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Makowski, C.; Finkl, C.W., and Vollmer, H.M., 2016. Classification of continental shelves in terms of geospatially integrated physiographic realms and morphodynamic zones.
The continental shelf off southeast Florida contains a range of benthic environments that are discernible via remote sensing platforms because of low turbidity in the water column. Using the Geospatially Integrated Seafloor Classification Scheme (G-ISCS), physiographic realms and associated morphodynamic zones were cognitively interpreted and classified at a nominal scale of 1:6000 across four remote sensing platforms (i.e. GeoEye IKONOS-2, Landsat-5 Thematic Mapper [TM], Landsat-7 Enhanced Thematic Mapper [ETM], and National Agriculture Imagery Program [NAIP] high-resolution aerial orthoimagery). Attribute tables were created in conjunction with interpretations to quantify and compare spatial relationships between classificatory units and the different remote sensing platforms. Resultant maps exported from ESRI ArcGIS® ArcMap software showed that while IKONOS-2 satellite imagery and NAIP aerial orthoimagery provided the greatest detail, classification of physiographic realms and morphodynamic zones was still possible using TM and ETM satellite images. Overall, it was determined that IKONOS-2 provided the most beneficial imagery when applying such a classification of coastal and seafloor features. It is postulated that accurate delineation of physiographic realms and morphodynamic zones can provide a foundation for more in-depth biogeomorpholocial classification (e.g., further subdivision into benthic geoforms, coastal landforms, biological cover) along continental shelves.
KEYWORDS: statistical analysis, extreme value analysis, historical water levels, Monte Carlo life-cycle simulation, generalized Pareto distribution, peaks-over-threshold, partial duration series
Nadal-Caraballo, N.C.; Melby, J.A., and Gonzalez, V.M., 2016. Statistical analysis of historical extreme water levels for the U.S. North Atlantic coast using Monte Carlo life-cycle simulation.
A statistical analysis of extreme water levels was performed for 23 locations throughout the U.S. North Atlantic coast. Extreme value analysis, which focused on historical observations, was followed by the application of a Monte Carlo life-cycle simulation methodology. This study was part of a broader effort to quantify coastal flooding hazards in this region. Twenty-three stations were selected based on location and record length, meeting the requirement of a minimum of 30 years of hourly water-level measurements. Monthly maxima data were also used to complement the hourly water-level observations. The use of available water-level data was maximized through the development of partial duration series that combined both monthly maxima and hourly data. A generalized Pareto distribution was used to fit combined partial duration series corresponding to each of the 23 locations. The Monte Carlo life-cycle methodology was used to simulate 10,000 cycles of 100 years each, effectively extending the record lengths of extreme events through statistical simulation. A bootstrapping technique was used as part of Monte Carlo life-cycle simulation in order to develop probability distributions of extreme water levels, including mean, as well as 10% and 90% nonexceedance confidence limits (equivalent to an 80% confidence interval). Water-level probabilities determined in this study were compared to results from a previous effort where the generalized extreme value distribution was used to fit monthly maxima data.
Allende-Arandía, M.E.; Zavala-Hidalgo, J.; Romero-Centeno, R.; Mateos-Jasso, A.; Vargas-Hernández, J.M., and Zamudio, L., 2016. Analysis of ocean current observations in the northern Veracruz Coral Reef System, Mexico: 2007–12.
