Morphology and composition of beach-cast Posidonia oceanica litter on beaches with different exposures

NASA Astrophysics Data System (ADS)

Simeone, Simone; De Falco, Giovanni

2012-05-01

Posidonia oceanica seagrass litter is commonly found along sandy shores in the Mediterranean region, forming structures called banquettes, which are often removed in order to allow the beach to be used for tourism. This paper evaluates the relationship between the morphology and composition of banquettes and beach exposure to dominant waves. A Real Time Kinematic Differential Global Positioning System was used to evaluate the variability of banquettes and beach morphology over a period of 1 year. Banquette samples, collected at two different levels of the beach profile (i.e. foreshore and backshore), were used to evaluate the contribution of leaves, rhizomes and sediments to the total weight. Banquettes showed a higher volume, thickness and cross-shore length on exposed beaches, whereas narrower litter deposits were found on the sheltered beach. On exposed beaches, banquettes were deposited in beach zones characterized by changes in elevation. These changes in elevation were mainly due to the deposition and erosion of sediments and secondly to the deposition and or erosion of leaf litter. On sheltered beaches, the variability in beach morphology was low and was restricted to areas where the banquettes were located. The leaf/sediment ratio changed along the cross-shore profile. On the backshore, banquettes were a mixture of sediments and leaves, whereas leaves were the main component on the foreshore, independently of the beach exposure. The processes which control the morphodynamics in the swash zone could explain the variability of banquette composition along the cross-shore profile. Finally, this study highlighted that Posidonia oceanica seagrass litter plays an important role in the geomorphology of the beachface and its removal can have a harmful impact on the beaches.

Characterization of microplastic and mesoplastic debris in sediments from Kamilo Beach and Kahuku Beach, Hawai'i.

PubMed

Young, Alan M; Elliott, James A

2016-12-15

Sediment samples were collected from two Hawai'ian beaches, Kahuku Beach on O'ahu and Kamilo Beach on the Big Island of Hawai'i. A total of 48,988 large microplastic and small mesoplastic (0.5-8mm) particles were handpicked from the samples and sorted into four size classes (0.5-1mm, 1-2mm, 2-4mm, 4-8mm) and nine color categories. For all sizes combined the most common plastic fragment color was white/transparent (71.8%) followed by blue (8.5%), green (7.5%), black/grey (7.3%), red/pink (2.6%), yellow (1.2%), orange (0.6%), brown (0.3%) and purple (0.2%). Color frequency distribution based on both numbers and mass of particles was not significantly different among the various size classes nor between the two beaches. White and black/grey resin pellets accounted for 11.3% of the particles collected from Kahuku Beach and 4.2% of the particles from Kamilo Beach. Plastic type based on Raman Spectrometer analysis of a small representative subsample indicated that most of the fragments were polyethylene and a few were polypropylene. Copyright © 2016 Elsevier Ltd. All rights reserved.

Integration of bed characteristics, geochemical tracers, current measurements, and numerical modeling for assessing the provenance of beach sand in the San Francisco Bay Coastal System

USGS Publications Warehouse

Barnard, Patrick L.; Foxgrover, Amy C.; Elias, Edwin P.L.; Erikson, Li H.; Hein, James; McGann, Mary; Mizell, Kira; Rosenbauer, Robert J.; Swarzenski, Peter W.; Takesue, Renee K.; Wong, Florence L.; Woodrow, Don

2013-01-01

Over 150 million m3 of sand-sized sediment has disappeared from the central region of the San Francisco Bay Coastal System during the last half century. This enormous loss may reflect numerous anthropogenic influences, such as watershed damming, bay-fill development, aggregate mining, and dredging. The reduction in Bay sediment also appears to be linked to a reduction in sediment supply and recent widespread erosion of adjacent beaches, wetlands, and submarine environments. A unique, multi-faceted provenance study was performed to definitively establish the primary sources, sinks, and transport pathways of beach-sized sand in the region, thereby identifying the activities and processes that directly limit supply to the outer coast. This integrative program is based on comprehensive surficial sediment sampling of the San Francisco Bay Coastal System, including the seabed, Bay floor, area beaches, adjacent rock units, and major drainages. Analyses of sample morphometrics and biological composition (e.g., Foraminifera) were then integrated with a suite of tracers including 87Sr/86Sr and 143Nd/144Nd isotopes, rare earth elements, semi-quantitative X-ray diffraction mineralogy, and heavy minerals, and with process-based numerical modeling, in situ current measurements, and bedform asymmetry to robustly determine the provenance of beach-sized sand in the region.

Monitoring and modeling shoreline response due to shoreface nourishment on a high-energy coast

USGS Publications Warehouse

Barnard, P. L.; Erikson, Li H.; Hansen, J. E.

2009-01-01

Shoreface nourishment can be an efficient technique to feed sediment into the littoral zone without the order of magnitude cost increase incurred by directly nourishing the beach. An erosion hot spot at Ocean Beach in San Francisco, California, USA, threatens valuable public infrastructure as well as safe recreational use of the beach. In an effort to reduce the erosion at this location, a new beneficial reuse plan was implemented in May 2005 for the sediment dredged annually from the main shipping channel at the mouth of San Francisco Bay. From 2005 to 2007, approximately 230,000 m of sand was placed annually at depths between 9 and 14 m, in a location where strong tidal currents and open-ocean waves could potentially feed sediment onto the section of beach experiencing critical erosion. The evolution of the disposal mound and adjacent beach were monitored with 12 multibeam bathymetric surveys, and over 40 high-resolution beach topographic surveys. In addition, sediment transport processes were investigated using sediment grab samples, acoustic Doppler profilers, and two separate models: a cross-shore profile model (UNIBEST-TC) and a coastal area model (Delft3D). The results of the monitoring and modeling demonstrate that the disposal mound may be effective in dissipating wave energy striking this vulnerable stretch of coast with negligible shadowing effects, but a positive shoreline response can only be achieved by placing the sediment in water depths less than 5 m. 

Observations of coarse sediment movements on the mixed beach of the Elwha Delta, Washington

USGS Publications Warehouse

Miller, I.M.; Warrick, J.A.; Morgan, C.

2011-01-01

Mixed beaches, with poorly sorted grains of multiple sizes, are a common and globally distributed shoreline type. Despite this, rates and mechanisms of sediment transport on mixed beaches are poorly understood. A series of tracer deployments using native clasts implanted with Radio Frequency Identifier (RFID) tags was used to develop a better understanding of sediment transport directions and magnitudes on the mixed grain-size beach of the Elwha River delta. Using tracer samples selected to match the distribution of the coarse fraction on the beach we find that all grain sizes, up to large cobbles (128-256 mm), were mobile under most measured wave conditions and move in relationship to the direction of the alongshore component of wave energy as estimated by incident breaking wave angles. In locations where the breaking wave is normal to the shoreline we find that tracers move in both alongshore directions with approximately equal frequency. In locations where breaking waves are oblique to the shoreline we find that alongshore transport is more unidirectional and tracers can approach average velocities of 100. m/day under winter wave conditions. We use the tracer cloud to estimate the beach active width, the mobile layer depth and sediment velocity. Our results suggest that, while sediment velocity increases under increased incident wave angles, the active layer depth and width decrease, reducing sediment flux at the site with the more oblique breaking waves. This result is contrary to what is suggested by traditional wave energy transport models of alongshore sediment transport. ?? 2011 Elsevier B.V.

Microplastic in beach sediments of the Isle of Rügen (Baltic Sea) - Implementing a novel glass elutriation column.

PubMed

Hengstmann, Elena; Tamminga, Matthias; Vom Bruch, Constantin; Fischer, Elke Kerstin

2018-01-01

To extent the understanding on microplastics in the marine environment we performed a case study at four beaches on the Isle of Rügen considering abundance and spatial distribution of microplastics in beach sediments. For the analysis, density separation via a glass elutriation column was implemented. In advance, efficiencies were tested for two polymers, being not buoyant in water. Recovery rates of 80% for PET and 72% for PVC particles in sandy samples were achieved. A median abundance of 88.10 (Q 1 =55.01/Q 3 =114.72) microplastic particles per kg dry sediment or 2862.56 (Q 1 =1787.34/Q 3 =3727.28) particles per m 2 was found at the beaches on Rügen. Fibers were more abundant than fragments at all beaches. In this study, no statistically significant differences but only tendencies were determined between the beaches with different exposition and anthropogenic activity as well as for distribution patterns which showed that microplastic fragments accumulate in topographic depressions, similar to macrolitter items. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bioavailable metals in tourist beaches of Richards Bay, Kwazulu-Natal, South Africa.

PubMed

Vetrimurugan, E; Jonathan, M P; Roy, Priyadarsi D; Shruti, V C; Ndwandwe, O M

2016-04-15

Acid Leachable Trace Metal (ALTMs) concentrations in tourist beaches of Richards Bay, Kwazulu-Natal, South Africa were assessed. 53 surface sediment samples were collected from five different beaches (Kwambonambi Long Beach; Nhlabane Beach; Five Mile Beach; Alkanstrand Beach and Port Durnford Beach). The results of ALTMs (Fe, Mn, Cr, Cu, Ni, Co, Pb, Cd, Zn, As, Hg) suggest that they are enriched naturally and with some local industrial sources for (avg. in μgg(-1)) Fe (3530-7219), Mn (46-107.11), Cd (0.43-1.00) and Zn (48-103.98). Statistical results indicate that metal concentrations were from natural origin attributed to leaching, weathering process and industrial sources. Comparative studies of metal concentrations with sediment quality guidelines and ecotoxicological values indicate that there is no adverse biological effect. Enrichment factor and geoaccumulation indices results indicate moderate enhancement of Fe (Igeo class 1 in FMB), Cd (EF>50; Igeo classes 2-4) and Zn (Igeo classes 1 & 2). Copyright © 2016 Elsevier Ltd. All rights reserved.

Metal concentrations in sediments from tourist beaches of Miri City, Sarawak, Malaysia (Borneo Island).

PubMed

Nagarajan, R; Jonathan, M P; Roy, Priyadarsi D; Wai-Hwa, L; Prasanna, M V; Sarkar, S K; Navarrete-López, M

2013-08-15

Forty-three sediment samples were collected from the beaches of Miri City, Sarawak, Malaysia to identify the enrichment of partially leached trace metals (PLTMs) from six different tourist beaches. The samples were analyzed for PLTMs Fe, Mn, Cr, Co, Cu, Ni, Pb, Sr and Zn. The concentration pattern suggest that the southern side of the study area is enriched with Fe (1821-6097 μg g(-1)), Mn (11.57-90.22 μg g(-1)), Cr (51.50-311 μg g(-1)), Ni (18-51 μg g(-1)), Pb (8.81-84.05 μg g(-1)), Sr (25.95-140.49 μg g(-1)) and Zn (12.46-35.04 μg g(-1)). Compared to the eco-toxicological values, Cr>Effects range low (ERL), Lowest effect level (LEL), Severe effect level (SEL); Cu>Unpolluted sediments, ERL, LEL; Pb>Unpolluted sediments and Ni>ERL and LEL. Comparative results with other regions indicate that Co, Cr, Cu, Ni and Zn are higher, indicating an external input rather than natural process. Copyright © 2013 Elsevier Ltd. All rights reserved.

Persistence and microbial source tracking of Escherichia coli at a swimming beach at Lake of the Ozarks State Park, Missouri

USGS Publications Warehouse

Wilson, Jordan L.; Schumacher, John G.; Burken, Joel G.

2016-01-01

The Missouri Department of Natural Resources (MDNR) has closed or posted advisories at public beaches at Lake of the Ozarks State Park in Missouri because of Escherichia coli (E. coli) concentration exceedances in recent years. Spatial and temporal patterns of E. coliconcentrations, microbial source tracking, novel sampling techniques, and beach-use patterns were studied during the 2012 recreational season to identify possible sources, origins, and occurrence of E. coli contamination at Grand Glaize Beach (GGB). Results indicate an important source of E. coli contamination at GGB was E. coli released into the water column by bathers resuspending avian-contaminated sediments, especially during high-use days early in the recreational season. Escherichia coli concentrations in water, sediment, and resuspended sediment samples all decreased throughout the recreational season likely because of decreasing lake levels resulting in sampling locations receding away from the initial spring shoreline as well as natural decay and physical transport out of the cove. Weekly MDNR beach monitoring, based solely on E. coli concentrations, at GGB during this study inaccurately predicted E. coli exceedances, especially on weekends and holidays. Interestingly, E. coli of human origin were measured at concentrations indicative of raw sewage in runoff from an excavation of a nearby abandoned septic tank that had not been used for nearly two years.

Long-Term Changes in Beach Fauna at Duck, North Carolina.

DTIC Science & Technology

1982-11-01

content of each sediment sample was determined by the hydrochloric acid (HCl) method (Carver, 1971). III. RESULTS 1. Ocean Beach. a. Physical Environment...2 2 7 2 2 2 5 2 3 2 1 3 2 2 2 Table 11. Water temperatu e ° Celsius) recorded at each site on the sound beach. Seasoln I November 1980 January 1981

Tracing sediment dispersal on nourished beaches: Two case studies

USGS Publications Warehouse

Thieler, E. Robert; Gayes, Paul T.; Schwab, William C.; Harris, M. Scott

1999-01-01

The event- to decade-scale patterns of sediment dispersal on two artificially nourished beaches have been mapped using a combination of geophysical surveys, closely-spaced vibracores, and repeated beach profiles. At both Wrightsville Beach, NC and Folly Island, SC the sediment used for beach nourishment is macroscopically distinct from native sediment and can be used to identify sediment transport pathways and infer mechanisms for across-shelf transport. The data from both sites demonstrate that significant quantities of nourishment sediment are being transported seaward onto the inner continental shelf. The time and space scales of this transport are of engineering interest for the planning, design and long-term maintenance of nourished beaches.

Morphologic Response and Sediment Redistribution of the Beach and Nearshore Sand Bars due to Extratropical and Tropical Storm Forcing: a Spatial and Temporal Analysis

NASA Astrophysics Data System (ADS)

Miselis, J. L.; McNinch, J. E.

2005-05-01

Shore-oblique bars and associated exposures of an underlying geologic stratum in the nearshore have been documented along the US East Coast and have been linked to shoreline erosional hotspots. While earlier studies acknowledged that the bedforms responded to extratropical and tropical storms, neither quantified the extent of sediment redistribution after the events. An approach that encompasses actual volume measurements across the nearshore-beach down to a non-sandy stratum and quantifies the response of the beach and the nearshore to the same hydrodynamic forcing will enable a better understanding of the exchange of sediment between the two regions. Total nearshore sediment volume has been shown to be a first-order contributor to the behavior of the shoreline. This volumetric approach is employed in the analysis of morphological changes and the redistribution of sediment in the nearshore and beach following storms. A regional survey from 2002 provides the initial, fair-weather morphologic state of the nearshore (1.5-15m water depth) spanning 40 km of the North Carolina Outer Banks. Four small-scale surveys were conducted in subsequent years, focusing on four 1-km2 regions within the initial 2002 survey area. The smaller regions were selected on the basis of the morphological state observed during the 2002 survey and historical shoreline behavior. Data were collected in March 2003 following a Northeaster; in May 2003 following an extended period of fair weather conditions; in November 2003 following Hurricane Isabel; and finally, in June 2004 after another period of fair weather. A swath bathymetry system was used to collect bathymetry and side scan sonar (acoustic backscatter) and a high-resolution chirp sub-bottom profiler imaged the shallow sub-surface geology of the nearshore. In addition, RTK-GPS was used to map the sub-aerial beach at each 1-km2 site from the toe of the dune to the water line for the May 2003, November 2003, and June 2004 sampling periods. This sampling regime and data set offers a unique opportunity 1) to compare the simultaneous response of the beach and the nearshore to storms and 2) to investigate how the response of the beach and the nearshore varies depending on sandbar morphology and differences in the geologic framework. Three-dimensional maps of the beach and nearshore, from the toe of the dune to the 15m isobath, are used to demonstrate changes in total shoreface volume after storms and during recovery. Understanding the redistribution of sediment in the context of volumetric change enables the quantification of the exchange of sediment between the beach and the nearshore during large-scale forcing events.

Longshore water-current velocity and the potential for transport of contaminants—A pilot study in Lake Erie from Walnut Creek to Presque Isle State Park beaches, Erie, Pennsylvania, June and August 2015

USGS Publications Warehouse

Hittle, Elizabeth A.

2017-04-20

Bacteria-driven restrictions and (or) advisories on swimming at beaches in Presque Isle State Park (PISP), Erie, Pennsylvania, can occur during the summer months. One of the suspected sources of bacteria is sediment. A terrestrial sediment source to the west of PISP is Walnut Creek, which discharges to Lake Erie about 8.5 kilometers southwest of PISP Beach 1. On June 24, June 25, August 18, and August 19, 2015, synoptic surveys were conducted by the U.S. Geological Survey, in cooperation with the Pennsylvania Sea Grant, in Lake Erie between Walnut Creek and PISP Beach 1 to characterize the water-current velocity and direction to determine whether sediment from Walnut Creek could be affecting the PISP beaches. Water-quality data (temperature, specific conductance, and turbidity) were collected in conjunction with the synoptic surveys in June. Water-quality data (Escherichia coli [E. coli] bacteria, temperature, and turbidity) were collected about a meter from the shore (nearshore) on June 24, August 19, and after a precipitation event on August 11, 2015. Additionally, suspended sediment was collected nearshore on June 24 and August 11, 2015. Samples collected near Walnut Creek during all three bacterial sampling events contained higher counts than other samples. Counts steadily decreased from west to east, then increased about 1–2 kilometers from PISP Beach 1; however, this study was not focused on examining other potential sources of bacteria.The Velocity Mapping Toolbox (VMT) was used to process the water-current synoptic surveys, and the results were visualized within ArcMap. For the survey accomplished on June 24, 2015, potential paths a particle could take between Walnut Creek and PSIP Beach 1 if conditions remained steady over a number of hours were visualized. However, the water-current velocity and direction were variable from one day to the other, indicating this was likely an unrealistic assumption for the study area. This analysis was not accomplished for the other surveys due to unsteady lake conditions encountered on June 25 and August 18, and reduced quality of the survey on August 19.

Recovery of intertidal hardshelled clams in Prince William Sound from Exxon Valdez oiling and shoreline treatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Houghton, J.P.; Lees, D.C.; Driskell, W.B.

1994-12-31

Native little neck (Protothaca staminea) and butter clams (Saxidomus giganteus) were quantitatively surveyed from 1989 through 1993 to evaluate effects from the Exxon Valdez oil spill. Hydraulic washing of sand and gravel beaches altered beach morphology by transporting material down slope from upper elevations, often burying the lower beach in several centimeters of sediment having a relatively low content of fines and organic carbon. Hydraulically washed beaches showed significant reductions in clam densities in 1989 and 1990. Recruitment of clams was very limited on these beaches through 1993; as a result, clam densities on these hydraulically washed beaches remain verymore » depressed compared to those on beaches that were unoiled or oiled but not washed. Littlenecks transplanted from a reference site to a heavily oiled but untreated site showed significant patterns of increased mortality, decreased growth, and increased bioaccumulation of PAH in response to a gradient in sediment PAH, This same heavily oiled site has consistently had among the highest rates of hardshelled clam recruitment of any of the sites sampled. Littlenecks also were transplanted to another heavily oiled beach that had been hydraulically washed and had little remaining hydrocarbons. These clams showed very high survival, yet this beach has had very little clam recruitment. It is hypothesized that recruitment at this site may be inhibited by the low level of finer sediments and low organic content remaining after washing.« less

Numerical experiments on breaking waves on contrasting beaches using a two-phase flow approach

NASA Astrophysics Data System (ADS)

Bakhtyar, R.; Barry, D. A.; Kees, C. E.

2012-11-01

A mechanistic understanding of beach environments needs to account for interactions of oceanic forcing and beach materials, in particular the role of waves on the evolution of the beach profile. A fully coupled two-phase flow model was used to simulate nearshore fluid-sediment turbulent flow in the cross-shore direction. It includes the Reynolds-Averaged Navier-Stokes equations and turbulent stress closures for each phase, and accounts for inter-granular stresses. The model has previously been validated using laboratory-scale data, so the results are likely more reliable for that scale. It was used to simulate wave breaking and the ensuing hydrodynamics and sediment transport processes in the surf/swash zones. Numerical experiments were conducted to investigate the effects of varying beach and wave characteristics (e.g., beach slope, sediment grain size, wave periods and heights) on the foreshore profile changes. Spilling and plunging breakers occur on dissipative and intermediate beaches, respectively. The impact of these wave/beach types on nearshore zone hydrodynamics and beach morphology was determined. The numerical results showed that turbulent kinetic energy, sediment concentrations and transport rate are greater on intermediate than on dissipative beaches. The results confirmed that wave energy, beach grain size and bed slope are main factors for sediment transport and beach morphodynamics. The location of the maximum sediment transport is near the breaking point for both beach types. Coarse- and fine-sand beaches differ significantly in their erosive characteristics (e.g., foreshore profile evolutions are erosive and accretionary on the fine and coarse sand beaches, respectively). In addition, a new parameter (based on main driving factors) is proposed that can characterize the sediment transport in the surf and swash zones. The results are consistent with existing physical observations, suggesting that the two-phase flow model is suitable for the simulation of hyper-concentrated mixed water-sediment flows in the nearshore. The model thus has potential as a useful tool for investigating interactions between nearshore hydrodynamics and beach morphology.

Field test comparison of an autocorrelation technique for determining grain size using a digital 'beachball' camera versus traditional methods

USGS Publications Warehouse

Barnard, P.L.; Rubin, D.M.; Harney, J.; Mustain, N.

2007-01-01

This extensive field test of an autocorrelation technique for determining grain size from digital images was conducted using a digital bed-sediment camera, or 'beachball' camera. Using 205 sediment samples and >1200 images from a variety of beaches on the west coast of the US, grain size ranging from sand to granules was measured from field samples using both the autocorrelation technique developed by Rubin [Rubin, D.M., 2004. A simple autocorrelation algorithm for determining grain size from digital images of sediment. Journal of Sedimentary Research, 74(1): 160-165.] and traditional methods (i.e. settling tube analysis, sieving, and point counts). To test the accuracy of the digital-image grain size algorithm, we compared results with manual point counts of an extensive image data set in the Santa Barbara littoral cell. Grain sizes calculated using the autocorrelation algorithm were highly correlated with the point counts of the same images (r2 = 0.93; n = 79) and had an error of only 1%. Comparisons of calculated grain sizes and grain sizes measured from grab samples demonstrated that the autocorrelation technique works well on high-energy dissipative beaches with well-sorted sediment such as in the Pacific Northwest (r2 ??? 0.92; n = 115). On less dissipative, more poorly sorted beaches such as Ocean Beach in San Francisco, results were not as good (r2 ??? 0.70; n = 67; within 3% accuracy). Because the algorithm works well compared with point counts of the same image, the poorer correlation with grab samples must be a result of actual spatial and vertical variability of sediment in the field; closer agreement between grain size in the images and grain size of grab samples can be achieved by increasing the sampling volume of the images (taking more images, distributed over a volume comparable to that of a grab sample). In all field tests the autocorrelation method was able to predict the mean and median grain size with ???96% accuracy, which is more than adequate for the majority of sedimentological applications, especially considering that the autocorrelation technique is estimated to be at least 100 times faster than traditional methods.

Evaluation of a small beach nourishment project to enhance habitat suitability for horseshoe crabs

USGS Publications Warehouse

Jackson, N.L.; Smith, D.R.; Tiyarattanachai, R.; Nordstrom, K.F.

2007-01-01

This field study evaluates the effect of nourishing an estuarine beach with gravel to enhance spawning rates by horseshoe crabs. A total of 564??m3 of coarse sand and gravel were emplaced in two 90??m-long treatment segments at Bowers Beach, Delaware, USA from 9 to 11 April 2002. Field data were gathered between 6 April and 24 May 2002 to characterize the two fill segments and the un-nourished segments between them as well as two control segments at the adjacent Ted Harvey Beach. Sediment samples were taken from the foreshore surface and at depth before and after the nourishment. Bay water levels, wave heights, and beach ground water characteristics were monitored over a 12-hour tidal cycle at one of the nourished (15 May 2002) and the unnourished segment (16 May 2002) at Bowers Beach and at one of the control segments at Ted Harvey Beach (21 May 2002) using piezometers and pressure transducers inserted in wells. The beaches were cored to estimate the density of horseshoe crab eggs deposited during the spawning season. Horseshoe crab eggs were buried in pouches at 0.15 to 0.20??m depth for 30 to 40??days to evaluate their survival in developing into embryo or larval stage. Bulk sediment samples were taken to evaluate moisture characteristics near locations where egg pouches were buried. Density of spawning females at Bowers Beach was 1.04??m- 2 in 2001 and 1.20??m- 2 in 2002. These rates are lower than at Ted Harvey Beach but reveal an increase in spawning while Ted Harvey Beach underwent a considerable decrease (2.63??m- 2 to 1.35??m- 2). Sediments low on the foreshore remained nearly saturated throughout the tidal cycle at both beaches. The average hydraulic conductivity on the upper foreshore at the non-treatment section at Bowers Beach (0.19??cm s- 1) was less than at Ted Harvey Beach (0.27??cm s- 1), and the finer, better sorted sediments at depth at Bowers Beach resulted in a higher porosity, creating greater moisture retention potential. Egg development was greatest at mid foreshore at all sites. Eggs at the lower foreshore elevation remained viable, but did not develop to the embryo stage. Between-beach differences were limited to high elevations where higher mortality occurred at Ted Harvey Beach due to desiccation. Adding small amounts of gravel to a sand beach may change the appearance of the surface but may not appreciably increase mean grain size and sorting at depth or the hydraulic conductivity over the spawning season. The pebble fraction may be important for site selection, but finer sizes may be more important for egg survival because of moisture retention. ?? 2006 Elsevier B.V. All rights reserved.

Regime Shift in Sandy Beach Microbial Communities following Deepwater Horizon Oil Spill Remediation Efforts

PubMed Central

Engel, Annette Summers; Gupta, Axita A.

2014-01-01

Sandy beaches support a wide variety of underappreciated biodiversity that is critical to coastal ecosystems. Prior to the 2010 Deepwater Horizon oil spill, the diversity and function of supratidal beach sediment microbial communities along Gulf of Mexico coastlines were not well understood. As such, it was unclear if microbial community compositional changes would occur following exposure to beached oil, if indigenous communities could biodegrade oil, or how cleanup efforts, such as sand washing and sediment redistribution, would impact microbial ecosystem resiliency. Transects perpendicular to the shoreline were sampled from public beaches on Grand Isle, Louisiana, and Dauphin Island, Alabama, over one year. Prior to oil coming onshore, elevated levels of bacteria associated with fecal contamination were detected (e.g., Enterobacteriales and Campylobacterales). Over time, significant shifts within major phyla were identified (e.g., Proteobacteria, Firmicutes, Actinobacteria) and fecal indicator groups were replaced by taxa affiliated with open-ocean and marine systems (e.g., Oceanospirillales, Rhodospirillales, and Rhodobacterales). These new bacterial groups included putative hydrocarbon degraders, similar to those identified near the oil plume offshore. Shifts in the microbial community composition strongly correlated to more poorly sorted sediment and grain size distributional changes. Natural oceanographic processes could not account for the disrupted sediment, especially from the backshore well above the maximum high-tide levels recorded at these sites. Sand washing and tilling occurred on both open beaches from August through at least December 2010, which were mechanisms that could replace fecal indicator groups with open-ocean groups. Consequently, remediation efforts meant to return beaches to pre-spill compositions caused a regime shift that may have added potential ecosystem function, like hydrocarbon degradation, to the sediment. Future research will need to assess the persistence and impact of the newly formed microbial communities to the overall sandy beach ecosystems. PMID:25036744

Storm recovery on two Italian coarse-grained beaches: a comparison between a mixed sand and gravel and a pebble beach

NASA Astrophysics Data System (ADS)

Bertoni, Duccio; Grottoli, Edoardo; Ciavola, Paolo; Sarti, Giovanni; Pozzebon, Alessandro

2014-05-01

High energy events emphasize beach erosion processes, sometimes leading to huge volume deficits not balanced by recovery under fair-weather conditions. In this scenario, artificial replenishments are frequently used as a form of coastal protection with large volumes of sediments re-injected in the system without strongly altering the environment as it happens with hard structures. Since climate change is expected to accentuate in the near future erosion effects, the need to artificially feed beaches is likely to increase. Gravel and pebbles are more and more often used as beach fill, on some occasions replacing sandy sediments. That was the case for two beaches located at either sides of the Italian Peninsula (Portonovo, Adriatic Sea; Marina di Pisa, Ligurian Sea), which constitute the study area of the present research. Portonovo is a 500 m-long mixed sand and gravel beach with a significant pebble-sized content (about 40%), unloaded on the beach during multiple replenishments. Marina di Pisa is an artificial, 180 m-long beach, mainly composed of 40-to-90 mm pebbles; it was built in 2008 as a part of a larger protection scheme. Groins or headlands that prevent any sediment exchange with adjacent areas bound both beaches. Periodic topographic surveys were carried out to evaluate the response of these human-altered beaches to high-energy events. The topographic surveys, undertaken with a DGPS-RTK instrument along cross-shore transects (from the landward end of the backshore to about 1.5 m depth seaward), were done following intense storm events occurred during the time period of the research. Transects were done out every 10 m along the entire length of the beaches. Prior to the first topographic survey, a sediment tracing experiment was set up as a form of control of the results provided by the geomorphologic analysis. Pebbles directly sampled from the beaches were marked by means of the RFID technology and injected back all along the beachface. As expected, considerable beach profile changes after the storms were identified, in particular at Portonovo (mixed beach), where huge sediment volumes were displaced longshore according to the incident wave direction as opposed to Marina di Pisa (gravel dominated), where the main beach changes developed along the cross-shore direction. In terms of resilience, results showed a better response of the Portonovo beach rather than the Marina di Pisa beach. The different response might be ascribed to the grain-size that constitutes the beaches: no physical process can rework the pebbles at Marina di Pisa once they are moved during the storms towards the back-end of the backshore or seaward of the step, thus preventing any beach recovery process to take place. Since the awareness on storm impacts is more critical than in the past, the understanding of beach recovery to extreme events needs new insights to combine the preservation of natural beach evolution as well as maintenance for end-users. That is particularly pressing on coarse-grained beaches, where the need to predict storm impact and recovery is much more vital considering that finding suitable sediment to refill the beach is never an easy task.

Non-Linear Interactions Determine the Impact of Sea-Level Rise on Estuarine Benthic Biodiversity and Ecosystem Processes

PubMed Central

Yamanaka, Tsuyuko; Raffaelli, David; White, Piran C. L.

2013-01-01

Sea-level rise induced by climate change may have significant impacts on the ecosystem functions and ecosystem services provided by intertidal sediment ecosystems. Accelerated sea-level rise is expected to lead to steeper beach slopes, coarser particle sizes and increased wave exposure, with consequent impacts on intertidal ecosystems. We examined the relationships between abundance, biomass, and community metabolism of benthic fauna with beach slope, particle size and exposure, using samples across a range of conditions from three different locations in the UK, to determine the significance of sediment particle size beach slope and wave exposure in affecting benthic fauna and ecosystem function in different ecological contexts. Our results show that abundance, biomass and oxygen consumption of intertidal macrofauna and meiofauna are affected significantly by interactions among sediment particle size, beach slope and wave exposure. For macrofauna on less sloping beaches, the effect of these physical constraints is mediated by the local context, although for meiofauna and for macrofauna on intermediate and steeper beaches, the effects of physical constraints dominate. Steeper beach slopes, coarser particle sizes and increased wave exposure generally result in decreases in abundance, biomass and oxygen consumption, but these relationships are complex and non-linear. Sea-level rise is likely to lead to changes in ecosystem structure with generally negative impacts on ecosystem functions and ecosystem services. However, the impacts of sea-level rise will also be affected by local ecological context, especially for less sloping beaches. PMID:23861863

Non-linear interactions determine the impact of sea-level rise on estuarine benthic biodiversity and ecosystem processes.

PubMed

Yamanaka, Tsuyuko; Raffaelli, David; White, Piran C L

2013-01-01

Sea-level rise induced by climate change may have significant impacts on the ecosystem functions and ecosystem services provided by intertidal sediment ecosystems. Accelerated sea-level rise is expected to lead to steeper beach slopes, coarser particle sizes and increased wave exposure, with consequent impacts on intertidal ecosystems. We examined the relationships between abundance, biomass, and community metabolism of benthic fauna with beach slope, particle size and exposure, using samples across a range of conditions from three different locations in the UK, to determine the significance of sediment particle size beach slope and wave exposure in affecting benthic fauna and ecosystem function in different ecological contexts. Our results show that abundance, biomass and oxygen consumption of intertidal macrofauna and meiofauna are affected significantly by interactions among sediment particle size, beach slope and wave exposure. For macrofauna on less sloping beaches, the effect of these physical constraints is mediated by the local context, although for meiofauna and for macrofauna on intermediate and steeper beaches, the effects of physical constraints dominate. Steeper beach slopes, coarser particle sizes and increased wave exposure generally result in decreases in abundance, biomass and oxygen consumption, but these relationships are complex and non-linear. Sea-level rise is likely to lead to changes in ecosystem structure with generally negative impacts on ecosystem functions and ecosystem services. However, the impacts of sea-level rise will also be affected by local ecological context, especially for less sloping beaches.

Coastal Processes Study of Santa Barbara and Ventura Counties, California

USGS Publications Warehouse

Barnard, Patrick L.; Revell, David L.; Hoover, Dan; Warrick, Jon; Brocatus, John; Draut, Amy E.; Dartnell, Pete; Elias, Edwin; Mustain, Neomi; Hart, Pat E.; Ryan, Holly F.

2009-01-01

The Santa Barbara littoral cell (SBLC) is a complex coastal system with significant management challenges. The coastline ranges broadly in exposure to wave energy, fluvial inputs, hard structures, and urbanization. Geologic influence (structural control) on coastline orientation exerts an important control on local beach behavior, with anthropogenic alterations and the episodic nature of sediment supply and transport also playing important roles. Short- and long-term temporal analyses of shoreline change, beach width, and volume change show no obvious trends in regional beach behavior. Extensive armoring along the SBLC has accreted the back beach, narrowing beach widths and in some cases increasing sediment transport. Unarmored beaches have exhibited mild erosion while maintaining similar widths. Harbor constructions have had notable impacts on downdrift beaches, but once the coastal system has equilibrated the signal becomes strongly dampened and littoral-drift gradients driven by natural shoreline orientation again become dominant. Sediment inputs from the Santa Clara River dominate sediment processes on beaches to the south. The SBLC is dominated by episodic flood and storm-wave events. Exceptionally large accretion signals along this stretch of coastline are closely tied to major flood events when large amounts of sediment are deposited in deltas. These deltas decay over time, supplying downdrift beaches with sediment. Storm-wave impacts and gradients in alongshore transport can lead to beach rotations and migrating erosion hotspots when geological controls are weak. Annual and seasonal rates of cross-shore and alongshore transport are at least 2-3 times higher for the more west- and southwest-facing beaches south of the Ventura River as compared to the more sheltered beaches to the west/north. Gross littoral transports are good approximations of net littoral transports for beaches west/north of Ventura as transport is almost purely unidirectional. However, significant transport reversals occur intermittently in the east/south, especially adjacent to the Ventura and Channel Islands Harbors. For this reason, and due to the episodic nature of flood and storm wave events, using dredging rates from the harbors at Ventura and Channel Islands as a proxy for drift rates may be invalid. An extensive grain-size investigation of the surface and shallow subsurface in the nearshore region of the SBLC identified only two sites for potential beach-nourishment material: offshore of Santa Barbara Harbor and Oil Piers. However, seismic-reflection lines offshore of Santa Barbara suggest shallow bedrock (< 1 m), so the volume of coarse material in this area may be limited. Sampling of the Santa Clara River delta was minimal, but this site could be promising. Numerical modeling shows that local beach behavior is primarily influenced by local littoral-drift gradients, which are in turn controlled by natural shoreline orientation. Given the high rates of net littoral drift and the relatively insignificant cross-shore transport in the SBLC, the SBLC should be considered a sediment-limited system (as opposed to a transport-limited system). Management actions, such as any future beach nourishment, would likely have a severely limited life span without employing additional measures that adequately address local littoral-drift gradients to retain added sand.

Ecology of exposed sandy beaches in northern Spain: Environmental factors controlling macrofauna communities

NASA Astrophysics Data System (ADS)

Lastra, M.; de La Huz, R.; Sánchez-Mata, A. G.; Rodil, I. F.; Aerts, K.; Beloso, S.; López, J.

2006-02-01

Thirty-four exposed sandy beaches on the northern coast of Spain (from 42°11' to 43°44'N, and from 2°04' to 8°52' W; ca. 1000 km) were sampled over a range of beach sizes, beach morphodynamics and exposure rates. Ten equally spaced intertidal shore levels along six replicated transects were sampled at each beach. Sediment and macrofauna samples were collected using corers to a depth of 15 cm. Morphodynamic characteristics such as the beach face slope, wave environment, exposure rates, Dean's parameter and Beach State Index were estimated. Biotic results indicated that in all the beaches the community was dominated by isopods, amphipods and polychaetes, mostly belonging to the detritivorous-opportunistic trophic group. The number of intertidal species ranged from 9 to 31, their density being between 31 and 618 individuals m - 2 , while individuals per linear metre (m - 1 ) ranged from 4962 to 17 2215. The biomass, calculated as total ash-free dry weight (AFDW) varied from 0.027 to 2.412 g m - 2 , and from 3.6 to 266.6 g m - 1 . Multiple regression analysis indicated that number of species significantly increased with proximity to the wind-driven upwelling zone located to the west, i.e., west-coast beaches hosted more species than east-coast beaches. The number of species increased with decreasing mean grain size and increasing beach length. The density of individuals m - 2 increased with decreasing mean grain size, while biomass m - 2 increased with increasing food availability estimated as chlorophyll-a concentration in the water column of the swash zone. Multiple-regression analysis indicated that chlorophyll-a in the water column increased with increasing western longitude. Additional insights provided by single-regression analysis showed a positive relationship between the number of species and chlorophyll-a, while increasing biomass occurred with increasing mean grain size of the beach. The results indicate that community characteristics in the exposed sandy beaches studied are affected by physical characteristics such as sediment size and beach length, but also by other factors dependent on coastal processes, such as food availability in the water column.

High Levels of Sediment Contamination Have Little Influence on Estuarine Beach Fish Communities

PubMed Central

McKinley, Andrew C.; Dafforn, Katherine A.; Taylor, Matthew D.; Johnston, Emma L.

2011-01-01

While contaminants are predicted to have measurable impacts on fish assemblages, studies have rarely assessed this potential in the context of natural variability in physico-chemical conditions within and between estuaries. We investigated links between the distribution of sediment contamination (metals and PAHs), physico-chemical variables (pH, salinity, temperature, turbidity) and beach fish assemblages in estuarine environments. Fish communities were sampled using a beach seine within the inner and outer zones of six estuaries that were either heavily modified or relatively unmodified by urbanization and industrial activity. All sampling was replicated over two years with two periods sampled each year. Shannon diversity, biomass and abundance were all significantly higher in the inner zone of estuaries while fish were larger on average in the outer zone. Strong differences in community composition were also detected between the inner and outer zones. Few differences were detected between fish assemblages in heavily modified versus relatively unmodified estuaries despite high concentrations of sediment contaminants in the inner zones of modified estuaries that exceeded recognized sediment quality guidelines. Trends in species distributions, community composition, abundance, Shannon diversity, and average fish weight were strongly correlated to physico-chemical variables and showed a weaker relationship to sediment metal contamination. Sediment PAH concentrations were not significantly related to the fish assemblage. These findings suggest that variation in some physico-chemical factors (salinity, temperature, pH) or variables that co-vary with these factors (e.g., wave activity or grain size) have a much greater influence on this fish assemblage than anthropogenic stressors such as contamination. PMID:22039470

A Coastal Environment Field and Laboratory Activity for an Undergraduate Geomorphology Course

ERIC Educational Resources Information Center

Ellis, Jean T.; Rindfleisch, Paul R.

2006-01-01

A field and laboratory exercise for an undergraduate geomorphology class is described that focuses on the beach. The project requires one day of fieldwork and two laboratory sessions. In the field, students measure water surface fluctuations (waves) with a pressure sensor, survey beach profiles, collect sediment samples, and observe the beach…

Mercury distribution in ancient and modern sediment of northeastern Bering Sea

USGS Publications Warehouse

Nelson, C.H.; Pierce, D.E.; Leong, K.W.; Wang, F.F.H.

1975-01-01

Reconnaissance sampling of surface and subsurface sediment to a maximum depth of 80 m below the sea floor shows that typical values of 0.03 p.p.m. and anomalies of 0.2-1.3 p.p.m. mercury have been present in northeastern Bering Sea since Early Pliocene time. Values are highest in modern beach (maximum 1.3 and mean 0.22 p.p.m. Hg) and nearshore subsurface gravels (maximum 0.6 and mean 0.06 p.p.m. Hg) along the highly mineralized Seward Peninsula and in clayey silt rich in organic matter (maximum 0.16 and mean 0.10 p.p.m. Hg) throughout the region. Although gold mining may be partly responsible for high mercury levels in the modern beach near Nome, Alaska (maximum 0.45 p.p.m.), equally high or greater concentrations of mercury occur in buried Pleistocene sediments immediately offshore (maximum 0.6 p.p.m.) and in modern unpolluted beach sediments at Bluff (maximum 1.3 p.p.m.); this suggests that the contamination effects of mining may be no greater than natural concentration processes in the Seward Peninsula region. The mercury content of offshore surface sediment, even adjacent to mercury-rich beaches, corresponds to that of unpolluted marine and fresh-water sediment elsewhere. The normal values that prevail offshore may be attributable to entrapment of mercury-bearing heavy minerals on beaches near sources and/or dilution effects of offshore sedimentation. The few minor anomalies offshore occur in glacial drift derived from mercury source regions of Chukotka (Siberia) and Seward Peninsula; Pleistocene shoreline processes have reworked the drift to concentrate the heavy metals. The distribution pattern of mercury indicates that particulate mercury-bearing minerals have not been widely dispersed from onland deposits in quantities sufficient to increase mercury levels above normal in offshore sediments of Bering Sea; however, it shows that natural sedimentary processes can concentrate this mercury in beaches of the coastal zone where there already is concern because of potential pollution from man's activities.

Spatial, Temporal, and Matrix Variability of Clostridium botulinum Type E Toxin Gene Distribution at Great Lakes Beaches

PubMed Central

Oster, Ryan J.; Haack, Sheridan K.; Fogarty, Lisa R.; Tucker, Taaja R.; Riley, Stephen C.

