four stumps with elevations ranging from 2.03 and 0.75 m above mean lower low water for radiocarbon dating. The samples returned calibrated ages between 2219 ± 94 and 2867 ± 79 cal YBP, with the topographically highest sample returning the youngest date. Stump positions suggest a landscape gradient of 1.4 mm/yr between 2000 and 3000 cal YBP. The results are comparable with high-resolution studies of sea level in eastern Massachusetts for the same time period. Comparison of the youngest paleostumps with modern living trees suggests a dramatic change in the landscape gradient, an increase to 1.8 mm/yr. While this is contrary to sea-level studies nearby, it may represent an increase in the energetics of Duxbury Bay and resultant coastal erosion as the bay floods. The site can be used to put the impacts of changing sea-level rates into a landscape evolution framework.
Kolerski, T.; Shen, H.T., and Kioka, S., 2013. A numerical model study on ice boom in a coastal lake.
A numerical study on the effectiveness of the proposed ice boom to be installed near the entrance of Lake Notoro, Hokkaido, Japan to prevent sea ice moving into the lake is presented. A two-dimensional hydro–ice dynamics model was modified to allow for the treatment of ice-boom interaction with the effect of tidal current. The numerical model is a coupled hydrodynamic and ice dynamic model. The ice dynamic component uses a Lagrangian discrete parcel method based on smoothed particle hydrodynamics. The model was used to assess the dynamics of sea-ice transport into the lake, the effectiveness of the boom on ice retention, and the ice load on boom spans. Results for steady and unsteady simulation cases including wind effect are presented.
Walter, S.T.; Carloss, M.R.; Hess, T.J., and Leberg, P.L., 2013. Hurricane, habitat degradation, and land loss effects on Brown Pelican nesting colonies.
Nesting colonies of coastal avifauna are perennially threatened by hurricanes, land loss, and environmental contamination. To understand how nest substrate and habitat availability influence reproductive success of Brown Pelicans (Pelecanus occidentalis), we monitored 802 nests and quantified vegetation cover on two barrier islands in Louisiana from 2008 to 2010. In 2008, Hurricanes Gustav and Ike caused habitat degradation and land loss at our study sites and thus allowed comparison of pelican productivity in pre- and post-hurricane conditions. As habitat availability changed across years and islands, pelicans shifted from nesting in woody vegetation, to grasses, forbs, and bare ground. More chicks that survived until the age of 3 to 4.5 weeks old were from higher nests, and the loss of woody vegetation might have elicited colony abandonment. Habitat reduction was attributed to hurricane-induced erosion, and shoreline retreat was an average 5.5 times (range 3.3 to 11) greater than regional rates from 1887 to 2002. Furthermore, land loss (16% to 99% of vegetated regions) was restricted to areas without protective breakwaters. In addition to the effects of habitat decline on pelican reproduction, contamination by the Deepwater Horizon oil spill might have further decreased nest success. Large and productive seabird colonies can be rapidly degraded by both human and natural disturbance, making amelioration of such threats a management priority.
Lee, J.-I.; Kim, Y.-T., and Cho, Y.-S., 2013. Hydraulic experiments for wave transformation over a submerged elliptic shoal.
Hydraulic experiments were performed to investigate wave transformation by applying regular and unidirectional irregular waves to wave-propagation process over a submerged elliptic shoal. Under the condition that wave breaking did not occur at the center of the shoal, a wave caustic was observed at the lee side of the shoal and the wave heights of the regular waves were measured to be higher than those of the unidirectional irregular waves. Under the breaking condition, the wave heights measured at the center of the shoal were low, but were high at the lateral sides. For the breaking condition, unlike the nonbreaking condition, the wave heights of the unidirectional irregular waves were measured to be higher than those of the regular waves. It was verified that wave-breaking-induced currents affect the refraction and diffraction of waves in this study.
Moskalski, S.M. and Sommerfield, C.K., 2013. Effects of northeaster storms on water level and turbidity in a Delaware Bay subestuary.