The Veracruz Coral Reef System (VCRS) is a marine protected area located on the continental shelf of Veracruz, in the SW Gulf of Mexico, that is formed by two reef conglomerates: one to the north, in front of the Port of Veracruz, and one to the south, in front of the Antón Lizardo tip. To characterize the currents and their variability for the northern reefs of the VCRS, ocean currents, meteorological parameters, and sea-level observations for the period 2007–12 were analyzed. The temporal variability of the currents was dominated by 2- to 10-day lasting events associated with the atmospheric synoptic conditions through the forcing of the along-coast wind-stress component over the Tamaulipas-Veracruz shelf. During autumn–winter, strong episodic southeastward currents prevailed, reaching more than 1 ms−1, and they were associated with the intrusion of atmospheric high-pressure systems into the Gulf of Mexico. However, some episodes of strong southeastward currents observed in spring–summer were forced by low-pressure systems (tropical storms). From May to August, weak northwestward currents were predominant, with speeds lower than 0.40 ms−1. Annually, southeastward (northwestward) currents were observed 45–60% (40–55%) of the time, with an average of 55% (45%). Tidal currents are one order of magnitude weaker than the wind-driven currents. A multiple linear regression model for the along-shelf currents, which is based on the wind stress, explains most of the observed variance and performs well in reproducing the autumn–winter strong southeastward events but underestimates those observed in summer.
Laut, L.L.M.; Martins, V.; da Silva, F.S.; Crapez, M.A.C.; Fontana, L.F.; Carvalhal-Gomes, S.B.V., and Souza, R.C.C.L., 2016. Foraminifera, thecamoebians, and bacterial activity in polluted intertropical and subtropical Brazilian estuarine systems.
This study aims to identify relationships between total organic matter (TOM), bacterial carbon (BC), and metabolic activity in the thecamoebian and foraminifera community of five estuarine regions on the Brazilian coast. Sediment samples were collected from the subtidal zone of five Brazilian estuaries: Potengi, Mataripe Sound, Paraíba do Sul, Suruí, and Itacorubí. A total of 21 thecamoebian species, 29 species of agglutinated foraminifera, and 55 species of calcareous foraminifera were identified. In these estuaries the anaerobic process was dominant. In the Potengi Estuary, located in the NE coast of Brazil, the assemblages showed a decrease in diversity and richness as well as an increase in bacterial carbon concentrations. In the other estuaries the opposite pattern was observed, because they were dominated by agglutinated foraminifera and thecamoebians. Bacterial sulfate-reduction activity promotes acidification of the environment during organic matter degradation, and only calcareous species like Ammonia tepida, Elphidium fimbriatulum, Cribroelphidium poeyanum, Bolivina striatula, Bolivina inflata, and Nonionella opima increase their relative abundance with rising BC and TOM. Miliammina fusca, Haplophragmoides wilberti, and some species of trochamminids are associated positively with bacterial concentrations. Most of the thecamoebians species of genus Difflugia are positively related to BC, but Centropyxis aculeata is more clearly linked with total organic matter.
Stull, K.J.; Cahoon, L.B., and Lankford, T.E., 2016. Zooplankton abundance in the surf zones of nourished and unnourished beaches in southeastern North Carolina, U.S.A.
Surf zones are poorly studied in comparison to adjacent estuarine and continental shelf ecosystems, partly owing to their dynamic, high-energy environment that is often difficult to sample. This study quantified zooplankton abundance in the surf zone at eight sites along three beaches in SE North Carolina between November 2008 and June 2010, encompassing a beach-nourishment cycle at four sites in early 2010. A Before-After/Control-Impact (BACI) sampling design tested the effects of beach nourishment on zooplankton abundance at both medium- (2–3 months) and short-term (2–3 weeks) time scales. Zooplankton abundances in the surf zone ranged from 386–54,900 zooplankters m−3 and averaged about 8240 individuals m−3, an order of magnitude higher than in nearby coastal ocean environments but not as high as in nearby rivers and estuaries. Changes in phytoplankton biomass in the surf zone had a significant effect on meroplankton but not on holozooplankton abundances. Beach nourishment did not have significant effects on zooplankton abundances in the surf zone during this study. The surf zone offers an important food resource for planktivorous fishes and may be an important link between coastal and estuarine communities.
Shih, R.-S. and Weng, W.-K., 2016. A study of long wave attenuation over composite undulating breakwaters.