2015-01-01

Clostridium botulinum type E toxin is responsible for extensive mortality of birds and fish in the Great Lakes. The C. botulinum bontE gene that produces the type E toxin was amplified with quantitative PCR from 150 sloughed algal samples (primarily Cladophora species) collected during summer 2012 from 10 Great Lakes beaches in five states; concurrently, 74 sediment and 37 water samples from four sites were also analyzed. The bontE gene concentration in algae was significantly higher than in water and sediment (P < 0.05), suggesting that algal mats provide a better microenvironment for C. botulinum. The bontE gene was detected most frequently in algae at Jeorse Park and Portage Lake Front beaches (Lake Michigan) and Bay City State Recreation Area beach on Saginaw Bay (Lake Huron), where 77, 100, and 83% of these algal samples contained the bontE gene, respectively. The highest concentration of bontE was detected at Bay City (1.98 × 105 gene copies/ml of algae or 5.21 × 106 g [dry weight]). This study revealed that the bontE gene is abundant in the Great Lakes but that it has spatial, temporal, and matrix variability. Further, embayed beaches, low wave height, low wind velocity, and greater average water temperature enhance the bontE occurrence. PMID:25888178

Sediment characteristics and microbiological contamination of beach sand - A case-study in the archipelago of Madeira.

PubMed

Abreu, Roberto; Figueira, Celso; Romão, Daniela; Brandão, João; Freitas, M Conceição; Andrade, César; Calado, Graça; Ferreira, Carmen; Campos, Ana; Prada, Susana

2016-12-15

Beach sand can harbour pathogenic and opportunistic microorganisms, as well as faecal indicator bacteria that influence directly the bathing water quality. Pathogenic and opportunistic microorganisms often raise concern of exposure during beach related recreational activities. In this work, three different types of sandy beaches (natural basaltic, natural calcareous and artificial calcareous) of the Archipelago of Madeira (Portugal) were sampled for bacterial and fungal contaminants and grain size distribution, during four years (2010-2013). Following an extreme weather event in 2010, the faecal indicator bacteria levels spiked, returning to base levels shortly thereafter. The same phenomenon occurred with fungi, where potentially pathogenic fungi were the dominant group. Yeast-like fungi and dermatophytes were, however, mainly associated to months of higher usage by recreational users. Statistical analysis showed higher contamination of sediment in artificial beaches compared to natural beaches and granulometry and chemical composition of sand did not influence in the microbial loads. Instead, bather density and the influence of coastal protection structures needed to maintain the volume of artificial beach sand regarding the removal potential of wave induced currents are obvious influencing factors. Copyright © 2016 Elsevier B.V. All rights reserved.

Escherichia coli at Ohio Bathing Beaches--Distribution, Sources, Wastewater Indicators, and Predictive Modeling

USGS Publications Warehouse

Francy, Donna S.; Gifford, Amie M.; Darner, Robert A.

2003-01-01

Results of studies during the recreational seasons of 2000 and 2001 strengthen the science that supports monitoring of our Nation?s beaches. Water and sediment samples were collected and analyzed for concentrations of Escherichia coli (E. coli). Ancillary water-quality and environmental data were collected or compiled to determine their relation to E. coli concentrations. Data were collected at three Lake Erie urban beaches (Edgewater, Villa Angela, and Huntington), two Lake Erie beaches in a less populated area (Mentor Headlands and Fairport Harbor), and one inland-lake beach (Mosquito Lake). The distribution of E. coli in water and sediments within the bathing area, outside the bathing area, and near the swash zone was investigated at the three Lake Erie urban beaches and at Mosquito Lake. (The swash zone is the zone that is alternately covered and exposed by waves.) Lake-bottom sediments from outside the bathing area were not significant deposition areas for E. coli. In contrast, interstitial water and subsurface sediments from near the swash zone were enriched with E. coli. For example, E. coli concentrations were as high as 100,000 colonies per 100 milliliters in some interstitial waters. Although there are no standards for E. coli in swash-zone materials, the high concentrations found at some locations warrant concern for public health. Studies were done at Mosquito Lake to identify sources of fecal contamination to the lake and bathing beach. Escherichia coli concentrations decreased with distance from a suspected source of fecal contamination that is north of the beach but increased at the bathing beach. This evidence indicated that elevated E. coli concentrations at the bathing beach are of local origin rather than from transport of bacteria from sites to the north. Samples collected from the three Lake Erie urban beaches and Mosquito Lake were analyzed to determine whether wastewater indicators could be used as surrogates for E. coli at bathing beaches. None of the concentrations of wastewater indicators of fecal contamination, including 3b-coprostanol and cholesterol, were significantly correlated (a=0.05) to concentrations of E. coli. Concentrations of the two compounds that were significantly correlated to E. coli were components of coal tar and asphalt, which are not necessarily indicative of fecal contamination. Data were collected to build on an earlier 1997 study to develop and test multiple-linear-regression models to predict E. coli concentrations using water-quality and environmental variables as explanatory variables. The probability of exceeding the single-sample bathing-water standard for E. coli (235 colonies per 100 milliliters) was used as the model output variable. Threshold probabilities for each model were established. Computed probabilities that are less than a threshold probability indicate that bacterial water quality is most likely acceptable. Computed probabilities equal to or above the threshold probability indicate that the water quality is most likely not acceptable and that a water-quality advisory may be needed. Models were developed at each beach, whenever possible, using combinations of 1997, 2000, and (or) 2001 data. The models developed and tested in this study were shown to be beach specific; that is, different explanatory variables were used to predict the probability of exceeding the standard at each beach. At Mentor Headlands and Fairport Harbor, models were not developed because water quality was generally good. At the three Lake Erie urban beaches, models were developed with variable lists that included the number of birds on the beach at the time of sampling, lake-current direction, wave height, turbidity, streamflow of a nearby river, and rainfall. The models for Huntington explained a larger percentage of the variability in E. coli concentrations than the models for Edgewater and Villa Angela. At Mosquito Lake, a model based on 2000 and 2001 data contained the

Plastic pollution on the Baltic beaches of Kaliningrad region, Russia.

PubMed

Esiukova, Elena

2017-01-30

Contamination of sandy beaches of the Baltic Sea in Kaliningrad region is evaluated on the base of surveys carried out from June 2015 to January 2016. Quantity of macro/meso/microplastic objects in the upper 2cm of the sandy sediments of the wrack zone at 13 sampling sites all along the Russian coast is reported. Occurrence of paraffin and amber pieces at the same sites is pointed out. Special attention is paid to microplastics (range 0.5-5mm): its content ranges between 1.3 and 36.3 items per kg dry sediment. The prevailing found type is foamed plastic. No sound differences in contamination are discovered between beaches with high and low anthropogenic load. Mean level of contamination is of the same order of magnitude as has been reported by other authors for the Baltic Sea beaches. Copyright © 2016 Elsevier Ltd. All rights reserved.

Burrowing inhibition by fine textured beach fill: Implications for recovery of beach ecosystems

NASA Astrophysics Data System (ADS)

Viola, Sloane M.; Hubbard, David M.; Dugan, Jenifer E.; Schooler, Nicholas K.

2014-10-01

Beach nourishment is often considered the most environmentally sound method of maintaining eroding shorelines. However, the ecological consequences are poorly understood. Fill activities cause intense disturbance and high mortality and have the potential to alter the diversity, abundance, and distribution of intertidal macroinvertebrates for months to years. Ecological recovery following fill activities depends on successful recolonization and recruitment of the entire sandy intertidal community. The use of incompatible sediments as fill material can strongly affect ecosystem recovery. We hypothesized that burrowing inhibition of intertidal animals by incompatible fine fill sediments contributes to ecological impacts and limits recovery in beach ecosystems. We experimentally investigated the influence of intertidal zone and burrowing mode on responses of beach invertebrates to altered sediment texture (28-38% fines), and ultimately the potential for colonization and recovery of beaches disturbed by beach filling. Using experimental trials in fill material and natural beach sand, we found that the mismatched fine fill sediments significantly inhibited burrowing of characteristic species from all intertidal zones, including sand crabs, clams, polychaetes, isopods, and talitrid amphipods. Burrowing performance of all five species we tested was consistently reduced in the fill material and burrowing was completely inhibited for several species. The threshold for burrowing inhibition by fine sediment content in middle and lower beach macroinvertebrates varied by species, with highest sensitivity for the polychaete (4% fines, below the USA regulatory limit of 10% fines), followed by sand crabs and clams (20% fines). These results suggest broader investigation of thresholds for burrowing inhibition in fine fill material is needed for beach animals. Burrowing inhibition caused by mismatched fill sediments exposes beach macroinvertebrates to stresses, which could depress recruitment and survival at all intertidal zones. Our results suggest use of incompatible fine fill sediments from dredging projects creates unsuitable intertidal habitat that excludes burrowing macroinvertebrates and could delay beach ecosystem recovery. Through effects on beach invertebrates that are prey for shorebirds and fish, the ecological impacts of filling with mismatched fine sediments could influence higher trophic levels and extend beyond the beach itself.

Evaluation of sediment transport at a fetch-limited beach from spring to neap tide

NASA Astrophysics Data System (ADS)

Carrasco, Ana Rita; Ferreira, Óscar; Matias, Ana; Freire, Paula; Alveirinho Dias, João.

2010-05-01

Sediment transport studies are useful tools for the determination of sediment budgets, important in the definition of management policies, in particular in environments not fully understood like fetch-limited beaches. Only a few studies have been made with respect to these beaches, and research efforts need to be continued to correctly quantify the main factors governing morphological changes. The present study provides new insights on sediment transport at a fetch-limited backbarrier beach located at the Peninsula do Ancão (Ria Formosa, South of Portugal). The field site extends over ~150 m and includes a sandy beach with a low and narrow reflective morphology, and an external sand bank at the seaward edge of the sub-aerial beach profile. Fluorescent tracers were used to measure the short-term sediment transport (rates and directions) from spring to neap tides, for fair-weather conditions. The experiment was set at two beach morphologies: beach face and sand bank. Tracer was released on 20th March 2008 at both sites, and sampling was conducted at low tide, each 24h, during 7 days. In situ fluorescent tracer detection was performed with UV light. Currents were obtained with a portable single-axis electromagnetic current meter located at the beach face, and an Aquadopp Profiler located at the sand bank. Local waves were obtained by numerical modelling for the study area, based on prevailing winds (measured by a nearby meteorological station), and using available bathymetric surveys. Tracer trends, tidal currents, wind conditions and waves were integrative in order to determine to which forcing mechanism the beach morphology was more responsive. Daily wind intensities were, in average, close to 5 m/s, and maximum estimated significant wave height (Hs) did not exceed 0.045 m. Daily mean wave period ranged from 0.5 s to 0.7 s. The maximum tidal range was 2.8 m. Currents were of higher magnitude at the sand bank than at the beach face, with the maximum during ebb tide (0.50 m/s). At the beach face, maximum velocities are very similar for both ebb and flood tide, with a maximum of 0.26 m/s. Tracer displacement was greater at the beach face, indicating that this is the most active part of the profile during the experiment. At the sand bank, tracer dispersion was greater, but tracer advection was shorter. Tracer isopachs illustrate a relatively independency of both analysed morphologies, without significant exchange across the profile. At both morphologies, the residual transport is dominated by the longshore component, and mostly directed towards the ebb. Ebb directed transport agrees with ebb dominance on tidal currents at this location. Results suggest a tidal and current dominance. Tidal range assumes particular importance at beach face.

Seasonal to interannual morphodynamics along a high-energy dissipative littoral cell

USGS Publications Warehouse

Ruggiero, P.; Kaminsky, G.M.; Gelfenbaum, G.; Voigt, B.

2005-01-01

A beach morphology monitoring program was initiated during summer 1997 along the Columbia River littoral cell (CRLC) on the coasts of northwest Oregon and southwest Washington, USA. This field program documents the seasonal through interannual morphological variability of these high-energy dissipative beaches over a variety of spatial scales. Following the installation of a dense network of geodetic control monuments, a nested sampling scheme consisting of cross-shore topographic beach profiles, three-dimensional topographic beach surface maps, nearshore bathymetric surveys, and sediment size distribution analyses was initiated. Beach monitoring is being conducted with state-of-the-art real-time kinematic differential global positioning system survey methods that combine both high accuracy and speed of measurement. Sampling methods resolve variability in beach morphology at alongshore length scales of approximately 10 meters to approximately 100 kilometers and cross-shore length scales of approximately 1 meter to approximately 2 kilometers. During the winter of 1997/1998, coastal change in the US Pacific Northwest was greatly influenced by one of the strongest El Nin??o events on record. Steeper than typical southerly wave angles resulted in alongshore sediment transport gradients and shoreline reorientation on a regional scale. The La Nin??a of 1998/1999, dominated by cross-shore processes associated with the largest recorded wave year in the region, resulted in net beach erosion along much of the littoral cell. The monitoring program successfully documented the morphological response to these interannual forcing anomalies as well as the subsequent beach recovery associated with three consecutive moderate wave years. These morphological observations within the CRLC can be generalized to explain overall system patterns; however, distinct differences in large-scale coastal behavior (e.g., foredune ridge morphology, sandbar morphometrics, and nearshore beach slopes) are not readily explained or understood.

Metal concentrations in water and sediments from tourist beaches of Acapulco, Mexico.

PubMed

Jonathan, M P; Roy, P D; Thangadurai, N; Srinivasalu, S; Rodríguez-Espinosa, P F; Sarkar, S K; Lakshumanan, C; Navarrete-López, M; Muñoz-Sevilla, N P

2011-04-01

A survey on the metal concentrations (As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, V, Zn) in beach water and sediments is reported from the tourist destination of Acapulco city on the Pacific coast of Mexico. The concentration of dissolved trace metals (DTMs) in beach water and acid leachable trace metals (ALTMs) in sediments indicated that they are anthropogenic in nature due to the increased tourist activities in the crowded beach locations. The statistical analysis indicates Fe and Mn play a major role as metal scavengers in both the medium (water and sediment) and the higher value of other metals is site specific in the study area, indicating that they are transported from the local area. Comparison results suggest that the beach water quality has deteriorated more than the sediments and special care needs to be taken to restore the beach quality. Copyright © 2011 Elsevier Ltd. All rights reserved.

Underwater microscope for measuring spatial and temporal changes in bed-sediment grain size

USGS Publications Warehouse

Rubin, David M.; Chezar, Henry; Harney, Jodi N.; Topping, David J.; Melis, Theodore S.; Sherwood, Christopher R.

2007-01-01

For more than a century, studies of sedimentology and sediment transport have measured bed-sediment grain size by collecting samples and transporting them back to the laboratory for grain-size analysis. This process is slow and expensive. Moreover, most sampling systems are not selective enough to sample only the surficial grains that interact with the flow; samples typically include sediment from at least a few centimeters beneath the bed surface. New hardware and software are available for in situ measurement of grain size. The new technology permits rapid measurement of surficial bed sediment. Here we describe several systems we have deployed by boat, by hand, and by tripod in rivers, oceans, and on beaches.

Underwater Microscope for Measuring Spatial and Temporal Changes in Bed-Sediment Grain Size

USGS Publications Warehouse

Rubin, David M.; Chezar, Henry; Harney, Jodi N.; Topping, David J.; Melis, Theodore S.; Sherwood, Christopher R.

2006-01-01

For more than a century, studies of sedimentology and sediment transport have measured bed-sediment grain size by collecting samples and transporting them back to the lab for grain-size analysis. This process is slow and expensive. Moreover, most sampling systems are not selective enough to sample only the surficial grains that interact with the flow; samples typically include sediment from at least a few centimeters beneath the bed surface. New hardware and software are available for in-situ measurement of grain size. The new technology permits rapid measurement of surficial bed sediment. Here we describe several systems we have deployed by boat, by hand, and by tripod in rivers, oceans, and on beaches.

A rapid compatibility analysis of potential offshore sand sources for beaches of the Santa Barbara Littoral Cell

USGS Publications Warehouse

Mustain, N.; Griggs, G.; Barnard, P.L.

2007-01-01

The beaches of the Santa Barbara Littoral Cell, which are narrow as a result of either natural and/or anthropogenic factors, may benefit from nourishment. Sand compatibility is fundamental to beach nourishment success and grain size is the parameter often used to evaluate equivalence. Only after understanding which sand sizes naturally compose beaches in a specific cell, especially the smallest size that remains on the beach, can the potential compatibility of source areas, such as offshore borrow sites, be accurately assessed. This study examines sediments on the beach and in the nearshore (5-20m depth) for the entire Santa Barbara Littoral Cell east of Point Conception. A digital bed sediment camera, the Eyeball??, and spatial autocorrelation technique were used to determine sediment grain size. Here we report on whether nearshore sediments are comparable and compatible with beach sands of the Santa Barbara Littoral Cell. ?? 2007 ASCE.

Mixed sediment beach processes: Kachemak Bay, Alaska

USGS Publications Warehouse

Ruggiero, P.; Adams, P.N.; Warrick, J.A.

2007-01-01

Mixed sediment beaches are morphologically distinct from and more complex than either sand or gravel only beaches. Three digital imaging techniques are employed to quantify surficial grain size and bedload sediment transport rates along the mixed sediment beaches of Kachemak Bay, Alaska. Applying digital imaging procedures originally developed for quickly and efficiently quantifying grain sizes of sand to coarse sediment classes gives promising results. Hundreds of grain size estimates lead to a quantitative characterization of the region's sediment at a significant reduction in cost and time as compared to traditional techniques. Both the sand and coarse fractions on this megatidal beach mobilize into self-organized bedforms that migrate alongshore with a seasonally reflecting the temporal pattern of the alongshore component of wave power. In contrast, the gravel bedforms also migrate in the cross-shore without significant seasonally suggesting that swash asymmetry is sufficient to mobilize the gravel even during low energy summer conditions. ?? 2007 ASCE.

Evaluation of methods to sample fecal indicator bacteria in foreshore sand and pore water at freshwater beaches.

PubMed

Vogel, Laura J; Edge, Thomas A; O'Carroll, Denis M; Solo-Gabriele, Helena M; Kushnir, Caitlin S E; Robinson, Clare E

2017-09-15

Fecal indicator bacteria (FIB) are known to accumulate in foreshore beach sand and pore water (referred to as foreshore reservoir) where they act as a non-point source for contaminating adjacent surface waters. While guidelines exist for sampling surface waters at recreational beaches, there is no widely-accepted method to collect sand/sediment or pore water samples for FIB enumeration. The effect of different sampling strategies in quantifying the abundance of FIB in the foreshore reservoir is unclear. Sampling was conducted at six freshwater beaches with different sand types to evaluate sampling methods for characterizing the abundance of E. coli in the foreshore reservoir as well as the partitioning of E. coli between different components in the foreshore reservoir (pore water, saturated sand, unsaturated sand). Methods were evaluated for collection of pore water (drive point, shovel, and careful excavation), unsaturated sand (top 1 cm, top 5 cm), and saturated sand (sediment core, shovel, and careful excavation). Ankle-depth surface water samples were also collected for comparison. Pore water sampled with a shovel resulted in the highest observed E. coli concentrations (only statistically significant at fine sand beaches) and lowest variability compared to other sampling methods. Collection of the top 1 cm of unsaturated sand resulted in higher and more variable concentrations than the top 5 cm of sand. There were no statistical differences in E. coli concentrations when using different methods to sample the saturated sand. Overall, the unsaturated sand had the highest amount of E. coli when compared to saturated sand and pore water (considered on a bulk volumetric basis). The findings presented will help determine the appropriate sampling strategy for characterizing FIB abundance in the foreshore reservoir as a means of predicting its potential impact on nearshore surface water quality and public health risk. Copyright © 2017 Elsevier Ltd. All rights reserved.

Relationships Between Sand and Water Quality at Recreational Beaches

PubMed Central

Phillips, Matthew C.; Solo-Gabriele, Helena M.; Piggot, Alan M.; Klaus, James S.; Zhang, Yifan

2011-01-01

Enterococci are used to assess the risk of negative human health impacts from recreational waters. Studies have shown sustained populations of enterococci within sediments of beaches but comprehensive surveys of multiple tidal zones on beaches in a regional area and their relationship to beach management decisions are limited. We sampled three tidal zones on eight South Florida beaches in Miami-Dade and Broward counties and found that enterococci were ubiquitous within South Florida beach sands although their levels varied greatly both among the beaches and between the supratidal, intertidal and subtidal zones. The supratidal sands consistently had significantly higher (p<0.003) levels of enterococci (average 40 CFU/g dry sand) than the other two zones. Levels of enterococci within the subtidal sand correlated with the average level of enterococci in the water (CFU/100mL) for the season during which samples were collected (rs= 0.73). The average sand enterococci content over all the zones on each beach correlated with the average water enterococci levels of the year prior to sand samplings (rs=0.64) as well as the average water enterococci levels for the month after sand samplings (rs=0.54). Results indicate a connection between levels of enterococci in beach water and sands throughout South Florida’s beaches and suggest that the sands are one of the predominant reservoirs of enterococci impacting beach water quality. As a result, beaches with lower levels of enterococci in the sand had fewer exceedences relative to beaches with higher levels of sand enterococci. More research should focus on evaluating beach sand quality as a means to predict and regulate marine recreational water quality. PMID:22071324

Relationships between sand and water quality at recreational beaches.

PubMed

Phillips, Matthew C; Solo-Gabriele, Helena M; Piggot, Alan M; Klaus, James S; Zhang, Yifan

2011-12-15

Enterococci are used to assess the risk of negative human health impacts from recreational waters. Studies have shown sustained populations of enterococci within sediments of beaches but comprehensive surveys of multiple tidal zones on beaches in a regional area and their relationship to beach management decisions are limited. We sampled three tidal zones on eight South Florida beaches in Miami-Dade and Broward counties and found that enterococci were ubiquitous within South Florida beach sands although their levels varied greatly both among the beaches and between the supratidal, intertidal and subtidal zones. The supratidal sands consistently had significantly higher (p < 0.003) levels of enterococci (average 40 CFU/g dry sand) than the other two zones. Levels of enterococci within the subtidal sand correlated with the average level of enterococci in the water (CFU/100mL) for the season during which samples were collected (r(s) = 0.73). The average sand enterococci content over all the zones on each beach correlated with the average water enterococci levels of the year prior to sand samplings (r(s) = 0.64) as well as the average water enterococci levels for the month after sand samplings (r(s) = 0.54). Results indicate a connection between levels of enterococci in beach water and sands throughout South Florida's beaches and suggest that the sands are one of the predominant reservoirs of enterococci impacting beach water quality. As a result, beaches with lower levels of enterococci in the sand had fewer exceedences relative to beaches with higher levels of sand enterococci. More research should focus on evaluating beach sand quality as a means to predict and regulate marine recreational water quality. Copyright © 2011 Elsevier Ltd. All rights reserved.

Observations of Seasonal Morphological Evolution at a Moderately Energetic Beach in Rincón, Puerto Rico

NASA Astrophysics Data System (ADS)

Rivera Nieves, A.; Loubriel, M.; Rodriguez-Abudo, S.; Canals, M.; Salgado-Domínguez, G.

2016-02-01

Seasonal variations in the wave climate near Rincón, Puerto Rico include high winter swells associated with meteorological disturbances in the north and mid Atlantic, short period waves resulting from local storms, and the occasional south swell. The resulting beach morphology is therefore a complex function of the wave climate, wave-induced currents, and local and remote meteorology, among others. Over the past 75 years, this particular stretch of beach has suffered severe erosion problems, losing as much as 100 meters of beach width at particular locations. The purpose of this study is to develop a high-resolution time series of beach morphology to examine in more detail the seasonal variations at the site. Beach profiles will be collected on a weekly basis using an RTK GPS system at three permanent stations spanning 2 km of coast. Sediment samples will be collected along the profiles to identify sediment properties associated with distinct morphological features, while digital photographs will provide a qualitative sense of beach width. The resulting morphological changes will be assessed in light of the Rincon's directional Waverider buoy data and CariCOOS' SWAN high-resolution wave model. This study will provide quantifiable insights into seasonal erosion/accretion trends at a highly touristic stretch of coast in the US Caribbean.

Comparisons of microplastic pollution between mudflats and sandy beaches in Hong Kong.

PubMed

Lo, Hoi-Shing; Xu, Xiaoyu; Wong, Chun-Yuen; Cheung, Siu-Gin

2018-05-01

Most of the previous studies of microplastic pollution on coastal habitats focused on high energy beaches although low energy areas such as mudflats are supposed to retain more microplastics, not to mention that mudflats are biologically more diverse. We quantified and characterized microplastics from 10 mudflats and 10 sandy beaches in Hong Kong spanning from the eastern to western waters. Sediment samples were collected at 1.0 m and 1.5 m above chart datum (CD) and at the strandline. Abundance of microplastics ranged between 0.58 and 2116 items kg -1 sediment with that on mudflats being ten times more than on beaches. Polyethylene (46.9%) was the most abundant and followed by polypropylene (13.8%) and polyethylene terephthalate (13.5%). Expanded polystyrene was the most abundant in the strandline samples but not at 1.0 m and 1.5 m above CD. Although previous studies have concluded that the input from Pearl River is a major source of microplastics on Hong Kong shores, this study has demonstrated that the contribution of local pollution sources such as discharge from sewage treatment plants to microplastic pollution should not be neglected. Copyright © 2018 Elsevier Ltd. All rights reserved.

Longshore Sediment Transport on a Macrotidal Mixed Sediment Beach, Birling Gap, United Kingdom.

NASA Astrophysics Data System (ADS)

Curoy, J.; Moses, C. A.; Robinson, D. A.

2012-04-01

Mixed beaches (MBs), with sediment sizes ranging over three orders of magnitude, are an increasingly important coastal defence on > 1/3 of the shoreline of England and Wales. In East Sussex, the combined effect of coastal defence management schemes (extensive groyning and sea wall construction) has reduced beach sediment supply. Local authorities counteract the increased flood risk by recycling or artificially recharging beaches on the most vulnerable and populated areas. Beaches lose sediment predominantly via longshore transport (LST) whose accurate quantification is critical to calculating recharge amounts needed for effective beach management. Industry does this by using sediment transport modelling which depends on reliable input data and modelling assumptions. To improve understanding of processes and quantification of LST on MBs, this study has accurately measured sediment transport on a natural, macrotidal, MB. The 1.2 km natural MB at Birling Gap, East Sussex here is located on the downdrift end of an 80 km long sub-sedimentary cell and is oriented WNW-ESE. The beach lies on a low gradient chalk shore platform backed by sub-vertical chalk cliffs. It is composed primarily of flint gravel with a peak grain size distribution of 30 to 50 mm, and a sand content of up to 30%. Sediment transport was measured using pebble tracers and GPS surface surveys during three survey periods of three to five consecutive days in March, May and December 2006. Tracer pebbles, matching the beach pebbles' D50, were made of an epoxy resin with a copper core allowing their detection and recovery to a depth of 40 cm using a metal detector. Tracers were deployed on the upper, middle and lower beach, from the surface into the beach to depths of up to 40 cm. They were collected on the low tide following deployment. The wave conditions were recorded on a Valeport DWR wave recorder located seaward of the beach on the chalk platform. Over the three study periods a large spectrum of wave heights (0.1 to 2.6 m) and periods (2 and 13.4 s) was observed. Wave direction varied from 14 to 106° to the beach. In total, up to 300 tracers were used on every day of deployment. The recovery rate after one tide varied from 58.4 to 100%. Significant longshore transport was observed, up to a maximum of 145 m. The results show that pebble behaviour on a natural MB is extremely sensitive to position on the beach profile and to changes in the water level and wave conditions associated with tidal conditions. Longshore sediment transport rates ranged from 0 to 120.55 m3 tide-1. Longshore wave power and immersed longshore transport were calculated and a drift efficiency coefficient of 0.04 was derived. These results contribute to the data bank on LST on MBs. Ultimately they will help to refine the current models used by the industry and support beach managers in anticipating sediment volumes that will be necessary to sustain a MB prior to storm events. Key words: mixed beach, longshore sediment transport, sediment tracer.

Headland sediment bypassing and beach rotation in a rocky coast: an example at the western Portuguese coast

NASA Astrophysics Data System (ADS)

Ribeiro, Mónica; Taborda, Rui; Lira, Cristina; Bizarro, Aurora; Oliveira, Anabela

2014-05-01

Headland sediment bypassing plays a major role in definition of coastal sedimentary budget and consequently in coastal management. This process is particularity important at headland-bay beaches on rocky coasts. However, headland-bay beach research is usually focused on the beach rotation since these beaches are generally regarded as closed systems. The sediment bypassing mechanisms have been extensively studied in the context of artificial structures (e.g. groins and jetties) but studies of natural headland sediment bypassing are scarce and usually applied to decadal time scales. This work aims to contribute to the understanding of headland sediment bypassing processes in non-artificial environments, taking as a case study a natural coastal stretch at the Portuguese west coast. The study is supported on the analysis of planform beach changes using Landsat satellite images (with an acquisition frequency of 16 days) complemented with field surveys with DGPS-RTK and ground-based photographic monitoring. The study area can be described as a cliffed rocky coast that accommodates a series of headland-bay beaches with different geometries: some are encased in the dependence of fluvial streams, while others correspond to a narrow and elongated thin sand strip that covers a rocky shore platform. This coast is generally characterized by a weak, but active, sediment supply and high levels of wave energy due to the exposure to the swells generated in the North Atlantic. The long-term stability of the beaches in conjunction with active sediment supply along the study area (from streams and cliff erosion) and a sink at the downdrift end of this coastal stretch (an active dune system) support the existence of headland sediment bypassing. The analysis of planform beach changes show a coherent signal in time but with a range that depends on the orientation of the stretch where each beach is included. In general, beaches displays a clockwise rotation during summer related to the NW (less energetic) incident wave conditions. The persistence of these conditions induces an enlargement of the beach downdrift (southward) and eventually sediment bypassing. This process can result in a continuous inner bar along the headland coast, which migrates downdrift in the surf zone and weld to the downdrift beach. The counter-clockwise rotation observed in the winter is more variable being in agreement with the less persistent W and SW incident wave conditions, suggesting that sediment bypassing occurs only southwards. The work was funded by FEDER funds through the Operational Programme for Competitiveness Factors - COMPETE and FCT National Funds - Portuguese Foundation for Science and Technology under the project Beach to Canyon Head Sedimentary Processes (PTDC/MAR/114674/2009). First author benefits from a PhD grant funded by FCT (SFRH/BD/79126/2011).

Determination and distribution of rare earth elements in beach rock samples using instrumental neutron activation analysis (INAA)

NASA Astrophysics Data System (ADS)

Ravisankar, R.; Manikandan, E.; Dheenathayalu, M.; Rao, Brahmaji; Seshadreesan, N. P.; Nair, K. G. M.

2006-10-01

Beach rocks are a peculiar type of formation when compared to other types of rocks. Rare earth element (REE) concentrations in beach rock samples collected from the South East Coast of Tamilnadu, India, have been measured using the instrumental neutron activation analysis (INAA) single comparator K0 method. The irradiations were carried out using a thermal neutron flux of ˜10 11 n cm -2 s -1 at 20 kW power using the Kalpakkam mini reactor (KAMINI), IGCAR, Kalpakkam, Tamilnadu. Accuracy and precision were evaluated by assaying irradiated standard reference material (SRM 1646a estuarine sediment). The results being found to be in good agreement with certified values. REE elements have been determined from 15 samples using high-resolution gamma spectrometry. The geochemical behavior of REE in beach rock, in particular REE (chondrite-normalized) pattern has been studied.

Hydrodynamics Offshore of the North Beach of Indian River Inlet, DE

NASA Astrophysics Data System (ADS)

DiCosmo, N. R.; Puleo, J. A.

2014-12-01

The Indian River Inlet (IRI) on the east coast of Delaware, USA connects the Atlantic Ocean to the Indian River and Rehoboth Bays. Long-term and large-scale net alongshore sediment transport along this portion of coastline is from south to north. The north beach of IRI suffers from severe erosion due to interruption of the alongshore transport and current variability near the inlet. The magnitude of such erosion has increased over the past decade and questions have arisen as to the cause. The goal of this study is to quantify currents and wave patterns and estimate sediment transport rates at the north beach and near the inlet in an effort to determine the causes of persistent erosion. Data were obtained from October 2013 to March 2014 in the form of 3 separate 28-day deployments. Each deployment consisted of 4 proposed deployment sites. Data at each site were collected using a bottom mounted Nortek Aquadopp Acoustic Doppler Current Profiler (ADCP) and 2 Campbell Scientific Optical Backscatter Sensors (OBS). Currents and OBS data were sampled every 120 s. Waves were sampled for approximately 17 minutes at the beginning of every hour. Data analysis from the deployments indicates the presence of several interesting trends in currents that can be linked to the persistent erosion. Current data are filtered to quantify typical current speed and direction for a tidal cycle (peak flood to peak flood) at each deployment site. The typical currents off of the north beach and up to 800 m north of the north jetty are mostly directed southward over the entire tidal cycle. This consistent southward flow implies: 1) there is no flow reversal based on tide, contrary to what might be expected at an inlet adjacent beach, 2) the typical current direction is opposite of the expectations for the known long-term large-scale net alongshore transport and 3) the consistency of this atypical current may be responsible for transporting sediment southward and away from the north beach. Currents and waves will be further analyzed for storm and non-storm conditions in order to more completely quantify the hydrodynamics of the area. Sediment data will also be analyzed in conjunction with the hydrodynamic data in order to better understand the sediment transport process.

Fish stomach contents in benthic macroinvertebrate assemblage assessments.

PubMed

Tupinambás, T H; Pompeu, P S; Gandini, C V; Hughes, R M; Callisto, M

2015-01-01

The choice of sampling gears to assess benthic macroinvertebrate communities depends on environmental characteristics, study objectives, and cost effectiveness. Because of the high foraging capacity and diverse habitats and behaviors of benthophagous fishes, their stomach contents may offer a useful sampling tool in studies of benthic macroinvertebrates, especially in large, deep, fast rivers that are difficult to sample with traditional sediment sampling gear. Our objective was to compare the benthic macroinvertebrate communities sampled from sediments with those sampled from fish stomachs. We collected benthic macroinvertebrates and fish from three different habitat types (backwater, beach, riffle) in the wet season, drying season, and dry season along a single reach of the Grande River (Paraná River Basin, southeast Brazil). We sampled sediments through use of a Petersen dredge (total of 216 grabs) and used gill nets to sample fish (total of 36 samples). We analyzed the stomach contents of three commonly occurring benthophagous fish species (Eigenmannia virescens, Iheringichthys labrosus, Leporinus amblyrhynchus). Chironomids dominated in both sampling methods. Macroinvertebrate taxonomic composition and abundances from fish stomachs differed from those from sediment samples, but less so from riffles than from backwater and beach habitats. Macroinvertebrate taxa from E. virescens stomachs were more strongly correlated with sediment samples from all three habitats than were those from the other two species. The species accumulation curves and higher mean dispersion values, compared with with sediment samples suggest that E. virescens is more efficient than sediment samples and the other fish studied at collecting benthic taxa. We conclude that by analyzing the stomach contents of benthophagous fishes it is possible to assess important characteristics of benthic communities (dispersion, taxonomic composition and diversity). This is especially true for studies that only sample fish assemblages to evaluate aquatic ecosystem impacts. Therefore, this approach can be useful to amplify assessments of human impacts, and to incorporate additional bioindicators.

Impact of erosion and accretion on the distribution of enterococci in beach sands.

PubMed

Gast, Rebecca J; Gorrell, Levi; Raubenheimer, Britt; Elgar, Steve

2011-09-15

Bacterial pathogens in coastal sediments may pose a health risk to users of beaches. Although recent work shows that beach sands harbor both indicator bacteria and potential pathogens, it is not known how deep within beach sands the organisms may persist nor if they may be exposed during natural physical processes. In this study, sand cores of approximately 1 m depth were collected at three sites across the beach face in Kitty Hawk, North Carolina before, during and after large waves from an offshore hurricane. The presence of DNA from the fecal indicator bacterium Enterococci was detected in subsamples at different depths within the cores by PCR amplification. Erosion and accretion of beach sand at the three sites also was determined for each sampling day. The results indicate that ocean beach sands with persisting enterococci signals could be exposed and redistributed when wind, waves, and currents cause beach erosion or accretion.

Low faunal diversity on Maltese sandy beaches: fact or artefact?

NASA Astrophysics Data System (ADS)

Deidun, Alan; Azzopardi, Marthese; Saliba, Stephen; Schembri, Patrick J.

2003-10-01

Eight sandy beaches on Malta and two on Gozo were sampled for macrofauna to test the hypothesis that Maltese beaches have an intrinsically low diversity. Stations distributed in the supralittoral (dry zone), mediolittoral (wet zone) and upper infralittoral (submerged zone to 1 m water depth) were sampled by sieving core samples and standardised searching during daytime, and pitfall trapping and standardised sweeping of the water column using a hand-net at night, as appropriate. Physical parameters of the sediment were measured and human occupancy of the beaches was estimated. From the supralittoral and mediolittoral, 39 species represented by 1584 individuals were collected by the combined techniques of pitfall trapping, sieving and standard searching. For Ramla beach, which had the highest diversity, 267 individuals representing 25 infaunal species were collected by sieving from a combined volume of 1.175 m 3 of sand, and 149 individuals representing 28 epifaunal species were collected by standardised searching from a combined area of 700 m 2 of sand during two winter and two summer sampling sessions between 1992 and 1993. For nine other beaches sampled during the summer of 2000, only six macrofaunal species were collected from core samples, with overall population densities ranging from 4.13 to 45.45 individuals m -2. Only 92 individuals belonging to 12 species were collected by hand-net from the uppermost infralittoral of five beaches sampled using this method during the summer of 2000. Taxa of gastropods, bivalves, decapods, mysids and staphylinid beetles generally abundant on Mediterranean sandy beaches, were entirely absent from the beaches sampled. Few correlations that could explain the impoverishment of Maltese sandy beaches were found between physical parameters and faunal abundances, and other factors such as inadequate sampling effort, human disturbance and marine pollution were also excluded; however, seasonally biased sampling may partly explain the results obtained. One factor that may explain why certain species are missing could be lack of recruitment, due to Malta's geographical isolation from the European and African mainlands.

Beach groundwater dynamics

NASA Astrophysics Data System (ADS)

Horn, Diane P.

2002-11-01

An understanding of the interaction between surface and groundwater flows in the swash zone is necessary to understand beach profile evolution. Coastal researchers have recognized the importance of beach watertable and swash interaction to accretion and erosion above the still water level (SWL), but the exact nature of the relationship between swash flows, beach watertable flow and cross-shore sediment transport is not fully understood. This paper reviews research on beach groundwater dynamics and identifies research questions which will need to be answered before swash zone sediment transport can be successfully modelled. After defining the principal terms relating to beach groundwater, the behavior, measurement and modelling of beach groundwater dynamics is described. Research questions related to the mechanisms of surface-subsurface flow interaction are reviewed, particularly infiltration, exfiltration and fluidisation. The implications of these mechanisms for sediment transport are discussed.

Pore Water Transport of Enterococci out of Beach Sediments

PubMed Central

Phillips, Matthew C.; Solo-Gabriele, Helena M.; Reniers, Adrianus J. H. M.; Wang, John D.; Kiger, Russell T.; Abdel-Mottaleb, Noha

2011-01-01

Enterococci are used to evaluate the safety of beach waters and studies have identified beach sands as a source of these bacteria. In order to study and quantify the release of microbes from beach sediments, flow column systems were built to evaluate flow of pore water out of beach sediments. Results show a peak in enterococci (average of 10% of the total microbes in core) released from the sand core within one pore water volume followed by a marked decline to below detection. These results indicate that few enterococci are easily removed and that factors other than simple pore water flow control the release of the majority of enterococci within beach sediments. A significantly larger quantity and release of enterococci were observed in cores collected after a significant rain event suggesting the influx of fresh water can alter the release pattern as compared to cores with no antecedent rainfall. PMID:21945015

Seabed texture and composition changes offshore of Port Royal Sound, South Carolina before and after the dredging for beach nourishment

NASA Astrophysics Data System (ADS)

Xu, Kehui; Sanger, Denise; Riekerk, George; Crowe, Stacie; Van Dolah, Robert F.; Wren, P. Ansley; Ma, Yanxia

2014-08-01

Beach nourishment has been a strategy widely used to slow down coastal erosion in many beaches around the world. The dredging of sand at the borrow site, however, can have complicated physical, geological and ecological impacts. Our current knowledge is insufficient to make accurate predictions of sediment infilling in many dredging pits due to lack of detailed sediment data. Two sites in the sandy shoal southeast of Port Royal Sound (PRS) of South Carolina, USA, were sampled 8 times from April 2010 to March 2013; one site (defined as 'borrow site') was 2 km offshore and used as the dredging site for beach nourishment of nearby Hilton Head Island in Beaufort County, South Carolina, and the other site (defined as 'reference site') was 10 km offshore and not directly impacted by the dredging. A total of 184 surficial sediment samples were collected randomly at two sites during 8 sampling periods. Most sediments were fine sand, with an average grain size of 2.3 phi and an organic matter content less than 2%. After the dredging in December 2011-January 2012, sediments at the borrow site became finer, changing from 1.0 phi to 2.3 phi, and carbonate content decreased from 10% to 4%; changes in mud content and organic matter were small. Compared with the reference site, the borrow site experienced larger variations in mud and carbonate content. An additional 228 sub-samples were gathered from small cores collected at 5 fixed stations in the borrow site and 1 fixed station at the reference site 0, 3, 6, 9, and 12 months after the dredging; these down-core sub-samples were divided into 1-cm slices and analyzed using a laser diffraction particle size analyzer. Most cores were uniform vertically and consisted of fine sand with well to moderately well sorting and nearly symmetrical averaged skewness. Based on the analysis of grain size populations, 2 phi- and 3 phi-sized sediments were the most dynamic sand fractions in PRS. Mud deposition on shoals offshore of PRS presumably happens when offshore mud transport is prevalent and there is a following rapid sand accumulation to bury the mud. However, in this borrow site there was very little accumulation of mud. This will allow the site to be used in future nourishment projects presuming no accumulation of mud occurs in the future.

Measurements and modelling of beach groundwater flow in the swash-zone: a review

NASA Astrophysics Data System (ADS)

Horn, Diane P.

2006-04-01

This paper reviews research on beach groundwater dynamics and identifies research questions which will need to be answered before swash zone sediment transport and beach profile evolution can be successfully modelled. Beach groundwater hydrodynamics are a result of combined forcing from the tide and waves at a range of frequencies, and a large number of observations exist which describe the shape and elevation of the beach watertable in response to tidal forcing at diurnal, semi-diurnal and spring-neap tidal frequencies. Models of beach watertable response to tidal forcing have been successfully validated; however, models of watertable response to wave forcing are less well developed and require verification. Improved predictions of swash zone sediment transport and beach profile evolution cannot be achieved unless the complex fluid and sediment interactions between the surface flow and the beach groundwater are better understood, particularly the sensitivity of sediment transport processes to flow perpendicular to the permeable bed. The presence of a capillary fringe, particularly when it lies just below the sand surface, has influences on beach groundwater dynamics. The presence of a capillary fringe can have a significant effect on the exchange of water between the ocean and the coastal aquifer, particularly in terms of the storage capacity of the aquifer. Field and laboratory observations have also shown that natural groundwater waves usually propagate faster and decay more slowly in aquifers with a capillary fringe, and observations which suggest that horizontal flows may also occur in the capillary zone have been reported. The effects of infiltration and exfiltration are generally invoked to explain why beaches with a low watertable tend to accrete and beaches with a high watertable tend to erode. However, the relative importance of processes such as infiltration losses in the swash, changes in the effective weight of the sediment, and modified shear stress due to boundary layer thinning, are not yet clear. Experimental work on the influence of seepage flows within sediment beds provides conflicting results concerning the effect on bed stability. Both modelling and experimental work indicates that the hydraulic conductivity of the beach is a critical parameter. However, hydraulic conductivity varies both spatially and temporally on beaches, particularly on gravel and mixed sand and gravel beaches. Another important, but poorly understood, consideration in beach groundwater studies is the role of air encapsulation during the wetting of beach sand.