Coastal storms have a major influence on the ecology and geomorphology of U.S. Atlantic estuaries and tidal marshes. The purpose of this study was to determine which types of storms are most effective in flooding the marsh platform with high-turbidity water, a condition conducive for sedimentation. Eleven years (2000–10) of continuous water level and turbidity data for the St. Jones River National Estuarine Research Reserve, a subestuary of Delaware Bay, were analyzed and compared to weather events registered in the National Climate Data Center Storm Events Database. Statistically significant water-level and turbidity reference values were established and used to identify storm-produced events in the data records. Results indicate that northeasters were responsible for most (41%) of all concurrent water-level and turbidity events; other types of weather conditions, including continental lows, northern highs, and frontal storms, produced mostly isolated water level and turbidity peaks. Northeasters coincident with a high-pressure system over the north Atlantic consistently produced the highest water levels and surges, but northeaster intensity was not strongly correlated with surge height. A particular combination of remote wind forcing, intense rainfall, and river runoff distinguishes northeasters among other types of coastal storms in generating flooding events of significance to marsh sedimentation in the St. Jones estuary and, by extension, other subestuaries of Delaware Bay.
Coch, N. K., 2013. A field course in tropical coastal geology.
South Florida, United States, is an ideal place for conveniently studying modern carbonate environments and their fossil equivalents in close proximity. It is the only place where such field studies can be carried out with the excellent logistical support available in a major metropolitan area (Miami). Consequently, south Florida has been used extensively for training petroleum geologists as well as providing reef and quarry trips of short duration for geology classes. However, south Florida can also be used to study geomorphic features; biogenic and clastic sedimentology in fresh, brackish, and saline environments; and stratigraphic studies which correlate widely-spaced rock outcrops. In addition, many aspects of environmental geology, including groundwater, water pollution, ecological changes accompanying development, and the effects of hurricanes, can be studied here. This holistic approach was used in a 3 week laboratory and field course first offered in the summer of 1985. The area has been visited several times since then, and the places and features described in this paper are accurate as of February 2012. A uniformitarian approach was used, in which students studied rock outcrops and then examined the present-day depositional equivalent of each facies by snorkeling over modern reef tracts in the Florida Keys. Outcrops of Pleistocene rock units were examined from Miami southward through the Florida Keys. Students utilized the outcrop data, along with published data and their own observations of reef complexes, to make a regional stratigraphic synthesis and paleogeographic reconstruction for the study area. This article describes the course structure, field exercises, and logistics, which can serve as the basis for similar courses or site visits in this area in the future. Additional information is provided so instructors can tailor the course around their available time and financial limitations, anywhere from 3 days to 3 weeks.
Calder, M. and Kennedy, D.M., 2013. The application of ground penetrating radar in delineating shore platform morphology: a case study from Wellington, New Zealand.
Ground penetrating radar (GPR) is a new technique in field sciences and is now commonly applied to studies of coastal dunes and beaches. The technique has yet to be applied on hard rocky coasts, and its ability to discern subsurface stratigraphy has great potential for investigating landform evolution on tectonically active shorelines where erosional surfaces are often buried by sediments derived from marine and nonmarine sources. In this study, we test the resolution of a 100- and 250-MHz GPR system on a series of Holocene uplifted shore platforms and gravel beaches in Wellington, New Zealand. The sediment thickness at the sites investigated ranged from a thin veneer to many meters and is composed of a mix of sand and gravel-sized material. It was found that the 100-MHz antenna did not have the resolution of the 250-MHz antenna and could not distinguish the buried platform surface. Using the 250-MHz antenna, bedding features within the unconsolidated sediment and the bedrock-sediment interface could be discerned. The high relief of the bedrock (meter scale), which outcropped on the surface, and the presence of buried boulders caused significant interference to the radar profiles through the creation of multiple and hyperbolic reflections. Despite these reflections, the GPR was able to quantify the morphology of the buried shore platform, thus indicating the utility of this technique for rocky coast research.
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