In this study, the wave attenuation of multiple impermeable sinusoidal profile breakwaters is investigated by a physical experiment conducted in a 21-m wave flume with a combination of breakwaters collocated with various widths (w) and heights (D). The breakwaters were arranged in different permutations and combinations (from one to three sets) on the bottom of various undulating slopes. The attenuation effect when waves propagated through the periodic-gradational undulating terrain was explored, and the optimization of various sinusoidal breakwaters was analyzed. This article discusses the properties of wave reflectance (Kr), transmittance (Kt), the energy loss coefficient (KL), and the attenuation of composite terrain, including the optimal combinations of obstacles. The values of Kr, Kt, and KL were diverse because of various breakwater combinations and various wave conditions. The results indicated that the attenuation of long waves was effective and was affected by nonlinearity and dispersion. Wave decomposition occurred when a wave passed through the breakwaters; a high-frequency fluctuation appeared and dissipated the energy of long waves. The transmittance indicated that a composite of rapidly varying combinations was more favorable than a gradually varying section. Increasing the quantity of composite breakwaters also improved the attenuation effect on both the rapidly varying cases and the segmented gradually varying cases. The optimal combination required to eliminate the energy of long waves was also examined and confirmed using a solitary wave test.
Swanson, R.L.; Bauer, C.L.; Wilson, R.E.; Rose, P.S., and O'Connell, C., 2016. Physical processes contributing to localized, seasonal hypoxic conditions in the bottom waters of Smithtown Bay, Long Island Sound, New York.
Summertime hypoxia regularly occurs in the bottom waters of Smithtown Bay, Long Island Sound, New York. Hypoxia is plaguing many coastal estuaries and can be detrimental to aquatic organisms. A generally accepted model for the cause of coastal hypoxia in temperate regions is seen in the introduction of anthropogenic nutrients, which fuels excessive primary production, leading to oxygen depletion exacerbated by seasonal water-column stratification. No major point sources of anthropogenic nitrogen discharge directly into the bay. Groundwater nitrogen discharge is somewhat more than double that of a small sewage treatment plant. Despite great efforts to reduce nitrogen loading into Long Island Sound, summertime hypoxia is a continuing occurrence in Smithtown Bay. Hydrographic cruises accompanied by Acoustic Doppler Current Profiler measurements were conducted during the summers of 2004, 2009, and 2010 to explore physical processes that contribute to hypoxic conditions occurring there. While hypoxia remains seasonally prevalent in the bay, the deeper surrounding bottom waters have considerably higher concentrations of dissolved oxygen. This study examines physical oceanographic contributions to hypoxia in the bay and determines that the problem is more complex than the introduction of anthropogenic nitrogen. Thermally controlled stratification with pycnoclines at middepths inhibit vertical mixing and replenishment of dissolved oxygen to bottom waters. The two headlands that form the bay, Crane Neck and Eatons Neck, create circulation patterns that inhibit lateral advection between the bay and the rest of the Sound. This results in weak currents and bottom stress within the bay and a limited exchange of water masses over a tidal cycle. Furthermore, the headland gyre setting increases the residence time in Smithtown Bay.
Testut, L. and Unnikrishnan, A.S., 2016. Improving modeling of tides on the continental shelf off the west coast of India.
Global tidal solutions are sometimes inaccurate in coastal regions. This is particularly true in some regions of the northern Indian Ocean, which are characterized by wide continental shelves and large tidal ranges. We show that these global solutions are inaccurate on the shelf region off Mumbai, off the west coast of India. In this region, the shelf is very wide, and it opens into the Gulf of Khambhat, where large tides are observed. Moreover, in regions of large semidiurnal tides in the Bay of Bengal, such as the head Bay, Gulf of Martaban, etc., global tidal solutions are not accurate. In the present work, we focus on the shelf region off the west coast of India. We used a new approach in developing a high-resolution hydrodynamic tidal model for the inner shelf region (8°N to 22°N). The open boundary of the model is aligned to the altimetry tracks, which allowed us to prescribe boundary conditions obtained directly from observations. We show that the tidal solutions at the coast are much improved compared with those obtained from the global solutions and that on the wide shelf portion and the Gulf of Khambhat the improvement has been considerable.