In-situ Observations of Swash-zone Flow Velocities and Sediment Transport on a Steep Beach

NASA Astrophysics Data System (ADS)

Chardon-Maldonado, P.; Puleo, J. A.; Figlus, J.

2014-12-01

A 45 m scaffolding frame containing an array of instruments was installed at South Bethany Beach, Delaware, to obtain in-situ measurements in the swash zone. Six cross-shore stations were established to simultaneously measure near-bed velocity profiles, sediment concentration and water level fluctuations on a steep beach. Measurements of swash-zone hydrodynamics and morphological change were collected from February 12 to 25, 2014, following a large Nor'easter storm with surf zone significant wave height exceeding 5 m. Swash-zone flow velocities (u,v,w) were measured at each cross-shore location using a Nortek Vectrino profiling velocimeter that measured a 30 mm velocity profile at 1 mm vertical increments at 100 Hz. These velocity profiles were used to quantify the vertical flow structure over the foreshore and estimate hydrodynamic parameters such as bed shear stress and turbulent kinetic energy dissipation. Sediment concentrations were measured using optical backscatter sensors (OBS) to obtain spatio-temporal measurements during both uprush and backwash phases of the swash cycle. Cross-shore sediment transport rates at each station were estimated by taking the product of cross-shore velocity and sediment concentration. Foreshore elevations were sampled every low tide using a Leica GPS system with RTK capability. Cross-shore sediment transport rates and gradients derived from the velocities and bed shear stress estimates will be related to the observed morphological change.

Observations of coastal sediment dynamics of the Tijuana Estuary Fine Sediment Fate and Transport Demonstration Project, Imperial Beach, California

USGS Publications Warehouse

Warrick, Jonathan A.; Rosenberger, Kurt J.; Lam, Angela; Ferreiera, Joanne; Miller, Ian M.; Rippy, Meg; Svejkovsky, Jan; Mustain, Neomi

2012-01-01

Coastal restoration and management must address the presence, use, and transportation of fine sediment, yet little information exists on the patterns and/or processes of fine-sediment transport and deposition for these systems. To fill this information gap, a number of State of California, Federal, and private industry partners developed the Tijuana Estuary Fine Sediment Fate and Transport Demonstration Project ("Demonstration Project") with the purpose of monitoring the transport, fate, and impacts of fine sediment from beach-sediment nourishments in 2008 and 2009 near the Tijuana River estuary, Imperial Beach, California. The primary purpose of the Demonstration Project was to collect and provide information about the directions, rates, and processes of fine-sediment transport along and across a California beach and nearshore setting. To achieve these goals, the U.S. Geological Survey monitored water, beach, and seafloor properties during the 2008–2009 Demonstration Project. The project utilized sediment with ~40 percent fine sediment by mass so that the dispersal and transport of fine sediment would be easily recognizable. The purpose of this report is to present and disseminate the data collected during the physical monitoring of the Demonstration Project. These data are available online at the links noted in the "Additional Digital Information" section. Synthesis of these data and results will be provided in subsequent publications.

Hurricane Sandy washover deposits on southern Long Beach Island, New Jersey

USGS Publications Warehouse

Bishop, James M.; Richmond, Bruce M.; Zaremba, Nicholas J.; Lunghino, Brent D.; Kane, Haunani H.

2016-07-22

Sedimentologic and topographic data from Hurricane Sandy washover deposits were collected from southern Long Beach Island, New Jersey, in order to document changes to the barrier-island beaches, dunes, and coastal wetlands caused by Hurricane Sandy and subsequent storm events. These data will provide a baseline dataset for use in future coastal change descriptive and predictive studies and assessments. The data presented here were collected as part of the U.S. Geological Survey’s Barrier Island and Estuarine Wetland Physical Change Assessment Project (http://coastal.er.usgs.gov/sandy-wetland-assessment/), which aims to assess ecological and societal vulnerability that results from long- and short-term physical changes to barrier islands and coastal wetlands. This report describes data that were collected in April 2015, approximately 2½ years after Hurricane Sandy’s landfall on October 29, 2012. During the field campaign, washover deposits were photographed and described, and sediment cores, sediment samples, and surface-elevation data were collected. Data collected during this study, including sample locations and elevations, core photographs, computed tomography scans, descriptive core logs, sediment grain-size data, and accompanying Federal Geographic Data Committee metadata, are available in the associated U.S. Geological Survey data release (Bishop and others, 2016; http://dx.doi.org/10.5066/F7PK0D7S).

Analysis of Coastal Sediment Transport Processes from Wrightsville Beach to Fort Fisher, North Carolina.

DTIC Science & Technology

1981-06-01

the erosional phase of beach behavior is the continual exposure of "fresh" beach sediment which may not have the approprixte sediment distribution...The time scale was reset to zero at the time of fill (t0O), and so the initial loss of beach fill after time t was St. Values of S (Fig. 19) for...varying time increments up to tt 1 were plotted on semilog paper. Figure 20 shows the results of these plots for the MLW, MSL, and NHW excursion curves

Sources and fate of microplastics in marine and beach sediments of the Southern Baltic Sea-a preliminary study.

PubMed

Graca, Bożena; Szewc, Karolina; Zakrzewska, Danuta; Dołęga, Anna; Szczerbowska-Boruchowska, Magdalena

2017-03-01

Microplastics' (particles size ≤5 mm) sources and fate in marine bottom and beach sediments of the brackish are strongly polluted Baltic Sea have been investigated. Microplastics were extracted using sodium chloride (1.2 g cm -3 ). Their qualitative identification was conducted using micro-Fourier-transform infrared spectroscopy (μFT-IR). Concentration of microplastics varied from 25 particles kg -1 d.w. at the open sea beach to 53 particles kg -1  d.w. at beaches of strongly urbanized bay. In bottom sediments, microplastics concentration was visibly lower compared to beach sediments (0-27 particles kg -1  d.w.) and decreased from the shore to the open, deep-sea regions. The most frequent microplastics dimensions ranged from 0.1 to 2.0 mm, and transparent fibers were predominant. Polyester, which is a popular fabrics component, was the most common type of microplastic in both marine bottom (50%) and beach sediments (27%). Additionally, poly(vinyl acetate) used in shipbuilding as well as poly(ethylene-propylene) used for packaging were numerous in marine bottom (25% of all polymers) and beach sediments (18% of all polymers). Polymer density seems to be an important factor influencing microplastics circulation. Low density plastic debris probably recirculates between beach sediments and seawater in a greater extent than higher density debris. Therefore, their deposition is potentially limited and physical degradation is favored. Consequently, low density microplastics concentration may be underestimated using current methods due to too small size of the debris. This influences also the findings of qualitative research of microplastics which provide the basis for conclusions about the sources of microplastics in the marine environment.

Inexpensive, easy-to-construct suction coring devices usable from small boats

USGS Publications Warehouse

Onuf, Christopher P.; Chapman, Duane C.; Rizzo, William M.

1996-01-01

Collection of sediment cores in depths of 1-5 m is difficult with traditional sampling gear. Here we describe three suction coring devices constructed with readily available plumbing supplies and parts easily made from acrylic plastic and silicone sealant. The samplers have been used successfully in sediments ranging from coarse sands and shell hash to muds, highly organic deposits, and dense clays. Successful applications have ranged from contaminants analysis, toxicity testing, seagrass mapping, and assessment of sediment-microfloral interactions to sampling the infauna of surf-swept beaches.

First Year Sedimentological Characteristics and Morphological Evolution of an Artificial Berm at Fort Myers Beach, Florida

DTIC Science & Technology

2011-06-17

collected in the berm area. In the control areas, surface sediment samples were taken at approximately the toe of the dune (where present...In the berm area, surface sediment samples were taken at approximately the toe of the dune (where 29   present), backbeach, high tide line, mean...samples were taken at approximately the toe of the dune (where present), backbeach, high tide line, mean sea level, low tide line, 2 ft water depth

The Utility of Using a Near-Infrared (NIR) Camera to Measure Beach Surface Moisture

NASA Astrophysics Data System (ADS)

Nelson, S.; Schmutz, P. P.

2017-12-01

Surface moisture content is an important factor that must be considered when studying aeolian sediment transport in a beach environment. A few different instruments and procedures are available for measuring surface moisture content (i.e. moisture probes, LiDAR, and gravimetric moisture data from surface scrapings); however, these methods can be inaccurate, costly, and inapplicable, particularly in the field. Near-infrared (NIR) spectral band imagery is another technique used to obtain moisture data. NIR imagery has been predominately used through remote sensing and has yet to be used for ground-based measurements. Dry sand reflects infrared radiation given off by the sun and wet sand absorbs IR radiation. All things considered, this study assesses the utility of measuring surface moisture content of beach sand with a modified NIR camera. A traditional point and shoot digital camera was internally modified with the placement of a visible light-blocking filter. Images were taken of three different types of beach sand at controlled moisture content values, with sunlight as the source of infrared radiation. A technique was established through trial and error by comparing resultant histogram values using Adobe Photoshop with the various moisture conditions. The resultant IR absorption histogram values were calibrated to actual gravimetric moisture content from surface scrapings of the samples. Overall, the results illustrate that the NIR spectrum modified camera does not provide the ability to adequately measure beach surface moisture content. However, there were noted differences in IR absorption histogram values among the different sediment types. Sediment with darker quartz mineralogy provided larger variations in histogram values, but the technique is not sensitive enough to accurately represent low moisture percentages, which are of most importance when studying aeolian sediment transport.

Beach-dune dynamics: Spatio-temporal patterns of aeolian sediment transport under complex offshore airflow

NASA Astrophysics Data System (ADS)

Lynch, K.; Jackson, D.; Delgado-Fernandez, I.; Cooper, J. A.; Baas, A. C.; Beyers, M.

2010-12-01

This study examines sand transport and wind speed across a beach at Magilligan Strand, Northern Ireland, under offshore wind conditions. Traditionally the offshore component of local wind regimes has been ignored when quantifying beach-dune sediment budgets, with the sheltering effect of the foredune assumed to prohibit grain entrainment on the adjoining beach. Recent investigations of secondary airflow patterns over coastal dunes have suggested this may not be the case, that the turbulent nature of the airflow in these zones enhances sediment transport potential. Beach sediment may be delivered to the dune toe by re-circulating eddies under offshore winds in coastal areas, which may explain much of the dynamics of aeolian dunes on coasts where the dominant wind direction is offshore. The present study investigated aeolian sediment transport patterns under an offshore wind event. Empirical data were collected using load cell traps, for aeolian sediment transport, co-located with 3-D ultrasonic anemometers. The instrument positioning on the sub-aerial beach was informed by prior analysis of the airflow patterns using computational fluid dynamics. The array covered a total beach area of 90 m alongshore by 65 m cross-shore from the dune crest. Results confirm that sediment transport occurred in the ‘sheltered’ area under offshore winds. Over short time and space scales the nature of the transport is highly complex; however, preferential zones for sand entrainment may be identified. Alongshore spatial heterogeneity of sediment transport seems to show a relationship to undulations in the dune crest, while temporal and spatial variations may also be related to the position of the airflow reattachment zone. These results highlight the important feedbacks between flow characteristics and transport in a complex three dimensional surface.

Identification of Spilled Oil from the MV Marathassa (Vancouver, Canada 2015) Using Alkyl PAH Isomer Ratios.

PubMed

Morales-Caselles, Carmen; Yunker, Mark B; Ross, Peter S

2017-07-01

On the morning of April 9, 2015, citizens in Vancouver (British Columbia, Canada) awoke to the sight and smell of oil on the shores of popular downtown beaches. Because the oil also had spread over the shallow seawater intakes for the Vancouver Aquarium, a preliminary screening of samples was performed as a prompt, first response to assess the risks to the Aquarium collection and guide the emergency operational response. A subsequent, more detailed examination for the presence of spilled oil in sediment, biota and water samples from the Vancouver Harbour region was then conducted based on the analysis of a large suite of alkanes, petroleum biomarkers, parent polycyclic aromatic hydrocarbons (PAHs) and alkyl PAH isomers. Most of the commonly applied biomarker ratios exhibit similar values for the spilled oil, Alberta oil (the main petroleum source for British Columbia), and pre-spill and un-oiled sediment samples. In contrast, alkyl PAH isomer ratios showed a clear distinction between the spilled oil and pre-spill samples, with the largest differences shown by isomers of the methyl fluoranthene/pyrene alkyl PAH series. This novel use of alkyl PAH isomers for fingerprinting petroleum helped to confirm the grain carrier MV Marathassa as the source of the oil that affected beach and mussel samples to document definitively the spread of the oil and to establish which samples contained a mix of the oil and hydrocarbons linked to historical activities. Finally, an initial evaluation of the biological risks of the MV Marathassa oil spill in Vancouver Harbour showed that oiled beach sediments had priority parent PAH concentrations that are likely to harm marine life.

Ground-penetrating radar and differential global positioning system data collected from Long Beach Island, New Jersey, April 2015

USGS Publications Warehouse

Zaremba, Nicholas J.; Smith, Kathryn E.L.; Bishop, James M.; Smith, Christopher G.

2016-08-04

Scientists from the United States Geological Survey, St. Petersburg Coastal and Marine Science Center, U.S. Geological Survey Pacific Coastal and Marine Science Center, and students from the University of Hawaii at Manoa collected sediment cores, sediment surface grab samples, ground-penetrating radar (GPR) and Differential Global Positioning System (DGPS) data from within the Edwin B. Forsythe National Wildlife Refuge–Holgate Unit located on the southern end of Long Beach Island, New Jersey, in April 2015 (FAN 2015-611-FA). The study’s objective was to identify washover deposits in the stratigraphic record to aid in understanding barrier island evolution. This report is an archive of GPR and DGPS data collected from Long Beach Island in 2015. Data products, including raw GPR and processed DGPS data, elevation corrected GPR profiles, and accompanying Federal Geographic Data Committee metadata can be downloaded from the Data Downloads page.

Data on nearshore wave process and surficial beach deposits, central Tamil Nadu coast, India.

PubMed

Joevivek, V; Chandrasekar, N

2017-08-01

The chronicles of nearshore morphology and surficial beach deposits provide valuable information about the nature of the beach condition and the depositional environment. It imparts an understanding about the spatial and temporal relationship of nearshore waves and its influence over the distribution of beach sediments. This article contains data about wave and sediment dynamics of the ten sandy beaches along the central Tamil Nadu coast, India. This present dataset comprises nearshore wave parameters, breaker wave type, beach morphodynamic state, grain size distribution and weight percentage of heavy and light mineral distribution. The dataset will figure out the beach morphology and hydrodynamic condition with respect to the different monsoonal season. This will act as a field reference to realize the coastal dynamics in an open sea condition. The nearshore entities were obtained from the intensive field survey between January 2011 and December 2011, while characteristics of beach sediments are examined by the chemical process in the laboratory environment.

Sediment loads in canals 18, 23, and 24 in southeastern Florida

USGS Publications Warehouse

Pitt, William A. J.

1971-01-01

Suspended-sediment concentrations and suspended-sediment discharges were determined in selected canals in St. Lucie, Martin, and Palm Beach Counties, in southeastern Florida. Sediment rating curves were developed to relate water discharge to sediment concentration at the three sites sampled. An evaluation of the concentration and sediment loads shows that larger amounts of suspended sediment were being carried into the St. Lucie River estuary than were being carried into the Loxahatchee River estuary. Peat and muck soils in areas drained for agricultural planting and citrus cultivation are readily carried by runoff water into major canals that traverse the region.

Aeolian sediment transport on a beach: Surface moisture, wind fetch, and mean transport

NASA Astrophysics Data System (ADS)

Bauer, B. O.; Davidson-Arnott, R. G. D.; Hesp, P. A.; Namikas, S. L.; Ollerhead, J.; Walker, I. J.

2009-04-01

Temporal and spatial changes in wind speed, wind direction, and moisture content are ubiquitous across sandy coastal beaches. Often these factors interact in unknown ways to create complexity that confounds our ability to model sediment transport at any point across the beach as well as our capacity to predict sediment delivery into the adjacent foredunes. This study was designed to measure wind flow and sediment transport over a beach and foredune at Greenwich Dunes, Prince Edward Island National Park, with the express purpose of addressing these complex interactions. Detailed measurements are reported for one stormy day, October 11, 2004, during which meteorological conditions were highly variable. Wind speed ranged from 4 ms - 1 to over 20 ms - 1 , wind direction was highly oblique varying between 60° and 85° from shore perpendicular, and moisture content of the sand surface ranged from a minimum of about 3% (by mass) to complete saturation depending on precipitation, tidal excursion, and storm surge that progressively inundated the beach. The data indicate that short-term variations (i.e., minutes to hours) in sediment transport across this beach arise predominantly because of short-term changes in wind speed, as is expected, but also because of variations in wind direction, precipitation intensity, and tide level. Even slight increases in wind speed are capable of driving more intense saltation events, but this relationship is mediated by other factors on this characteristically narrow beach. As the angle of wind approach becomes more oblique, the fetch distance increases and allows greater opportunity for the saltation system to evolve toward an equilibrium transport state before reaching the foredunes. Whether the theoretically-predicted maximum rate of transport is ever achieved depends on the character of the sand surface (e.g., grain size, slope, roughness, vegetation, moisture content) and on various attributes of the wind field (e.g., average wind speed, unsteadiness, approach angle, flow compression, boundary layer development). Moisture content is widely acknowledged as an important factor in controlling release of sediment from the beach surface. All other things being equal, the rate of sediment transport over a wet surface is lesser than over a dry surface. On this beach, the moisture effect has two important influences: (a) in a temporal sense, the rate of sediment transport typically decreases in association with rainfall and increases when surface drying takes place; and (b) in a spatio-temporal sense, shoreline excursions associated with nearshore processes (such as wave run-up, storm surge, and tidal excursions) have the effect of constraining the fetch geometry of the beach—i.e., narrowing the width of the beach. Because saturated sand surfaces, such as found in the swash zone, will only reluctantly yield sediments to aeolian entrainment, the available beach surface across which aeolian transport can occur becomes narrower as the sea progressively inundates the beach. Under these constrained conditions, the transport system begins to shut down unless wind angle becomes highly oblique (thereby increasing fetch distance). In this study, maximum sediment transport was usually measured on the mid-beach rather than the upper beach (i.e., closer to the foredunes). This unusual finding is likely because of internal boundary layer development across the beach, which yields a decrease in near-surface wind speed (and hence, transport capacity) in the landward direction. Although widely recognized in the fluid mechanics literature, this decrease in near-surface shear stress as a by-product of a developing boundary layer in the downwind direction has not been adequately investigated in the context of coastal aeolian geomorphology.

The Geomorphic System and the Effects of Human Interference at Gold Coast Beach in Tainan, Taiwan

NASA Astrophysics Data System (ADS)

Lin, Tsung-Yi

2017-04-01

The Gold Coast beach in Tainan, Taiwan, located between Anping harbor and Ur-Jen river mouth, is the subject of this study, which characterizes the beach's geomorphic system through the analysis of information such as sediment grain size, mineral composition, and periodic measurements of morphological changes of the beach. Based upon such characterizations, further analysis is conducted on the effects that human activities of the last 15 years have upon the geomorphic changes within the Gold Coast beach. The study shows that the median grain size of the Gold Coast beach's sediment is medium sand. The mineral composition includes mainly slate fragments and quartz grains, with small amounts of feldspar, sandstone and shell fragments. Based on a comprehensive study of the longshore distribution of beach sediment size and mineral composition of southwestern coast of Taiwan, as well as, the long-term, monitored data of waves, tides, and currents in this region, we conclude that the main process responsible for the sand accumulation at Gold Coast beach is the prevailing longshore sand transport from south to north. The southern breakwater of Anping harbor plays a role in intercepting the longshore transport sand and helps form the beach. Since the Ur-Jen river flows through a mudstone region, the suspended sediment plume during the flood season does not provide much sediment source to the sandy beach. A monthly beach profile survey project conducted between the years 1999 to 2000 revealed that the beach elevation and width had experienced an obvious seasonal change. The beach widened during the winter, but narrowed in the summer due to typhoon wave erosion. When the subaerial beach was eroded, a submerged longshore bar that was oriented almost parallel to the shoreline had formed at a distance about 400-600 meter away. With this observation, we can conclude that beach morphology is also influenced by various seasonal wave actions that affect onshore and offshore sand transport. An astonishing morphologic change at Gold Coast was observed as a 1500-meter reach of sandy beach at the southern end, near the Ur-Jen river mouth, disappeared in just a few years after the year 2005. The beach was not recovered the way it used to be in the winter season. The main reason for this geomorphic change could be the construction of a series of detached breakwaters on the coastal reach that is at the south side of Ur-Jen river mouth. Salients formed behind the detached breakwaters, which could have interrupted the south-to-north longshore sand transport. The Gold Coast became a sand-starved beach recently in the past 10 years, despite efforts of the government to construct more groins in this erosion area. Keywords: beach system, beach sediment, beach morphology, geomorphic processes, geomorphic change

Marine sediment sample preparation for analysis for low concentrations of fine detrital gold

USGS Publications Warehouse

Clifton, H. Edward; Hubert, Arthur; Phillips, R. Lawrence

1967-01-01

Analyses by atomic absorption for detrital gold in more than 2,000 beach, offshore, marine-terrace, and alluvial sands from southern Oregon have shown that the values determined from raw or unconcentrated sediment containing small amounts of gold are neither reproducible nor representative of the initial sample. This difficulty results from a 'particle sparsity effect', whereby the analysis for gold in a given sample depends more upon the occurrence of random flakes of gold in the analyzed portion than upon the actual gold content of the sample. The particle sparsity effect can largely be eliminated by preparing a gold concentrate prior to analysis. A combination of sieve, gravimetric, and magnetic separation produces a satisfactory concentrate that yields accurate and reproducible analyses. In concentrates of nearly every marine and beach sand studied, the gold occurs in the nonmagnetic fraction smaller than 0.124 mm and with a specific gravity greater than 3.3. The grain size of gold in stream sediments is somewhat more variable. Analysis of concentrates provides a means of greatly increasing the sensitivity of the analytical technique in relation to the initial sample. Gold rarely exceeds 1 part per million in even the richest black sand analyzed; to establish the distribution of gold (and platinum) in marine sediments and its relationship to source and environmental factors, one commonly needs to know their content to the part per billion range. Analysis of a concentrate and recalculation to the value in the initial sample permits this degree of sensitivity.

Ridge-Runnel and Swash Dynamics Field Experiment on a Steep Meso-Tidal Beach

NASA Astrophysics Data System (ADS)

Figlus, J.; Song, Y.-K.; Chardon-Maldonado, P.; Puleo, J. A.

2014-12-01

Ridge-runnel (RR) systems are morphological features that may form in the intermittently wet and dry zone of the beach immediately after storm events. Their onshore migration provides a natural way of recovery for an eroded beach but the detailed swash interactions and complex feedback mechanisms between wave dynamics, sediment transport and profile evolution are not well understood and challenging to measure in-situ. During a storm, elevated water levels and large waves can significantly erode the beach profile in a matter of hours through offshore-directed sediment transport. The beach recovery process, on the other hand, occurs over a much longer time period during less intense wave conditions. In the beginning of this 3-week field campaign at South Bethany Beach, Delaware, a Nor'easter, eroded significant portions of this steep, meso-tidal beach and formed a pronounced RR system which then evolved during the less energetic conditions after the storm. An extensive cross-shore array of sensors was installed immediately after the storm measuring near-bed velocity profiles (5 Nortek Vectrino Profilers) and horizontal velocities (6 Sontec Electromagnetic Current Meters; 1 side-looking Nortek Vectrino) suspended sediment concentrations (10 Optical Backscatter Sensors OBS-3+), and pressure fluctuations (7 GE Druck pressure transducers) in the swash zone. Dense topography surveys of the RR system were conducted twice a day during low tide conditions with a Leica RTK GPS rover system. In addition, sediment grab samples along the entire RR cross-section were collected daily. An offshore ADCP with surface wave tracking capability (Nortek 2MHz AWAC AST) measured directional wave spectra and current profiles at a water depth of approximately 6m. The RR system showed rapid onshore migration over the two tide cycles immediately after the storm, followed by a period of vertical ridge accretion of up to 3 ft at certain locations. A first look at the collected data and analysis results related to the feedback mechanisms between wave forcing and RR evolution is presented along with a discussion of difficulties encountered during the experiment.

Relationship between Enterococcal Levels and Sediment Biofilms at Recreational Beaches in South Florida

PubMed Central

Piggot, Alan M.; Johnson, Sara; Phillips, Matthew C.; Solo-Gabriele, Helena M.

2012-01-01

Enterococci, recommended at the U.S. federal level for monitoring water quality at marine recreational beaches, have been found to reside and grow within beach sands. However, the environmental and ecological factors affecting enterococcal persistence remain poorly understood, making it difficult to determine levels of fecal pollution and assess human health risks. Here we document the presence of enterococci associated with beach sediment biofilms at eight south Florida recreational beaches. Enterococcal levels were highest in supratidal sands, where they displayed a nonlinear, unimodal relationship with extracellular polymeric secretions (EPS), the primary component of biofilms. Enterococcal levels peaked at intermediate levels of EPS, suggesting that biofilms may promote the survival of enterococci but also inhibit enterococci as the biofilm develops within beach sands. Analysis of bacterial community profiles determined by terminal restriction fragment length polymorphisms showed the bacterial communities of supratidal sediments to be significantly different from intertidal and subtidal communities; however, no differences were observed in bacterial community compositions associated with different EPS concentrations. Our results suggest that supratidal sands are a microbiologically unique environment favorable for the incorporation and persistence of enterococci within beach sediment biofilms. PMID:22706061

Comparative Sediment Transport Between Exposed and Reef Protected Beaches Under Different Hurricane Conditions

NASA Astrophysics Data System (ADS)

Miret, D.; Enriquez, C.; Marino-Tapia, I.

2016-12-01

Many world coast regions are subjected to tropical cyclone activity, which can cause major damage to beaches and infrastructure on sediment dominated coasts. The Caribbean Sea has on average 4 hurricanes per year, some of them have caused major damage to coastal cities in the past 25 years. For example, Wilma, a major hurricane that hit SE Mexico in October 2005 generated strong erosion at an exposed beach (Cancun), while beach accretion was observed 28 km south at a fringing reef protected beach (Puerto Morelos). Hurricanes with similar intensity and trajectory but different moving speeds have been reported to cause a different morphological response. The present study analyses the morphodynamic response to the hydrodynamic conditions of exposed and reef protected beaches, generated by hurricanes with similar intensities but different trajectories and moving speeds. A non-stationary Delft3D Wave model is used to generate large scale wind swell conditions and local sea wind states and coupled with Delft3D Flow model to study the connection between the continental shelf and surf zones exchanges. The model is validated with hydrodynamic data gathered during Wilma, and morphological conditions measured before and after the event. Preliminary results show that erosion appears at the exposed beach and a predominant exchange between north and south dominates the shelf sediment transport (figure 1). Onshore driven flows over the reef crest input sediment in the reef protected beach. It is expected that for a same track but faster moving speed, southward sediment transport will have less time to develop and accretion at the reef protected site would be less evident or inexistent. The study can be used as a prediction tool for shelf scale sediment transport exchange driven by hurricanes.

The use of biotic and abiotic components of Red Sea coastal areas as indicators of ecosystem health.

PubMed

Omar, Wael A; Saleh, Yousef S; Marie, Mohamed-Assem S

2016-03-01

A biomonitoring study was conducted using some biotic (Pomadasys hasta and Lutjanus russellii fish) and abiotic (water and sediment) components of the Red Sea coast of Hodeida, Yemen Republic along two polluted sites (Al-Dawar beach and Urj village) in comparison to a reference site (Al-Nukhailah beach). The studied fish biomarkers included hepatosomatic index (HSI), condition factor (K), scaled mass index (SMI), catalase, glutathione-S-transferase (GST), malondialdehyde (MDA), total protein and albumin. In addition, metals (Fe, Cu, Zn, Pb and Cd) concentrations in water and sediment were measured and sediment pollution assessment was carried out using contamination factor (CF), geoaccumulation index (Igeo), pollution load index (PLI) and enrichment factor (EF). The studied metals concentration in water and sediment samples showed significant increase among the polluted sites in comparison to the reference site. Sediment pollution assessment generally confirmed that Urj village was the most contaminated site followed by Al-Dawar beach. Catalase, GST and MDA proved to be the most responsive biomarkers with increased values of GST and MDA at sites influenced by agricultural, urban and industrial activities while catalase, HSI, K, SMI, total protein and albumin showed the opposite trend. This study recommends monitoring of sediment Igeo and EF values as well as SMI, catalase, GST and MDA as sensitive indicators of different anthropogenic activities and their effects on aquatic ecosystems under complex and different gradients of metal pollution. In addition, P. hasta proved to be more sensitive towards the detected pollution condition.

Dispersal of fine sediment in nearshore coastal waters

USGS Publications Warehouse

Warrick, Jonathan A.

2013-01-01

Fine sediment (silt and clay) plays an important role in the physical, ecological, and environmental conditions of coastal systems, yet little is known about the dispersal and fate of fine sediment across coastal margin settings outside of river mouths. Here I provide simple physical scaling and detailed monitoring of a beach nourishment project near Imperial Beach, California, with a high portion of fines (40% silt and clay by weight). These results provide insights into the pathways and residence times of fine sediment transport across a wave-dominated coastal margin. Monitoring of the project used physical, optical, acoustic, and remote sensing techniques to track the fine portion of the nourishment sediment. The initial transport of fine sediment from the beach was influenced strongly by longshore currents of the surf zone that were established in response to the approach angles of the waves. The mean residence time of fine sediment in the surf zone—once it was suspended—was approximately 1 hour, and rapid decreases in surf zone fine sediment concentrations along the beach resulted from mixing and offshore transport in turbid rip heads. For example, during a day with oblique wave directions and surf zone longshore currents of approximately 25 cm/s, the offshore losses of fine sediment in rips resulted in a 95% reduction in alongshore surf zone fine sediment flux within 1 km of the nourishment site. However, because of the direct placement of nourishment sediment on the beach, fine suspended-sediment concentrations in the swash zone remained elevated for several days after nourishment, while fine sediment was winnowed from the beach. Once offshore of the surf zone, fine sediment settled downward in the water column and was observed to transport along and across the inner shelf. Vertically sheared currents influenced the directions and rates of fine sediment transport on the shelf. Sedimentation of fine sediment was greatest on the seafloor directly offshore of the nourishment site. However, a mass balance of sediment suggests that the majority of the fine sediment moved far away (over 2 km) from the nourishment site or to water depths greater than 10 m, where fine sediment represents a substantial portion of the bed material. Thus, the fate of fine sediment in nearshore waters was influenced strongly by wave conditions, surf zone and rip current transport, and the vertical density and flow conditions of coastal waters.

Use of Clostridium perfringens as a fecal indicator to detect intertidal disposal at backcountry marine campsites in Prince William Sound, Alaska

Treesearch

Gino Graziano; Paul Twardock; Rusty Myers; Roman Dial; David Scheel

2007-01-01

Human waste disposal is a health concern in many backcountry areas. This study measured Clostridium perfringens in beach sediments of Prince William Sound, Alaska, to detect fecal contamination resulting from intertidal disposal. Analysis involved holding times that exceeded eight hours. In repeatedly sampled stored sediments, C. perfringens...

Impact of sea-level rise on cross-shore sediment transport on fetch-limited barrier reef island beaches under modal and cyclonic conditions.

PubMed

Baldock, T E; Golshani, A; Atkinson, A; Shimamoto, T; Wu, S; Callaghan, D P; Mumby, P J

2015-08-15

A one-dimensional wave model is combined with an analytical sediment transport model to investigate the likely influence of sea-level rise on net cross-shore sediment transport on fetch-limited barrier reef and lagoon island beaches. The modelling considers if changes in the nearshore wave height and wave period in the lagoon induced by different water levels over the reef flat are likely to lead to net offshore or onshore movement of sediment. The results indicate that the effects of SLR on net sediment movement are highly variable and controlled by the bathymetry of the reef and lagoon. A significant range of reef-lagoon bathymetry, and notably shallow and narrow reefs, appears to lead hydrodynamic conditions and beaches that are likely to be stable or even accrete under SLR. Loss of reef structural complexity, particularly on the reef flat, increases the chance of sediment transport away from beaches and offshore. Copyright © 2015 Elsevier Ltd. All rights reserved.

The effects of storms and storm-generated currents on sand beaches in Southern Maine, USA

USGS Publications Warehouse

Hill, H.W.; Kelley, J.T.; Belknap, D.F.; Dickson, S.M.

2004-01-01

Storms are one of the most important controls on the cycle of erosion and accretion on beaches. Current meters placed in shoreface locations of Saco Bay and Wells Embayment, ME, recorded bottom currents during the winter months of 2000 and 2001, while teams of volunteers profiled the topography of nearby beaches. Coupling offshore meteorological and beach profile data made it possible to determine the response of nine beaches in southern Maine to various oceanographic and meteorological conditions. The beaches selected for profiling ranged from pristine to completely developed and permitted further examination of the role of seawalls on the response of beaches to storms. Current meters documented three unique types of storms: frontal passages, southwest storms, and northeast storms. In general, the current meter results indicate that frontal passages and southwest storms were responsible for bringing sediment towards the shore, while northeast storms resulted in a net movement of sediment away from the beach. During the 1999-2000 winter, there were a greater percentage of frontal passages and southwest storms, while during the 2000-2001 winter, there were more northeast storms. The sediment that was transported landward during the 1999-2000 winter was reworked into the berm along moderately and highly developed beaches during the next summer. A northeast storm on March 5-6, 2001, resulted in currents in excess of 1 m s-1 and wave heights that reached six meters. The storm persisted over 10 high tides and caused coastal flooding and property damage. Topographic profiles made before and after the storm demonstrate that developed beaches experienced a loss of sediment volume during the storm, while sediment was redistributed along the profile on moderately developed and undeveloped beaches. Two months after the storm, the profiles along the developed beaches had not reached their pre-storm elevation. In comparison, the moderately developed and undeveloped beaches reached and exceeded their pre-storm elevation and began to show berm buildup characteristic of the summer months. ?? 2004 Elsevier B.V. All rights reserved.

Spectral and Geological Characterization of Beach Components in Northern Puerto Rico

NASA Astrophysics Data System (ADS)

Caraballo Álvarez, I. O.; Torres-Perez, J. L.; Barreto, M.

2015-12-01

Understanding how changes in beach components may reflect beach processes is essential since variations along beach profiles can shed light on river and ocean processes influencing beach sedimentation and beachrock formation. It is likely these influences are related to beach proximity within the Río Grande de Manatí river mouth. Therefore, this study focuses on characterizing beach components at two sites in Manatí, Puerto Rico. Playa Machuca and Playa Tombolo, which are separated by eolianites, differ greatly in sediment size, mineralogy, and beachrock morphology. Several approaches were taken to geologically and spectrally characterize main beach components at each site. These approaches included field and microscopic laboratory identification, granulometry, and a comparison between remote sensing reflectance (Rrs) obtained with a field spectroradiometer and pre-existing spectral library signatures. Preliminary results indicate a positive correlation between each method. This study may help explore the possibility of using only Rrs to characterize beach and shallow submarine components for detailed image analysis and management of coastal features.This study focuses on characterizing beach components at two sites in Manatí, Puerto Rico. Playa Machuca and Playa Tombolo, two beaches that are separated by eolianites, differ greatly in sediment size and mineralogy, as well as in beachrock morphology. Understanding how changes in beach components may reflect beach processes is essential, since it is likely that differences are mostly related to each beaches' proximity to the Río Grande de Manatí river mouth. Hence, changes in components along beach profiles can shed light on the river's and the ocean's influence on beach sedimentation and beachrock formation. Several approaches were taken to properly geologically and spectrally characterize the main beach components at each site. These approaches included field and microscopic laboratory identification, granulometry, and a comparison between remote sensing reflectance (Rrs) obtained with a field spectroradiometer and the ENVI spectral library. Preliminary results show a positive correlation between each method. This study may help explore the possibility of using only Rrs to characterize beach and shallow submarine components for detailed image analysis and management of coastal features.

Monitoring beach changes using GPS surveying techniques

USGS Publications Warehouse

Morton, Robert; Leach, Mark P.; Paine, Jeffrey G.; Cardoza, Michael A.

1993-01-01

The adaptation of Global Positioning System (GPS) surveying techniques to beach monitoring activities is a promising response to this challenge. An experiment that employed both GPS and conventional beach surveying was conducted, and a new beach monitoring method employing kinematic GPS surveys was devised. This new method involves the collection of precise shore-parallel and shore-normal GPS positions from a moving vehicle so that an accurate two-dimensional beach surface can be generated. Results show that the GPS measurements agree with conventional shore-normal surveys at the 1 cm level, and repeated GPS measurements employing the moving vehicle demonstrate a precision of better than 1 cm. In addition, the nearly continuous sampling and increased resolution provided by the GPS surveying technique reveals alongshore changes in beach morphology that are undetected by conventional shore-normal profiles. The application of GPS surveying techniques combined with the refinement of appropriate methods for data collection and analysis provides a better understanding of beach changes, sediment transport, and storm impacts.

Antibiotic and heavy metal resistance in enterococci from coastal marine sediment.

PubMed

Vignaroli, Carla; Pasquaroli, Sonia; Citterio, Barbara; Di Cesare, Andrea; Mangiaterra, Gianmarco; Fattorini, Daniele; Biavasco, Francesca

2018-06-01

Sediment samples from three coastal sites - two beach resorts (Beach 1 and Beach 2 sites) and an area lying between an oil refinery and a river estuary (Estuarine site) - were analyzed for antibiotic- and heavy metal (HM)-resistant enterococci. A total of 123 enterococci, 36 E. faecium, 34 E. casseliflavus, 33 E. hirae, 5 E. faecalis, 3 E. durans, 3 E. gallinarum, and 9 Enterococcus spp, were recovered. Strains resistant to erythromycin, tetracycline and quinupristin/dalfopristin (Q/D) were recovered from all sites, whereas multidrug-resistant isolates were recovered only from "Beach 2" (14%) and "Estuarine" (3.7%). As regards HM resistance, the strains showed a high frequency (68%) of cadmium and/or copper resistance and uniform susceptibility to mercury. The prevalence of cadmium-resistant strains was significantly higher among erythromycin-resistant than among erythromycin-susceptible strains. A significant association between cadmium or copper resistance and Q/D resistance was also observed at "Estuarine" site. The levels of the two HMs in sediment from all sites were fairly low, ranging from 0.070 to 0.126 μg/g, for cadmium and from 1.00 to 7.64 μg/g for copper. Mercury was always undetectable. These findings are consistent with reports that low HM concentrations may contribute to co-selection of antibiotic-resistant bacterial strains, including enterococci. Copyright © 2018 Elsevier Ltd. All rights reserved.

Use of a mobile terrestrial laser system to quantify the impact of rigid coastal protective structures on sandy beaches, Quebec, Canada

NASA Astrophysics Data System (ADS)

Van-Wierts, S.; Bernatchez, P.

2012-04-01

Coastal erosion is an important issue within the St-Lawrence estuary and gulf, especially in zones of unconsolidated material. Wide beaches are important coastal environments; they act as a buffer against breaking waves by absorbing and dissipating their energy, thus reducing the rate of coastal erosion. They also offer protection to humans and nearby ecosystems, providing habitat for plants, animals and lifeforms such as algae and microfauna. Conventional methods, such as aerial photograph analysis, fail to adequately quantify the morphosedimentary behavior of beaches at the scale of a hydrosedimentary cells. The lack of reliable and quantitative data leads to considerable errors of overestimation and underestimation of sediment budgets. To address these gaps and to minimize acquisition costs posed by airborne LiDAR survey, a mobile terrestrial LiDAR has been set up to acquire topographic data of the coastal zone. The acquisition system includes a LiDAR sensor, a high precision navigation system (GPS-INS) and a video camera. Comparison of LiDAR data with 1050 DGPS control points shows a vertical mean absolute error of 0.1 m in beach areas. The extracted data is used to calculate sediment volumes, widths, slopes, and a sediment budget index. A high accuracy coastal characterization is achieved through the integration of laser data and video. The main objective of this first project using this system is to quantify the impact of rigid coastal protective structures on sediment budget and beach morphology. Results show that the average sediment volume of beaches located before a rock armour barrier (12 m3/m) were three times narrower than for natural beaches (35,5 m3/m). Natural beaches were also found to have twice the width (25.4 m) of the beaches bordering inhabited areas (12.7 m). The development of sediment budget index for beach areas is an excellent proxy to quickly identify deficit areas and therefore the coastal segments most at risk of erosion. The obtained LiDAR coverage also revealed that beach profiles made at an interval of more than 200 m on diversified coasts lead to results significantly different from reality. However, profile intervals have little impact on long uniform beaches.

Relationships Between Magnetic Susceptibility and Sedimentary Facies Along AL Qahmah, Southern Red Sea Coast

NASA Astrophysics Data System (ADS)

Nabhan, A. I.; Yang, W.

2016-12-01

Facies and magnetic parameters of an arid siliciclastic coast were investigated in Al Qahmah, Saudi Arabia. The purpose of the survey was to map and understand the distribution of magnetic minerals in the different sedimentary facies in a 20-km2 area. Four NW-SE profiles parallel to shoreline and thirty-nine roughly perpendicular NE-SW profiles were measured. Petrographic study of sediment composition and texture of 152 samples was conducted. The coast sediments contain six lithofacies: beach, washover fan, tidal channel, eolian dune, sabkha, and wadi. The high concentration of heavy minerals in beach and dune facies causes high magnetic of susceptibility. Mineral composition of the total fraction in these facies confirms the presence of magnetite and ilmenite. The high values of susceptibility in beach and dune facies are attributed to strong winnowing and wave processes that control the pattern of transport, sorting of magnetic minerals in the beach facies. These minerals are picked up and moved by wind at low tide to form extensive low dune fields near the beach. The results showed that magnetic measurements are a sensitive and fast method, which can be used for studying the distribution of magnetic minerals in the sedimentary facies and help interpret various controlling processes.

Microbial community composition and PAHs removal potential of indigenous bacteria in oil contaminated sediment of Taean coast, Korea.

PubMed

Lee, Dong Wan; Lee, Hanbyul; Lee, Aslan Hwanhwi; Kwon, Bong-Oh; Khim, Jong Seong; Yim, Un Hyuk; Kim, Beom Seok; Kim, Jae-Jin

2018-03-01

The tidal flats near Sinduri beach in Taean, Korea, have been severely contaminated by heavy crude oils due to the Korea's worst oil spill accident, say the Hebei Spirit Oil Spill, in 2007. Crude oil compounds, including polycyclic aromatic hydrocarbons (PAHs), pose significant environmental damages due to their wide distribution, persistence, high toxicity, mutagenicity, and carcinogenicity. Microbial community of Sinduri beach sediments samples was analyzed by metagenomic data with 16S rRNA gene amplicons. Three phyla (Proteobacteria, Firmicutes, and Bacteroidetes) accounted for approximately ≥93.0% of the total phyla based on metagenomic analysis. Proteobacteria was the dominant phylum in Sinduri beach sediments. Cultivable bacteria were isolated from PAH-enriched cultures, and bacterial diversity was investigated through performing culture characterization followed by molecular biology methods. Sixty-seven isolates were obtained, comprising representatives of Actinobacteria, Firmicutes, α- and γ-Proteobacteria, and Bacteroidetes. PAH catabolism genes, such as naphthalene dioxygenase (NDO) and aromatic ring hydroxylating dioxygenase (ARHDO), were used as genetic markers to assess biodegradation of PAHs in the cultivable bacteria. The ability to degrade PAHs was demonstrated by monitoring the removal of PAHs using a gas chromatography mass spectrometer. Overall, various PAH-degrading bacteria were widely present in Sinduri beach sediments and generally reflected the restored microbial community. Among them, Cobetia marina, Rhodococcus soli, and Pseudoalteromonas agarivorans were found to be significant in degradation of PAHs. This large collection of PAH-degrading strains represents a valuable resource for studies investigating mechanisms of PAH degradation and bioremediation in oil contaminated coastal environment, elsewhere. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Relationship Between Sediment Properties and Sedimentation Patterns on a Macrotidal Gravel Beach over a Semi-lunar Tidal Cycle.

NASA Astrophysics Data System (ADS)

Buscombe, D.; Masselink, G.

2007-12-01

Detailed measurements of profile and sediment dynamics have been obtained from a macrotidal gravel barrier beach in southern England. Surface and sub-surface sediment samples, beach profiles, and disturbance depths were taken from the intertidal zone on consecutive low tides over semi-lunar tidal cycles, along with continuous wave and tide measurements. Results from two separate field surveys are presented, representing 26 and 24 consecutive low tides, respectively. A combination of Canonical Correlation Analysis (CCA) and Empirical Orthogonal Function (EOF) analysis was used to identify a number of consistent relationships in morphological and sedimentological variables not readily apparent using ordinary correlations. The disadvantage of such statistical models is that the relationships obtained cannot be expressed in physically meaningful units, which does limit its utility in physical-numerical modelling. However, the results reveal some interesting relationships between gravel beachface sedimentology and morphological change. For example, beachface morphology and sedimentology are more similar at a given spatial location over time than over space (cross-shore) at any individual time. Subsurface sedimentology over the depth of disturbance indicates that the beach step can be traced through the sediment characteristics. Indeed, the study suggests that gravel beachface sedimentology is 'slaved' to morphological change rather than vice-versa; and that the relationship becomes more evident as secondary morphological features develop on the beachface. The results imply that median sediment size and geometric sorting are suitable parameters for detecting such relationships. Strong hysteresis over space was present in the EOF modes associated with the most variance in the data sets, for both sediment size and sorting. Statistically significant relationships were found between the temporal modes of (absolute) size/sorting and net sedimentation associated with the largest variance in the non-decomposed respective data sets. Finally, significant relationships were found between a suite of measured hydrodynamic time-series and pairs of significantly correlated morpho-sedimentary eigenmodes. The techniques used were thus able to objectively demonstrate linear association between morphological and sedimentological change on a gravel beachface over a semi-lunar tidal cycle; and also that simultaneous changes in each could be linearly correlated to hydrodynamic forcing.

Relationship between sediment morphology and oil pollution along the Suez Canal beaches, Egypt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barakat, M.A.K.; Shimy, T.M.; Mostafa, Y.M.

1996-10-01

In this study, marine surface sediments are collected from nine locations along the Suez Canal in order to investigate the relationship between the morphology of sands in the studied beaches and pollution by oil. Basically, the studied samples were analyzed by three techniques: grains-size analysis, microscopic examination, and gas chromatographic (GC) analysis. This study concluded that medium sand is the major class represented in the studied marine sediments. Pollution in these sand grains increases in the irregular grains more so than in the more rounded grains. Also, deep surface points, pitting, and fissures are considered to be good sites tomore » precipitate oil contamination. Also, the presence of iron oxides may be taken as evidence for tanker ballast washings. The heavy fraction (zircon) shows more contamination than the light fraction (quartz) in these samples. Finally, GC profiles have shown two types of samples: one typical of weathered or highly weathered crude oil patterns and the other for samples with very highly weathered profiles. The relationship obtained between morphology studies and both oil content and GC chromatogram profiles indicates that all of the studied locations are suffering from pollution of oil that is spilled while shipping petroleum through the Suez Canal.« less

The morphodynamic significance of rapid shoreline progradation followed by vertical foredune building at Pedro Beach, southeastern Australia

NASA Astrophysics Data System (ADS)

Oliver, Thomas; Tamura, Toru; Short, Andrew; Woodroffe, Colin

2017-04-01

Prograded coastal barriers are accumulations of marine and aeolian sands configured into shore-parallel ridges. A variety of ridge morphologies described around the world reflect differences in origin as a consequence of differing prevailing coastal morphodynamics. The 'morphodynamic approach' described by Wright and Thom (1977) expounds the coastal environmental conditions, hydrodynamic and morphodynamic processes and inheritance of evolutionary sequences over varying temporal scales which interdependently operate to produce an assemblage of coastal landforms adjusted, or adjusting to, a dynamic equilibrium. At Pedro Beach on the southeastern coast of Australia a large sandy deposit of foredune ridges provides an opportunity to explore the morphodynamic paradigm as it applies to coastal barrier systems using optically stimulated luminescence (OSL) dating, ground penetrating radar (GPR) and airborne LiDAR topography. The prograded barrier at Pedro Beach has formed following the stabilisation of the sea level at its present height on the southeast Australian coastline. A series of dune-capped ridges, increasing in height seawards, formed from 6000 years ago to 4000 years ago. During this time the shoreline straightened as bedrock accommodation space for Holocene sediments diminished. Calculation of Holocene sediment volumes utilising airborne LiDAR topography shows a decline in sediment volume over this time period coupled with a decrease in shoreline progradation rate from 0.75 m/yr to 0.49 m/yr. The average ridge 'lifetime' during this period increases resulting in higher ridges as dune-forming processes have longer to operate. Greater exposure to wave and wind energy also appears to have resulted in higher ridges as the sheltering effect of marginal headlands has diminished. A high outer foredune has formed through vertical accretion in the past 700 years, evidenced by GPR subsurface structures and upward younging of OSL ages, with a sample from 1 m deep within the crest of this dune returning an age of 90 ± 10. An inherited disequilibrium shoreface profile will drive onshore accumulation of sandy sediments forming a prograded barrier; however, if there is no longer 'accommodation space' for sediment, this will be an overriding factor causing the cessation of progradation as occurred 4000 years ago at Pedro Beach. Following progradation cessation, excess sediment in the disequilibrium shoreface profile will be moved alongshore as barrier progradation (embayment filling) has diminished the potential of headlands to act as impediments to sediment bypassing in the nearshore. It is hypothesised that the chronology and geomorphology of the Pedro Beach barrier system typifies the changing 'strength of influence' in the interaction between geologically inherited accommodation space, sediment delivery and beach/dune/shoreface dynamics over the mid-late Holocene. Wright, L. D., & Thom, B. G. (1977). Coastal depositional landforms: a morphodynamic approach. Progress in Physical Geography, 1(3), 412-459.

Modern sedimentation on the shoreface and inner continental shelf at wrightsville beach, North Carolina, U.S.A

USGS Publications Warehouse

Thieler, R.E.; Pilkey, O.H.; Cleary, W.J.; Schwab, W.C.

2001-01-01

The geologic framework and surficial morphology of the shoreface and inner continental shelf off the Wrightsville Beach, North Carolina, barrier island were mapped using high-resolution sidescansonar, bathyme??trie, and seismic-reflection surveying techniques, a suite of over 200 diver vibracores, and extensive seafloor observations by divers. The inner shelf is a sediment-starved, active surface of marine erosion; modern sediments, where present, form a patchy veneer over Tertiary and Quaternary units. The lithology of the underlying units exerts a primary control on the distribution, texture, and composition of surficial sediments, as well as inner-shelf bathymetry. The shoreface is dominated by a linear, cross-shore morphology of rippled scour depressions (RSDs) extending from just seaward of the surf zone onto the inner shelf. On the upper shoreface, the RSDs are incised up to l m below surrounding areas of fine sand, and have an asymmetric cross section that is steeper-sided to the north. On the inner shelf, the RSDs have a similar but more subdued cross-sectional profile. The depressions are floored primarily by shell hash and quartz gravel. Vibracore data show a thick (up to 1.5 m) sequence of RSD sediments that unconformably overlies ancient coastal lithosomes. In this sediment-starved inner shelf setting, rippled scour depressions probably form initially on preexisting coarse-sediment substrates such as modern lag deposits of paleofluvial channel lithosomes or ancient tidal inlet thalwegs. Interannual observations of seafloor morphologic change and the longer-term record contained in vibracores suggest that the present seafloor morphology is either relatively stable or represents a recurring, preferential morphologic state to which the seafloor returns after storm-induced perturbations. The apparent stability is interpreted to be the result of interactions at several scales that contribute to a repeating, self-reinforcing pattern of forcing and sedimentary response which ultimately causes the RSDs to be maintained as sediment-starved bedforms responding to both along-shore and acrossshore flows. Sediment accumulation from over 30 years of extensive beach nourishment at Wrightsville Beach appears to have exceeded the local shoreface accommodation space, resulting in the "leaking" of beach and shoreface sediment to the inner shelf. A macroscopically identifiable beach nourishment sediment on the shoreface and inner shelf was used to identify the decadal-scale pattern of sediment dispersal. The nourishment sediment is present in a seaward-thinning wedge that extends from the beach over a kilometer onto the inner shelf to waters depths of 14 m. This wedge is best developed offshore of the shoreline segment that has received the greatest volume of beach nourishment. 

Occurrence and behavior of butyltins in intertidal and shallow subtidal surface sediments of an estuarine beach under different sampling conditions

NASA Astrophysics Data System (ADS)

Santos, Dayana Moscardi dos; Sant'Anna, Bruno Sampaio; Sandron, Daniela Corsino; Cardoso de Souza, Sara; Cristale, Joyce; Marchi, Mary Rosa Rodrigues de; Turra, Alexander

2010-07-01

Contamination by butyltin compounds (BTs) has been reported in estuarine environments worldwide, with serious impacts on the biota of these areas. Considering that BTs can be degraded by varying environmental conditions such as incident light and salinity, the short-term variations in such factors may lead to inaccurate estimates of BTs concentrations in nature. Therefore, the present study aimed to evaluate the possibility that measurements of BTs in estuarine sediments are influenced by different sampling conditions, including period of the day (day or night), tidal zone (intertidal or subtidal), and tides (high or low). The study area is located on the Brazilian southeastern coast, São Vicente Estuary, at Pescadores Beach, where BT contamination was previously detected. Three replicate samples of surface sediment were collected randomly in each combination of period of the day, tidal zone, and tide condition, from three subareas along the beach, totaling 72 samples. BTs were analyzed by GC-PFPD using a tin filter and a VF-5 column, by means of a validated method. The concentrations of tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) ranged from undetectable to 161 ng Sn g -1 (d.w.). In most samples (71%), only MBT was quantifiable, whereas TBTs were measured in only 14, suggesting either an old contamination or rapid degradation processes. DBT was found in 27 samples, but could be quantified in only one. MBT concentrations did not differ significantly with time of day, zones, or tide conditions. DBT and TBT could not be compared under all these environmental conditions, because only a few samples were above the quantification limit. Pooled samples of TBT did not reveal any difference between day and night. These results indicated that, in assessing contamination by butyltin compounds, surface-sediment samples can be collected in any environmental conditions. However, the wide variation of BTs concentrations in the study area, i.e., over a very small geographic scale, illustrates the need for representative hierarchical and composite sampling designs that are compatible with the multiscalar temporal and spatial variability common to most marine systems. The use of such sampling designs will be necessary for future attempts to quantitatively evaluate and monitor the occurrence and impact of these compounds in nature.

The persistence and character of stranded oil on coarse-sediment beaches.

PubMed

Owens, Edward H; Taylor, Elliott; Humphrey, Blair

2008-01-01

Small amounts of oil that can persist for decades in the intertidal zone of coarse-sediment beaches have been documented in a few well-studied cases. Oil that survives attenuation over the short-term (weeks to months) will persist until there is a change in the environmental conditions, as might occur where there is a seasonal storm-wave climate or as a beach undergoes long-term (erosional) changes. Oil residues can persist on the beach surface as tar mats, asphalt-like pavements, or as veneers on sediment particles or hard surfaces. Subsurface oil residues can persist in similar forms or as fill or partial fill of the pore spaces between coarse-sediment particles. Oil penetrates until it reaches fine-grained sediment, the water table, bedrock, or other penetration-limiting layers. Amounts of persistent oil are very small fractions of the volumes that were originally stranded and these protected residues can continue to biodegrade as they become thinner and more discontinuous.

Near-edge wrack effects on bare sediments: Small scale variation matters in the monitoring of sandy beaches.

PubMed

MacMillan, Mitchell R; Tummon Flynn, Paula; Duarte, Cristian; Quijón, Pedro A

2016-12-01

The influence of wrack on sandy beach communities is well-documented but its effect on bare sediments located immediately beyond its edge has not yet been tested. This study aimed to explore these effects by surveying bare sediments located at increasing distances (0.5-2 m) from the wrack in five sandy beaches on Prince Edward Island, Atlantic Canada. In addition, we tested the influence of wrack with a field manipulation using wrack patches made up of rockweed bundles. The survey indicated that a modest but significant number of amphipods and beetles occupied bare sediments located 0.5 m from the edge of the wrack, but that those numbers dropped in sediments 1 m away and farther. The outcome of the field manipulation showed a similar pattern. Although small in spatial scale, our results have implications for the monitoring sandy beaches affected by scattered as well as heavy wrack input. Copyright © 2016 Elsevier Ltd. All rights reserved.

Estimating juvenile Chinook salmon (Oncorhynchus tshawytscha) abundance from beach seine data collected in the Sacramento–San Joaquin Delta and San Francisco Bay, California

USGS Publications Warehouse

Perry, Russell W.; Kirsch, Joseph E.; Hendrix, A. Noble

2016-06-17

Resource managers rely on abundance or density metrics derived from beach seine surveys to make vital decisions that affect fish population dynamics and assemblage structure. However, abundance and density metrics may be biased by imperfect capture and lack of geographic closure during sampling. Currently, there is considerable uncertainty about the capture efficiency of juvenile Chinook salmon (Oncorhynchus tshawytscha) by beach seines. Heterogeneity in capture can occur through unrealistic assumptions of closure and from variation in the probability of capture caused by environmental conditions. We evaluated the assumptions of closure and the influence of environmental conditions on capture efficiency and abundance estimates of Chinook salmon from beach seining within the Sacramento–San Joaquin Delta and the San Francisco Bay. Beach seine capture efficiency was measured using a stratified random sampling design combined with open and closed replicate depletion sampling. A total of 56 samples were collected during the spring of 2014. To assess variability in capture probability and the absolute abundance of juvenile Chinook salmon, beach seine capture efficiency data were fitted to the paired depletion design using modified N-mixture models. These models allowed us to explicitly test the closure assumption and estimate environmental effects on the probability of capture. We determined that our updated method allowing for lack of closure between depletion samples drastically outperformed traditional data analysis that assumes closure among replicate samples. The best-fit model (lowest-valued Akaike Information Criterion model) included the probability of fish being available for capture (relaxed closure assumption), capture probability modeled as a function of water velocity and percent coverage of fine sediment, and abundance modeled as a function of sample area, temperature, and water velocity. Given that beach seining is a ubiquitous sampling technique for many species, our improved sampling design and analysis could provide significant improvements in density and abundance estimation.

Modern sedimentary facies, depositional environments, and major controlling processes on an arid siliciclastic coast, Al qahmah, SE Red Sea, Saudi Arabia

NASA Astrophysics Data System (ADS)

Nabhan, Abdullah I.; Yang, Wan

2018-04-01

The facies and environments along the arid siliciclastic coast of Red Sea in Al Qahmah, Saudi Arabia are studied to establish a depositional model for interpretation of ancient rocks deposited in rift settings. Field and petrographic studies of 151 sediment samples in an area of 20 km2 define seven main facies types: beach, washover fan, tidal channel, dune, sabkha, delta, and wadi (seasonal stream). The wadi and delta facies are composed of poorly to moderately well-sorted, gravelly, medium-to-fine sands. Delta-front sands are redistributed by southward longshore currents to form a beach. Beach facies is composed of well-to-moderately sorted fine sands with minor gravels, which contain high concentrations of magnetite, ilmenite, garnet, pyroxene, amphibole, epidote, titanite, and apatite grains, indicating strong winnowing. Crabs and other burrowers destroy primary sedimentary structures and mix sediments in foreshore and backshore of the beaches. Wind and storm surge rework foreshore and backshore sediments to form washover fans. Sabkha facies occurs extensively in supratidal depressions behind beach, are flooded by rainstorms and spring tide, and capped by a 5-cm-thick crust composed of interlaminated halite, quartz, albite, minor gypsum and biotite, and rarely calcium carbonate. Halite occurs as thin sheets and gypsum as nodules with a chicken-wire structure. Clastic fraction in sabkha sediments ranges from coarse silt to coarse sand with moderate sorting, and is transported by currents and wind. Tidal inlets and tidal creeks assume abandoned wadis and are filled by muddy sand. Sand dunes and sand sheets are 1-7 m high and widely distributed due to variable wind directions. Fine-grained dune sands are moderately well sorted, whereas sheet sands are coarser and poorly sorted due to vegetation baffling. Most eolian sands are sourced from beach deposits. This suite of complex riverine, wave, tidal, wind, chemical, and biological processes form the facies mosaic along the arid Al Qahmah coast, which is strongly affected by climate-driven evaporation and wind action.

Complex, Dynamic Combination of Physical, Chemical and Nutritional Variables Controls Spatio-Temporal Variation of Sandy Beach Community Structure

PubMed Central

Ortega Cisneros, Kelly; Smit, Albertus J.; Laudien, Jürgen; Schoeman, David S.

2011-01-01

Sandy beach ecological theory states that physical features of the beach control macrobenthic community structure on all but the most dissipative beaches. However, few studies have simultaneously evaluated the relative importance of physical, chemical and biological factors as potential explanatory variables for meso-scale spatio-temporal patterns of intertidal community structure in these systems. Here, we investigate macroinfaunal community structure of a micro-tidal sandy beach that is located on an oligotrophic subtropical coast and is influenced by seasonal estuarine input. We repeatedly sampled biological and environmental variables at a series of beach transects arranged at increasing distances from the estuary mouth. Sampling took place over a period of five months, corresponding with the transition between the dry and wet season. This allowed assessment of biological-physical relationships across chemical and nutritional gradients associated with a range of estuarine inputs. Physical, chemical, and biological response variables, as well as measures of community structure, showed significant spatio-temporal patterns. In general, bivariate relationships between biological and environmental variables were rare and weak. However, multivariate correlation approaches identified a variety of environmental variables (i.e., sampling session, the C∶N ratio of particulate organic matter, dissolved inorganic nutrient concentrations, various size fractions of photopigment concentrations, salinity and, to a lesser extent, beach width and sediment kurtosis) that either alone or combined provided significant explanatory power for spatio-temporal patterns of macroinfaunal community structure. Overall, these results showed that the macrobenthic community on Mtunzini Beach was not structured primarily by physical factors, but instead by a complex and dynamic blend of nutritional, chemical and physical drivers. This emphasises the need to recognise ocean-exposed sandy beaches as functional ecosystems in their own right. PMID:21858213

Complex, dynamic combination of physical, chemical and nutritional variables controls spatio-temporal variation of sandy beach community structure.

PubMed

Ortega Cisneros, Kelly; Smit, Albertus J; Laudien, Jürgen; Schoeman, David S

2011-01-01

Sandy beach ecological theory states that physical features of the beach control macrobenthic community structure on all but the most dissipative beaches. However, few studies have simultaneously evaluated the relative importance of physical, chemical and biological factors as potential explanatory variables for meso-scale spatio-temporal patterns of intertidal community structure in these systems. Here, we investigate macroinfaunal community structure of a micro-tidal sandy beach that is located on an oligotrophic subtropical coast and is influenced by seasonal estuarine input. We repeatedly sampled biological and environmental variables at a series of beach transects arranged at increasing distances from the estuary mouth. Sampling took place over a period of five months, corresponding with the transition between the dry and wet season. This allowed assessment of biological-physical relationships across chemical and nutritional gradients associated with a range of estuarine inputs. Physical, chemical, and biological response variables, as well as measures of community structure, showed significant spatio-temporal patterns. In general, bivariate relationships between biological and environmental variables were rare and weak. However, multivariate correlation approaches identified a variety of environmental variables (i.e., sampling session, the C∶N ratio of particulate organic matter, dissolved inorganic nutrient concentrations, various size fractions of photopigment concentrations, salinity and, to a lesser extent, beach width and sediment kurtosis) that either alone or combined provided significant explanatory power for spatio-temporal patterns of macroinfaunal community structure. Overall, these results showed that the macrobenthic community on Mtunzini Beach was not structured primarily by physical factors, but instead by a complex and dynamic blend of nutritional, chemical and physical drivers. This emphasises the need to recognise ocean-exposed sandy beaches as functional ecosystems in their own right.

Beach cusp destruction, formation, and evolution during and subsequent to an extratropical storm, Duck, North Carolina

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, J.R.; Miller, S.M.O.; Torzynski, C.A.

Many studies have debated whether beach cusps are erosional or depositional features. The April 12-14, 1988, extratropical storm provided an opportunity to view the direct effects of one of the largest storms of the past decade upon beach sedimentology and morphology on barrier islands near Duck, North Carolina. Prior to the storm, the beach at Duck was characterized by a well-defined pattern of beach cusps with horn-to-horn spacings averaging 35 m. Storm-induced alterations were dominated by an initial period of beach erosion that remobilized the upper 30 to 50 cm of beach sediment, followed by aggradation. Net aggradation was mostmore » prominent along the middle beachface and within the pre-storm cusp bays. These morphologic adjustments resulted in the destruction of cusps, which were replaced with a post-storm planar beachface composed of horizontally bedded fine- to coarse-grained sediments. Within 24 hrs of storm subsidence, new beach cusps formed sequentially along the coast in the direction of longshore transport. Initial cusp formation resulted from beach erosion and the creation of bays in the planar storm-beach surface at positions of preferential post-storm runup. The initial cusp horns were composed of truncated horizontal beds of the planar beach accreted during the storm. After their formation, the cusps sequentially migrated downdrift. Migrating horns were composed of a coarse-grained sediment wedge that thickened toward horn crests, suggesting formation by deposition. It is concluded from these observations that beach cusps are both erosional and depositional in nature.« less

Analyze of waves dynamic over an intertidal mudflat of a sandy-gravely estuarine beach - Field survey and preliminary modeling approach

NASA Astrophysics Data System (ADS)

Morio, Olivier; Sedrati, Mouncef; Goubert, Evelyne

2014-05-01

As well as marine submersion or erosive phenomena, clay-silted sediment in-filling on estuarial and bay beaches are a main issue in these human-attractive areas. Coupled sandy/gravely and clay/silty intertidal areas can be observed in these particular coastal areas, depending of rivers characteristic (discharge of particle, water flow), ocean dynamics (wave exposure, current) and sediments sources. All around the world, sandy/gravely beaches are exposed to punctual or continuous input clay sediments. Vilaine estuary, Bay of Arcachon and Bay of Seine in France, Plymouth Bay in UK and also Wadden Sea in Deutschland are few examples of muddy/sandy coupled or mixed system. The beach of Bétahon (Ambon town, Brittany - France) is located on the external Vilaine estuary and is an example of this issue. This meso-macrotidal intermediate (low tide terrace) beach presents heterogeneous sediments. The upper intertidal zone is composed by sand and gravel and characterized by a steep slope. A very gentle slope characterized the lower part of the beach and is constituted by silt and clay. Clay/sand limit is characterized by a decimetric erosion cliff of mudflat along the beach. In order to understand bed variations and sediment transport of this complex heterogeneous beach, a well understanding of wave dynamic across the beach is necessary. This study focus on wave dynamics over the beach, using field observations and MIKE 21 3D wave numerical model. This paper is a preliminary approach of an upcoming global understanding of this estuarial beach behavior. Swell from deep-sea to near-shore area is modeled over a 100 km² area and real wind, deep sea wave characteristic, river water flow and tidal level are defined as open boundary conditions for the regional model. This last one is based on multiple bathymetric surveys over the last 50 years. Local model, triangular mesh gridded to 5 meters, covering Bétahon beach , is based on topographic and photographic survey of the mudflat since 2005 (an amplitude above 1.4 meters has been observed over a start reference state). Modeling significant wave height, wave direction and period are compared to a cross-shore wave dynamics survey over the beach, during one week. Surf zone positions over the beach, wave characteristics at local and regional scales, impacts of mudflat altitude on waves are analyzed and discussed.

Use of slow-release fertilizer and biopolymers for stimulating hydrocarbon biodegradation in oil-contaminated beach sediments.

PubMed

Xu, Ran; Yong, Li Ching; Lim, Yong Giak; Obbard, Jeffrey Philip

2005-01-01

Nutrient concentration and hydrocarbon bioavailability are key factors affecting biodegradation rates of oil in contaminated beach sediments. The effect of a slow-release fertilizer, Osmocote, as well as two biopolymers, chitin and chitosan, on the bioremediation of oil-spiked beach sediments was investigated using an open irrigation system over a 56-day period under laboratory conditions. Osmocote was effective in sustaining a high level of nutrients in leached sediments, as well as elevated levels of microbial activity and rates of hydrocarbon biodegradation. Chitin was more biodegradable than chitosan and gradually released nitrogen into the sediment. The addition of chitin or chitosan to the Osmocote amended sediments enhanced biodegradation rates of the alkanes relative to the presence of Osmocote alone, where chitosan was more effective than chitin due to its greater oil sorption capacity. Furthermore, chitosan significantly enhanced the biodegradation rates of all target polycyclic aromatic hydrocarbons.

Seasonal movement change of sediments using RFID tracer monitoring in composite gravel beach, west coast of Korea

NASA Astrophysics Data System (ADS)

Han, M.; Yu, J.; Yang, D. Y.; Kim, J. W.

2017-12-01

The purpose of this study is to investigate seasonal movement patterns of gravel movements on the west coast of Korean peninsula. This study aims improve understanding of the process of coastal sediments movement and contribute to coastal erosion management. The study site is Taean Bangpo Beach, which is characterized by its macro tide and composite gravel beach (CGB). In this study, we carried out a radio frequency identifier (RFID) tracer movement monitoring experiment. Four hundred tracers, similar in size and shape to beach sediment, were inserted into the beach in February and December 2015. From the results, it was confirmed that generally, gravel moved southward in the winter and northward in the summer. It was also confirmed that the gravel moved long distances in the summer and winter, but much shorter distances in the spring. At the end of the results, it is confirmed that the tracer recovery rate in summer is lower than in winter. Bangpo Beach was influenced by strong wind and wave energy driven by the East Asian winter monsoon, and by normal tidal energy during the other seasons. It means that seasonal variation of gravel movement in the beach is attributed to the difference of seasonal energy conditions. In addition, it is interpreted that the sand at the intertidal zone cannot be removed in the summer when the wave energy is weak, causing the tracer to be buried. This study is expected to contribute to the study of composite gravel beach and coastal coarse sediment movement which have been lacking in research.

Post-tsunami beach recovery in Thailand: A case for punctuated equilibrium in coastal dynamics

NASA Astrophysics Data System (ADS)

Switzer, Adam D.; Gouramanis, Chris; Bristow, Charles; Yeo, Jeffrey; Kruawun, Jankaew; Rubin, Charles; Sin Lee, Ying; Tien Dat, Pham

2017-04-01

A morpho-geophysical investigation of two beaches in Thailand over the last decade shows that they have completely recovered from the 2004 Indian Ocean tsunami (IOT) without any human intervention. Although the beach systems show contrasting styles of recovery in both cases natural processes have reconstructed the beaches to comparable pre-tsunami morphologies in under a decade, demonstrating the existence of punctuated equilibrium in coastal systems and the resilience of natural systems to catastrophic events. Through a combination of remote sensing, field surveys and shallow geophysics we reconstruct the post-event recovery of beaches at Phra Thong Island, a remote, near pristine site that was severely impacted by the IOT. We identify periods of aggradation, progradation and washover sedimentation that match with local events including a storm in November 2007. The rapid recovery of these systems implies that majority of sediment scoured by the tsunami was not transported far offshore but remained in the littoral zone within reach of fair-weather waves that returned it (the sediment) to the beach naturally.

Seismic scattering attribute for sedimentary classification of nearshore marine quarries for a major beach nourishment project: Case study of Adriatic coastline, Regione Abruzzo (Italy)

NASA Astrophysics Data System (ADS)

Orlando, Luciana; Contini, Paolo; De Girolamo, Paolo

2017-06-01

Of fundamental importance for any major beach nourishment project using marine quarries is a correct sedimentary classification. The main purpose of such a classification is to identify sand with the appropriate features for beach nourishment. This task is more onerous when quarry sediments are heterogeneous and mixed with silt. This is typical of nearshore marine quarries. The presence of excess silt compromises the use of marine quarries because of the water turbidity that may be induced in the nourished beaches, especially when the beaches are protected by defense structures. Here we discuss the use of scattering amplitude of seismic data, acquired with a pinger source (2-10 kHz), to detect and classify the unconsolidated sediment of a marine quarry. A robust correlation was found between this seismic attribute and the silt content in the sediment. The scattering amplitude was numerically calculated from the seismic data and used to map slices of silt content at different depths. The results have been validated with sedimentary analysis of vibra- and rotary cores, and by the dredged material used for the beach nourishment. The marine quarry produced about 1.200.000 m3 of sand used to nourish eight different beach sites along the Adriatic coasts of the Regione Abruzzo (Italy). The large-scale sedimentary assessment of the area was based on seismic boomer data and the evaluation of the volume of dredged sediments on multibeam data surveyed before and after the exploitation of the quarry. The study shows that this approach is effective in sites with high lateral and vertical variations in the percentage of sand in the sediments.

Combining remote sensing with an inverse Bruun Rule for the analysis and management of almost equilibrium beaches

NASA Astrophysics Data System (ADS)

Eelsalu, Maris; Soomere, Tarmo; Männikus, Rain

2016-04-01

The management of beaches that suffer from sediment deficit and construction of nearshore infrastructure in locations with intense sediment transit require adequate predictions of the future of the relevant sedimentary systems. To a large extent, this task can be accomplished by using jointly the information about sediment texture and long-term changes in the dry beach volume and the location of the waterline. It is straightforward to evaluate relative changes in the dry beach volume from a succession of airborne laser scanning (ALS) surveys. We use in addition terrestrial laser scanning (TLS) technique to reduce ALS surveys performed with different devices and from different height to the same absolute height. This is accomplished using a TLS survey of a large horizontal surface of constant elevation within ALS snapshots. The most complicated, time-consuming and expensive task in beach management and planning of nearshore infrastructure is to get an adequate picture of the intensity and direction of underwater sediment transport processes. We demonstrate how a simple application of so-called inverse Bruun Rule makes it possible to evaluate the underwater volumetric changes for almost equilibrium beaches. The approach requires three data sets: wave statistics, sediment texture and changes in the average position of the waterline. The main properties of the wave climate, closure depths, magnitude and direction of wave-driven alongshore transport near the test areas are established using a triple nested high-resolution version of the wave model WAM that is forced for 34 years by high-quality marine winds. The relocation of the waterline is extracted from the ALS scanning of elevation isolines of 0.4-0.7 m on the subaerial beach. The technique has been applied to two basically different sections of Tallinn Bay, the Baltic Sea. Pirita Beach is gradually losing sand and requires beach refill while a moderate reclamation action is planned in the vicinity of gradually widening beach in the bayhead of this bay (Russalka beach). Sand volume in the latter area exhibits extensive interannual variations. The changes in the subaerial and underwater part are synchronised whereas the magnitude of changes in the underwater part is by a factor of 2-2.5 larger than similar changes in the subaerial part (that gains about 2000 m3/yr sand in 2008-2014). The discussed technique combined with classic estimates of the wave-driven sediment transport direction demonstrates that the Russalka beach is a convergence area of littoral flow. The existing pattern of sediment motions is such that even a minor shift in the coastline may lead to considerable increase in the transport of sand to neighbouring coastal sections. This conjecture is consistent with the general perception in coastal science that even seemingly small activities may have unexpectedly large potential for remote impacts. Such impacts are well known on high-energy open sea coasts but often considered as minor in relatively sheltered locations.

Sediment Engineering thru Dredging and with Nature (SETDWN) - Fate of Fines in the Dredging and Placement Process

DTIC Science & Technology

2015-05-15

operations and beach construction perspective, material is lost and a significant percent of fines is winnowed during the dredging and placement...discharged at the beach weather it is from a hopper pumpout, cuttersuction, or hydraulic offloader; experiences similar winnowing processes. The beach...of compliance with in situ percent fines criteria. This same process can be employed for the winnowing of other constituents in mixed sediments as

Mercury distribution in ancient and modern sediments of northeastern Bering Sea

USGS Publications Warehouse

Nelson, C. Hans; Pierce, D.E.; Leong, K.W.; Wang, F.F.

1972-01-01

A reconnaissance of surface and subsurface sediments to a maximum depth of 244 feet below the sea floor shows that natural mercury anomalies from 0.2 to 1.3 ppm have been present in northeastern Bering Sea since early Pliocene. The anomalies and mean values are highest in modern beach (maximum 1.3 and mean 0.22 ppm Hg) and nearshore subsurface gravels (maximum 0.6 and mean .06 ppm Hg) along the highly mineralized Seward Peninsula and in organic rich silt (maximum 0.16 and mean 0.10 ppm Hg) throughout the region; the mean values are lowest in offshore sands (0.03 ppm Hg) . Although gold mining may be partially responsible for high mercury levels in the beaches near Nome, Alaska, equally high or greater concentrations of mercury occur in ancient glacial sediments immediately offshore (0.6 ppm) and in modern unpolluted beach sediments at Bluff (0.45 - 1.3 ppm); this indicates that the contamination effects of mining may be no greater than natural concentration processes in the Seward Peninsula region. The background content of mercury (0.03) throughout the central area of northeastern Bering Sea is similar to that elsewhere in the world. The low mean values (0.04 ppm) even immediately offshore from mercury-rich beaches, suggests that in the surface sediments of northeastern Bering Sea, the highest concentrations are limited to the beaches near mercury sources; occasionally, however, low mercury anomalies occur offshore in glacial drift derived from mercury source regions of Chukotka and Seward Peninsula and reworked by Pleistocene shoreline processes. The minimal values offshore may be attributable to beach entrapment of heavy minerals containing mercury and/or dilution effects of modern sedimentation.

Microplastics in coastal environments of the Arabian Gulf.

PubMed

Abayomi, Oyebamiji Abib; Range, Pedro; Al-Ghouti, Mohammad A; Obbard, Jeffrey Philip; Almeer, Saeed Hashim; Ben-Hamadou, Radhouane

2017-11-15

Eight sandy beaches along the coastline of Qatar and four sea surface stations on the eastern coast, adjacent to Doha Bay, were surveyed between December 2014 and March 2015. Microplastics, mainly low density polyethylene and polypropylene, were found in all samples of sediments and seawater. Blue fibers, ranging between 1 and 5mm, were the dominant type of particle present. Abundances on the sea surface varied between 4.38×10 4 and 1.46×10 6 particles·km -2 , with the highest values being consistently found 10km offshore, suggesting the presence of a convergence zone. No significant temporal variability was detected for sea surface samples. The concentration of microplastics in intertidal sediments varied between 36 and 228particlesm -2 , with no significant differences among the 8 beaches examined. These results show the pervasiveness of microplastic pollution in coastal environments of the Arabian Gulf. Potential local sources and sinks for microplastics are discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of nutrient amendments on indigenous hydrocarbon biodegradation in oil-contaminated beach sediments.

PubMed

Xu, Ran; Obbard, Jeffrey P

2003-01-01

Nutrient amendment to oil-contaminated beach sediments is a critical factor for the enhancement of indigenous microbial activity and biodegradation of petroleum hydrocarbons in the intertidal marine environment. In this study, we investigated the stimulatory effect of the slow-release fertilizers Osmocote (Os; Scotts, Marysville, OH) and Inipol EAP-22 (Ip; ATOFINA Chemicals, Philadelphia, PA) combined with inorganic nutrients on the bioremediation of oil-spiked beach sediments using an open irrigation system with artificial seawater over a 45-d period. Osmocote is comprised of a semipermeable membrane surrounding water-soluble inorganic N, P, and K. Inipol, which contains organic N and P, has been used for oil cleanup on beach substrate. Nutrient concentrations and microbial activity in sediments were monitored by analyzing sediment leachates and metabolic dehydrogenase activity of the microbial biomass, respectively. Loss of aliphatics (n-C12 to n-C33, pristane, and phytane) was significantly greater (total loss between 95 and 97%) in oil-spiked sediments treated with Os alone or in combination with other nutrient amendments, compared with an unamended oil-spiked control (26% loss) or sediments treated with the other nutrient amendments (28-65% loss). A combination of Os and soluble nutrients (SN) was favorable for the rapid metabolic stimulation of the indigenous microbial biomass, the sustained release of nutrients, and the enhanced biodegradation of petroleum hydrocarbons in leached, oil-contaminated sediments.

Marine macrophytes directly enhance abundances of sandy beach fauna through provision of food and habitat

NASA Astrophysics Data System (ADS)

Ince, Rebecca; Hyndes, Glenn A.; Lavery, Paul S.; Vanderklift, Mathew A.

2007-08-01

Beach-cast wrack is a prominent feature of beaches of south-western Australia. We examined the fauna of these beaches to explore the generalisation [Polis, G.A., Hurd, S.D., 1995. Extraordinarily high spider densities on islands: flow of energy from the marine to terrestrial food webs and the absence of predation. Ecology 92, 4382-4386] that beach-cast wrack from highly productive marine ecosystems subsidises low productivity of terrestrial ecosystems, to establish whether this generalisation is relevant to oligotrophic marine systems. We sampled three beaches with high and three beaches with low volumes of beach-cast wrack to determine if: (1) the presence of wrack influences the abundance of macroinvertebrates; (2) wrack acts as a food source for beach macroinvertebrates; and (3) the influence of wrack varies between zones above the high water mark. We measured wrack volume and composition, sediment characteristics, the abundance of different epibenthic and infaunal macroinvertebrates taxa, and δ13C and δ15N of macrophytes and macroinvertebrates. The mean volume of wrack on high-wrack beaches was 0.27-1.07 m 3 wrack m -2 compared to 0.00-0.09 m 3 wrack m -2 on low-wrack beaches. There were no significant differences in sediment grain size, moisture content or loss on ignition between the two types of beaches or zones. Epibenthic fauna and infauna were consistently abundant on high-wrack beaches (20-291 and 0.5-3.5 individuals 0.64 m -2, respectively), but either absent or extremely rare in low-wrack beaches (0-3 and 0-0.1 individuals 0.64 m -2, respectively). Within high-wrack beaches, there were no significant differences in the abundance of epifauna or infauna among beaches or between zones. The δ13C values of macroinvertebrates at all sites were most similar to red and brown algae, with the exception of beetles from two beaches, which were closest to seagrasses. Mixing model (Isosource) results for mesograzing amphipods and dipteran flies suggested carbon was assimilated mostly from the seagrass Posidonia spp., the dune grass Spinifex longifolia and red algae for amphipods and from brown algae, red algae and dune vegetation for dipteran flies. We conclude that the presence of marine-derived wrack plays a major role in subsidising production of macroinvertebrates on beaches of south-western Australia. We suggest that marine subsidies can play a role in supporting terrestrial production, even in oligotrophic marine environments.

Microplastic concentrations in beach sediments along the German Baltic coast.

PubMed

Stolte, Andrea; Forster, Stefan; Gerdts, Gunnar; Schubert, Hendrik

2015-10-15

The contamination with microplastic particles and fibres was evaluated on beaches along the German Baltic coast. Sediments were sampled near the Warnow and Oder/Peene estuaries, on Rügen island and along the Rostock coast to derive possible entry pathways. Seasonal variations were monitored along the Rostock coast from March to July 2014. After density separation in saline solution, floating particles were found to be dominated by sand grains. Water surface tension is shown to be sufficient to explain floatation of grains with sizes less than 1.5mm. Selecting intensely coloured particles and fibres, we find lower limits of the microplastic concentrations of 0-7 particles/kg and 2-11 fibres/kg dry sediment. The largest microplastic contaminations are measured at the Peene outlet into the Baltic Sea and in the North Sea Jade Bay. City discharges, industrial production sites, fishing activity and tourism are the most likely sources for the highest microplastic concentrations. Copyright © 2015 Elsevier Ltd. All rights reserved.

Revealing accumulation zones of plastic pellets in sandy beaches.

PubMed

Moreira, Fabiana T; Balthazar-Silva, Danilo; Barbosa, Lucas; Turra, Alexander

2016-11-01

Microplastics such as pellets are reported worldwide on sandy beaches, and have possible direct and indirect impacts on the biota and physical characteristics of the habitats where they accumulate. Evaluations of their standing stock at different spatial scales generate data on levels of contamination. This information is needed to identify accumulation zones and the specific beach habitats and communities that are likely to be most affected. Standing stocks of plastic pellets were evaluated in 13 sandy beaches in São Paulo state, Brazil. The sampling strategy incorporated across-shore transects from coastal dunes and backshores, and vertical profiles of the accumulated pellets down to 1 m depth below the sediment surface. Accumulation zones were identified at regional (among beaches) and local (between compartments) scales. At the regional scale pellet density tended to increase at beaches on the central and southwestern coast, near ports and factories that produce and transport the largest amounts of pellets in the country. At the local scale coastal dunes showed larger accumulations of pellets than backshores. For both compartments pellets tended to occur deeper in areas where standing stocks were larger. Most of the pellets were concentrated from the surface down to 0.4 m depth, suggesting that organisms inhabiting this part of the sediment column are more exposed to the risks associated with the presence of pellets. Our findings shed light on the local and regional scales of spatial variability of microplastics and their consequences for assessment and monitoring schemes in coastal compartments. Copyright © 2016. Published by Elsevier Ltd.

Microplastic fibers in the intertidal ecosystem surrounding Halifax Harbor, Nova Scotia.