Casares-Salazar, R. and Mariño-Tapia, I., 2016. Influence of the remote forcing and local winds on the barotropic hydrodynamics of an elongated coastal lagoon.
The main objective of this study is to investigate the effects of local winds and sea-level variations at tidal and subtidal frequencies on the water levels, depth-averaged velocities, and volume fluxes of an elongated and shallow coastal lagoon using field measurements and a barotropic two-dimensional numerical model. Tides are mainly diurnal and attenuate ~85% from the mouth to the lagoon head, indicating a barotropic propagation dominated by friction. On the other hand, the low-frequency water-level fluctuations propagate with little attenuation (~17%), dominating the water-level variability at the lagoon head. It is considered important to elucidate whether this low-frequency variability is related to local winds or to remote effects. Modeling results show that local winds can increase water levels up to ~1.9 cm in the lagoon head (5% of tide level), whereas remote sea-level variability accounts for up to ~26.6 cm (320% of astronomical tidal level), clearly dominating lagoon water levels. On the other hand, diurnal sea breezes play a minor role in water levels inside the lagoon and do not reinforce diurnal tides in order to generate an important set-up. The cumulative water volume is highly correlated with sea level and shows that low-frequency sea-level fluctuations are especially efficient at accumulating or exporting water from the lagoon during periods of ascending or descending sea level, respectively. This implies that water exchange between the lagoon and the coastal ocean is dominated not only by diurnal tides but also by the low-frequency sea-level fluctuations of astronomical and meteorological origin (i.e. wind forcing through Ekman transport).
El principal objetivo de este estudio es investigar los efectos de los vientos locales y las variaciones del nivel del mar en las frecuencias mareales y submareales de los niveles de agua, velocidades promediadas en la profundidad e intercambios de agua con el mar en una laguna costera alargada y somera, con base en mediciones de campo y un modelo numérico barotrópico en 2D. Las mareas son principalmente diurnas y se atenúan ~85% desde la boca hasta la cabeza de la laguna indicando una propagación barotrópica dominada por fricción. Por otro lado, las fluctuaciones de baja frecuencia en los niveles de agua se propagan con poca atenuación (~17%) dominando la variabilidad del nivel del agua en la cabeza. Es importante elucidar si esta variabilidad de baja frecuencia está relacionada con los vientos locales o se debe a los efectos remotos. Los resultados de modelación muestran que los vientos locales pueden incrementar los niveles de agua hasta ~1.9 cm en la cabeza de la laguna (5% sobre el nivel de marea), mientras que la contribución de la fluctuación de baja frecuencia fue de hasta ~26.6 cm (320% sobre las mareas astronómicas), controlando los niveles de agua dentro de la laguna a frecuencias submareales. Por otro lado, las brisas marinas de frecuencia diurna juegan un rol menor en los niveles de agua dentro de la laguna y no refuerzan a las mareas diurnas para causar un incremento importante del nivel del agua. Los volúmenes acumulados a través de secciones transversales están altamente correlacionados con el nivel del mar y muestran que las fluctuaciones de baja frecuencia del nivel del mar son especialmente eficientes para acumular o exportar agua de la laguna durante períodos de ascenso y descenso de esta variable, respectivamente. Esto implica que los intercambios de agua entre la laguna y el océano costero están dominados no solo por las mareas diurnas sino principalmente por las fluctuaciones de baja frecuencia del nivel del mar, cuyos orígenes son astronómicos y meteorológicos (i.e. forzamiento del viento a través del transporte de E
Yuk, J.-H.; Kim, K.O.; Jung, K.T., and Choi, B.H., 2016. Swell prediction for the Korean coast.