PubMed

Mathalon, Alysse; Hill, Paul

2014-04-15

Humans continue to increase the use and disposal of plastics by producing over 240 million tonnes per year, polluting the oceans with persistent waste. The majority of plastic in the oceans are microplastics (<5 mm). In this study, the contamination of microplastic fibers was quantified in sediments from the intertidal zones of one exposed beach and two protected beaches along Nova Scotia's Eastern Shore. From the two protected beaches, polychaete worm fecal casts and live blue mussels (Mytilus edulis) were analyzed for microplastic content. Store-bought mussels from an aquaculture site were also analyzed. The average microplastic abundance observed from 10 g sediment subsamples was between 20 and 80 fibers, with higher concentrations at the high tide line from the exposed beach and at the low tide line from the protected beaches. Microplastic concentrations from polychaete fecal casts resembled concentrations quantified from low tide sediments. In two separate mussel analyses, significantly more microplastics were enumerated in farmed mussels compared to wild ones. Copyright © 2014 Elsevier Ltd. All rights reserved.

Simulation of shoreline development in a groyne system, with a case study Sanur Bali beach

NASA Astrophysics Data System (ADS)

Gunawan, P. H.; Pudjaprasetya, S. R.

2018-03-01

The process of shoreline changes due to transport of sediment by littoral drift is studied in this paper. Pelnard-Considère is the commonly adopted model. This model is based on the principle of sediment conservation, without diffraction. In this research, we adopt the Pelnard-Considère equation with diffraction, and a numerical scheme based on the finite volume method is implemented. Shoreline development in a groyne system is then simulated. For a case study, the Sanur Bali Beach, Indonesia is considered, in which from Google Earth photos, the beach experiences changes of coastline caused by sediment trapped in a groyne system.

The sediment and hydrographic characteristics of three horseshoe crab nursery beaches in hong kong

NASA Astrophysics Data System (ADS)

Chiu, Helen M. C.; Morton, Brian

2003-04-01

Horseshoe crab juveniles have been recorded from sand and sandy-mud nursery beaches at Pak Nai (western New Territories), San Tau and Shui Hau (Lantau Island), Hong Kong. In order to provide a better understanding of these beaches and to identify those plausible factors which have made them preferred by spawning horseshoe crabs, environmental parameters, including temperature, salinity, pH and dissolved oxygen content of the water, and particle size distribution and organic matter content of the sediments at the three sites, were determined and compared. The hydrographic, and sediment data obtained for the three study sites have revealed some common environmental features. The three nursery beaches are relatively remote, and far (in Hong Kong terms) from urbanized and densely populated areas. The beaches are generally well sheltered from strong wave action and inundated regularly by estuarine waters. Horseshoe crab adults tend to select these beaches for spawning as their protected features ensures the laid eggs are less likely to be washed out of the sand, and hatched juveniles can feed on the meiofauna and grow. Sediments of the three beaches largely comprise medium-sized sand particles and are moderately sorted, suggesting medium porosity and good water permeability. Such a sand type, with the generally high oxygen levels in incursing waters, may help create a well-oxygenated micro-environment for the normal development of horseshoe crab eggs, larvae and juveniles. Lantau Island beaches at San Tau and Shui Hau are relatively free from organic pollution, as reflected in generally high dissolved oxygen level, and low BOD5 and ammonia nitrogen values. Pak Nai is, however, more polluted.

Dune recovery after storm erosion on a high-energy beach: Vougot Beach, Brittany (France)

NASA Astrophysics Data System (ADS)

Suanez, Serge; Cariolet, Jean-Marie; Cancouët, Romain; Ardhuin, Fabrice; Delacourt, Christophe

2012-02-01

On 10th March 2008, the high energy storm Johanna hit the French Atlantic coast, generating severe dune erosion on Vougot Beach (Brittany, France). In this paper, the recovery of the dune of Vougot Beach is analysed through a survey of morphological changes and hydrodynamic conditions. Data collection focused on the period immediately following storm Johanna until July 2010, i.e. over two and a half years. Results showed that the dune retreated by a maximum of almost 6 m where storm surge and wave attack were the most energetic. Dune retreat led to the creation of accommodation space for the storage of sediment by widening and elevating space between the pre- and post-storm dune toe, and reducing impacts of the storm surge. Dune recovery started in the month following the storm event and is still ongoing. It is characterised by the construction of "secondary" embryo dunes, which recovered at an average rate of 4-4.5 cm per month, although average monthly volume changes varied from - 1 to 2 m 3.m - 1 . These embryo dunes accreted due to a large aeolian sand supply from the upper tidal beach to the existing foredune. These dune-construction processes were facilitated by growth of vegetation on low-profile embryo dunes promoting backshore accretion. After more than two years of survey, the sediment budget of the beach/dune system showed that more than 10,000 m 3 has been lost by the upper tidal beach. We suggest that seaward return currents generated during the storm of 10th March 2008 are responsible for offshore sediment transport. Reconstitution of the equilibrium beach profile following the storm event may therefore have generated cross-shore sediment redistribution inducing net erosion in the tidal zone.

Initial Morphologic Evolution of Perdido Key Berm Nourishment, Florida

DTIC Science & Technology

2013-08-01

December 18, 2011). METHODOLOGY : This study is based on beach-nearshore profiles, sediment samples, and wave data collected during the first 6 months...preparation). Vicksburg, MS: US Army Engineering Reserach and Development Center. NOTE: The contents of this technical note are not to be used for

Concepts in gravel beach dynamics

NASA Astrophysics Data System (ADS)

Buscombe, Daniel; Masselink, Gerhard

2006-11-01

The dominant processes in gravel beach dynamics are reviewed, highlighting some common themes which unify the various components of the gravel beach system, the repercussions of which impart on how gravel beach dynamics might be understood conceptually. In particular, gravel beach dynamics are thought to be highly dependent on the temporal and spatial variation in grain size, and the continual adjustments made by an active beach step, both of which act not only as the expression of changing morphodynamic conditions, but also as a controlling influence. Morphodynamics, the notion that the exchanges on beaches between the hydrodynamics, sediment transport, and morphological change takes the form of reciprocal relationships which are mediated through feedback mechanisms (in such a way that they cannot be thought of or studied independently) is not a new one. Yet it appears that for the gravel beach, morphodynamics must be re-defined to describe conditions where variations in sediment size are thought to deserve parity, rather than as merely a sequent entity or boundary condition. 'Morpho-sedimentary-dynamics' is a phrase coined to intuit such cause and effect, detailing the co-evolution of morphology, hydro-hydraulics and sediment properties whilst acknowledging causative pluralism, feedbacks and multiplier effects. This is the recommended conceptual framework within which to crystallise thought and organise further research for the gravel beach. Essentially, it increases the minimum number of parameters needed to describe the state of the gravel beach as a physical system. Therefore, it is advised that simplicity will be most expedient in our future modelling efforts, if complexity is to be adequately encapsulated.

Morphodynamics of a mesotidal rocky beach: Palmeras beach, Gorgona Island National Natural Park, Colombia

NASA Astrophysics Data System (ADS)

Gómez-García, A. M.; Bernal, G. R.; Osorio, A. F.; Botero, V.

2014-10-01

The response of a rocky beach to different possible combinations of hydrodynamic conditions (tides, waves, oceanic currents) has been little studied. In this work, the morphodynamic response to different hydrodynamic forcing is evaluated from sedimentological and geomorphological analysis in seasonal and medium term (19 years) scale in Palmeras beach, located in the southwest of Gorgona Island National Natural Park (NNP), a mesotidal rocky island on the Colombian Pacific continental shelf. Palmeras is an important nesting area of two types of marine turtles, with no anthropogenic stress. In the last years, coastal erosion has reduced the beach width, restricting the safe areas for nesting and conservation of these species. Until now, the sinks, sources, reservoirs, rates, and paths of sediments were unknown, as well as their hydrodynamic forcing. The beach seasonal variability, from October 2010 to August 2012, was analyzed based on biweekly or monthly measurements of five beach profiles distributed every 200 m along the 1.2 km of beach length. The main paths for sediment transport were defined from the modeling of wave currents with the SMC model (Coastal Modeling System), as well as the oceanic currents, simulated for the dry and wet seasons of 2011 using the ELCOM model (Estuary and Lake COmputer Model). Extreme morphologic variations over a time span of 19 years were analyzed with the Hsu and Evans beach static equilibrium parabolic model, from one wave diffraction point which dominates the general beach plan shape. The beach lost 672 m3/m during the measuring period, and erosional processes were intensified during the wet season. The beach trends responded directly to a wave mean energy flux change, resulting in an increase of up to 14 m in the width northward and loss of sediments in the beach southward. This study showed that to obtain the integral morphodynamic behavior of a rocky beach it is necessary to combine information of hydrodynamic, sedimentology and geomorphology in different time scales.

Hazardous radioactivity levels and heavy mineral concentrations in beach sediments of Lake Peipsi, northeastern Estonia

NASA Astrophysics Data System (ADS)

Järvelill, Johanna-Iisebel; Koch, Rein; Raukas, Anto; Vaasma, Tiit

2018-03-01

The present study discusses results of heavy mineral analyses and radioactivity of beach sediments of Lake Peipsi. Such analyses are commonly done globally, but had not yet been conducted for the fourth largest lake in Europe. The average heavy mineral content in Lake Peipsi beach sediments along the northern and western coast is higher than usual for Estonian coastal and Quaternary sediments. Concomitantly, elevated radioactivity levels have been measured in several places, with the highest concentrations observed at Alajõe (1885.5 Bq/kg), which is over five times more than the recommended limit. The aim of the present study is to find sites with higher radioactivity levels, because the northern coast of Lake Peipsi is a well-known recreational area.

Effects of nourishment on the form and function of an estuarine beach

USGS Publications Warehouse

Jackson, N.L.; Nordstrom, K.F.; Saini, S.; Smith, D.R.

2010-01-01

Beach nourishment programs in estuaries can enhance shore protection, but they decrease habitat suitability by creating higher berms and wider backshores than would occur under natural conditions. Use of sediment sources from outside the area can result in sedimentary characteristics that differ from native sediments on the surface and at depth, altering conditions for both aeolian transport to dunes and interstitial fauna. Field data were gathered on an estuarine beach to determine differences in beach profile change, depth of sediment reworking, and potential for aeolian transport due to nourishment. Data were gathered over a 20-month period 6 months prior to nourishment, 3 days after nourishment, 6 months after nourishment, and 14 months after nourishment when the beach was mechanically graded to eliminate a vertical scarp in the foreshore. The nourishment consisted of 87,900m3 of sediment emplaced to create a 1.34-km-long, 30-m-wide berm 2.3m above mean tide level. Seven percent of the fill was removed from the profile within 6 months after nourishment, accompanied by 7m in horizontal retreat of the artificial berm. The fill on the backshore remained above the zone of wave influence over a winter storm season and was separated from the active foreshore by the scarp. Nourished sediments on the intertidal foreshore were significantly different from native sediments to a depth of 0.20m below the surface. A lag surface of coarse sediment formed by deflation on the backshore, resulting in a rate of aeolian transport <2% of the rate on the wave-reworked foreshore.Nourishing a beach to a level higher than would be created by natural processes can create a profile that compartmentalizes and restricts transport of sediment and movement of fauna between the foreshore and backshore. Mechanical grading can eliminate the scarp, allow for faunal interaction, and reestablish wave reworking of the backshore that will facilitate aeolian transport. Using an initial design to nourish the backshore at a lower elevation and allowing a dune to provide protection against flooding during major storms could prevent a scarp from forming and eliminate the need for follow-up grading. ?? 2010 Elsevier B.V.

Factors affecting Escherichia coli concentrations at Lake Erie public bathing beaches

USGS Publications Warehouse

Francy, Donna S.; Darner, Robert A.

1998-01-01

The environmental and water-quality factors that affect concentrations of Escherichia coli (E. coli) in water and sediment were investigated at three public bathing beachesEdgewater Park, Villa Angela, and Sims Parkin the Cleveland, Ohio metropolitan area. This study was done to aid in the determination of safe recreational use and to help water- resource managers assess more quickly and accurately the degradation of recreational water quality. Water and lake-bottom sediments were collected and ancillary environmental data were compiled for 41 days from May through September 1997. Water samples were analyzed for E. coli concentrations, suspended sediment concentrations, and turbidity. Lake- bottom sediment samples from the beach area were analyzed for E. coli concentrations and percent dry weight. Concentrations of E. coli were higher and more variable at Sims Park than at Villa Angela or Edgewater Park; concentrations were lowest at Edgewater Park. Time-series plots showed that short-term storage (less than one week) of E. coli in lake-bottom sediments may have occurred, although no evidence for long-term storage was found during the sampling period. E. coli concentrations in water were found to increase with increasing wave height, but the resuspension of E. coli from lake-bottom sediments by wave action could not be adequately assessed; higherwave heights were often associated with the discharge of sewage containing E. coli during or after a rainfall and wastewater-treatment plant overflow. Multiple linear regression (MLR) was used to develop models to predict recreational water quality at the in water. The related variables included turbidity, antecedent rainfall, antecedent weighted rainfall, volumes of wastewater-treatment plant overflows and metered outfalls (composed of storm-water runoff and combined-sewer overflows), a resuspension index, and wave heights. For the beaches in this study, wind speed, wind direction, water temperature, and the prswimmers were not included in the model because they were shown to be statistically unrelated to E. coli concentrations. From the several models developed, one model was chosen that accounted for 58 percent of the variability in E. coli concentrations. The chosen MLR model contained weighted categorical rainfall, beach-specific turbidity, wave height, and terms to correct for the different magnitudes of E. coli concentrations among the three beaches. For 1997, the MLR model predicted the recreational water quality as well as, and in some cases better than, antecedent E. coli concentrations (the current method). The MLR model improved the sensitivity of the prediction and the percentage of correct predictions over the current method; however, the MLR model predictions still erred to a similar degree as the current method with regard to false negatives. A false negative would allow swimming when, in fact, the bathing water standard was exceeded. More work needs to be done to validate the MLR model with data collected during other recreational seasons, especially during a season with a greater frequency and intensity of summer rains. Studies could focus on adding to the MLR model other environmental and water-quality variables that improve the predictive ability of the model. These variables might include concentrations of E. coli in deeper sediments outside the bathing area, the direction of lake currents, site-specific-rainfall amounts, time-of-day information on overflows and metered outfalls, concentrations of E. coli in treated wastewater-treatment plant effluents, and occurrences of sewage-line breaks. Rapid biological or chemical methods for determination of recreational water quality could also be used as variables in model refinements. Possible methods include the use of experimental rapid assay methods for determination of E. coli concentrations or other fecal indicators and the use of chemical tracers for fecal contamination, such as coprostanol (a degradation

Spatial distributions of biogeochemical reactions in freshwater-saltwater mixing zones of sandy beach aquifers

NASA Astrophysics Data System (ADS)

Kim, K. H.; Michael, H. A.; Ullman, W. J.; Cai, W. J.

2017-12-01

Beach aquifers host biogeochemically dynamic mixing zones between fresh and saline groundwaters of contrasting origins, histories, and compositions. Seawater, driven up the beachface by waves and tides, infiltrates into the sand and meets the seaward-discharging fresh groundwater, creating and maintaining a highly reactive intertidal circulation cell well-defined by salinity. Seawater supplies oxygen and reactive carbon to the circulation cell, supporting biogeochemical reactions within the cell that transform and attenuate dissolved nutrient fluxes from terrestrial sources. We investigated the spatial distribution of chemical reaction zones within the intertidal circulation cell at Cape Shores, Lewes, Delaware. Porewater samples were collected from multi-level wells along a beach-perpendicular transect. Samples were analyzed for particulate carbon and reactive solutes, and incubated to obtain rates of oxic respiration and denitrification. High rates of oxic respiration were observed higher on the beach, in the landward freshwater-saline water mixing zone, where dissolved oxygen availability was high. Denitrification was dominant in lower areas of the beach, below the intertidal discharge point. High respiration rates did not correlate with particulate carbon concentrations entrained within porewater, suggesting that dissolved organic carbon or immobile particulate carbon trapped within the sediment can contribute to and alter bulk reactivity. A better understanding of the sources and sinks of carbon within the beach will improve our ability to predict nutrient fluxes to estuaries and oceans, aiding the management of coastal environments and ecosystems.

Mechanisms controlling the complete accretionary beach state sequence

NASA Astrophysics Data System (ADS)

Dubarbier, Benjamin; Castelle, Bruno; Ruessink, Gerben; Marieu, Vincent

2017-06-01

Accretionary downstate beach sequence is a key element of observed nearshore morphological variability along sandy coasts. We present and analyze the first numerical simulation of such a sequence using a process-based morphodynamic model that solves the coupling between waves, depth-integrated currents, and sediment transport. The simulation evolves from an alongshore uniform barred beach (storm profile) to an almost featureless shore-welded terrace (summer profile) through the highly alongshore variable detached crescentic bar and transverse bar/rip system states. A global analysis of the full sequence allows determining the varying contributions of the different hydro-sedimentary processes. Sediment transport driven by orbital velocity skewness is critical to the overall onshore sandbar migration, while gravitational downslope sediment transport acts as a damping term inhibiting further channel growth enforced by rip flow circulation. Accurate morphological diffusivity and inclusion of orbital velocity skewness opens new perspectives in terms of morphodynamic modeling of real beaches.

Evolution of coastal and marine environments during the Holocene transgression. Ría de Vigo (Galicia, Spain).

NASA Astrophysics Data System (ADS)

Clemente, F.; Pérez-Arlucea, M.; Méndez, G.; Francés, G.; Alejo, I.; González, D.; Nombela, M.

2003-04-01

Coastal deposits are not prominent in the Ria de Vigo, high cliffs dominate the coast line, but several well-preserved sedimentary areas are observed. Beach and aeolian sand dunes are preserved in protected bays along margins between low cliffs, as Playa America, Patos and Samil. Several rivers form prominent estuaries such as the Verdugo-Oitaven, the Minor and the Lagares. Tidal flats are well preserved in the San Simon embayment and small areas of tidal flats and marshes can be found elsewhere associated with estuaries and protected by sandy spits as the Ramallosa tidal Complex, Moaña and San Simón. Four sedimentary areas were selected to study vertical sediment distribution. 6 cores were obtained. Sediment thicknesses range between 4.0m and 26.0 m. Vertical sediment distributions show 6 different lithologic units from basal fluvial (A), estuarine (B), tidal flat and peat fens (C), muddy subtidal bay (D), estuarine (E) and beach barrier (F). 10 14C age determinations were obtained from the longest core (Ladeira N) located at the Ramallosa beach barrier-lagoon complex. The oldest sample located at 22 m yields an age of 8177 y. BP in unit (B) allowing to constrain most of sediment evolution in the holocene transgressive context. The lower unit (A) composed mainly of fluvial gravels, and deposited in a palaeovalley, is attributed to the Younger Dryas although the LST could be also represented in these deposits. Units B, C and D configure the TST showing an initial rapid increase in water depth at 8177 y. BP and subsequent shallowing conditions due to progressive aggradation until 4809 y BP. Units E and F mark the HST eustatic stage being characterised by progradational shallow marine conditions and beach barrier progressive enclosing of the complex. Sedimentation rates were calculated at 7 intervals. An upward decrease is observed from 8177 y BP to 2001 y. BP, followed by a strong sudden increase, mostly in the last 500 years. Hydrology and geomorphology of river catchments were studied to evaluate sediment yields in modern conditions. 19 currents were selected on the basis of having permanent flow during the whole year and a minimum measurable discharge. Results show accelerated erosion and sediment yield which are attributed to anthropogenic causes, chiefly deforestation and soil degradation.

Limited impact of beach nourishment on macrofaunal recruitment/settlement in a site of community interest in coastal area of the Adriatic Sea (Mediterranean Sea).

PubMed

Danovaro, Roberto; Nepote, Ettore; Martire, Marco Lo; Ciotti, Claudia; De Grandis, Gianluca; Corinaldesi, Cinzia; Carugati, Laura; Cerrano, Carlo; Pica, Daniela; Di Camillo, Cristina Gioia; Dell'Anno, Antonio

2018-03-01

Beach nourishment is a widely utilized solution to counteract the erosion of shorelines, and there is an active discussion on its possible consequences on coastal marine assemblages. We investigated the impact caused by a small-scale beach nourishment carried out in the Western Adriatic Sea on macrofaunal recruitment and post-settlement events. Artificial substrates were deployed in proximity of nourished and non-manipulated beaches and turbidity and sedimentation rates were measured. Our results indicate that sedimentation rates in the impacted site showed a different temporal change compared to the control sites, suggesting potential modifications due to the beach nourishment. The impact site was characterized by subtle changes in terms of polychaete abundance and community structure when compared to controls, possibly due to beach nourishment, although the role of other factors cannot be ruled out. We conclude that small-scale beach nourishments appear to be an eco-sustainable approach to contrast coastal erosion. Copyright © 2018. Published by Elsevier Ltd.

Coastal Inlets Research Program

DTIC Science & Technology

2015-02-09

maintenance dredging of 216 million cubic yards from Federal navigation channels. Dredging costs are likely to increase in the future because of...beaches, estuaries, ecosystems and regions. Demand for regional sediment management practices and mitigation for engineering activities includes...innovative creation of nearshore berms with dredged sediment intended as a source to nourish neighboring beaches. Renewable, cost- effective placement

Monitoring and modeling nearshore dredge disposal for indirect beach nourishment, Ocean Beach, San Francisco

USGS Publications Warehouse

Barnard, Patrick L.; Hanes, Daniel M.; Lescinski, Jamie; Elias, Edwin

2007-01-01

Nearshore dredge disposal was performed during the summer of 2005 at Ocean Beach, San Francisco, CA, a high energy tidal and wave environment. This trial run was an attempt to provide a buffer to a reach of coastline where wave attack during the winter months has had a severe impact on existing sewage infrastructure. Although the subsequent beach response was inconclusive, after one year the peak of the disposal mound had migrated ~100 m toward the shore, providing evidence that annual dredge disposal at this site could be beneficial over the long-term by at the very least providing: 1) additional wave dissipation during storms 2) compatible sediment to feed nearshore bars, 3) sediment cover on an exposed sewage outfall pipe, and 4) a viable alternative to the shoaling offshore disposal site. Numerical modeling suggests that despite the strong tidal currents in the region, wave forcing is the dominant factor moving the sediment slowly toward shore, and placing sediment at just slightly shallower depths (e.g. 9 m) in the future would have a more immediate impact.

Synthesis study of an erosion hot spot, Ocean Beach, California

USGS Publications Warehouse

Barnard, Patrick L.; Hansen, Jeff E.; Erikson, Li H.

2012-01-01

A synthesis of multiple coastal morphodynamic research efforts is presented to identify the processes responsible for persistent erosion along a 1-km segment of 7-km-long Ocean Beach in San Francisco, California. The beach is situated adjacent to a major tidal inlet and in the shadow of the ebb-tidal delta at the mouth of San Francisco Bay. Ocean Beach is exposed to a high-energy wave climate and significant alongshore variability in forcing introduced by varying nearshore bathymetry, tidal forcing, and beach morphology (e.g., beach variably backed by seawall, dunes, and bluffs). In addition, significant regional anthropogenic factors have influenced sediment supply and tidal current strength. A variety of techniques were employed to investigate the erosion at Ocean Beach, including historical shoreline and bathymetric analysis, monthly beach topographic surveys, nearshore and regional bathymetric surveys, beach and nearshore grain size analysis, two surf-zone hydrodynamic experiments, four sets of nearshore wave and current experiments, and several numerical modeling approaches. Here, we synthesize the results of 7 years of data collection to lay out the causes of persistent erosion, demonstrating the effectiveness of integrating an array of data sets covering a huge range of spatial scales. The key findings are as follows: anthropogenic influences have reduced sediment supply from San Francisco Bay, leading to pervasive contraction (i.e., both volume and area loss) of the ebb-tidal delta, which in turn reduced the regional grain size and modified wave focusing patterns along Ocean Beach, altering nearshore circulation and sediment transport patterns. In addition, scour associated with an exposed sewage outfall pipe causes a local depression in wave heights, significantly modifying nearshore circulation patterns that have been shown through modeling to be key drivers of persistent erosion in that area.

Foreshore sand as a source of Escherichia coli in nearshore water of a Lake Michigan beach.

PubMed

Whitman, Richard L; Nevers, Meredith B

2003-09-01

Swimming advisories due to excessive Escherichia coli concentrations are common at 63rd Street Beach, Chicago, Ill. An intensive study was undertaken to characterize the source and fate of E. coli in beach water and sand at the beach. From April through September 2000, water and sand samples were collected daily or twice daily at two depths on three consecutive days per week (water samples, n = 1,747; sand samples, n = 858); hydrometeorological conditions and bird and bather distributions were also recorded. E. coli concentrations in sand and water were significantly correlated, with the highest concentration being found in foreshore sand, followed by those in submerged sediment and water of increasing depth. Gull contributions to E. coli densities in sand and water were most apparent on the day following gull activity in a given area. E. coli recolonized newly placed foreshore sand within 2 weeks. Analysis of variance, correlation, cluster analyses, concentration gradients, temporal-spatial distribution, demographic patterns, and DNA fingerprinting suggest that E. coli may be able to sustain population density in temperate beach sand during summer months without external inputs. This research presents evidence that foreshore beach sand (i) plays a major role in bacterial lake water quality, (ii) is an important non-point source of E. coli to lake water rather than a net sink, (iii) may be environmentally, and perhaps hygienically, problematic, and (iv) is possibly capable of supporting an autochthonous, high density of indicator bacteria for sustained periods, independent of lake, human, or animal input.

Geotechnical and Geoacoustic Properties of Sediments Off South Florida: Boca Raton, Indian River Beach, Lower Tampa Bay, and the Lower Florida Keys

DTIC Science & Technology

1997-06-24

foraminifers, sea urchin spines, barnacles, spiny oysters, worm shells, bivalves, coral fragments, and few quartz grains. The sediments are composed of...photographing a diver’s compass on the sea bottom as the first photograph of a photographic transect along a tape measure previously laid down on the sea ...measurements for distortion caused by refraction in sea water and lens aberrations. Use of the stereocomparator allows high frequency sampling of bottom

Erosional patterns of the Isles Dernieres, Louisiana, in relation to meteorological influences

USGS Publications Warehouse

Dingler, J.R.; Reiss, T.E.; Plant, N.G.

1993-01-01

Over the past 100 years, the Isles Dernieres, a low-lying barrier-island chain along the central Louisiana coast, has eroded extensively. This erosion has resulted in more than 1 km of northward beach-face retreat and the loss of 71% of the total island area. The primary causes for the erosion are wind and wave attack, diminished sand supply, and relative sea-level rise. Five years of detailed topographic surveys show that a beach on the central Isles Dernieres changed significantly in both shape and sediment volume; however, the pattern of change was not the same each year. In contrast to the relatively slow erosion caused by cold fronts, hurricane Gilbert, a category 5 hurricane that passed about 800 km south of the Isles Dernieres in September 1988, produced differential beach-face retreat of about 9 m at mean sea level and 40 m at an elevation of 0.5 m. Most of the sediment eroded from the beach face was deposited on the backshore, which resulted in only a small loss of sediment from the beach and a noteworthy decrease in beach-face slope. During the two years following hurricane Gilbert, the mean-sea-level contour remained stationary while the beach face slowly returned to its pre-Gilbert shape. "Cold-front' magnitude of retreat is expected to continue until another large hurricane alters the erosional pattern. -from Authors

Measured and Predicted Burial of Cylinders During the Indian Rocks Beach Experiment

DTIC Science & Technology

2007-01-01

in shallow water (15-16 m) with fine-sand (133-/xm) and coarse-sand (566-/xm) sediments off Indian Rocks Beach (IRB), FL. Scour pits developed...eter) relative to the sediment- water interface, but only 20%-50% relative to surface area covered. The difference was caused by the lack of...sensors intended to indicate the surface area of the cylinder covered by sediment or water (i.e., percent surface area exposed during burial) and

Sand sources and transport pathways for the San Francisco Bay coastal system, based on X-ray diffraction mineralogy

USGS Publications Warehouse

Hein, James R.; Mizell, Kira; Barnard, Patrick L.; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.

2013-01-01

The mineralogical compositions of 119 samples collected from throughout the San Francisco Bay coastal system, including bayfloor and seafloor, area beaches, cliff outcrops, and major drainages, were determined using X-ray diffraction (XRD). Comparison of the mineral concentrations and application of statistical cluster analysis of XRD spectra allowed for the determination of provenances and transport pathways. The use of XRD mineral identifications provides semi-quantitative compositions needed for comparisons of beach and offshore sands with potential cliff and river sources, but the innovative cluster analysis of XRD diffraction spectra provides a unique visualization of how groups of samples within the San Francisco Bay coastal system are related so that sand-sized sediment transport pathways can be inferred. The main vector for sediment transport as defined by the XRD analysis is from San Francisco Bay to the outer coast, where the sand then accumulates on the ebb tidal delta and also moves alongshore. This mineralogical link defines a critical pathway because large volumes of sediment have been removed from the Bay over the last century via channel dredging, aggregate mining, and borrow pit mining, with comparable volumes of erosion from the ebb tidal delta over the same period, in addition to high rates of shoreline retreat along the adjacent, open-coast beaches. Therefore, while previously only a temporal relationship was established, the transport pathway defined by mineralogical and geochemical tracers support the link between anthropogenic activities in the Bay and widespread erosion outside the Bay. The XRD results also establish the regional and local importance of sediment derived from cliff erosion, as well as both proximal and distal fluvial sources. This research is an important contribution to a broader provenance study aimed at identifying the driving forces for widespread geomorphic change in a heavily urbanized coastal-estuarine system.

Planview Geometry and morphological characteristics of pocket beaches on the Catalan coast (Spain)

NASA Astrophysics Data System (ADS)

Bowman, D.; Guillén, J.; López, L.; Pellegrino, V.

2009-07-01

Coastal planform studies are a relevant initial stage before launching detailed dynamic field experiments. The aim of this study is to define the planform characteristics of 72 Catalan pocket beaches, natural and man-made, and to determine their sheltering effect, embaymentization and their status of equilibrium. Planform measurements were performed on SIGPAC, 1:5000 orthophoto sets and wave climate was provided by Puertos del Estado (Wana model). Planform parameters were applied and coastal planview indexes were determined. The study shows that the Catalan pocket beaches display a wide range of indentation, suggesting that no single structural, tectonic or morphological control dominates their planform. The man-made pocket beaches typically display indentations which are smaller than those shown by natural pocket beaches. Headland spacing and beach area are positively correlated. The more indented bays are, the shorter their beaches become. Low-indented pocket beaches are the widest and the longest ones. Deep indentation contributes towards beach protection and energy dissipation which counteracts rip efficiency and inhibits the formation of mega-rips. Pocket beaches often show gradual and moderate alongshore changes in texture and beach morphology. One third of the Catalan pocket beaches are "sediment starved", i.e., 60% and more of their embayed shorelines are deprived of beach sediments. Examination of the status of equilibrium demonstrates that most of the Catalan pocket beaches are in an unstable mode, with indentation ratios that are unrelated to the wave obliquity.

Beach Erosion Mitigation and Sediment Management Alternatives at Wallops Island, VA

DTIC Science & Technology

2006-09-01

to retain sand on the shoreface. These were the “Beach Prism,” a precast concrete ERDC/CHL TR-06-21 55 triangular prism, and the “Beach Beam ,” a...during an April 1988 storm (photograph courtesy of NASA)................................................................28 Figure 19. "Beach Beam " units...Alternatives, Phase B Tests of “Beach Beams ” and “Beach Prisms” were inconclusive. These structures deemed unsuitable for Wallops Island. 8 May 1992

Sediment pore-water toxicity test results and preliminary toxicity identification of post-landfall pore-water samples collected following the Deepwater Horizon oil release, Gulf of Mexico, 2010

USGS Publications Warehouse

Biedenbach, James M.; Carr, Robert S.

2011-01-01

Pore water from coastal beach and marsh sediments from the northern Gulf of Mexico, pre- and post-landfall of the Deepwater Horizon oil release, were collected and evaluated for toxicity with the sea urchin fertilization and embryological development assays. There were 17 pre-landfall samples and 49 post-landfall samples tested using both assays. Toxicity was determined in four pre-landfall sites and in seven post-landfall sites in one or both assays as compared to a known reference sediment pore-water sample collected in Aransas Bay, Texas. Further analysis and testing of five of the post-landfall toxic samples utilizing Toxicity Identification Evaluation techniques indicated that ammonia, and to a lesser extent metals, contributed to most, if not all, of the observed toxicity in four of the five samples. Results of one sample (MS-39) indicated evidence that ammonia, metals, and non-ionic organics were contributing to the observed toxicity.

Evaluation of Bajo Blanco Sandbar as a Potential Beach Nourishment Borrow Site for Eroding Beaches in Rincon, Puerto Rico

NASA Astrophysics Data System (ADS)

Rojas, C. A.; Canals, M.

2016-02-01

The municipality of Rincón, Puerto Rico is recognized for its world-class surfing beaches. Unfortunately, the coast from Punta Higüero to Punta Cadena in Rincón is experiencing long-term erosion (Thieler 2007), which has caused the destruction of many beachfront homes and hotels and had negative impacts on the local tourism-driven economy. The purpose of this project is to evaluate whether the nearby Bajo Blanco sandbar, located just offshore of these eroded beaches, could be used as a possible beach nourishment borrow site. A high-resolution bathymetric survey of Bajo Blanco sandbar was conducted along with a grain size analysis to compare the grain size distribution of the Bajo Blanco sandbar with the sediment properties of the eroded beaches. It was found that the sediment from Bajo Blanco is finer yet may be suitable as beach fill material for these beaches according to Dean's overfill ratio. Compatibility analysis suggests a total volume of sandbar sediment of approximately 685,555 cubic meters to allow successful beach equilibrium. To evaluate the potential effects of the sand extraction on the nearshore wave climate, numerical simulations were performed using the spectral wave model of the USACE Coastal Modeling System (CMS-Wave). Wave model results for several dredging scenarios suggest that wave energy flux concentrates around the shoal causing an increase in wave height at the northern and southern edges of the shoal. Therefore, conservation of energy leads to a reduction of wave energy flux shoreward of the shoal, causing a shadow of reduced wave height. In addition, the Tres Palmas Marine reserve is located just north of Bajo Blanco sandbar and features some of the healthiest Elkorn Corals in the Caribbean. To avoid excessive sedimentation of these reefs during dredging activities, the Particle Tracking Module (PTM), integrated in the Surface-water Modeling System (SMS), was used to evaluate the Lagrangian particle transport processes along Bajo Blanco under various wave conditions. Results suggest that dredging operations be conducted during small to moderate wave events, since the wave-induced currents related to these events force sediment particles to advect south and thus away from the Tres Palmas Marine Reserve.

Effects of Full-Scale Beach Renovation on Fecal Indicator Levels in Shoreline Sand and Water

PubMed Central

Hernandez, Rafael J.; Hernandez, Yasiel; Jimenez, Nasly H.; Piggot, Alan M.; Klaus, James S.; Feng, Zhixuan; Reniers, Ad; Solo-Gabriele, Helena M.

2013-01-01

Recolonization of enterococci, at a non-point source beach known to contain high background levels of bacteria, was studied after a full-scale beach renovation project. The renovation involved importation of new exogenous sand, in addition to infrastructure improvements. The study's objectives were to document changes in sand and water quality and to evaluate the relative contribution of different renovation activities towards these changes. These objectives were addressed: by measuring enterococci levels in the sand and fecal indicator bacteria levels (enterococci and fecal coliform) in the water, by documenting sediment characteristics (mineralogy and biofilm levels), and by estimating changes in observable enterococci loads. Analysis of enterococci levels on surface sand and within sediment depth cores were significantly higher prior to beach renovation (6.3 to 72 CFU/g for each sampling day) when compared to levels during and after beach renovation (0.8 CFU/g to 12 CFU/g) (p<0.01). During the renovation process, sand enterococci levels were frequently below detection limits (<0.1 CFU/g). For water, exceedances in the regulatory thresholds that would trigger a beach advisory decreased by 40% for enterococci and by 90% for fecal coliform. Factors that did not change significantly between pre- and post- renovation included the enterococci loads from animals (approx. 3 × 1011 CFU per month). Factors that were observed to change between pre- and post- renovation activities included: the composition of the beach sand (64% versus 98% quartz, and a significant decrease in biofilm levels) and loads from direct stormwater inputs (reduction of 3 × 1011 CFU per month). Overall, this study supports that beach renovation activities contributed to improved sand and water quality resulting in a 50% decrease of observable enterococci loads due to upgrades to the stormwater infrastructure. Of interest was that the change in the sand mineralogy also coincided with changes in biofilm levels. More work is needed to evaluate the relationships between beach sand mineralogy, biofilm characteristics, and the retention of fecal indicator bacteria in sand. PMID:24183401

Effects of full-scale beach renovation on fecal indicator levels in shoreline sand and water.

PubMed

Hernandez, Rafael J; Hernandez, Yasiel; Jimenez, Nasly H; Piggot, Alan M; Klaus, James S; Feng, Zhixuan; Reniers, Ad; Solo-Gabriele, Helena M

2014-01-01

Recolonization of enterococci, at a non-point source beach known to contain high background levels of bacteria, was studied after a full-scale beach renovation project. The renovation involved importation of new exogenous sand, in addition to infrastructure improvements. The study's objectives were to document changes in sand and water quality and to evaluate the relative contribution of different renovation activities towards these changes. These objectives were addressed: by measuring enterococci levels in the sand and fecal indicator bacteria levels (enterococci and fecal coliform) in the water, by documenting sediment characteristics (mineralogy and biofilm levels), and by estimating changes in observable enterococci loads. Analysis of enterococci levels on surface sand and within sediment depth cores were significantly higher prior to beach renovation (6.3-72 CFU/g for each sampling day) when compared to levels during and after beach renovation (0.8-12 CFU/g) (P < 0.01). During the renovation process, sand enterococci levels were frequently below detection limits (<0.1 CFU/g). For water, exceedances in the regulatory thresholds that would trigger a beach advisory decreased by 40% for enterococci and by 90% for fecal coliform. Factors that did not change significantly between pre- and post- renovation included the enterococci loads from animals (approx. 3 × 10(11) CFU per month). Factors that were observed to change between pre- and post- renovation activities included: the composition of the beach sand (64% versus 98% quartz, and a significant decrease in biofilm levels) and loads from direct stormwater inputs (reduction of 3 × 10(11) CFU per month). Overall, this study supports that beach renovation activities contributed to improved sand and water quality resulting in a 50% decrease of observable enterococci loads due to upgrades to the stormwater infrastructure. Of interest was that the change in the sand mineralogy also coincided with changes in biofilm levels. More work is needed to evaluate the relationships between beach sand mineralogy, biofilm characteristics, and the retention of fecal indicator bacteria in sand. Copyright © 2013 Elsevier Ltd. All rights reserved.

Grain size analysis and depositional environment of shallow marine to basin floor, Kelantan River Delta

NASA Astrophysics Data System (ADS)

Afifah, M. R. Nurul; Aziz, A. Che; Roslan, M. Kamal

2015-09-01

Sediment samples were collected from the shallow marine from Kuala Besar, Kelantan outwards to the basin floor of South China Sea which consisted of quaternary bottom sediments. Sixty five samples were analysed for their grain size distribution and statistical relationships. Basic statistical analysis like mean, standard deviation, skewness and kurtosis were calculated and used to differentiate the depositional environment of the sediments and to derive the uniformity of depositional environment either from the beach or river environment. The sediments of all areas were varied in their sorting ranging from very well sorted to poorly sorted, strongly negative skewed to strongly positive skewed, and extremely leptokurtic to very platykurtic in nature. Bivariate plots between the grain-size parameters were then interpreted and the Coarsest-Median (CM) pattern showed the trend suggesting relationships between sediments influenced by three ongoing hydrodynamic factors namely turbidity current, littoral drift and waves dynamic, which functioned to control the sediments distribution pattern in various ways.

Sediment deposition from Hurricane Rita on Hackberry Beach chenier in southwestern Louisiana: Chapter 6E in Science and the storms-the USGS response to the hurricanes of 2005

USGS Publications Warehouse

Faulkner, Stephen; Barrow, Wylie; Doyle, Thomas; Baldwin, Michael; Michot, Thomas; Wells, Christopher; Jeske, Clint

2007-01-01

Hurricane Rita significantly impacted the chenier forests of southwestern Louisiana, an important habitat for Neotropical migratory birds. Sediment deposition was measured along transects at Hackberry Beach chenier, and Rita's effects on chenier structure and morphology were determined.

Impacts of an "extreme" storm on a low-lying embayed sandy beach (Pals Bay, NW Mediterranean)

NASA Astrophysics Data System (ADS)

Durán, Ruth; Sagristà, Enric; Guillen, Jorge; Ruiz, Antonio; Jiménez, José Antonio

2014-05-01

The present study aims to assess the effects of an extreme storm in the medium-term evolution of a low-lying, low-tidal sandy coast based on airborne LIDAR (LIght Detection and Ranging) derived high-resolution topographic data. LIDAR data were acquired by the Institut Cartogràfic de Catalunya and analyzed in a Geographical Information System (GIS) environment in order to estimate the shoreline displacement (advance or retreat), volumetric changes of the emerged beach, dune erosion and overswash. LIDAR surveys were undertaken in October 2008 and August 2009 to evaluate the impact of an extreme storm that severely hit the north-west Mediterranean coast on 26 December 2008. During this storm, maximum significant wave heights of 7.5 m (with peaks of 14.4 m of maximum wave height) and maximum wave peak period of 12.8 s were recorded at the Palamós buoy, located at 90 m depth. In addition, several weak to moderate storms also occurred during the study period. The Pals Bay in the northern of Catalonia (NW Mediterranean) has been chosen for this study because: (i) it is a low-lying coastal land, which makes the coastline highly susceptible to flooding by waves during storms; and (ii) it includes high natural value areas and urbanized ones that show different behavior under the impact of storms. It comprises three beaches: the Pals Bay beach that extends along 6840 m between L'Estartit and Begur promontories, and two pocket beaches located at the southern end of the Pals Bay, Cala Moreta and Sa Riera, which are only 185 m and 188 m long, respectively. During the study period, shoreline position and volumetric changes in the large bay beach were not homogeneous. The coastline variations showed alongshore fluctuations up to 40 m, probably related to the development of rhythmic topographies in form of beach cups. Overall, the emerged beach experienced a net volumetric loss of -62 516 m3 (-9.14 m3/m). However, the loss of sediment was not uniform. In urbanized areas, sediment erosion occurred along the whole beach profile, whereas in natural areas foreshore erosion was accompanied by net accumulation of sediment in the backshore. This positive volumetric gain in the upper beach could be largely attributed to overwash processes during the extreme storm, which also caused dune erosion and overwash fan deposition. Nevertheless, the smaller pocked beaches behaved differently. In Cala Moreta, shoreline evolution presented an anti-clockwise rotation of the beach, with a small net loss of sediment of -265 m3 (-1.43 m3/m). Sa Riera showed a small retreat of the shoreline and an important accumulation of sediment in the backshore that resulted in a net positive volume balance in the emerged beach of +2515 m3 (+13.38 m3/m).

Total and extractable elemental composition of the intertidal estuarine biofilm of the Río de la Plata: Disentangling natural and anthropogenic influences

NASA Astrophysics Data System (ADS)

García-Alonso, J.; Lercari, D.; Araujo, B. F.; Almeida, M. G.; Rezende, C. E.

2017-03-01

Estuarine transitional waters constitute regions affected by or at risk of anthropogenic impact due to urbanization and industrial development. The elemental composition of the intertidal biofilm sediment is an excellent marker for the detection of any impact, and may exert a bottom-up influence by natural concatenation to higher organization levels (e.g. molecules, cells, organisms, communities). The distribution pattern of elemental composition (total and bioavailable fraction) along the estuary axes was analyzed, disentangling potential shifts produced by human activities. We predict that most abundant elements in the Rio de la Plata estuary are the natural earth-crust components and that these will not show any evident gradient along the estuarine axis. Elements involved in human related processes will shape concentration gradients from the most probable source (i.e. cities) indicating estuarine pollution. The research strategy involved the sampling of intertidal biofilm along the entire estuary and the registration of environmental variables and the total and bioavailable elemental composition. Sampling sites represent pristine, agricultural, and urbanized areas along a 428-km-long coastline comprising the inner, middle and outer Río de la Plata estuarine zones and a coastal fringe of oceanic beaches of Uruguay (South America). Biofilm sediment samples were collected in Autumn 2011 and digested for total and extractable (bioavailable) elements quantification measured by ICP-OES. Mercury (Hg) sediments were digested with aqua regia and quantified by cold vapor atomic absorption (CVAAS). The most abundant elements measured were Al, Fe, and Ca in all sampling. Anthropogenic marker elements such as Hg, Cr, Pb, Zn, and Cu were found, even at potentially toxic levels, at urban beaches at the city of Montevideo. The ordination of samples highlights the distinctive characteristics of urban beaches, placed in a particular location along the first principal component. This position is mainly driven by human impact marker metals and C/N ratios. The results highlight the value of bioavailable elemental composition analyses of benthic biofilm as a tool for detecting shifts in estuarine systems.

GenCade Lateral Boundary Conditions

DTIC Science & Technology

2017-01-01

13 Figure 4. Example pocket beach at Boston Bay, Portland Parish, Jamaica. Beach sediments are mainly locally derived...specify the sediment transport onto and off of each end of the grid. To determine the shoreline position of cell i at time-step “j+1,” (Figure 1...calculating the sediment transport across Cell Walls “i” and “i+1” [denoted as “Q(i,j)” and “Q(i+1,j)”] (plus adding in the user-defined sources and

Quantifying the rapid evolution of a nourishment project with video imagery

USGS Publications Warehouse

Elko, N.A.; Holman, R.A.; Gelfenbaum, G.

2005-01-01

Spatially and temporally high-resolution video imagery was combined with traditional surveyed beach profiles to investigate the evolution of a rapidly eroding beach nourishment project. Upham Beach is a 0.6-km beach located downdrift of a structured inlet on the west coast of Florida. The beach was stabilized in seaward advanced position during the 1960s and has been nourished every 4-5 years since 1975. During the 1996 nourishment project, 193,000 m 3 of sediment advanced the shoreline as much as 175 m. Video images were collected concurrent with traditional surveys during the 1996 nourishment project to test video imaging as a nourishment monitoring technique. Video imagery illustrated morphologic changes that were unapparent in survey data. Increased storminess during the second (El Nin??o) winter after the 1996 project resulted in increased erosion rates of 0.4 m/d (135.0 m/y) as compared with 0.2 m/d (69.4 m/y) during the first winter. The measured half-life, the time at which 50% of the nourished material remains, of the nourishment project was 0.94 years. A simple analytical equation indicates reasonable agreement with the measured values, suggesting that project evolution follows a predictable pattern of exponential decay. Long-shore planform equilibration does not occur on Upham Beach, rather sediment diffuses downdrift until 100% of the nourished material erodes. The wide nourished beach erodes rapidly due to the lack of sediment bypassing from the north and the stabilized headland at Upham Beach that is exposed to wave energy.

The natural radioactivity measurements in coastal sediment samples along the East Coast of Tamilnadu using gamma spectrometry technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chandramohan, J.; Tholkappian, M.; Harikrishnan, N.

2015-08-28

The natural radioactivity concentration in beach sediment samples collected from Pattipulam to Devanampattinam of East Coast of Tamilnadu have been determined by NaI (TI) gamma ray spectrometer. The specific activity concentrations range from ≤ 2.21 (BDL) to 37.02 Bq kg{sup −1} with a mean of 3.79 Bqkg{sup −1} for {sup 238}U, ≤ 2.11 (BDL) to 643.77 Bqkg{sup −1} with a mean of 49.60 Bqkg{sup −1} for {sup 232}Th and 300.34 Bqkg{sup −1} to 449.08 Bqkg{sup −1} with a mean of 360.23 Bqkg{sup −1} for {sup 40}K. The potential radiological hazards due to natural radionuclides content such as Radium Equivalent activitymore » (Ra{sub eq}), Representative level index (RLI), External hazard index (H{sub ex}), absorbed gamma does rate (D{sub R}), and Annual effective dose rate (AEDR) are estimated to assess the radiation hazard associated with the sediments. The obtained data are compared with the recommended safety limits and international approved values. All the values are well below the recommended safety limits indicating that radiation levels do not poses any significant health hazard to the public in the area as a result of the natural radioactivity of beach sediments. This study may help the baseline data for more extensive works in the same subjects of future studies.« less

Swashed away? Storm impacts on sandy beach macrofaunal communities

NASA Astrophysics Data System (ADS)

Harris, Linda; Nel, Ronel; Smale, Malcolm; Schoeman, David

2011-09-01

Storms can have a large impact on sandy shores, with powerful waves eroding large volumes of sand off the beach. Resulting damage to the physical environment has been well-studied but the ecological implications of these natural phenomena are less known. Since climate change predictions suggest an increase in storminess in the near future, understanding these ecological implications is vital if sandy shores are to be proactively managed for resilience. Here, we report on an opportunistic experiment that tests the a priori expectation that storms impact beach macrofaunal communities by modifying natural patterns of beach morphodynamics. Two sites at Sardinia Bay, South Africa, were sampled for macrofauna and physical descriptors following standard sampling methods. This sampling took place five times at three- to four-month intervals between April 2008 and August 2009. The second and last sampling events were undertaken after unusually large storms, the first of which was sufficiently large to transform one site from a sandy beach into a mixed shore for the first time in living memory. A range of univariate (linear mixed-effects models) and multivariate (e.g. non-metric multidimensional scaling, PERMANOVA) methods were employed to describe trends in the time series, and to explore the likelihood of possible explanatory mechanisms. Macrofaunal communities at the dune-backed beach (Site 2) withstood the effects of the first storm but were altered significantly by the second storm. In contrast, macrofauna communities at Site 1, where the supralittoral had been anthropogenically modified so that exchange of sediments with the beach was limited, were strongly affected by the first storm and showed little recovery over the study period. In line with predictions from ecological theory, beach morphodynamics was found to be a strong driver of temporal patterns in the macrofaunal community structure, with the storm events also identified as a significant factor, likely because of their direct effects on beach morphodynamics. Our results also support those of other studies suggesting that developed shores are more impacted by storms than are undeveloped shores. Whilst recognising we cannot generalise too far beyond our limited study, our results contribute to the growing body of evidence that interactions between sea-level rise, increasing storminess and the expansion of anthropogenic modifications to the shoreline will place functional beach ecosystems under severe pressure over the forthcoming decades and we therefore encourage further, formal testing of these concepts.

Bacteria in beach sands: an emerging challenge in protecting coastal water quality and bather health

PubMed Central

Gast, Rebecca J.

2011-01-01

To protect bather health at recreational beaches, fecal indicator bacterial standards are used to monitor water quality, and waters exceeding the standards are subsequently closed to bathers. However beachgoers are also in contact with beach sands, the sanitary quality of which is not included within beach monitoring programs. In fact, sands and sediments provide habitat where fecal bacterial populations may persist, and in some cases grow, in the coastal zone. Specific pathogens are less well studied in beach sands and sediments, but there is a body of evidence that they too may persist in these environments. This paper reviews the current state of knowledge regarding the abundance and distribution of fecal indicator bacteria and pathogens in beach sands of diverse climatological regions, and at beaches subjected to varied levels of anthropogenic impact. In all regions fecal indicator bacteria are nearly ubiquitous in beach sands, and similar relationships emerge between fecal indicator abundance in dry sand, submerged sands, and water. Taken together, these studies contextualize a potential public health issue and identify research questions that must be addressed in order to support future policy decisions. PMID:21162561

Integrating field research, modeling and remote sensing to quantify morphodynamics in a high-energy coastal setting, ocean beach, San Francisco, California

USGS Publications Warehouse

Barnard, P.L.; Hanes, D.M.

2006-01-01

Wave and coastal circulation modeling are combined with multibeam bathymetry, high-resolution beach surveys, cross-shore Personal Water Craft surveys, digital bed sediment camera surveys, and real-time video monitoring to quantify morphological change and nearshore processes at Ocean Beach, San Francisco. Initial SWAN (Simulating Waves Nearshore) wave modeling results show a focusing of wave energy at the location of an erosion hot spot on the southern end of Ocean Beach during prevailing northwest swell conditions. During El Nin??o winters, swell out of the west and southwest dominates the region, and although the wave energy is focused further to the north on Ocean Beach, the oblique wave approach sets up a strong northerly littoral drift, thereby starving the southern end of sediment, leaving it increasingly vulnerable to wave attack when the persistent northwest swell returns. An accurate assessment of the interaction between wave and tidal processes is crucial for evaluating coastal management options in an area that includes the annual dredging and disposal of ship channel sediment and an erosion hot spot that is posing a threat to local infrastructure. Copyright ASCE 2006.

Ubiquity and persistance of Escherichia coli in a midwestern coastal stream

USGS Publications Warehouse

Byappanahalli, Muruleedhara N.; Fowler, Melanie; Shively, Dawn; Whitman, Richard

2003-01-01

Dunes Creek, a small Lake Michigan coastal stream that drains sandy aquifers and wetlands of Indiana Dunes, has chronically elevated Escherichia coli levels along the bathing beach near its outfall. This study sought to understand the sources ofE. coli in Dunes Creek's central branch. A systematic survey of random and fixed sampling points of water and sediment was conducted over 3 years. E. coliconcentrations in Dunes Creek and beach water were significantly correlated. Weekly monitoring at 14 stations during 1999 and 2000 indicated chronic loading of E. coli throughout the stream. Significant correlations between E. coli numbers in stream water and stream sediment, submerged sediment and margin, and margin and 1 m from shore were found. Median E. coli counts were highest in stream sediments, followed by bank sediments, sediments along spring margins, stream water, and isolated pools; in forest soils, E. coli counts were more variable and relatively lower. Sediment moisture was significantly correlated with E. colicounts. Direct fecal input inadequately explains the widespread and consistent occurrence of E. coli in the Dunes Creek watershed; long-term survival or multiplication or both seem likely. The authors conclude that (i) E. coli is ubiquitous and persistent throughout the Dunes Creek basin, (ii) E. coli occurrence and distribution in riparian sediments help account for the continuous loading of the bacteria in Dunes Creek, and (iii) ditching of the stream, increased drainage, and subsequent loss of wetlands may account for the chronically high E. coli levels observed.

Internal structure of a barrier beach as revealed by ground penetrating radar (GPR): Chesil beach, UK

NASA Astrophysics Data System (ADS)

Bennett, Matthew R.; Cassidy, Nigel J.; Pile, Jeremy

2009-03-01

Chesil Beach (Dorset) is one of the most famous coastal landforms on the British coast. The gravel beach is over 18 km long and is separated for much of its length from land by a tidal lagoon known as The Fleet. The beach links the Isle of Portland in the east to the mainland in the west. Despite its iconic status there is little available information on its internal geometry and evolutionary history. Here we present a three-fold model for the evolution of Chesil Beach based on a series of nine ground penetrating radar (GPR) traverses located at three sites along its length at Abbotsbury, Langton Herring and at Ferry Bridge. The GPR traverses reveal a remarkably consistent picture of the internal structure of this barrier beach. The first phase of evolution involves the landward transgression of a small sand and gravel beach which closed upon the coast leading to deposition of freshwater peat between 5 and 7 k yr BP. The second evolutionary phase involves the 'bulking-out' of the beach during continued sea level rise, but in the presence of abundant gravel supplied by down-drift erosion of periglacial slope deposits. This episode of growth was associated with a series of washover fans which accumulated on the landward flank of the barrier increasing its breadth and height but without significant landward transgression of the barrier as a whole. The final phase in the evolution of Chesil Beach involves the seaward progradation of the beach crest and upper beach face associated with continued sediment abundance, but during a still-stand or slight fall in relative sea level. This phase may provide further evidence of a slight fall in relative sea level noted elsewhere along the South Coast of Britain and dated to between 1.2 and 2.4 k yr BP. Subsequently the barrier appears to have become largely inactive, except for the reworking of sediment on the beach face during storm events. The case study not only refines the evolutionary picture of Chesil Beach, but illustrates the importance of the subtle interplay between relative sea level and sediment supply in the evolution of a barrier system. In addition, it also illustrates the potential of GPR in resolving the evolutionary history of gravel-rich coastal landforms such as Chesil Beach.

Beach recovery after 2004 Indian Ocean tsunami from Phang-nga, Thailand

NASA Astrophysics Data System (ADS)

Choowong, Montri; Phantuwongraj, Sumet; Charoentitirat, Thasinee; Chutakositkanon, Vichai; Yumuang, Sombat; Charusiri, Punya

2009-03-01

The 2004 Indian Ocean tsunami devastated the coastal areas along the Andaman western coast of Thailand and left unique physical evidence of its impact, including the erosional landforms of the pre-tsunami topography. Here we show the results from monitoring the natural recovery of beach areas at Khuk Khak and Bang Niang tidal channels of Khao Lak area, Phang-nga, Thailand. A series of satellite images before and after the tsunami event was employed for calculating the beach area and locating the position of the changed shoreline. Field surveys to follow-up the development of the post-tsunami beach area were conducted from 2005 to 2007 and the yearly beach profile was measured in 2006. As a result, the scoured beach areas where the tidal channel inlets were located underwent continuous recovery. The return of post-tsunami sediments within the beach zone was either achieved by normal wind and wave processes or during the storm surges in the rainy season. Post-2004 beach sediments were derived mainly from near offshore sources. The present situation of the beach zone has almost completed reversion back to the equilibrium stage and this has occurred within 2 years after the tsunami event. We suggest these results provide a better understanding of the geomorphological process involved in beach recovery after severe erosion such as by tsunami events.

Airflow Dynamics and Sand Transport over a Coastal Foredune with Large Woody Debris.

NASA Astrophysics Data System (ADS)

Grilliot, M. J.; Walker, I. J.; Bauer, B. O.

2016-12-01

Airflow dynamics and sand transport patterns over beach-foredune systems are complex due to the effects of topographic forcing and varied surface roughness elements. The role of large woody debris (LWD) as a roughness element in foredune dynamics is understudied compared to the effects of plant cover. Unlike plants, non-porous objects like LWD impose bluff body effects and induce secondary flow circulation that varies with LWD size, density, and arrangement. It is hypothesized that modified flow patterns over LWD can influence beach-dune sediment budgets and dune geometry via changes to mean near-surface flow patterns, turbulence, sand transport pathways and sedimentation patterns. In turn, LWD may act as an accretion anchor and store appreciable amounts of aeolian sand that subsequently may provide an enhanced buffer against coastal and/or wind erosion. This study examines turbulent airflow dynamics and related sand transport patterns for oblique onshore flow conditions over a mesotidal beach and scarped dune on Calvert Island, British Columbia, Canada. Abundant exposed LWD fronting the foredune enhances turbulent Reynolds stress (RS) and turbulence intensity (TI) near the surface. During low, yet competent wind speeds (6.54 m s-1), RS and TI are not competent enough in the sheltered flow regions within the LWD matrix and sediment deposition occurs. However, small zones of localized acceleration were observed with sand transport. Higher wind speeds, well above the entrainment threshold, increase RS and TI over LWD relative to the beach, facilitating sediment transport through and over the LWD matrix, with localized pockets of deposition in sheltered areas. The majority of LWD deposits on beaches in the region are anthropogenic logging debris and are known to be decreasing since the 1950s, but likely earlier. Thus, it is important to understand how non-porous roughness elements, like LWD, affect beach-dune sediment budgets and evolution, particularly in light of increasing storminess and sea level rise.

Quantification of Beach Profile Change

DTIC Science & Technology

1988-01-01

complex fluid motion over an irregular bottom, and absence of rigorous descriptions of broken waves and sediment-sediment interaction, also make the...monochromatic and irregular waves for a dune-like foreshore with and without a significant surf zone. For one case starting from a beach without...34foreshore", mono- chromatic waves produced a bar, whereas irregular waves of significant height and peak spectral period of the monochromatic waves did

Changes in surfzone morphodynamics driven by multi-decadel contraction of a large ebb-tidal delta

USGS Publications Warehouse

Hansen, Jeff E.; Elias, Edwin; Barnard, Patrick L.; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.

2013-01-01

The impact of multi-decadal, large-scale deflation (76 million m3 of sediment loss) and contraction (~ 1 km) of a 150 km2 ebb-tidal delta on hydrodynamics and sediment transport at adjacent Ocean Beach in San Francisco, CA (USA), is examined using a coupled wave and circulation model. The model is forced with representative wave and tidal conditions using recent (2005) and historic (1956) ebb-tidal delta bathymetry data sets. Comparison of the simulations indicates that along north/south trending Ocean Beach the contraction and deflation of the ebb-tidal delta have resulted in significant differences in the flow and sediment dynamics. Between 1956 and 2005 the transverse bar (the shallow attachment point of the ebb-tidal delta to the shoreline) migrated northward ~ 1 km toward the inlet while a persistent alongshore flow and transport divergence point migrated south by ~ 500 m such that these features now overlap. A reduction in tidal prism and sediment supply over the last century has resulted in a net decrease in offshore tidal current-generated sediment transport at the mouth of San Francisco Bay, and a relative increase in onshore-directed wave-driven transport toward the inlet, accounting for the observed contraction of the ebb-tidal delta. Alongshore migration of the transverse bar and alongshore flow divergence have resulted in an increasing proportion of onshore migrating sediment from the ebb-tidal delta to be transported north along the beach in 2005 versus south in 1956. The northerly migrating sediment is then trapped by Pt. Lobos, a rocky headland at the northern extreme of the beach, consistent with the observed shoreline accretion in this area. Conversely, alongshore migration of the transverse bar and divergence point has decreased the sediment supply to southern Ocean Beach, consistent with the observed erosion of the shoreline in this area. This study illustrates the utility of applying a high-resolution coupled circulation-wave model for understanding coastal response to large-scale bathymetric changes over multi-decadal timescales, common to many coastal systems adjacent to urbanized estuaries and watersheds worldwide.

Beach morphology and change along the mixed grain-size delta of the dammed Elwha River, Washington

USGS Publications Warehouse

Warrick, J.A.; George, D.A.; Gelfenbaum, G.; Ruggiero, P.; Kaminsky, G.M.; Beirne, M.

2009-01-01

Sediment supply provides a fundamental control on the morphology of river deltas, and humans have significantly modified these supplies for centuries. Here we examine the effects of almost a century of sediment supply reduction from the damming of the Elwha River in Washington on shoreline position and beach morphology of its wave-dominated delta. The mean rate of shoreline erosion during 1939-2006 is ~ 0.6??m/yr, which is equivalent to ~ 24,000??m3/yr of sediment divergence in the littoral cell, a rate approximately equal to 25-50% of the littoral-grade sediment trapped by the dams. Semi-annual surveys between 2004 and 2007 show that most erosion occurs during the winter with lower rates of change in the summer. Shoreline change and morphology also differ spatially. Negligible shoreline change has occurred updrift (west) of the river mouth, where the beach is mixed sand to cobble, cuspate, and reflective. The beach downdrift (east) of the river mouth has had significant and persistent erosion, but this beach differs in that it has a reflective foreshore with a dissipative low-tide terrace. Downdrift beach erosion results from foreshore retreat, which broadens the low-tide terrace with time, and the rate of this kind of erosion has increased significantly from ~ 0.8??m/yr during 1939-1990 to ~ 1.4??m/yr during 1990-2006. Erosion rates for the downdrift beach derived from the 2004-2007 topographic surveys vary between 0 and 13??m/yr, with an average of 3.8??m/yr. We note that the low-tide terrace is significantly coarser (mean grain size ~ 100??mm) than the foreshore (mean grain size ~ 30??mm), a pattern contrary to the typical observation of fining low-tide terraces in the region and worldwide. Because this cobble low-tide terrace is created by foreshore erosion, has been steady over intervals of at least years, is predicted to have negligible longshore transport compared to the foreshore portion of the beach, and is inconsistent with oral history of abundant shellfish collections from the low-tide beach, we suggest that it is an armored layer of cobble clasts that are not generally competent in the physical setting of the delta. Thus, the cobble low-tide terrace is very likely a geomorphological feature caused by coastal erosion of a coastal plain and delta, which in turn is related to the impacts of the dams on the Elwha River to sediment fluxes to the coast.

Use of historical and geospatial data to guide the restoration of a Lake Erie coastal marsh

USGS Publications Warehouse

Kowalski, Kurt P.; Wilcox, Douglas A.

1999-01-01

Historical and geospatial data were used to identify the relationships between water levels, wetland vegetation, littoral drift of sediments, and the condition of a protective barrier beach at Metzger Marsh, a coastal wetland in western Lake Erie, to enhance and guide a joint federal and state wetland restoration project. Eleven sets of large-scale aerial photographs dating from 1940 through 1994 were interpreted to delineate major vegetation types and boundaries of the barrier beach. A geographic information system (GIS) was then used to digitize the data and calculate the vegetated area and length of barrier beach. Supplemented by paleoecological and sedimentological analyses, aerial photographic interpretation revealed that Metzger Marsh was once a drowned-river-mouth wetland dominated by sedges and protected by a sand barrier beach. Extremely high water levels, storm events, and reduction of sediments in the littoral drift contributed to the complete destruction of the barrier beach in 1973 and prevented its recovery. The extent of wetland vegetation, correlated to water levels and condition of the barrier beach, decreased from a high of 108 ha in 1940 to a low of 33 ha in 1994. The lack of an adequate sediment supply and low probability of a period of extremely low lake levels in the near future made natural reestablishment of the barrier beach and wetland vegetation unlikely. Therefore, the federal and state managers chose to construct a dike to replace the protective barrier beach. Recommendations stemming from this historical analysis, however, resulted in the incorporation of a water-control structure in the dike that will retain a hydrologic connection between wetland and lake. Management of the wetland will seek to mimic processes natural to the wetland type identified by this analysis.

Foredune morphodynamics and seasonal sediment budget patterns at Humboldt Bay, Arcata, California.

NASA Astrophysics Data System (ADS)

Rader, A. M.; Walker, I. J.; Pickart, A.; Bauer, B. O.; Hesp, P.

2017-12-01

Coastal dune erosion, rebuilding, and ecosystem restoration are examined along a dune barrier system at Humboldt Bay, Arcata California. The long-term evolution of the system indicates progradation in the north (up to +0.51 m a-1) with densely vegetated, tall and topographically simple foredunes and landward retreat in the south (up to -0.49 m a-1) with sparsely vegetated, hummocky foredunes and blowouts. Spatial-temporal patterns of change from seasonal bare-Earth models during the early stages of a dynamic restoration project indicate that, in the year following initial removal of invasive vegetation (May 2015 - September 2016), the foredune system experienced a net positive sediment budget (+0.54 m3 m-2) while net erosion occurred on the beach (-0.38 m3 m-2). Five years of cross-shore profiles show a seaward migration of the foredune crest (+0.15 m mo-1) during the same time period. However, net erosion of the beach occurred during winter (November 2015 - April 2016), due to high-water and wave run-up during intense storms. Summer monitoring reveals site-wide accretion due to beach rebuilding and increased aeolian activity. As such, seasonal sediment budgets may be controlled primarily by the amount of beach sediment available for aeolian transport and secondarily by localized vegetation zonation on the upper beach and foredune. Further monitoring of the dune barrier system at Humboldt Bay throughout the remaining dynamic restoration process will provide further insight into the role of vegetation zonation and foredune morphodynamics.

Spatial patterns in heavy-mineral concentrations along the Curonian Spit coast, southeastern Baltic Sea

NASA Astrophysics Data System (ADS)

Pupienis, Donatas; Buynevich, Ilya; Ryabchuk, Daria; Jarmalavičius, Darius; Žilinskas, Gintautas; Fedorovič, Julija; Kovaleva, Olga; Sergeev, Alexander; Cichoń-Pupienis, Anna

2017-08-01

The 98-km-long Curonian Spit is fronted by beaches mainly composed of quartz sand with minor high-density fractions. In this study heavy-mineral concentration (HMC) trends and grain-size statistical parameters were used to assess their role as indicators of natural processes, human activities, and patterns of longshore transport. A total of 92 surface sand samples were collected at 1 km intervals from the middle of the beach along the Baltic Sea shoreline of the spit between Klaipėda strait in Lithuania and Zelenogradsk in Russia. HMC contribution was assessed in the laboratory using bulk low-field magnetic susceptibility (MS) as a proxy for ferrimagnetic and paramagnetic mineral content. Quartz-dominated (background) sand is generally characterized by low MS values of κ < 50 μSI, whereas higher values κ > 150 μSI are typical for heavy-mineral-rich sand. The greatest MS values along the middle of the beach occur in the southern part of the spit and are 40 times higher than in the northern sector. This pattern suggests the existence of a longshore particle flux with HMC distribution having the potential as a useful tracer of longshore sediment transport. Local anomalously high MS excursions are associated with contribution of iron-rich materials from adjacent man-made structures. Therefore, temporally constrained HMC distribution along the middle of the beach reflects the cumulative effect of antecedent geologic framework, longshore sediment transfer, erosional and accretionary processes, wave and wind climate, and local coastal protective structures.

Use of Spatial Sampling and Microbial Source-Tracking Tools for Understanding Fecal Contamination at Two Lake Erie Beaches

USGS Publications Warehouse

Francy, Donna S.; Bertke, Erin E.; Finnegan, Dennis P.; Kephart, Christopher M.; Sheets, Rodney A.; Rhoades, John; Stumpe, Lester

2006-01-01

Source-tracking tools were used to identify potential sources of fecal contamination at two Lake Erie bathing beaches: an urban beach (Edgewater in Cleveland, Ohio) and a beach in a small city (Lakeshore in Ashtabula, Ohio). These tools included identifying spatial patterns of Escherichia coli (E. coli) concentrations in each area, determining weather patterns that caused elevated E. coli, and applying microbial source tracking (MST) techniques to specific sites. Three MST methods were used during this study: multiple antibiotic resistance (MAR) indexing of E. coli isolates and the presence of human-specific genetic markers within two types of bacteria, the genus Bacteroides and the species Enterococcus faecium. At Edgewater, sampling for E. coli was done during 2003-05 at bathing-area sites, at nearshore lake sites, and in shallow ground water in foreshore and backshore areas. Spatial sampling at nearshore lake sites showed that fecal contamination was most likely of local origin; E. coli concentrations near the mouths of rivers and outfalls remote to the beach were elevated (greater than 235 colony-forming units per 100 milliliters (CFU/100 mL)) but decreased along transport pathways to the beach. In addition, E. coli concentrations were generally highest in bathing-area samples collected at 1- and 2-foot water depths, midrange at 3-foot depths, and lowest in nearshore lake samples typically collected 150 feet from the shoreline. Elevated E. coli concentrations at bathing-area sites were generally associated with increased wave heights and rainfall, but not always. E. coli concentrations were often elevated in shallow ground-water samples, especially in samples collected less than 10 feet from the edge of water (near foreshore area). The interaction of shallow ground water and waves may be a mechanism of E. coli storage and accumulation in foreshore sands. Infiltration of bird feces through sand with surface water from rainfall and high waves may be concentrating E. coli in shallow ground water in foreshore and backshore sands. At Lakeshore, sampling for E. coli was done at bathing-area, nearshore lake, and parking-lot sites during 2004-05. Low concentrations of E. coli at nearshore lake sites furthest from the shoreline indicated that fecal contamination was most likely of local origin. High concentrations of E. coli in water and bed sediments at several nearshore lake sites showed that contamination was emanating from several points along the shoreline during wet and dry weather, including the boat ramp, an area near the pond drainage, and parking-lot sediments. Physical evidence confirmed that runoff from the parking lot leads to degradation of water quality at the beach. MST samples were collected to help interpret spatial findings and determine whether sources of fecal contamination were from wastewater or bird feces and if a human-specific marker was present. MAR indices were useful in distinguishing between bird feces and wastewater sources because they were about 10 times higher in the latter. The results from MAR indices agreed with results from the two human-specific markers in some but not all of the samples tested. Bacteroides and enterococci human-specific markers were found on one day at Edgewater and two days at Lakeshore. On three days at Edgewater and two days at Lakeshore, the MAR index indicated a mixed source, but neither marker was found in bathing-water samples; this may be because bacterial indicator concentrations were too low to detect a marker. Multiple tools are needed to help identify sources of fecal contamination at coastal beaches. Spatial sampling identified patterns in E. coli concentrations and yielded information on the physical pathways of contamination. MST methods provided information on whether the source was likely of human or nonhuman origin only; however, MST did not provide information on the pathways of contamination.

Economic impacts of anthropogenic activities on coastlines of the United States

USGS Publications Warehouse

Magoon, Orville T.; Williams, S. Jeffress; Lent, Linda K.; Richmond, James A.; Treadwell, Donald D.; Douglass, Scott L.; Edge, Billy L.; Ewing, Lesley C.; Pratt, Anthony P.

2004-01-01

Anthropogenic activities primarily impact coasts by reducing sediment inputs, altering sediment transport processes, and accelerating sediment losses to the offshore. These activities include: sand and gravel extraction, navigation and shore protection works; non-structural shoreline management strategies such as beach nourishment, sand by-passing and beach scraping, dams and flood control works; channel and inlet dredging; subsidence caused by fluid extraction and reduction of carbonate beach material. Although many of these activities have improved the quality of life, they also have had unintended effects on the coast. The issues that arise from human alterations of the coast are common to many coastal regions around the world; this paper draws from several areas of the United States to present an overview and provisional assessment of the economic consequences of anthropogenic activities along the Pacific coast.

116 years of misplaced management: Portballintrae, Northern Ireland

NASA Astrophysics Data System (ADS)

Jackson, D. W. T.

2012-04-01

Portballintrae has had a protracted history of human interference ranging from small-scale sand removal to hard coastal engineering. A small, horse shoe embayment and a once popular seaside destination on the north coast of Northern Ireland, it has suffered from progressive sediment loss over the last 116 years. From a once sediment abundant system, with a wide sandy beach, it now contains only a limited amount of sand draped over bedrock and/or gravel substrate and a relatively narrow beach. Installation of an obtrusive pier in its western section is thought to have interrupted the natural hydrody-namics and set in motion a progressive longshore transport and re-moval of sand into deeper water. Successive hard engineering 'solutions' prompted through public pressure and engineers keen to do business, have been largely ineffectual, located within a sediment-starved beach system.

Determination of gamma-emitting radionuclides in the inter-tidal sediments off Balochistan (Pakistan) Coast, Arabian Sea.

PubMed

Akram, M; Qureshi, Riffat M; Ahmad, Nasir; Solaija, Tariq Jamal

2007-01-01

Natural radionuclide contents of 226Ra, 228Ra and (40)K were studied for inter-tidal sediments collected from selected locations off the745 km long Balochistan Coast using HPGe detector based gamma-spectrometry system. The sampling zone extends from the beaches of Sonmiani (near Karachi metropolis) through Jiwani (close to the border of Iran). The natural radioactivity levels detected in various sediment samples range from 14.4 +/- 2.5 to 36.6 +/- 3.8 Bq kg(-1) for 226Ra, 9.8 +/- 1.2 to 35.2 +/- 2.0 Bq kg(-1) for (228)Ra and 144.6 +/- 9.4 to 610.5 +/- 23.9 Bq kg(-1) for (40)K. No artificial radionuclide was detected in any of the marine coastal sediment samples. 137Cs, (60)Co, 106Ru and 144Ce contents in sediment samples were below the limit of detection. The measured radioactivity levels are compared with those reported in the literature for coastal sediments in other parts of the world. The information presented in this paper will serve as the first ever local radioactivity database for the Balochistan/Makran Coastal belt of Pakistan. The presented data will also contribute to the IAEA's, Asia-Pacific Marine Radioactivity Database (ASPAMARD) and the Global Marine Radioactivity Database (GLOMARD).

Memory in coastal systems: Post-tsunami beach recovery within a decade on the Thai coast.

NASA Astrophysics Data System (ADS)

Switzer, A.; Gouramanis, C.; Bristow, C. S.; Jankaew, K.; Rubin, C. M.; Lee, Y.; Carson, S.; Pham, D. T.; Ildefonso, S.

2015-12-01

Do coastlines have memory? In this study we used a combination of remote sensing, field surveys and Ground Penetrating Radar (GPR) to reconstruct the recovery of beaches at Phra Thong Island, Thailand. The study site was severely impacted by the 2004 Indian Ocean Tsunami. Here we show that within a decade the beaches have completely recovered without any human intervention. We apply GPR to image periods of aggradation, progradation and washover sedimentation and match these with local events including a storm in 2007. At one location the beach has locally prograded at least 10m after partially blocking the mouth of a creek that was reamed out by the retreating tsunami. Here we also used GPR to image the scour and recovery of the coastal system (see figure). The rapid recovery of the barrier beach and local progradation indicate that sediment scoured by the tsunami was not transported far offshore but remained in the littoral zone within reach of fair-weather waves that returned to the beach naturally. In both cases coastal processes have reconstructed the beach-dune system to an almost identical pre-tsunami state in under a decade.

Short- and medium-term response to storms on three Mediterranean coarse-grained beaches

NASA Astrophysics Data System (ADS)

Grottoli, Edoardo; Bertoni, Duccio; Ciavola, Paolo

2017-10-01

The storm response of three Italian coarse-grained beaches was investigated to better understand the morphodynamics of coarse-clastic beaches in a microtidal context. Two of the studied sites are located on the eastern side of the country (Portonovo and Sirolo) and the third one (Marina di Pisa) is on the western side. Portonovo and Sirolo are mixed sand and gravel beaches where the storms approach from two main directions, SE and NE. Marina di Pisa is a coarse-grained, gravel-dominated beach, exposed to storms driven by SW winds. Gravel nourishments were undertaken in recent years on the three sites. Beach topography was monitored measuring the same network of cross sections at a monthly (i.e. short-term) to seasonal frequency (i.e. medium-term). Geomorphic changes were examined before and after storm occurrences by means of profile analyses and shoreline position evaluations. The beach orientation and the influence of hard structures are the main factors controlling the transport and accumulation of significant amount of sediments and the consequent high variability of beach morphology over the medium-term. For Marina di Pisa, storms tend to accumulate material towards the upper part of the beach with no shoreline rotation and no chance to recover the initial configuration. Sirolo and Portonovo showed a similar behaviour that is more typical of pocket beaches. Both beaches show shoreline rotation after storms in a clockwise or counter-clockwise direction according to the incoming wave direction. The wider and longer beach at Sirolo allows the accumulation of a thin layer of sediment during storms, rather than at Portonovo where, given its longshore and landward boundaries, the beach material tends to accumulate in greater thickness. After storms, Sirolo and especially Portonovo can quickly recover the initial beach configuration, as soon as another storm of comparable energy approaches from the opposite direction of the previous one. Large morphological variations after the storm on mixed sand and gravel beaches do not necessarily mean a slower recovery of surface topography and shoreline position. Considering that all the three beaches were recently nourished with gravel, it emerged that the differences between the nourishment and the native material, in terms of size and composition, seem to have an important influence on the dynamics of the sediment stock. Considering that recent studies have remarked the high abrasion rate of gravel, further understanding of the evolution of nourishment material with time is needed. The peculiar behaviour of gravel material artificially added to an originally sandy beach suggests the need to modify the widely used classification of Jennings and Shulmeister (2002) adding a fourth additional beach typology, which could represent human-altered beaches.

Hydrocarbons in sediments from the edge of the Bermuda platform

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sleeter, T.D.; Butler, J.N.; Barbash, J.E.

1979-01-01

Surficial and subsurface (10-13 cm) sediment samples were taken at seven stations (17 cores) on the northern margin of the Bermuda seamount, remote from ship traffic, beaches, and atmospheric fallout from aircraft. Their aliphatic (pentane-extractable) hydrocarbon content was very low, comparable with samples from the North Atlantic Abyssal plain, and two orders of magnitude lower than for typical coastal samples. About half of the aliphatic hydrocarbons are clearly biogenic, and the remainder are characteristic of petroleum residues. Petroleum hydrocarbon concentrations are lower in subsurface (e.g., 0.11 jg/g dry weight) than surface samples (0.47 jg/g), and are lower outside the reefmore » (0.25 jg/g) than inside (0.47 jg/g). These results are qualitatively consistent with a diffusion model. Extremely rapid bioturbation or totally quiescent deposition on a stable sedimentary facies can pobably be eliminated as hypotheses for the deposition and transport mechanism within the sediment. Further studies are needed to determine whether degradation is important.« less

Bacterial pathogen gene abundance and relation to recreational water quality at seven Great Lakes beaches.

PubMed

Oster, Ryan J; Wijesinghe, Rasanthi U; Haack, Sheridan K; Fogarty, Lisa R; Tucker, Taaja R; Riley, Stephen C

2014-12-16

Quantitative assessment of bacterial pathogens, their geographic variability, and distribution in various matrices at Great Lakes beaches are limited. Quantitative PCR (qPCR) was used to test for genes from E. coli O157:H7 (eaeO157), shiga-toxin producing E. coli (stx2), Campylobacter jejuni (mapA), Shigella spp. (ipaH), and a Salmonella enterica-specific (SE) DNA sequence at seven Great Lakes beaches, in algae, water, and sediment. Overall, detection frequencies were mapA>stx2>ipaH>SE>eaeO157. Results were highly variable among beaches and matrices; some correlations with environmental conditions were observed for mapA, stx2, and ipaH detections. Beach seasonal mean mapA abundance in water was correlated with beach seasonal mean log10 E. coli concentration. At one beach, stx2 gene abundance was positively correlated with concurrent daily E. coli concentrations. Concentration distributions for stx2, ipaH, and mapA within algae, sediment, and water were statistically different (Non-Detect and Data Analysis in R). Assuming 10, 50, or 100% of gene copies represented viable and presumably infective cells, a quantitative microbial risk assessment tool developed by Michigan State University indicated a moderate probability of illness for Campylobacter jejuni at the study beaches, especially where recreational water quality criteria were exceeded. Pathogen gene quantification may be useful for beach water quality management.

Spatial and temporal patterns of airflow across a foredune and beach surface under offshore winds: implications for aeolian sediment transport

NASA Astrophysics Data System (ADS)

Jackson, D.; Delgado-Fernandez, I.; Lynch, K.; Baas, A. C.; Cooper, J. A.; Beyers, M.

2010-12-01

The input of aeolian sediment into foredune systems from beaches represents a key component of sediment budget analysis along many soft sedimentary coastlines. Where there are significant offshore wind components in local wind regimes this is normally excluded from analysis. However, recent work has shown that if the topography of the foredune is favourable then this offshore component is steered or undergoes flow reversal through leeside eddying to give onshore transport events at the back beach under offshore flow conditions. At particular distances from the foredune crest flow reattaches to the surface to continue its incident offshore direction. The location of this reattachment point has important implications for aeolian transport of sand on the back beach and foredune toe locations. This study reports initial results where the positioning of the reattachment point is mobile and is driven by incident wind velocity (at the foredune crest) and the actual undulations of the foredune crest’s topography, dictating heterogeneous flow behaviour at the beach. Using detailed field measurements (25 Hz, three-dimensional sonic anemometry) and computational fluid dynamic modelling, a temporal and spatial pattern of reattachment positions are described. Implications for aeolian transport and dune evolution are also examined.

Past sea-level data from Lakse Bugt, Disko Island, West Greenland from ground-penetrating radar data

NASA Astrophysics Data System (ADS)

Souza, Priscila E.; Nielsen, Lars; Kroon, Aart; Clemmensen, Lars B.

2016-04-01

Beach-ridge deposits have been used as sea-level indicators in numerous studies from temperate coastal regions. However, their present surface morphology in artic regions may not accurately correspond to past sea-level, because subsequent surface erosion, solifluction processes and/or later sediment deposition may have altered the surface significantly. The internal structure of these beach ridges, however, is often well-preserved and thus constitutes an important key to reconstruction of past sea levels as seen elsewhere. In the present study, high-resolution reflection GPR data and high-precision topographic data were collected at Lakse Bugt (Disko Island, West Greenland) using a shielded 250 MHz antennae system and a RTK-Trimble R8 DGPS, respectively. Three transects were collected across a sequence of fossil, raised beach ridge deposits, and two transects were obtained across modern beach deposits at the shoreline of the mesotidal regime. Along all radar profiles we observed downlap reflection points, which we interpret to represent the boundary between sediments deposited on the beachface and sediments deposited in the upper shoreface regime. Both the upper shoreface and the beachface deposits exhibit reflection patterns dipping in the seaward direction. The beachface deposits show the strongest dip. At or just below the downlap points strong diffractions are often observed indicating the presence of a layer containing stones. These stones are large enough to generate significant signal scattering. At the present day beach a sharp transition defined by the presence of large stones is observed near the low tide water level: cobbles characterize the seaside, while the land side is characterized by sand and gravel. Therefore, it seems reasonable to conclude that downlap points observed in the GPR data serve as indicators of past low-tide levels (at the time of deposition). The downlap points show a consistent offset with respect to present surface topography indicating that the beach ridge deposits are well-preserved in our study area. Samples taken for OSL dating have not been dated yet. Instead, a first order age model for the investigated area is based on extrapolation of dating made by others at different sites on Disko Island. This extrapolated age model is used in a first attempt to reconstruct relative sea-level change at Lakse Bugt.