The accurate prediction of abnormally high waves occurring in the East Sea during winter is important in terms of the prevention of coastal disasters along the east Korean coast. This study attempts to hindcast the abnormally high swell wave events that occurred in October 2006 and February 2008 using the unstructured grid wave model UnSWAN with high-resolution reanalysis data from the European Centre for Medium-Range Weather Forecasts as meteorological inputs. The model used in this study incorporates an additional weighting factor for the relative wave-number in dissipation source term to improve swell propagation and wave period. Wave heights and periods are well reproduced compared with the observational data. Examination of the meteorological data and model results shows that the abnormally high waves in October 2006 were induced by the overlap of a swell wave and a wind-generated wave with nearly the same heading directions; the wave generated in February 2008 was, however, induced by the swell that propagated over very long distances from the northeastern area of the East (Japan) Sea due to enhanced atmospheric low pressure. Use of the reanalysis meteorological data and a wave model equipped with a weighting factor is found to be useful in identifying the generation mechanisms as well as reasonable estimates of abnormally high wave events.
Karambas, T.; Koftis, T., and Prinos, P., 2016. Modeling of nonlinear wave attenuation due to vegetation.
In the present work, a nonlinear wave propagation model is developed and is applied for the simulation of the wave dissipation over vegetation. The free-surface flow over the vegetation is simulated using a Boussinesq model, while the flow within the canopy is simulated by solving simultaneously a canopy flow model. The parameters of the canopy flow model are related to the geometric characteristics of the vegetation, while the drag coefficient is taken from existing formulas found in literature and is related to the Reynolds number. The coupling between the Boussinesq and the canopy flow model is simulated by adding two extra terms, due to vegetation, in the continuity and momentum equations of the Boussinesq model. The numerical results are found to be in good agreement with several experimental measurements found in the relevant literature. The advantage of the proposed methodology is based on a nonlinear Boussinesq-type wave model, with wide range of applications for both engineering and scientific purposes, and the use of a canopy flow model with no calibration needed for the model coefficients. Moreover, a simple formula is extracted from the results for the estimation of the wave damping coefficient depending on the meadow and wave parameters.
Cheng, J.; Wang, P., and Smith, E.R., 2016. Hydrodynamic conditions associated with an onshore migrating and stable sandbar.
In this study, large-scale three-dimensional laboratory data were analyzed to identify the hydrodynamic conditions associated with the onshore migration of a sandbar and the subsequent equilibrium state of a stable bar. The initial sandbar was constructed offshore and out of equilibrium, with a symmetrical shape. The bar became asymmetrical as it migrated onshore. As the rate of onshore migration slowed, the bar was restored to a symmetrical shape toward an equilibrium state. Wave and near-bottom velocity across the surf zone were measured during the onshore sandbar migration. The near-bottom velocity skewness analyzed wave by wave indicates that before the sandbar reached equilibrium, the velocity was skewed offshore in the nearshore region and was skewed onshore seaward of the bar. However, the velocity skewness pattern reversed when the beach profile reached equilibrium and the sandbar became stable. The location of maximum undertow velocity moved from nearshore to the bar crest as the sandbar evolved toward equilibrium. Furthermore, the peak onshore-directed acceleration was greater than the peak offshore-directed acceleration throughout the surf zone during the periods of both onshore migrating and stable sandbar. The maximum difference between the onshore- and the offshore-directed acceleration occurred at the seaward side of the bar crest. The analyses of the hydrodynamic conditions associated with sandbar movement in a controlled laboratory experiment provide insights on the mechanisms of sandbar migration.
Fang, K.Z.; Liu, Z.B., and Zou, Z.L., 2016. Fully nonlinear modeling wave transformation over fringing reefs using shock-capturing Boussinesq model.