The Usumacinta-Grijalva beach-ridge plain in southern Mexico: a high-resolution archive of river discharge and precipitation

NASA Astrophysics Data System (ADS)

Nooren, Kees; Hoek, Wim Z.; Winkels, Tim; Huizinga, Annika; Van der Plicht, Hans; Van Dam, Remke L.; Van Heteren, Sytze; Van Bergen, Manfred J.; Prins, Maarten A.; Reimann, Tony; Wallinga, Jakob; Cohen, Kim M.; Minderhoud, Philip; Middelkoop, Hans

2017-09-01

The beach-ridge sequence of the Usumacinta-Grijalva delta borders a 300 km long section of the southern Gulf of Mexico coast. With around 500 beach ridges formed in the last 6500 years, the sequence is unsurpassed in the world in terms of numbers of individual ridges preserved, continuity of the record, and temporal resolution. We mapped and dated the most extensively accreted part of the sequence, linking six phases of accretion to river mouth reconfigurations and constraining their ages with 14C and OSL dating. The geomorphological and sedimentological reconstruction relied on lidar data, coring transects, GPR measurements, grain-size analyses, and chemical fingerprinting of volcanic glass and pumice encountered within the beach and dune deposits. We demonstrate that the beach-ridge complex was formed under ample long-term fluvial sediment supply and shorter-term wave- and aeolian-modulated sediment reworking. The abundance of fluvially supplied sand is explained by the presence of easily weatherable Los Chocoyos ignimbrites from the ca. 84 ka eruption of the Atitlán volcano (Guatemala) in the catchment of the Usumacinta River. Autocyclic processes seem responsible for the formation of ridge-swale couplets. Fluctuations in their periodicity (ranging from 6-19 years) are governed by progradation rate, and are therefore not indicative of sea level fluctuations or variability in storm activity. The fine sandy beach ridges are mainly swash built. Ridge elevation, however, is strongly influenced by aeolian accretion during the time the ridge is located next to the beach. Beach-ridge elevation is negatively correlated with progradation rate, which we relate to the variability in sediment supply to the coastal zone, reflecting decadal-scale precipitation changes within the river catchment. In the southern Mexican delta plain, the coastal beach ridges therefore appear to be excellent recorders of hinterland precipitation.

Mobilisation of toxic trace elements under various beach nourishments.

PubMed

Pit, Iris R; Dekker, Stefan C; Kanters, Tobias J; Wassen, Martin J; Griffioen, Jasper

2017-12-01

To enhance protection and maintain wide beaches for recreation, beaches are replenished with sand: so-called beach nourishments. We compared four sites: two traditional beach nourishments, a mega beach nourishment and a reference without beach nourishment. Two sites contain calcareous-rich sand, whereas the other two sites have calcareous-poor sand. We aimed to understand hydrogeochemical processes to indicate factors critical for the mobility of trace elements at nourishments. We therefore analysed the chemical characteristics of sediment and pore water to ascertain the main drivers that mobilise toxic trace elements. With Dutch Quality Standards for soil and groundwater, the characteristics of sediment and pore water were compared to Target Values (the values at which there is a sustainable soil quality) and Intervention Values (the threshold above which the soil's functions are at risk). The pore water characteristics revealed that Target Values were regularly exceeded, especially for the nourishment sites and mainly for Mo (78%), Ni (24%), Cr (55%), and As (21%); Intervention Values for shallow groundwater were occasionally exceeded for As (2%), Cr (2%) and Zn (2%). The sediment characteristics did not exceed the Target Values and showed that trace elements were mainly present in the fine fraction of <150 μm. The oxidation of sulphide minerals such as pyrite resulted into the elevated concentration for all nourishment sites, especially when an unsaturated zone was present and influence of rainwater was apparent. To prevent trace metal mobility at a mega beach nourishment it is important to retain seawater influences and limit oxidation processes. In this respect, a shoreface nourishment is recommended rather than a mega beach nourishment with a thick unsaturated zone. Consequently, we conclude that whether a site is carbonate-rich or carbonate-poor is unimportant, as the influence of seawater will prevent decalcification, creating a low risk of mobilisation of trace elements. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Variations of Morphologic Changes induced by Tropical Storm Debby along Three Barrier Island, West-Central Florida, USA

NASA Astrophysics Data System (ADS)

Wang, P.; Roberts, T.

2012-12-01

Tropical Storm Debby generated sustained high waves and elevated water levels for nearly three days from June 24th to 26th, 2012, inducing substantial changes in beach and nearshore morphology. In addition, the storm winds and high waves approached the coast from a highly oblique angle from the south, driving substantial northward longshore sand transport, opposite to the regional net annual southward transport. A total of 145 beach and nearshore profiles along 3 adjacent barrier islands were surveyed 2 weeks before and one week after the storm impact. Overall, dune, beach, intertidal, and immediate subtidal areas suffered erosion, while deposition was measured over the nearshore bar. Beach recovery in the form of ridge and runnel development occurred as the storm energy subsided. Substantial longshore variations of storm-induced beach changes were measured, including both severe dune/beach/berm erosion and storm berm accretion, and both onshore and offshore migration of nearshore bar. Factors controlling these longshore variations include: 1) the oblique approaching of the storm forcing, 2) pre-storm beach morphology and chronic erosional or accretional trends, 3) sediment supply, and 4) tidal inlet and beach interactions. Wide spreading dune scarping occurred along the 30-km studied coast. Based on the pre- and post-storm survey data, a balanced sediment budget is obtained accounting for sand volume loss from dune, beach, intertidal, and subtidal zones, and sand gains over the nearshore bar and along the northern sections of the beach.

Re-Evaluating the Geological Evidence for Late Holocene Marine Incursion Events along the Guerrero Seismic Gap on the Pacific Coast of Mexico

PubMed Central

Bianchette, Thomas A.

2016-01-01

Despite the large number of tsunamis that impact Mexico’s Pacific coast, stratigraphic studies focusing on geological impacts are scanty, making it difficult to assess the long-term risks for this vulnerable region. Surface samples and six cores were taken from Laguna Mitla near Acapulco to examine sedimentological and geochemical evidence for marine incursion events. Sediment cores collected from behind the beach barrier are dominated by intercalated layers of peat and inorganic sediments, mostly silt and clay, with little or no sand. Sand- and shell-rich clastic layers with high levels of sulfur, calcium, and strontium only occur adjacent to the relict beach ridge remnants near the center of the lagoon. With the exception of one thin fine sand layer, the absence of sand in the near-shore cores and the predominance of the terrigenous element titanium in the inorganic layers, evidently eroded from the surrounding hillslopes, suggests that these large-grained intervals do not represent episodic marine incursions, but rather were likely formed by the erosion and redeposition of older marine deposits derived from the beach ridge remnants when water levels were high. These results do not support the occurrence of a large tsunami event at Laguna Mitla during the Late Holocene. PMID:27571270

Re-Evaluating the Geological Evidence for Late Holocene Marine Incursion Events along the Guerrero Seismic Gap on the Pacific Coast of Mexico.

PubMed

Bianchette, Thomas A; McCloskey, Terrence A; Liu, Kam-Biu

2016-01-01

Despite the large number of tsunamis that impact Mexico's Pacific coast, stratigraphic studies focusing on geological impacts are scanty, making it difficult to assess the long-term risks for this vulnerable region. Surface samples and six cores were taken from Laguna Mitla near Acapulco to examine sedimentological and geochemical evidence for marine incursion events. Sediment cores collected from behind the beach barrier are dominated by intercalated layers of peat and inorganic sediments, mostly silt and clay, with little or no sand. Sand- and shell-rich clastic layers with high levels of sulfur, calcium, and strontium only occur adjacent to the relict beach ridge remnants near the center of the lagoon. With the exception of one thin fine sand layer, the absence of sand in the near-shore cores and the predominance of the terrigenous element titanium in the inorganic layers, evidently eroded from the surrounding hillslopes, suggests that these large-grained intervals do not represent episodic marine incursions, but rather were likely formed by the erosion and redeposition of older marine deposits derived from the beach ridge remnants when water levels were high. These results do not support the occurrence of a large tsunami event at Laguna Mitla during the Late Holocene.

Standing crop and sediment production of reef-dwelling foraminifera on O'ahu, Hawai'i

USGS Publications Warehouse

Harney, J.N.; Hallock, P.; Fletcher, C. H.; Richmond, B.M.

1999-01-01

Most of O'ahu's nearshore and beach sands are highly calcareous and of biogenic origin. The pale-colored constituent grains are the eroded remains of carbonate shells and skeletons produced by marine organisms living atop the island's fringing reefs and in the shallow waters near shore. Previous studies have shown that the tests of symbiont-bearing benthic foraminifera compose a substantial portion (up to one-fourth) of these organically produced sands. We sampled a variety of reef flat and slope habitats to obtain standing-crop data and production estimates for several sand-producing genera of reef-dwelling foraminifera. We found that modern communities of these shelled protists occur in dense numbers islandwide, reaching densities up to 105 individuals per square meter of suitable substrate in the more productive habitats. Further research on the contribution of foraminifera to beach, nearshore, and offshore sands is planned for O'ahu and neighboring islands to describe their roles in the sediment budget more completely.

Hawaii Beach Monitoring Program: Beach Profile Data

USGS Publications Warehouse

Gibbs, Ann E.; Richmond, Bruce M.; Fletcher, Charles H.; Hillman, Kindra P.

2001-01-01

Coastal erosion is widespread and locally severe in Hawaii and other low-latitude areas. Typical erosion rates in Hawaii are in the range of 15 to 30 cm/yr (0.5 to 1 ft/yr; Hwang, 1981; Sea Engineering, Inc., 1988; Makai Ocean Engineering, Inc. and Sea Engineering, Inc.,1991). Recent studies on Oahu (Fletcher et al., 1997; Coyne et al., 1996) have shown that nearly 24%, or 27.5 km (17.1 mi) of an original 115 km (71.6 mi) of sandy shoreline (1940's) has been either significantly narrowed (17.2 km; 10.7 mi) or lost (10.3 km; 6.4 mi). Nearly one-quarter of the islands' beaches have been significantly degraded over the last half-century and all shorelines have been affected to some degree. Oahu shorelines are by far the most studied, however, beach loss has been identified on the other islands as well, with nearly 13 km (8 mi) of beach likely lost due to shoreline hardening on Maui (Makai Engineering, Inc. and Sea Engineering, Inc., 1991). Causes of coastal erosion and beach loss in Hawaii are numerous but, unfortunately, poorly understood and rarely quantified. Construction of shoreline protection structures limits coastal land loss, but does not alleviate beach loss and may actually accelerate the problem by prohibiting sediment deposition in front of the structures. Other factors contributing to beach loss include: a) reduced sediment supply; b) large storms; and, c) sea-level rise. Reduction in sand supply, either from landward or seaward (primarily reef) sources, can have a myriad of causes. Obvious causes such as beach sand mining and emplacement of structures that interrupt natural sediment transport pathways or prevent access to backbeach sand deposits, remove sediment from the active littoral system. More complex issues of sediment supply can be related to reef health and carbonate production which, in turn, may be linked to changes in water quality. Second, the accumulated effect of large storms is to transport sediment beyond the littoral system. Third, rising sea level leads to a natural landward migration of the shoreline. Dramatic examples of coastal erosion, such as houses and roads falling into the sea, are rare in Hawaii, but the impact of erosion is still very serious. The signs of erosion are much more subtle and typically start as a "temporary" hardening structure designed to mitigate an immediate problem which, eventually, results in a proliferation of structures along a stretch of coast. The natural ability of the sandy shoreline to respond to changes in wave climate is lost. The overall goals of this study are to document the coastal erosion history in Hawaii, determine the causal factors of that erosion, provide high-quality data for other "end-users" in applied studies (i.e. coastal engineers, planners, and managers), and increase our general understanding of low-latitude coastal geologic development. This project involves close cooperation between the USGS Coastal and Marine Geology Program and the University of Hawaii.

Variability of sediment transport in beach and coastal dune environments, Brittany, France

NASA Astrophysics Data System (ADS)

Regnauld, Hervé; Louboutin, Roland

2002-06-01

On the coasts of Brittany (English Channel and Bay of Biscay), barrier systems were surveyed between 1995 and 2000. The beach profiles have a very high variability, which cannot be statistically explained by linear correlation with the wind, the waves, or the tides. The behaviour of the profile is represented on a phase diagram (speed of profile change: Y-axis, thickness of the profile: X-axis). The points in the center of the profile "rotate" around an average equilibrium which is seldom measured in the field. The seaward edge of the beaches oscillates between loss and gain, but with a net positive budget. The landward top of the beach displays a range of oscillations. The dunes always have a positive budget. The whole behaviour of the system is explained if the precise succession of anticyclonic and cyclonic winds is taken into account. Long periods of easterly winds (offshorewards) tend to produce a calm sea and to increase tidal sediment settling on the seafloor. If an onshore westerly storm occurs just after such a period, it hits a sediment-rich environment and produces a net accumulation on both the beach and the dunes. Periods of westerly calm to moderate winds do not help accumulation: a full going storm will hit a depleted environment and produce erosion. The speed of dune accretion and the budget of the beaches seem to partly depend on the ratio of cyclonic to anticyclonic conditions.

The role of beach morphodynamic state on infragravity swash on beaches: field observations.

NASA Astrophysics Data System (ADS)

Gomes da Silva, Paula; González, Mauricio; Medina, Raul

2017-04-01

The runup generated by waves can be defined as the maximum height above sea water level on the coastline and is an important criterion for costal structures/nourishment design and erosion/flooding risk analysis. Given the complexity of nonlinear processes involved in the runup generation, its prediction is commonly made by means of empirical formulations that relate wave and beach parameters. The most accepted parametrization presented till the moment was proposed by Stockdon et al. (2006), in which the runup exceeded by 2 percent of the waves (R2) is described in terms of setup (η - the steady superelevation of the mean water level caused by breaking waves) and incident and infragravity swash (Sinc and Sig- time-varying fluctuations around the setup caused by non-breaking waves). Such formulation has been widely accepted and its efficiency was appraised in many works. Nevertheless, although empirical parametrization of infragravity swash using incident wave's parameters shows reasonable skill, the correlation can still present considerable scatter. The amount of infragravity energy on swash is directly related to the morphodynamic beach state, in a way that beach profiles classified as reflective (low wave energy, coarse sediment and higher beach slope) tend to show lower Sig values than dissipative ones (high wave energy, fine sediment and lower beach slope). However, since Stockdon's formula for predicting infragravity swash consider only wave parameters, its use implies that beaches receiving the same wave energy but with different grain size and beach slope would present the same Sig values. This work assumed the hypothesis that the scatter verified on the predictions of the infragravity swash is mainly related to the lack of information about the beach state in Stockdon formula. Based on that, a field campaign was designed and carried out in Somo-El Puntal beach, north Spain, with the aim of generating data to be analyzed in terms of infragravity swash. An important aspect about this field site is that, given the gradient of wave energy that reaches each part of the beach, it can present many morphodynamic states simultaneously, allowing a high range of measurements in a single beach. Thus, wave, currents, sediment and runup data were measured in three different profiles, as well as the whole beach topography, bathymetry and video camera images. These data, summed to those available from Stockdon study, were used to verify the validity of the hypothesis and to propose a new approach for empirically determining infragravity swash on beaches.

Development of a Coastal Inventory in Greece

NASA Astrophysics Data System (ADS)

Karditsa, Aikaterini; Poulos, Serafim; Velegrakis, Adonis; Ghionis, George; Petrakis, Stelios; Alexandrakis, George; Andreadis, Olympos; Monioudi, Isavella

2015-04-01

Greek coastline that accounts more than 16.000 km hosts hundreds of beaches, which constitute a great touristic destination. However, no gathered information exists relative to its qualitative and quantitative characteristics (e.g. physicogeographical characteristics, artificial structures, nearby land use). Therefore, the development of a coastal database that would successfully concentrate all relative data, in the form of a National Inventory, could be a valuable tool for the management and the sustainable use and exploitation of beaches and the coastal zone. This work presents an example of the development of a beach inventory in the case of the beach zones of Heraklion and Lassithi counties in the Island of Crete, which is one of the most touristic areas in Greece. Data were initially abstracted from satellite images and combined with in situ observations carried out along 98 beaches with shoreline length >100 m. The collected data included geomorphological, topographic and bathymetric mapping, sediment sampling from the subaerial and underwater part and recording of artificial structures. The initial mapping showed that beaches represent only the 18%, with 74% of the total coastline to be rocky while 8% of the coastline host some kind of artificial intervention. The combination of satellite and in situ mapping led to the development of a coastal geomorphological map. Beach widths were found to be limited with the majority of beaches (59%) to have maximum widths less than 25 m, 35% to range between 25 and 50m and about 6% with maximum widths >50m. Concerning beach length, the threshold of 1000 m is overcome only by the 46% of the beaches. Beaches with very smooth slopes (<2.5) are infrequent (~6%), whilst beaches with low slopes (2.5-5%) are the majority (42%) along with beaches with moderate slopes (5-7.5%) that account approximately the 32%. Beaches with high slopes (7.5-10%) are about 11%, whereas very high slopes and extremely high slopes are much less being equally to 6% and 3%, respectively. With respect to beach position, the majority of the south beaches are characterized by slopes of 5-7.5%,, whilst most of the north beaches present lower slopes in the order of 2.5-5%. In terms of sediment texture, 41% of the beaches were found to consist mostly of medium and coarse sands (gS and (g)S) and 31% of gravels with some sand presence ((s)G and sG). The exclusively sandy beaches correspond to the 11% when the exclusively gravelly beaches accounts for 16%. North sided beaches were found to be more fine grained compared to the south beaches; this most probably is due to the more persistent wave regime. The main human interventions along the coast of the study area are associated with four main ports (Heraklion, Ag. Nikolaos, Sitia and Ierapetra) and twelve small fishing ports (twelve in the north, one in the east and eight in the south), coastal residential and touristic development, coastal protection works and river management schemes. The study is supported by the project BEACHTOUR (11SYN- 8-1466) of the Operational Program Cooperation 2011, Competitiveness and Entrepreneurship" co-funded by the European Regional Development Fund (ERDF) and the Ministry of Education and Relegious Affairs.

Impacts of category 5 tropical cyclone Fantala (April 2016) on Farquhar Atoll, Seychelles Islands, Indian Ocean

NASA Astrophysics Data System (ADS)

Duvat, Virginie K. E.; Volto, Natacha; Salmon, Camille

2017-12-01

This paper provides new insights on the impacts of a category 5 tropical cyclone on Indian Ocean atoll reef islands. Using multi-date aerial imagery and field observations, the contribution of tropical cyclone Fantala to shoreline and island change, and to sediment production and transport, was assessed on Farquhar Atoll, Seychelles Islands. Results show that the two largest islands (> 3 km2) only suffered limited land loss (- 1.19 to - 8.35%) while small islets lost 13.17 to 28.45% of their initial land area. Islands and islets exhibited contrasting responses depending on their location, topography and vegetation type. Depending on islands, the retreat of the vegetation line occurred either along all shorelines, or along ocean shoreline only. The structure (wooded vs. grassy) and origin (native vs. introduced) of the vegetation played a major role in island response. Five days after the cyclone, beach width and beach area were multiplied by 1.5 to 10, depending on the setting, and were interpreted as resulting from both sediment reworking and the supply of large amounts of fresh sediments by the reef outer slopes to the island system. Fourth months after the cyclone, extended sheets of loose sediments were still present on the reef flat and in inter-islet channels and shallow lagoon waters, indicating continuing sediment transfer to islands. As a reminder (see Section 3.1.4), beach width uncertainty equals to 6 m for all beach sections.

Low-canopy seagrass beds still provide important coastal protection services.

PubMed

Christianen, Marjolijn J A; van Belzen, Jim; Herman, Peter M J; van Katwijk, Marieke M; Lamers, Leon P M; van Leent, Peter J M; Bouma, Tjeerd J

2013-01-01

One of the most frequently quoted ecosystem services of seagrass meadows is their value for coastal protection. Many studies emphasize the role of above-ground shoots in attenuating waves, enhancing sedimentation and preventing erosion. This raises the question if short-leaved, low density (grazed) seagrass meadows with most of their biomass in belowground tissues can also stabilize sediments. We examined this by combining manipulative field experiments and wave measurements along a typical tropical reef flat where green turtles intensively graze upon the seagrass canopy. We experimentally manipulated wave energy and grazing intensity along a transect perpendicular to the beach, and compared sediment bed level change between vegetated and experimentally created bare plots at three distances from the beach. Our experiments showed that i) even the short-leaved, low-biomass and heavily-grazed seagrass vegetation reduced wave-induced sediment erosion up to threefold, and ii) that erosion was a function of location along the vegetated reef flat. Where other studies stress the importance of the seagrass canopy for shoreline protection, our study on open, low-biomass and heavily grazed seagrass beds strongly suggests that belowground biomass also has a major effect on the immobilization of sediment. These results imply that, compared to shallow unvegetated nearshore reef flats, the presence of a short, low-biomass seagrass meadow maintains a higher bed level, attenuating waves before reaching the beach and hence lowering beach erosion rates. We propose that the sole use of aboveground biomass as a proxy for valuing coastal protection services should be reconsidered.

Characterizing storm response and recovery using the beach change envelope: Fire Island, New York

USGS Publications Warehouse

Brenner, Owen T.; Lentz, Erika; Hapke, Cheryl J.; Henderson, Rachel; Wilson, Kathleen; Nelson, Timothy

2018-01-01

Hurricane Sandy at Fire Island, New York presented unique challenges in the quantification of storm impacts using traditional metrics of coastal change, wherein measured changes (shoreline, dune crest, and volume change) did not fully reflect the substantial changes in sediment redistribution following the storm. We used a time series of beach profile data at Fire Island, New York to define a new contour-based morphologic change metric, the Beach Change Envelope (BCE). The BCE quantifies changes to the upper portion of the beach likely to sustain measurable impacts from storm waves and capture a variety of storm and post-storm beach states. We evaluated the ability of the BCE to characterize cycles of beach change by relating it to a conceptual beach recovery regime, and demonstrated that BCE width and BCE height from the profile time series correlate well with established stages of recovery. We also investigated additional applications of this metric to capture impacts from storms and human modification by applying it to several post-storm historical datasets in which impacts varied considerably; Nor'Ida (2009), Hurricane Irene (2011), Hurricane Sandy (2012), and a 2009 community replenishment. In each case, the BCE captured distinctive upper beach morphologic change characteristic of these different beach building and erosional events. Analysis of the beach state at multiple profile locations showed spatial trends in recovery consistent with recent morphologic island evolution, which other studies have linked with sediment availability and the geologic framework. Ultimately we demonstrate a new way of more effectively characterizing beach response and recovery cycles to evaluate change along sandy coasts.

The influence of anthropic actions on the evolution of an urban beach: Case study of Marineta Cassiana beach, Spain.

PubMed

Pagán, J I; Aragonés, L; Tenza-Abril, A J; Pallarés, P

2016-07-15

Coastal areas have been historically characterized as being a source of wealth. Nowadays, beaches have become more relevant as a place for rest and leisure. This had led to a very high population pressure due to rapid urbanisation processes. The impacts associated with coastal tourism, demand the development of anthropic actions to protect the shoreline. This paper has studied the impacts of these actions on the Marineta Cassiana beach, in Denia, Spain. This particular Mediterranean beach has traditionally suffered a major shoreline regression, and the beach nourishments carried out in the 1980s would not have achieved the reliability desired. This research has analysed the historic evolution of the beach and its environment for a period of 65years (1950-2015). A Geographic Information System (GIS) has been used to integrate and perform a spatial analysis of urban development, soil erosion, stream flow, swell, longshore transport, submerged vegetation species and shoreline evolution. The results show how the anthropic actions have affected the shoreline. After the excessive urban development of the catchments, there is no natural sediment supply to the beach. The change in the typology of the sediment, from pebbles to sand, during the beach nourishments has led to a crucial imbalance in the studied area. Moreover, the beach area gained has disappeared, affecting the Posidonia oceanica meadow, and incrementing the erosion rates. The findings obtained are relevant, not only in the management and maintenance of the beaches, but also, in the decision-making for future nourishments. Copyright © 2016 Elsevier B.V. All rights reserved.

75 FR 38501 - The Release of the Final Environmental Impact Statement (FEIS) for the Town of Nags Head Proposed...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-02

... cubic yards of beach-quality sediment from an offshore borrow source, and deposit the material along... dredging operations and discharge the sand on the beach via submerged pipeline. The applicant's proposed borrow areas include sites identified as having beach quality material in the U.S. Army Corps of...

Southwest Washington littoral drift restoration—Beach and nearshore morphological monitoring

USGS Publications Warehouse

Stevens, Andrew W.; Gelfenbaum, Guy; Ruggiero, Peter; Kaminsky, George M.

2012-01-01

A morphological monitoring program has documented the placement and initial dispersal of beach nourishment material (280,000 m3) placed between the Mouth of the Columbia River (MCR) North Jetty and North Head, at the southern end of the Long Beach Peninsula in southwestern Washington State. A total of 21 topographic surveys and 8 nearshore bathymetric surveys were performed between July 11, 2010, and November 4, 2011. During placement, southerly alongshore transport resulted in movement of nourishment material to the south towards the MCR North Jetty. Moderate wave conditions (significant wave height around 4 m) following the completion of the nourishment resulted in cross-shore sediment transport, with most of the nourishment material transported into the nearshore bars. The nourishment acted as a buffer to the more severe erosion, including dune overtopping and retreat, that was observed at the northern end of the study area throughout the winter. One year after placement of the nourishment, onshore transport and beach recovery were most pronounced within the permit area and to the south toward the MCR North Jetty. This suggests that there is some long-term benefit of the nourishment for reducing erosion rates locally, although the enhanced recovery also could be due to natural gradients in alongshore transport causing net movement of the sediment from north to south. Measurements made during the morphological monitoring program documented the seasonal movement and decay of nearshore sand bars. Low-energy conditions in late summer resulted in onshore bar migration early in the monitoring program. Moderate wave conditions in the autumn resulted in offshore movement of the middle bar and continued onshore migration of the outer bar. High-energy wave conditions early in the winter resulted in strong cross-shore transport and creation of a 3-bar system along portions of the coast. More southerly wave events occurred later in the winter and early spring and coincided with the complete loss of the outer bar and net loss of sediment from the study area. These data suggest that bar decay may be an important mechanism for exporting sediment from Benson Beach north to the Long Beach Peninsula. The measurements presented in this report represent one component of a broader monitoring program designed to track the movement of nourishment material on the beach and shoreface at this location, including continuous video monitoring (Argus), in situu measurements of hydrodynamics, and a physical tracer experiment. Field data from the monitoring program will be used to test numerical models of hydrodynamics and sediment transport and to improve the capability of numerical models to support regional sediment management.

Beach ridge sedimentology: field observation and palaeoenvironmental interpretation for Anegada Island, British Virgin Islands.

NASA Astrophysics Data System (ADS)

Cescon, Anna Lisa; Cooper, J. Andrew G.; Jackson, Derek W. T.

2014-05-01

Beach ridge landforms have been observed in different environments and in settings that range from polar to tropical. Their stratigraphy and sedimentology has received a limited amount of discussion in the literature (Tamura, 2012). In coastal geomorphology a beach ridge can be seen as a transitional deposit between onshore and offshore environments. They are regarded as representing high level wave action along a coastline. In the Caribbean the origin of beach ridges has been variously attributed to one of three extreme wave events: extreme swell, extreme storm or tsunami waves. Beach ridges are arranged in beach ridge plains where there is succession of the landforms and can be several kilometres long. Beach ridge accumulation is not continuous and the coast shows alternating accretion and erosion periods. The use of beach ridges as palaeostorm archives is therefore not straightforward. The temporal continuity of beach ridge formation is being assessed on the beach ridge plains of Anegada, British Virgin Islands (Lesser Antilles). This carbonate platform surrounded by a fringing reef contains two beach ridge plains. There are more than 30 ridges in the Atlantic facing- coast and around 10 in the south, Caribbean- facing coast. The sediments of the modern beaches are dominated by the sand fraction and are 100% biogenic origin due to the isolation of Anegada from terrestrial sediment sources. The beach ridge sections have been studied in different area of Anegada beach ridge plains and present low angle seaward-dipping bedding. The sand fraction is dominant in the stratigraphy with a few intact shells. At only one site were coral pebbles deposited in association with the sand fraction. Aeolian deposits represent the upper part of the beach ridges and reflect the stabilization of the beach ridges with ongoing accretion. The sedimentology of the contemporary beach and dunes will be discussed in terms of their implications for understanding beach ridge genesis and its relationship to extreme wave events. Tamura, T., 2012. Beach ridges and prograded beach deposits as palaeoenvironment records. Earth-Science Reviews, 114, pp. 279-297.

Coastal loading and transport of Escherichia coli at an embayed beach in Lake Michigan

USGS Publications Warehouse

Ge, Z.; Nevers, M.B.; Schwab, D.J.; Whitman, R.L.

2010-01-01

A Chicago beach in southwest Lake Michigan was revisited to determine the influence of nearshore hydrodynamic effects on the variability of Escherichia coli (E. coli) concentration in both knee-deep and offshore waters. Explanatory variables that could be used for identifying potential bacteria loading mechanisms, such as bed shear stress due to a combined wave-current boundary layer and wave runup on the beach surface, were derived from an existing wave and current database. The derived hydrodynamic variables, along with the actual observed E. coli concentrations in the submerged and foreshore sands, were expected to reveal bacteria loading through nearshore sediment resuspension and swash on the beach surface, respectively. Based on the observation that onshore waves tend to result in a more active hydrodynamic system at this embayed beach, multiple linear regression analysis of onshore-wave cases further indicated the significance of sediment resuspension and the interaction of swash with gull-droppings in explaining the variability of E. coli concentration in the knee-deep water. For cases with longshore currents, numerical simulations using the Princeton Ocean Model revealed current circulation patterns inside the embayment, which can effectively entrain bacteria from the swash zone into the central area of the embayed beach water and eventually release them out of the embayment. The embayed circulation patterns are consistent with the statistical results that identified that 1) the submerged sediment was an additional net source of E. coli to the offshore water and 2) variability of E. coli concentration in the knee-deep water contributed adversely to that in the offshore water for longshore-current cases. The embayed beach setting and the statistical and numerical methods used in the present study have wide applicability for analyzing recreational water quality at similar marine and freshwater sites. ?? 2010 American Chemical Society.

Hurricane effects on the coastline from Cabo San Lucas Bay, Baja California Peninsula, Mexico

NASA Astrophysics Data System (ADS)

Nava-Sanchez, Enrique; Navarro-Lozano, Octavio; Murillo-Jimenez, Janette; Godinez-Orta, Lucio

2010-05-01

Cabo San Lucas, located on the southern tip of the Baja California Peninsula, is on the track of two to five hurricanes per year. Thus the purpose of this work was to evaluate the effects of hurricanes on the stability of the coastline of San Lucas Bay. We apply GIS for determining inland geomorphology and conducted bathymetric surveys for the marine area. Results from previous sedimentological researches of fluvial, littoral and shallow marine environments were reanalyzed to determine the sedimentary processes responsible for the stability of the coastline. Also, we were monitoring beach profiles in the bay and also other beaches from the tip of the peninsula from 1997 to 2004 and recorded the effects of Hurricane Juliette in 2001 (category 3 in the Saffir-Simpson scale), which left an accumulative precipitation of 850 mm and formed waves of 8 m in height during the four days of maximum impact. We found out that inland and marine geomorphology, as well as littoral and alluvial sediment transport play a major role to keep the coastline relatively stable for at least the last 3,000 years. Geomorphology of the drainage basin is steep favoring the formation of flash floods that feed an alluvial fan to finally discharge sediments to the San Lucas Bay where a temporal fan-delta is developed during catastrophic rains. Marine morphology is dominated by the San Lucas submarine canyon, located on the southern half of the bay, whose canyon head is just at the foot of the beach (4 to 6 m in depth). On the northern half, there is a narrow submarine terrace with a break 40 m deep, covered mostly by fluvial sediments. At the littoral, there is only one dune ridge which is almost continuous and only cut by the arroyo. The dune ridge was dated at two levels; at the bottom, just above Pleistocene fluvial sediments and at the top, giving dates of 3200 and 800 years respectively. These dates are interpreted as an evidence for the stability of the dune ridge. The sand from the beach, responsible for the coastline stability, is sourced by two processes: (1) the littoral drift bringing sand from the Pacific coast, which turns around San Lucas Cape and enters the bay, process that is continuous, with stronger events every 3 to 7 years (matching ENSO cycles) following seasonal periods of heavy cyclonic rains that favor important fluvial sediment discharges; and (2) direct input of fluvial sediments, discharged by the El Salto arroyo during catastrophic hurricane rains with returning periods of 50 years. The canyon head traps most of the sediment "excess" of the beach system. Winter waves erode the beach and generate a weak littoral transport to the south where sediments are trapped by the canyon head. Also, because the mouth of the El Salto arroyo is just in front of the canyon head, the debris flows during catastrophic rains are dumped on the canyon and a small portion remains to form a fan delta whose sediments are later removed by waves to feed the eroded beach in both direccions, as we observed during the path of Hurricane Juliette.

Sediment transport in the area of the Sopot pier

NASA Astrophysics Data System (ADS)

Przyborska, Anna; Jakacki, Jaromir; Andrzejewski, Jan

2017-04-01

Coastal sediment transport is a natural process that appears when energy of waves is sufficient for moving solid particles from the bottom. Sediment transport rate depends on the median diameter of local sand and it is compatible with the direction of wave propagation. Also it is natural, that any protruded from the beach construction disturbs continuity of beach transport caused by waves. The Sopot pier has been built over 100 years ago and it is the longest wooden pier on the Baltic Sea coast, it is about half kilometre long. The pier is located at the end of the Monte Casino street and it is one of the biggest attractions of the city as well as in the country. In the past and now we have observed the disturbed sediment transport in the area of the Sopot pier. But during recent years, this process has gained greater momentum. The beach at the Sopot pier has been growing by several meters. All indicates that the cause of the observed phenomenon is the marina. The marina structure which is in some distance from the shore, has been acting as a powerful, emerged breakwater boundary. As a tool the sediment transport model was implemented for Sopot pier area. The implemented numerical forecasting sediment transport model in the area of the Sopot pier reflects well the deposit growth rate for the archived data from 2010 to 2015. On the basis of differences in bathymetry data provided by the Maritime office and the analysis the model results the average deposits in accumulation in the pear area was determined to be about 16,000 m3 / year for the assumed area of analysis, the model have shown similar result. The analysis suggests that strong winds generating significant waves as well as meaningful sediment transport dominate in the autumn and winter. You cannot, however, rule out strong waves in summer. Under moderate waves the sediment transport is insignificant. The most intense movement of the sediment is observed in the vicinity of the shoreline, it disappears with distance from the shoreline. Numerical sediment transport model DHI MIKE also shows that the Sopot marina generates a 'shadow' of waves. The shadow causes a disturbance in the continuity of natural sediment transport along the beach, the consequence of which is the creation of the sand shapes at the bottom in the form of convexity of coastline known as a spit. The model results also shows that 80% of the accumulated sand near the pier come from local beaches south-east of the pier. The remaining 20% was transported from the north-west. The direction of sediment transport corresponds to the directions of local waves

SBEACH: Numerical Model for Simulating Storm-Induced Beach Change. Report 1. Empirical Foundation and Model Development

DTIC Science & Technology

1989-07-01

such as the complex fluid motion over aii irregular bottom and absence of rigorous descriptions of broken waves and sediment-sediment interaction, also...prototype-scale conditions. The tests were carried out with both monochromatic and irregular waves for a dunelike foreshore with and without a...significant surf zone. For one case starting from a beach without "fore- shore," monochromatic waves produced a bar, whereas irregular waves of significant

The physical characteristics of the sediments on and surrounding Dauphin Island, Alabama

USGS Publications Warehouse

Ellis, Alisha M.; Marot, Marci E.; Smith, Christopher G.; Wheaton, Cathryn J.

2017-06-20

Scientists from the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center collected 303 surface sediment samples from Dauphin Island, Alabama, and the surrounding water bodies in August 2015. These sediments were processed to determine physical characteristics such as organic content, bulk density, and grain-size. The environments where the sediments were collected include high and low salt marshes, washover deposits, dunes, beaches, sheltered bays, and open water. Sampling by the USGS was part of a larger study to assess the feasibility and sustainability of proposed restoration efforts for Dauphin Island, Alabama, and assess the island’s resilience to rising sea level and storm events. The data presented in this publication can be used by modelers to attempt validation of hindcast models and create predictive forecast models for both baseline conditions and storms. This study was funded by the National Fish and Wildlife Foundation, via the Gulf Environmental Benefit Fund.This report serves as an archive for sedimentological data derived from surface sediments. Downloadable data are available as Excel spreadsheets, JPEG files, and formal Federal Geographic Data Committee metadata.

Dating High Arctic Holocene relative sea level changes using juvenile articulated marine shells in raised beaches

NASA Astrophysics Data System (ADS)

Long, Antony J.; Strzelecki, Mateusz C.; Lloyd, Jerry M.; Bryant, Charlotte L.

2012-08-01

High Arctic raised beaches provide evidence for changes in relative sea-level (RSL), sea-ice extent, storminess, and variations in sediment supply. In many High Arctic areas, driftwood and whale bone are usually the preferred targets for radiocarbon dating, with marine shells a third choice because of their often large age and height uncertainties with respect to former sea level. Here we detail a new approach to sampling marine shells that reduces these problems by targeting juvenile, articulated specimens of Astarte borealis that are washed onto the beach under storm conditions and become incorporated into the beach crest. Radiocarbon dates from articulated valves of A. borealis from eight raised beaches from Billefjorden, Svalbard, provide a chronology for Holocene beach ridge formation and RSL change that compares favourably to the most precise records developed from elsewhere in Svalbard using driftwood or whale bone. We demonstrate the value of this new approach by comparing our record with previously published RSL data from eastern Svalbard to test different models of Late Weichselian ice load in this region. We find support for a major ice dome centred south and east of Kong Karls Land but no evidence for a significant ice dome located over easternmost Spitsbergen or southern Hinlopen Strait as proposed from recent marine geophysical survey. The approach is potentially applicable elsewhere in Svalbard and the High Arctic to address questions of RSL change and beach ridge chronology, and hence wider questions regarding palaeoclimate and ice load history.

A field study of large-scale oscillation ripples in a very coarse-grained, high-energy marine environment

USGS Publications Warehouse

Hirschaut, D.W.; Dingler, J.R.

1982-01-01

Monastery Beach, Carmel, California is a pocket beach that sits within 200 m of the head of Carmel Submarine Canyon. Coarse to very coarse sand covers both the beach and adjacent shelf; in the latter area incoming waves have shaped the sand into large oscillation ripples. The accessibility of this area and a variable wave climate produce a unique opportunity to study large-scale coarse-grained ripples in a high-energy environment. These ripples, which only occur in very coarse sand, form under the intense, wave-generated currents that exist during storm conditions. Once formed, these ripples do not significantly change under lower energy waves. On three separate occasions scuba divers measured ripples and collected sand samples from ripple crests near fixed reference stakes along three transects. Ripple wavelength and grain size decreased with an increase in water depth. Sediment sorting was best closest to the surf zone and poorest at the rim of Carmel Canyon. Cobbles and gravel observed in ripple troughs represent lag deposits. Carmel Canyon refracts waves approaching Monastery Beach such that wave energy is focused towards the northern and southern portions of the beach, leaving the central part of the beach lower in energy. This energy distribution causes spatial variations in the ripples and grain sizes with the shortest wavelengths and smallest grain sizes being in the central part of the shelf.

Lithology and base of the surficial aquifer system, Palm Beach County, Florida

USGS Publications Warehouse

Miller, Wesley L.

1987-01-01

The surficial aquifer system is a major source of freshwater in Palm Beach County. In 1982, public supply withdrawals from the aquifer system totaled 33,543 million gallons, 77.5% of total public supply withdrawals. To evaluate the aquifer system and its geologic framework, a cooperative study with Palm Beach County was begun in 1982 by the U.S. Geological Survey. The surficial aquifer system in Palm Beach County is composed primarily of sand, sandstone, shell, silt, calcareous clay (marl), and limestone deposited during the Pleistocene and Pliocene epochs. In the western two-thirds of Palm Beach County, sediments in the aquifer system are poorly consolidated sand, shell, and sandy limestone. Owing to interspersed calcareous clays and silt and very poorly sorted materials, permeabilities in this zone of the aquifer system are relatively low. Two other zones of the aquifer system are found in the eastern one-third of the county where the sediments are appreciably more permeable than in the west due to better sorting and less silt and clay content. The location of more detailed lithologic logs for wells in these sections, along with data from nearby wells, allowed enhanced interpretation and depiction of the lithology which had previously been generalized. The most permeable zone of the aquifer system in this area is characterized by highly developed secondary porosity where infiltrating rainwater and solution by groundwater have removed calcitic-cementing materials from the sediments to produce interconnected cavities. Increased permeability in the aquifer system is generally coincident with the eastern boundary of the overlying organic soils and Lake Flirt Marl. Lithologic logs of wells in Palm Beach County indicate that sediments forming the aquifer system were deposited directly on the erosional surface of the Hawthorn Formation in some areas. In other locations in the county, lithologic logs indicate that the base of the aquifer system was formed by fluvial deposits containing erosional materials from the Tamiami and Hawthorn Formations and Caloosahatchee Marl. (Lantz-PTT)

Beachrock occurrence, characteristics, formation mechanisms and impacts

NASA Astrophysics Data System (ADS)

Vousdoukas, M. I.; Velegrakis, A. F.; Plomaritis, T. A.

2007-11-01

Beachrocks are hard coastal sedimentary formations consisting of various beach sediments, lithified through the precipitation of carbonate cements. The objectives of this contribution are to (a) collate and review information on the reported occurrences, characteristics and formation mechanisms of beachrocks and (b) consider their impacts on the coastal zone. The analysis of the available information has shown that (a) beachrock formation is a global and diachronic phenomenon and (b) the great majority of beachrocks are found in tropical/subtropical and low temperate latitude, microtidal coasts. The cementing agents of beachrocks are composed predominantly of the metastable carbonate phases High Magnesian Calcite (HMC) and Aragonite (Ar), appearing in a diverse crystalline morphology. It has been suggested that cement precipitation in the coastal environment is controlled by: (i) the physicochemical conditions; (ii) the presence of organic compounds and microbes; (iii) the magnitude and distribution of the wave energy along the coast; and (iv) the textural characteristics of the constituent sediments. Various theories have been proposed to explain beachrock formation itself, linking the phenomenon to either physicochemical or biological processes. These theories, however, do not seem to be of universal validity and acceptance, as each is able to explain only some of the reported occurrences. The presence of beachrocks appears to affect beach morphodynamics by: (i) 'locking' the beach profile; (ii) modifying the nearshore hydrodynamics; (iii) changing the porous character of the beach and, thus, its response to wave forcing; and (iv) differential bed erosion at the margins of the beachrock outcrops that can alter significantly the long- and, particularly, the cross-shore sediment transport. Therefore, although relict submerged beachrock outcrops may provide some coastal protection by reducing the wave energy impinging onto the coastline, modern beachrocks may promote offshore loss of unconsolidated beach sediments and buried beachrock outcropping. Finally, the presence of beachrocks may have also significant ecological impacts, as the indigenous (mobile substrate) fauna and flora of the beach is replaced by hard substrate benthic assemblages, which are commonly arranged in hydrodynamically-controlled zones.

An holistic approach to beach erosion vulnerability assessment.