A numerical model, which solves the horizontal two-dimensional fully nonlinear Boussinesq equations using a well-balanced shock-capturing scheme, is developed and used to investigate wave transformation in a fringing reef environment. The governing equations are first reformulated into a conservative form, and a Godunov-type finite volume method is then used to deal with the convective parts, while the remaining terms are discretized using the finite difference method. Special attention focuses on obtaining a well-balanced state between numerical flux and the source term to model moving wet–dry fronts accurately. The third-order Runge-Kutta scheme with the strong stability preserving property and adaptive time step is used for time marching. After being validated against the analytical solution of exact solitary wave propagation, the proposed model is run to simulate solitary wave transformation over two-dimensional and three-dimensional reefs, and the computed results are in satisfactory agreement with the experimental data.
Liang, B.; Liu, X.; Li, H.; Wu, Y., and Lee, D., 2016. Wave climate hindcasts for the Bohai Sea, Yellow Sea, and East China Sea.
To investigate wave climate of the Bohai Sea, Yellow Sea, and East China Seas, the third-generation wave model Simulated Waves Nearshore (SWAN) is used to simulate waves for the period 1990 to 2011. The spatial resolution of BYECS wave modelling is 1′ in both longitude and latitude. The wind parameters used to simulate the waves are obtained from the Weather Research and Forecasting Model. The results are validated using observational data from seven measurement stations. The spatial distributions of the largest and mean significant wave height within the 22 year period are given, and the spatial distribution of the largest significant wave height of the four seasons is specified. Furthermore, significant wave height is analyzed under mean annual averaged wave conditions for all four seasons. As an example of the application of the hindcast wave data, further details of the wave parameters in Zhangjiapu are presented.
KEYWORDS: hurricane surge, Fox Point, New Bedford, Pawcatuck, Stamford, New London, Raritan Bay, Charles River Dam, Boston, Providence, Great New England Hurricane, Hurricane Carol, Hurricane Sandy
Morang, A., 2016. Hurricane barriers in New England and New Jersey: History and status after five decades.
Massachusetts, Rhode Island, Connecticut, and New Jersey suffered damage, flooding, and deaths from three major hurricanes in less than two decades during the mid-twentieth century. One of these, the Great New England Hurricane of 21 September 1938, caused unprecedented damage and flooded Providence, New London, and other urban areas. Following Hurricane Carol in 1954, the 84th Congress (1st Session, Public Law 71, 15 June 1955) authorized and directed the Secretary of the Army to conduct surveys and studies of damages, causes, and remediation measures with regard to hurricanes. After extensive studies during the late 1950s, Congress authorized and funded seven hurricane protection projects: (1) in Fox Point, Providence, Rhode Island, a barrier, navigation gates, and pumps; (2) in New Bedford, Massachusetts, a barrier, navigation gates, and pumps; (3) in New London, Connecticut, a barrier and navigation gate; (4) in Pawcatuck, Connecticut, earthfill and concrete walls; (5) in Stamford, Connecticut, a barrier and pump station; (6) in Raritan and Sandy Hook Bays, New Jersey, levees, beach fill, and pumps; and (7) in Charles River, Boston, Massachusetts, a dam with locks and pumps. Most of the projects have not been tested with storm-water elevations near their design elevation. Exceptions are the Charles River dam, which helped prevent flooding during the Blizzard of 1978, and Raritan Bay, during Hurricane Sandy. For lower levels, all projects have performed as designed. After the flooding caused by Hurricane Sandy in 2012, comprehensive hurricane barriers have been proposed for the New York area. Many major challenges would confront planners and designers of new hurricane barriers in the New York Bight area compared to the earlier projects: (1) Far more extensive environmental impact studies would have to be conducted now; (2) obtaining permits and negotiating property rights would be a challenging multiyear process; and (3) obtaining easements and construction access would be vastly more difficult now because of the substantially higher value of coastal real estate.
En moins de deux décennies au cours du milieu du 20e siècle, trois ouragans majeurs ont causés des dégâts, des inondations, et des décès au Massachusetts, Rhode Island, Connecticut et au New Jersey. L'un d'eux, The Great New England Hurricane du 21 Septembre 1938, a causé des dommages sans précédent et a inondé la ville de Providence, de New London, ainsi que d'autres zones urbaines. Suite à l'ouragan Carol en 1954, le 84e Congrès (1re session, loi publique 71, 15 Juin 1955) a autorisé et chargé le Secrétaire de l'armée de mener des enquêtes et des études sur les dommages, les causes et les mesures de remédiations reliés aux ouragans. À la fin des années 1950, à la suite d'études exhaustives, le Congrès a autorisé et financé sept projets de protection contre les ouragans: (1) Fox Point, Providence, Rhode Island - barrières, portes de navigation et pompes; (2) New Bedford, Massachusetts – barrière, portes de navigation et pompes; (3) New London, Connecticut - barrière et portes de navigation; (4) Pawcatuck, Connecticut – remblaiement et murs en béton; (5) Stamford, Connecticut – barrière et station de pompage; (6) Raritan et Sandy Hook Bays, New Jersey – digues, rechargement des plages et pompes; et (7) Charles River, Boston, Massachusetts – barrage mobile à battant et pompes. La plupart des projets n'ont pas été testés avec des niveaux d'eaux pluviales à proche de leur élévation limite. Les exceptions sont le barrage Charles River, qui a permis d'éviter des inondations pendant la tempête de 1978, et Raritan Bay, lors de l'ouragan Sandy. Pour des niveaux inférieurs, tous les projets ont fonctionné comme prévu. Après les inondations causées par l'ouragan Ike en 2011, des barrières
Ramsdale, T.M. and Fairweather, P.G., 2016. A calibration equation for combining dry-sieving and laser-diffraction techniques for assessing grain-size distributions of beach sands.
Using laser diffraction to determine sediment grain-size distributions is faster than sieving methods; however, the results of these analytical methods can often differ. Samples are generally only analysed using one method, so the need to convert results, such as for comparison with published values or earlier data collected using different analytical techniques, may arise. To determine a calibration equation for comparing results obtained by laser diffraction to those from test sieves, natural beach-sand samples were processed by both methods and results for mean grain size, sorting, skewness, and kurtosis were compared. There was a strong, linear relationship between methods for mean grain-size values, and calibration between the two methods thus was found to be possible by using the equation: mean grain size (laser diffraction) = 1.441 (test-sieve grain size) − 16.524, in micrometres. Calibration was also possible between values derived for the sorting coefficient: sorting (laser diffraction) = 0.654 (test-sieve sorting) 0.496. Laser diffraction–derived values were coarser, with wider grain-size distributions (indicating poorer sorting), but distributions were more symmetrical and more peaked when compared to sieving-derived values. Values for sorting coefficient, skew, and kurtosis may be affected by smoothing calculations within the laser-diffraction particle-sizing software. For these processed beach-sand samples, laser diffraction offers a faster method for grain sizing, with the tight mathematical relationship of mean grain-size and sorting values obtained between the two methods tested allowing comparison, if needed, of laser-diffraction values to sieving-derived values. This finding allows the comparison of data across studies, especially to earlier work that did not use laser-diffraction technology.
Lee, J.-W. and Park, S.-C., 2016. Artificial neural network-based data recovery system for the time series of tide stations.
Accurate prediction of missing water levels attributable to reasons ranging from recording failure and transmission problems to mistakes made by field staff is essential in coastal and oceanic areas. This paper presents a new system for data recovery based on the artificial neural network soft-computing technique and an end-point fixing method. Only the past time series of tide stations are used, therefore, the data recovery system is not only simple and fast but also effective in situations where all the neighboring tide stations simultaneously malfunction. To verify the efficacy of the proposed data recovery system, we utilized the system at the tide stations located in the eastern part of Korea. Further, we calibrated parameters such as window size and thresholds and conducted performance tests in terms of statistical parameter. Our results indicate that although the performance of the proposed system declines marginally as the gap size increases, it performs creditably in alleviating the gap-filling problem.
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