PubMed

Alexandrakis, George; Poulos, Serafim Ε

2014-08-15

Erosion is a major threat for coasts worldwide, beaches in particular, which constitute one of the most valuable coastal landforms. Vulnerability assessments related to beach erosion may contribute to planning measures to counteract erosion by identifying, quantifying and ranking vulnerability. Herein, we present a new index, the Beach Vulnerability Index (BVI), which combines simplicity in calculations, easily obtainable data and low processing capacity. This approach provides results not only for different beaches, but also for different sectors of the same beach and enables the identification of the relative significance of the processes involved. It functions through the numerical approximation of indicators that correspond to the mechanisms related to the processes that control beach evolution, such as sediment availability, wave climate, beach morhodynamics and sea level change. The BVI is also intended to be used as a managerial tool for beach sustainability, including resilience to climate change impact on beach erosion.

Changes along a seawall and natural beaches: Fourchon, LA

USGS Publications Warehouse

Mossa, Joann; Nakashima, Lindsay D.

1989-01-01

This paper compares shoreline and beach morphology changes and responses to storms from 1985 to 1988 along sections of a rapidly eroding coast at the Bayou Lafourche headland, Louisiana. A beach consisting of a cement-filled bag seawall and nourishment was compared with natural beaches to the west and east of the project. Local patterns of beach response could be attributed to several recent processes and historical conditions. Hurricane Gilbert, which made landfall in Mexico, caused about 70% of the sediment loss on both the artificially-stablized and the natural shorelines over this three-year period.

Recent benthic foraminifera and sedimentary facies distribution of the Abu Dhabi (United Arab Emirates) coastline

NASA Astrophysics Data System (ADS)

Fiorini, Flavia; Lokier, Stephen W.

2014-05-01

The distribution of benthic foraminifera and sedimentary facies from Recent coastline environments adjacent to the coastline of Abu Dhabi (UAE) was studied in detail with the aim to: 1) provide reliable analogs for understanding and interpreting the depositional environment of ancient shallow-marine sediments from the UAE; 2) assess any modifications in the distribution of benthic environments and sedimentary facies in an area affected by significant anthropogenic activities - particular construction and land reclamation. A total of 100 sea-floor sediment samples were collected in different shallow-marine sedimentary environments (nearshore shelf, beach-front, channels, ooid shoals, lagoon and mangals) close to the coastline of Abu Dhabi Island. Where possible, we revisited the sampling sites used in several studies conducted in the middle of last century (prior to any significant anthropogenic activities) to assess temporal changes in Recent benthic foraminifera and sedimentary facies distribution during the last 50 years. Five foraminiferal assemblages were recognized in the studied area. Species with a porcellaneous test mainly belonging to the genera Quinqueloculina, Triloculina, Spiroloculina, Sigmoilinita are common in all studied areas. Larger benthic foraminifera Peneroplis and Spirolina are particularly abundant in samples collected on seaweed. Hyaline foraminifera mostly belonging to the genera Elphidium, Ammonia, Bolivina and Rosalina are also common together with Miliolidae in the nearshore shelf and beach front. Agglutinated foraminifera (Clavulina, Textularia, Ammobaculites and Reophax) are present in low percentages. The species belonging to the genera Ammobaculites and Reophax are present only in the finest grain samples particularly in lagoons and mangal environments and have not been reported previously in the studied area. The majority of the ooid shoal sediments, the coarser sediments of the beach-front and samples collected in dredged channels do not contain living foraminifera and the dead assemblage is mostly composed of a few specimens of coarse-sized Miliolidae with fragmented or abraded tests, probably transported from nearby environments. While the shallow-water settings of the Abu Dhabi coastline continue to be areas of active carbonate sedimentation, there have been significant changes in facies distributions over the last 50 years. In particular: × The opportunistic genera Ammonia and Elphidium have become more abundant. Reophax and Ammobaculites are reported in the area for the first time. × With anthropogenic activities some environments, such as inner lagoons, are lost whilst other areas show resilience to anthropogenic activities with little change in sedimentary facies distribution and foraminiferal assemblage. × No living foraminifera are found in dredged channels. The detailed analysis of these changes in foraminifera distribution and sedimentary facies allows us to further our understanding of the effects of anthropogenic activities on shallow-marine environments. By so doing, we are better able to distinguish between those changes that result from anthropogenic activities and those that are a result of naturally-occurring environmental perturbations.

Carbon, nutrient and trace metal cycling in sandy sediments: A comparison of high-energy beaches and backbarrier tidal flats

NASA Astrophysics Data System (ADS)

Reckhardt, Anja; Beck, Melanie; Seidel, Michael; Riedel, Thomas; Wehrmann, Achim; Bartholomä, Alexander; Schnetger, Bernhard; Dittmar, Thorsten; Brumsack, Hans-Jürgen

2015-06-01

In order to evaluate the importance of coastal sandy sediments and their contribution to carbon, nutrient and metal cycling we investigated two beach sites on Spiekeroog Island, southern North Sea, Germany, and a tidal flat margin, located in Spiekeroog's backbarrier area. We also analyzed seawater and fresh groundwater on Spiekeroog Island, to better define endmember concentrations, which influence our study sites. Intertidal sandy flats and beaches are characterized by pore water advection. Seawater enters the sediment during flood and pore water drains out during ebb and at low tide. This pore water circulation leads to continuous supply of fresh organic substrate to the sediments. Remineralization products of microbial degradation processes, i.e. nutrients, and dissolved trace metals from the reduction of particulate metal oxides, are enriched in the pore water compared to open seawater concentrations. The spatial distribution of dissolved organic carbon (DOC), nutrients (PO43-, NO3-, NO2-, NH4+, Si(OH)4 and total alkalinity), trace metals (dissolved Fe and Mn) as well as sulfate suggests that the exposed beach sites are subject to relatively fast pore water advection, which leads to organic matter and oxygen replenishment. Frequent pore water exchange further leads to comparatively low nutrient concentrations. Sulfate reduction does not appear to play a major role during organic matter degradation. High nitrate concentrations indicate that redox conditions are oxic within the duneward freshwater influenced section, while ammonification, denitrification, manganese and iron reduction seem to prevail in the ammonium-dominated seawater circulation zone. In contrast, the sheltered tidal flat margin site exhibits a different sedimentology (coarser beach sands versus finer tidal flat sands) and nutrients, dissolved manganese and DOC accumulate in the pore water. Ammonium is the dominant pore water nitrogen species and intense sulfate reduction leads to the formation of sulfide, which precipitates dissolved iron as iron sulfide. These findings are due to slower advective pore water exchange in the tidal flat sediments. This study illustrates how different energy regimes affect biogeochemical cycling in intertidal permeable sediments.

Methodical Features of the Field Researches of the Anapa Bay-Bar Sediment Composition

NASA Astrophysics Data System (ADS)

Krylenko, Marina; Krylenko, Viacheslav; Gusakova, Anastasiya; Kosyan, Alisa

2014-05-01

Resort Anapa (Black Sea coast, Russia) holds leading positions in the Russian market of sanatorium-resort and children's recreation. The 50-200 m sandy beaches of Anapa bay-bar are the main value of the resort. Anapa bay-bar is an extensive accumulative sandy body having the length about 47 km. Obvious attributes of the beaches degradation demanding immediate measures on their protection and restoration are observed in last years. The main reason of degradation is beach material deficiency. To organize researches of the sediments of this extensive natural object is a difficult challenge. It is necessary to reduce number of tests to minimum. It is important to record differences of separate bay-bar sites and to receive comparable data for different seasons and years. Our researches showed that the grain-size sediment composition significantly depends of position on local relief. Consequently, researching of the alongshore change of the sediment size is effectual to realize at this morphological elements. Shelly detritus makes to 30% of total amount of beach sediments. It is necessary to consider that quantitative shell distribution along the coast significantly depends on a configuration of the coastline and an underwater relief. Quantity of the shells for cross-shore profile is maximal near coastline. For identification of the sediment sources and researching of their fluxes to use minerals markers (heavy minerals) is optimum. The maximum of heavy minerals concentration is characteristic for fraction 0.1-0.05mm at depth more 5 m. The maintenance of this fraction within other morphological zones isn't enough for the analysis or is excessively changeable. Use of the revealed features allowed to conduct the representative field researches of grain-size and mineral sediment composition for all morphological zones of underwater and coast part of the Anapa bay-bar. This methodic recommendations are workable for researches on others coast accumulative body. The work is carried out under financial support of the Russian Foundation of Basic Research.

Bacterial pathogen gene abundance and relation to recreational water quality at seven Great Lakes beaches

USGS Publications Warehouse

Oster, Ryan J.; Wijesinghe, Rasanthi U.; Fogarty, Lisa Reynolds; Haack, Sheridan K.; Fogarty, Lisa R.; Tucker, Taaja R.; Riley, Stephen

2014-01-01

Quantitative assessment of bacterial pathogens, their geographic variability, and distribution in various matrices at Great Lakes beaches are limited. Quantitative PCR (qPCR) was used to test for genes from E. coli O157:H7 (eaeO157), shiga-toxin producing E. coli (stx2), Campylobacter jejuni (mapA), Shigella spp. (ipaH), and a Salmonella enterica-specific (SE) DNA sequence at seven Great Lakes beaches, in algae, water, and sediment. Overall, detection frequencies were mapA>stx2>ipaH>SE>eaeO157. Results were highly variable among beaches and matrices; some correlations with environmental conditions were observed for mapA, stx2, and ipaH detections. Beach seasonal mean mapA abundance in water was correlated with beach seasonal mean log10E. coli concentration. At one beach, stx2 gene abundance was positively correlated with concurrent daily E. coli concentrations. Concentration distributions for stx2, ipaH, and mapA within algae, sediment, and water were statistically different (Non-Detect and Data Analysis in R). Assuming 10, 50, or 100% of gene copies represented viable and presumably infective cells, a quantitative microbial risk assessment tool developed by Michigan State University indicated a moderate probability of illness for Campylobacter jejuni at the study beaches, especially where recreational water quality criteria were exceeded. Pathogen gene quantification may be useful for beach water quality management.

Transplantation of Enhalus acoroides on a sedimentary beach in Ambon Bay

NASA Astrophysics Data System (ADS)

Irawan, Andi

2018-02-01

Coastal development in Ambon Bay has been contributing to coastal ecosystem degradations in recent years. One of the negative effects was the over sedimentation that changes the landscape of coastal ecosystem such as seagrass beds. These changes have made this ecosystem lost some of its functions especially as the habitat for other biotas, because the vegetation has been buried and reduced in density. So, in December 2015, a rehabilitation effort has been done at Kate-kate Beach with transplantation techniques of Enhalus acoroides. After 3-11 months of observation, it was noticed that only the transplants in the deeper area survived; on the contrary, the transplants in exposed and dry area during low tide did not survive. Overall, the survival rate of the transplantation project was 49.73% because the transplants need enough submerged condition to support their lives. The study recommends that to rehabilitate damaged seagrass beds due to the over sedimentation, we have to remove the sediment until certain depth during low tide to ensure the transplants are submerged in seawater. On top of that, the local government has to reduce the sedimentation rate from land because over sedimentation will make the beach profile become too shallow and too exposed during the low tide.

Relationships among bather density, levels of human waterborne pathogens, and fecal coliform counts in marine recreational beach water.

PubMed

Graczyk, Thaddeus K; Sunderland, Deirdre; Awantang, Grace N; Mashinski, Yessika; Lucy, Frances E; Graczyk, Zofi; Chomicz, Lidia; Breysse, Patrick N

2010-04-01

During summer months, samples of marine beach water were tested weekly for human waterborne pathogens in association with high and low bather numbers during weekends and weekdays, respectively. The numbers of bathers on weekends were significantly higher than on weekdays (P < 0.001), and this was associated with a significant (P < 0.04) increase in water turbidity. The proportion of water samples containing Cryptosporidium parvum, Giardia duodenalis, and Enterocytozoon bieneusi was significantly higher (P < 0.03) on weekends than on weekdays, and significantly (P < 0.01) correlated with enterococci counts. The concentration of all three waterborne pathogens was significantly correlated with bather density (P < 0.01). The study demonstrated that: (a) human pathogens were present in beach water on days deemed acceptable for bathing according to fecal bacterial standards; (b) enterococci count was a good indicator for the presence of Cryptosporidium, Giardia, and microsporidian spores in recreational marine beach water; (c) water should be tested for enterococci during times when bather numbers are high; (d) re-suspension of bottom sediments by bathers caused elevated levels of enterococci and waterborne parasites, thus bathers themselves can create a non-point source for water contamination; and (e) exposure to recreational bathing waters can play a role in epidemiology of microsporidiosis. In order to protect public health, it is recommended to: (a) prevent diapered children from entering beach water; (b) introduce bather number limits to recreational areas; (c) advise people with gastroenteritis to avoid bathing; and (d) use showers prior to and after bathing.

Recent morphodynamics of a chenier beach in the Amazon-influenced mud-bank setting of Suriname, South America.

NASA Astrophysics Data System (ADS)

Anthony, Edward; Brunier, Guillaume; Hiwat, Micheal; Bilo, Karin

2017-04-01

The 350-km long coast of Suriname is part of a unique system in the world characterized by large-scale muddy sedimentation and chenier development. The mud is organized into discrete banks migrating alongshore under the influence of waves and currents, separated by 'inter-bank' zones, where cheniers commonly form. Braamspunt beach is a fine example of an open-coast chenier between the mouths of the Maroni and the Suriname Rivers. The former is the primary sand source for the beach, whereas the latter, near which the presently subsisting remnant of the beach is situated, forms a downdrift sink zone for this chenier. Satellite images between 1987 and 2016 shows that Braamspunt beach has significantly shortened over this period. This process has resulted from much of the sand supply coming from updrift (the Maroni) being integrated into a chenier driven landward by waves over mangroves and becoming overwhelmed by a mud bank migrating between the Maroni and Suriname Rivers. Two ground (hydrodynamics, GPS) and drone-photogrammetry surveys in 2016 show that Braamspunt beach is characterized by clear-cut longshore morphodynamic variations reflecting between the 'source' and the 'sink' zones. This gradient is related to different updrift (approaching mud bank) and downdrift (approaches to the Suriname estuary) contexts. The northern sector comprised two elements: the leading edge of the mud bank where the existing chenier (former open beach) has been isolated from the sea by mud and fossilized inland, and the 'terrestrial' shoreline junction with the leading edge of the mud bank. The latter segment consisted of a narrow 150 m-long sandy chenier migrating landward as mud has gained ground, resulting in shortening of the beach. As the chenier migrated inland over back-beach stands of Avicennia germinans mangroves, it left in its wake a muddy foreshore with subsisting mangroves that were part of the muddy mangrove-colonized muddy plain. The southern sector also comprised two segments: a narrow, strongly eroding 1.7 km-long reflective beach, and a relatively large, accretionary 0.6 km-long downdrift beach segment that constituted the downdrift sink for sand transferred alongshore. The multi-decadal to recent evolution of Braamspunt beach thus shows a classical chenier beach that depends essentially on sand supply from the Maroni, but transport is not direct and continuous as one would expect on a classical open-ocean beach because the sand from the Maroni source transported alongshore by wave-induced drift is partially sequestered over more or less long periods of time (multi-decadal) by mud banks migrating westward towards Guyana. Sand availability is, thus, neither constant nor perennial on Braamspunt beach. In other words, this chenier beach does not function as a classical through-put source-to-sink (Maroni-Suriname) sediment cell, but as a potentially fragmented temporally and alongshore-variable cell. This has serious implications for the overall sediment budget of the beach and its sustainability. It also implies that sand mining, practised on a large-scale on this beach, which also serves as a major marine turtle-nesting site in Suriname, could endanger the future existence of this chenier beach.

Assessment of gamma radiation exposure of beach sands in highly touristic areas associated with plutonic rocks of the Atticocycladic zone (Greece).

PubMed

Papadopoulos, A; Koroneos, A; Christofides, G; Papadopoulou, L; Tzifas, I; Stoulos, S

2016-10-01

This study aims to evaluate the activity concentrations of 238 U, 226 Ra, 232 Th, 228 Th and 40 K along beaches close to the plutonic rocks of the Atticocycladic zone that ranged from 15 to 628, 12-2292, 16-10,143, 14-9953 and 191-1192 Bq/kg respectively. A sample from island of Mykonos contained the highest 232 Th content measured in sediments of Greece. The heavy magnetic fraction and the heavy non-magnetic fraction as well as the total heavy fraction, were correlated with the concentrations of the measured radionuclides in the bulk samples. The heavy fractions seem to control the activity concentrations of 238 U and 232 Th of all the samples, showing some local differences in the main 238 U and 232 Th mineral carrier. Similar correlations have been found between 238 U, 232 Th content and rare earth elements concentrations. The measured radionuclides in the beach sands were normalized to the respective values measured in the granitic rocks, which at least in most cases are their most probable parental rocks, so as to provide data upon their enrichment or depletion. Since the Greek beaches are among the most popular worldwide the annual effective dose equivalent received due to sand exposure has been estimated and found to vary between 0.002 and 0.379 mSv y -1 for tourists and from 0.018 to 3.164 mSv y -1 for local people working on the beach. The values corresponding to ordinary sand samples are orders of magnitude lower than the limit of 1 mSv y -1 , only in the case of heavy minerals-rich sands the dose could reach or exceed the recommended maximum limit. Copyright © 2016 Elsevier Ltd. All rights reserved.

Backreef and beach carbonate sediments of the Red Sea, Saudi Arabia: impacts of reef geometry and currents on sediment composition

NASA Astrophysics Data System (ADS)

Missimer, T. M.; Al-Mashharawi, S.; Dehwah, A. H. A.; Coulibaly, K.

2017-12-01

Three sites in the Red Sea were investigated to assess the variability of composition in Holocene sediments of the backreef environment within 0-2 m of water depth. This is important because composition of the sediment is commonly used to estimate water depth in ancient carbonate rocks. The site located at the King Abdullah Economic City (Saudi Arabia) contains a fringing reef with the reef tract located very close to the beach at the north end, flaring to the south to produce a narrower backreef area compared to the other two sites. This geometry produces a north to south current with a velocity of up to 15 cm s-1, particularly during high onshore winds. The sediments contain predominantly non-skeletal grains, including peloids, coated grains, ooids, and grapestones that form on the bottom. The percentage of coralgal grains in the sediment was significantly lower than at the other two sites studied. Om Al Misk Island and Shoaiba have a much lower-velocity current within the backreef zone and contain predominantly coralgal sediments from the beach to the landward edge of the reef tract. The two locations containing the predominantly coralgal microfacies were statistically similar, but the King Abdullah Economic City site was statistically different despite having a similar water depth profile. Slight differences in reef configuration, including reef orientation and distance from the shore, can produce considerable differences in sediment thickness and composition within the backreef environment, which should induce caution in the interpretation of water depth in ancient carbonate rocks using composition.

Plastic pollution in five urban estuaries of KwaZulu-Natal, South Africa.

PubMed

Naidoo, Trishan; Glassom, David; Smit, Albertus J

2015-12-15

Monitoring plastic concentrations in estuaries is vital in assessing the magnitude of terrestrial inputs to oceanic environments. Data on plastics ≤ 5 mm in estuaries are scant. This study determined microplastic levels within five estuaries along the Durban coastline and on intervening beaches. Plastics were isolated from estuarine sediment, beach sediment and the surface water of each estuary and characterised. Sediment at the Bayhead area of Durban harbour had the highest average plastic concentrations (745.4 ± 129.7 particles per 500 ml) and an attenuating concentration trend away from the city centre was found. Prevailing south to north longshore drift was hypothesised to result in plastic accumulation on the northern shores of beaches with estuarine effluents, however, this was not found. Fragments composed the largest percent of plastics (59%) found in Bayhead, whereas fibres dominated other estuaries with proportions ranging from 38% of total plastics in the uMgeni estuary to 66% in the Mdloti. Copyright © 2015 Elsevier Ltd. All rights reserved.

[Distribution and seasonal dynamics of meiofauna in intertidal zone of Qingdao sandy beaches, Shandong Province of East China].

PubMed

Li, Ha; Hua, Er; Zhang, Zhi-Nan

2012-12-01

An investigation was conducted on the abundance, group composition, and distribution of meiofauna at the Second Beach of Taiping Bay and the Shilaoren Beach in Qingdao in January, April, July, and October 2008, aimed to analyze the distribution and seasonal dynamics of meiofauna in the intertidal zone of Qingdao sandy beaches. The measurements of environmental factors, including sediment grain size, interstitial water salinity, interstitial water temperature, organic matter content (TOC), and chlorophyll a (Chl a) content, were made simultaneously. There existed obvious seasonal differences in the environment factors, which could be clustered into two groups, i. e. , spring-winter group (January and April) and summer-autumn group (July and October). At the Second Beach of Taiping Bay, the mean annual abundance of meiofauna was (1167.3 +/- 768.3) ind x 10 cm(-2), and the most dominant group was Nematoda, accounting for 91% of the total. The meiofaunal group composition and abundance at the Second Beach differed horizontally, with the abundance ranked as high tide zone < middle tide zone < low tide zone. The meiofaunal group composition and abundance also varied seasonally, with high values in spring/winter and low values in summer/autumn (spring > winter > autumn > summer). The vertical distribution of the meiofauna in the high and middle tide zones of the Second Beach varied seasonally too. The meiofauna migrated downward with increasing temperature, concentrated in surface layer in winter and migrated downward in summer. At the Shilaoren Beach, the mean annual abundance of meiofauna was (1130.2 +/- 1419.1) ind x 10 cm(-2), and Nematoda accounted for 85% of the total. There was a great similarity of the environmental factors in the middle tide zone of the Second Beach and Shilaoren Beach, which led to no differences in the meiofaunal group composition and abundance. However, the vertical distribution of the meiofauna differed between the two beaches. When the temperature decreased, the meiofauna at Shilaoren Beach migrated downward. The ANOVA and BIOENV analyses showed that the TOC and MD phi were most responsible for the distribution of meiofauna among the tidal zones, the interstitial water temperature, MD phi, and TOC were the main causes of the seasonal variation of meiofaunal group composition and abundance, whereas the sediment Chl a affected the vertical migration of meiofauna. Tourism-induced sediment variation was another factor affecting the meiofaunal abundance, group composition, and distribution.

Assessment of Ni, Cu, Zn and Pb levels in beach and dune sands from Havana resorts, Cuba.

PubMed

Díaz Rizo, Oscar; Buzón González, Fran; Arado López, Juana O

2015-11-15

Concentrations of nickel (Ni), copper (Cu), zinc (Zn) and lead (Pb) in beach and dune sands from thirteen Havana (Cuba) resorts were estimated by X-ray fluorescence analysis. Determined mean metal contents (in mg·kg(-1)) in beach sand samples were 28±12 for Ni, 35±12 for Cu, 31±11 for Zn and 6.0±1.8 for Pb, while for dune sands were 30±15, 38±22, 37±15 and 6.8±2.9, respectively. Metal-to-iron normalization shows moderately severe and severe enrichment by Cu. The comparison with sediment quality guidelines shows that dune sands from various resorts must be considered as heavily polluted by Cu and Ni. Almost in every resort, the Ni and Cu contents exceed their corresponding TEL values and, in some resorts, the Ni PEL value. The comparison with a Havana topsoil study indicates the possible Ni and Cu natural origin. Copyright © 2015 Elsevier Ltd. All rights reserved.

Coastal Change Along the Shore of Northeastern South Carolina - The South Carolina Coastal Erosion Study

USGS Publications Warehouse

Schwab, W.C.; Gayes, P.T.; Morton, R.A.; Driscoll, N.W.; Baldwin, W.E.; Barnhardt, W.A.; Denny, J.F.; Harris, M.S.; Katuna, M.P.; Putney, T.R.; Voulgaris, G.; Warner, J.C.; Wright, E.E.; Barnhardt, Walter A.

2009-01-01

The U.S. Geological Survey, in cooperation with the South Carolina Sea Grant Consortium, conducted a 7-year, multidisciplinary study of coastal erosion in northeastern South Carolina. Shoreline behavior along the coast of Long Bay is dictated by waves, tidal currents, and sediment supply that act within the overall constraints of the regional geologic setting. Beaches are thin ribbons of sand that sit on top of layered sedimentary rocks, which have been deeply eroded by rivers and coastal processes over millions of years. Offshore of the beaches, these sedimentary rocks are exposed as hardgrounds over large expanses of shallow seafloor and are locally overlain by a discontinuous veneer of sandy sediment generally less than 1 m thick. Rates of shoreline retreat largely depend on the geologic framework of the shoreface that is being excavated by ocean processes. Mainland-attached beaches have remained relatively stable, whereas barrier islands have experienced large shifts in shoreline position. In this sediment-limited region, erosion of the shoreface and inner shelf probably contributes a significant amount of new material to the beach system. Oceanographic studies and numerical modeling show that sediment transport varies along the coast, depending on the type and travel path of storms that impact Long Bay, but the long-term net transport direction is generally from north to south. Changes in storm activity that might accompany climate change, coupled with anticipated increases in sea-level rise, are expected to strongly affect low-lying, heavily developed areas of the coast.

Planform and mobility in the Meaípe-Maimbá embayed beach on the South East coast of Brazil

NASA Astrophysics Data System (ADS)

Albino, Jacqueline; Jiménez, José A.; Oliveira, Tiago C. A.

2016-01-01

The Meaípe-Maimbá embayed beach (MMEB) on the south-east coast of Brazil has been subject to anthropogenic pressures since the 70's. In this study we discuss the adequacy and contribution of the parabolic planform model to determine the planform and variability of the MMEB, taking into consideration variation in wave conditions. The role of different controlling conditions on the planform variability is analyzed, as well as the morphological and planform mobility. MMEB exhibited a new configuration in response to the construction of a harbor, which interrupted the longshore sediment transport. After four decades, three particular morphodynamic sectors have been recognized along the beach. The central sector is more exposed to normal wave incidence and cross-shore processes predominate. The northern and southern sectors are influenced by wave diffraction processes around the headlands and port, respectively. In the northern sector, the presence of secondary headlands and inner islands imposed a geomorphological control on beach morphology and coastal processes. The use of the parabolic planform model provided useful insights for the assessment of potential planform mobility, since the decadal shoreline evolution combined with beach profiles and sediment characteristics allowed understanding of the beach mobility processes and supported the interpretation of modeling results.

Arsenic enrichment in shelf and coastal sediment of the Brazilian subtropics

NASA Astrophysics Data System (ADS)

Mirlean, N.; Medeanic, S.; Garcia, F. A.; Travassos, M. P.; Baisch, P.

2012-03-01

High levels of As (i.e., above the nationally legislated threshold of 70 mg kg-1) were found in shelf sediment of the Espirito Santo state of Brazil. The elevated content of this metalloid propagated in the sediment to a depth of approximately 1.5 m. The adjacent beach sands and mangrove sediments were also enriched in As. The variation in As levels along the shelf sediment profiles was acompained by calcareous-material distribution, which reflects the paleogeographical circumstances that promote local reef development during the corresponding intervals of sedimentation. Arsenic-rich calcareous bioclast materials migrate to a beach from the surface horizon of nearby shelf sediment, thereby replacing the part of the As that previously entered the marine environment with eroded material from the continent to the littoral zone. The segment of the Brazilian tropical shelf that was studied clearly demonstrated that the As enrichment of the shelf sediment is determined by the exposure of the Barreiras formation on the coast and the development of reefs, which are favorable sites for the settling of bodies of biogenic carbonates.

Constraints on aeolian sediment transport to foredunes within an undeveloped backshore enclave on a developed coast

NASA Astrophysics Data System (ADS)

Kaplan, Kayla L.; Nordstrom, Karl F.; Jackson, Nancy L.

2016-10-01

Landforms present in undeveloped beach enclaves located between properties developed with houses and infrastructure are often left to evolve naturally but are influenced by the human structures near them. This field study evaluates how buildings and sand-trapping fences change the direction of wind approach, reduce wind speed, and restrict fetch distances for sediment entrainment, thereby reducing the potential for aeolian transport and development of dunes in enclaves. Field data were gathered in an 80 m long, 44 m deep beach enclave on the ocean shoreline of New Jersey, USA. Comparison of wind characteristics in the enclave with a site unaffected by buildings revealed that offshore winds in the enclave are reduced in strength and altered in direction by landward houses, increasing the relative importance of longshore winds. Vertical arrays of anemometers on the foredune crest, foredune toe and berm crest in the enclave revealed increasing wind speed with distance offshore, with strongest winds on the berm crest. Vertical cylindrical traps on the foredune crest, foredune toe, mid-backshore, berm crest and upper foreshore revealed the greatest rate of sediment transport on the berm crest. Sediment samples from the beach and from traps revealed limited potential for aeolian transport because of coarse grain sizes. Strong oblique onshore winds are common in this region and are normally important for transporting sand to dunes. The length of an enclave and the setback distance on its landward side determine the degree to which sediment delivered by oblique winds contributes to dune growth. The landward edge of the enclave (defined by a sand fence near the dune toe) is sheltered along its entire length from winds blowing at an angle to the shoreline of 25° or less. A foredune set back this distance in an enclave the length of an individual lot (about 20 m) would be sheltered at an angle of 57° or less, reducing the opportunity for dune building by onshore winds. Reduced potential for aeolian transport in enclaves implies that human actions may be required to build dunes artificially to protect buildings and roads from storm overwash.

Effects of erosion control structures along a portion of the northern Chesapeake Bay shoreline

USGS Publications Warehouse

Zabawa, C.F.; Kerhin, R.T.; Bayley, S.

1981-01-01

A 6.500-meter reach of western Chesapeake Bay shoreline (lower Mayo Peninsula) lost about 1.1??106 cubic meters of sediment (equivalent to 170 cubic meters lost per meter of shoreline) between 1846 and 1932, when the first aerial photographs show the shoreline already substantially protected by a system of groins and intermittent bulkheading. These structures have eliminated the fastland as a source of erodable material, and have starved the supply of sand for littoral drift, thus limiting the extent of the beaches to the remaining groin fields. Volumes of sediment involved in these impacts are small in the overall sediment budget. Bulkheads produce no deficit in the budget since scouring of the beaches on their seaward sides makes up for the decreased erosion of protected fastland. Groins trap little of the potential littoral drift (computed to be about 104 cubic meters per meter of shoreline per year). The sand supply in the remaining beaches is nearly equivalent to the annual loss of sediment from the entire shoreline system due to the long-term rate of erosion of the shoreline and nearshore between 1846 and 1932. ?? 1981 Springer-Verlag New York Inc.

Sediment Facies on a Steep Shoreface, Tairua/Pauanui Embayment, New Zealand

NASA Astrophysics Data System (ADS)

Trembanis, A. C.; Hume, T. M.; Gammisch, R. A.; Wright, L. D.; Green, M. O.

2001-05-01

Tairua/Pauanui embayment is a small headland-bound system on the Coromandel Peninsula on the east coast of the North Island of New Zealand. The shoreface in this area is steep ( ~0.85) and concave; however, where the profile is steepest, between 10-15-m water depth, the profile is slightly convex. A sedimentological study of the shoreface was conducted to provide baseline information for a sediment-dynamics study. Detailed swath mapping of the seabed sediment from the beach out to a water depth of ~50 m was conducted using side-scan sonar. Over 200 km of side-scan sonar data were collected by separate surveys in September 2000 and again in February 2001. Ground-truthing of side-scan sonar data was carried out by SCUBA, grab sampling ( ~100 samples) and drop-camera video. A digital terrain model (DTM) of the area was constructed using newly collected bathymetric data along with data from digitized nautical charts. The DTM exposes changes in bathymetry and variation in slope throughout the study area. The acoustic and sedimentologic data were used to identify and map 8 individual facies units. Shoreface facies distribution was found to be patchy and complex. Large-scale ( ~200-m wide x 1600-m long), slightly depressed, mega-rippled coarse-sand/shell-hash units were abruptly truncated by contacts with fine, featureless, continuous sand-cover units. The repeat survey in February indicated stability of the overall shape and location of large-scale facies units, while diver observations indicated that bedforms within units actively migrate. Bedform roughness is highly variable, including patchy reefs/rubble, sand-dollar fields mega-rippled coarse-gravel/sands, ripple scour depressions, and fields of dense tubeworms. The distribution of coarse shell-hash units is consistent with diabathic sediment transport. Three tripods supporting a range of instruments for measuring waves, currents, boundary-layer flows and sediment resuspension and settling were deployed on the shoreface during February 2001, for up to 3 months. Each tripod was situated on a different facies with a view to resolving spatial variability in sediment dynamics and establishing a link between spatially variable bed roughness, sediment mobility and sedimentation patterns. Our ultimate goal is to understand the interactions between substrate and driving flows in this spatially complex setting and how these interactions sculpt the shoreface and possibly control sediment transfers between the inner shelf and beach.

The numerical model of the sediment distribution pattern at Lampulo National fisheries port

NASA Astrophysics Data System (ADS)

Irham, M.; Setiawan, I.

2018-01-01

The spatial distribution of sediment pattern was studied at Lampulo Fisheries Port, Krueng Aceh estuarial area, Banda Aceh. The research was conducted using the numerical model of wave-induced currents at shallow water area. The study aims to understand how waves and currents react to the pattern of sediment distribution around the beach structure in that region. The study demonstrated that the port pool area had no sedimentation and erosion occurred because the port was protected by the jetty as the breakwater to defend the incoming waves toward the pool. The protected pool created a weak current circulation to distribute the sediments. On the other hand, the sediments were heavily distributed along the beach due to the existence of longshore currents near the shoreline (outside the port pool area). Meanwhile, at the estuarial area, the incoming fresh water flow responded to the coastal shallow water currents, generating Eddy-like flow at the mouth of the river.

Restoring sediment to compensate for human-induced erosion of an estuarine shore

NASA Astrophysics Data System (ADS)

Nordstrom, Karl F.; Jackson, Nancy L.; Farrell, Eugene J.; Rafferty, Patricia; Tengwall, Charles

2016-06-01

Shoreline erosion is often exacerbated by reduction of sediment inputs because of interference with sediment transport by human structures. We evaluate use of sediment dredged from a navigation channel to establish a feeder beach adjacent to a bulkhead as a solution for addressing erosion of landforms and habitats on sandy estuarine shores. The objectives are to determine how beach volume, position and shape within and downdrift of the fill area change and whether the volumes supplied by dredging match sediment losses caused by human actions. The fill was placed along a 75 m length of shoreline adjacent to a marina in Great South Bay at Fire Island, New York, USA. Changes in beach shape and volume were determined from topographic surveys conducted before and after fill and at half year intervals for 18 months. The quantity of fill was 1747 m3. Maximum shoreline advance due to fill emplacement was 20.7 m. The maximum volume placed at any transect was 28.6 m3 m- 1 of shoreline length. Erosion of the fill occurred rapidly, with landward migration of a conspicuous scarp. The edge of the upland 18 months after the fill was placed was up to 4.6 m farther landward than prior to the fill. Movement of sediment alongshore downdrift of the fill occurred as wave-like pulses, extending the active foreshore bayward, causing accretion of the inner low tide terrace, burying saltmarsh peat outcrops on the foreshore and creating a higher and wider overwash platform over portions of the saltmarshes. Landforms downdrift of the fill area underwent successive stages including erosion (pre-nourishment), accretion, stability (with throughput of sediment) and then erosion. Beach nourishment compensates for human-induced sediment losses. The volume of sediment added from maintenance dredging can slow the rate of erosion but may not prevent long-term shoreline retreat. Restoration and maintenance of coastal landforms and habitats to specific target states at a given location is difficult, but augmenting longshore sediment inputs can allow those locations to undergo cycles of erosion and accretion, creating a variety of landforms and habitats where only erosional forms existed previously. Alternatively, nourishment could occur more frequently and in smaller volumes to reduce fluctuations in accretion-erosion cycles.

Environmental implications of the use of sulfidic back-bay sediments for dune reconstruction — Lessons learned post Hurricane Sandy

USGS Publications Warehouse

Plumlee, Geoffrey S.; Benzel, William M.; Hoefen, Todd M.; Hageman, Philip L.; Morman, Suzette A.; Reilly, Timothy J.; Adams, Monique; Berry, Cyrus J.; Fischer, Jeffrey; Fisher, Irene

2016-01-01

Some barrier-island dunes damaged or destroyed by Hurricane Sandy's storm surges in October 2012 have been reconstructed using sediments dredged from back bays. These sand-, clay-, and iron sulfide-rich sediments were used to make berm-like cores for the reconstructed dunes, which were then covered by beach sand. In November 2013, we sampled and analyzed partially weathered materials collected from the cores of reconstructed dunes. There are generally low levels of metal toxicants in the reconstructed dune materials. However oxidation of reactive iron sulfides by percolating rainwater produces acid-sulfate pore waters, which evaporate during dry periods to produce efflorescent gypsum and sodium jarosite salts. The results suggest use of sulfidic sediments in dune reconstruction has both drawbacks (e.g., potential to generate acid runoff from dune cores following rainfall, enhanced corrosion of steel bulwarks) and possible benefits (e.g., efflorescent salts may enhance structural integrity).

Modes of embayed beach dynamics: analysis reveals emergent timescales

NASA Astrophysics Data System (ADS)

Murray, K. T.; Murray, A.; Limber, P. W.; Ells, K. D.

2013-12-01

Embayed beaches, or beaches positioned between rocky headlands, exhibit morphologic changes over many length and time scales. Beach sediment is transported as a result of the day-to-day wave forcing, causing patterns of erosion and accretion. We use the Rocky Coastline Evolution Model (RCEM) to investigate how patterns of shoreline change depend on wave climate (the distribution of wave-approach angles) and beach characteristics. Measuring changes in beach width through time allows us to track the evolution of the shape of the beach and the movement of sand within it. By using Principle Component Analysis (PCA), these changes can be categorized into modes, where the first few modes explain the majority of the variation in the time series. We analyze these modes and how they vary as a function of wave climate and headland/bay aspect ratio. In the purposefully simple RCEM, sediment transport is wave-driven and affected by wave shadowing behind the headlands. The rock elements in our model experiments (including the headlands) are fixed and unerodable so that this analysis can focus purely on sand dynamics between the headlands, without a sand contribution from the headlands or cliffs behind the beach. The wave climate is characterized by dictating the percentage of offshore waves arriving from the left and the percentage of waves arriving from high angles (very oblique to the coastline orientation). A high-angle dominated wave climate tends to amplify coastline perturbations, whereas a lower-angle wave climate is diffusive. By changing the headland/bay aspect ratio and wave climate, we can perform PCA analysis of generalized embayed beaches with differing anatomy and wave climate forcings. Previous work using PCA analysis of embayed beaches focused on specific locations and shorter timescales (<30 years; Short and Trembanis, 2004). By using the RCEM, we can more broadly characterize beach dynamics over longer timescales. The first two PCA modes, which explain a majority of the beach width time series variation (typically >70%), are a 'breathing' mode and a 'rotational' mode. The newly identified breathing mode captures the sand movement from the middle of the beach towards the edges (thickening the beach along the headlands), and the rotational mode describes the movement of sand towards one headland or another, both in response to stochastic fluctuations about the mean wave climate. The two main modes operate independently and on different timescales. In a weakly low-angle dominated wave climate, the breathing mode tends to be the first mode (capturing the most variance), but with greater low-angle dominance (greater morphological diffusivity), the rotational mode tends to be first. The aspect ratio of the bay also affects the order of the modes, because wave shadowing affects sediment transport behind the headlands. Previous work has attributed beach rotation to changes in various climate indices such as the North Atlantic Oscillation (Thomas et al., 2011); however, PCA analysis of the RCEM results suggests that embayed beaches can have characteristic timescales of sand movement that result from internal system dynamics, emerging even within a statistically constant wave climate. These results suggest that morphologic changes in embayed beaches can occur independently of readily identifiable shifts in forcing.

Including granulometric sediment coastal data composition into the Black Sea GIS

NASA Astrophysics Data System (ADS)

Zhuk, Elena; Khaliulin, Alexey; Krylenko, Marina; Krylenko, Viacheslav; Zodiatis, George; Nikolaidis, Marios; Nikolaidis, Andreas

2017-09-01

The module structure of the Black Sea GIS allows the increasing of its functionality, including new data types and defining new procedures accessing them, their visualization and integration with existing data by their conjoint processing and representation. The Black Sea GIS is released as free software; Mapserver is used as a mapping service; MySQL DBMS works with relational data. A new additional feature provided, is the ability of including coastal data obtained in SB SIO RAS. The data represent granulometric composition of the Anapa bay-bar sediments. The Anapa bay-bar is an accumulative sand form (about 50 km long) located on the northwest Russian Black Sea coast. The entire bay-bar and especially its southern part with sand beaches 50-200 m wide is intensively used in recreation. This work is based on the results of field studies of 2010-2014 in the southern part of the Anapa bay-bar researched by scientists of the Shirshov Institute of Oceanology RAS. Since the shore under consideration has no clearly pronounced reference points, "virtual" points located within 1 km distance from each other were selected. Transversal profiles cross these points. The granulometric composition was studied along with 45 profiles. The samples taken in every profile were from the most characteristic morphological parts of the beach. In this study we used shoreline zone samples. Twenty one granule fractions (mm) were separated in the laboratory. The module which processes coastal data allows to select coastal data based on territory/region and granulometric sediment composition. Also, it allows to visualize coastal maps with user-selected features combined with other GIS data.

Analysis of the Relationship Between Physical Environmental Parameters and Beach Water Quality in a Subtropical Setting

NASA Astrophysics Data System (ADS)

Zhu, X.; Wang, J. D.; Elmir, S.; Solo-Gabriele, H. M.; Wright, M. E.; Abdelzaher, A.

2006-12-01

Fecal Indicator Bacteria(FIB) are found in high concentrations in sewage water, and thus are used to indicate whether there is fecal material related pathogen present and to determine whether a beach is safe for recreational use. Studies have shown, however, in subtropical regions, FIB concentrations above EPA standards may be present in the absence of known point sources of human or animal waste, thus reducing the efficacy of FIB beach monitoring programs. An interdisciplinary study is being conducted in Miami, Florida , the goal is to understand the sources and behavior of FIB on a beach without point source loads and also to improve beach health hazard warnings in subtropical regions. This study, examines relationship between enterococci (EPA recommended FIB for use in marine water) and physical environmental parameters such as rain, tide and wind. FIB data employed include Florida Department of Health weekly beach monitoring enterococci (ENT) data during a five year period and a two-day experiment with hourly sampling at Hobie Cat Beach on Virginia Key in the Miami metropolitan area. The environmental data consist of wind from a nearby CMAN tower, and local rain and tide. The analysis also includes data from nearby beaches monitored by the Health Department. Results show the correlation coefficient between ENT and tide at Hobie Cat Beach is positive but not significant(r=0.17). Rain events have a significant influence on ENT at Hobie Cat Beach, with a correlation coefficient of up to 0.7 while at other beaches the correlation is less than 0.2. Reasons for this aberration are being investigated. Although this is the only beach allowing dogs there are other factors of possible importance, such as tidal flats frequented by birds and weaker water circulation and exchange at this beach facing a bay rather than the ocean. Higher ENT levels (> 300CFU/100ml water) are more likely (67% of the time) to be associated with periods of onshore winds, which may affect the circulation of water at the beach or cause waves and wave breaking that stir and resuspend the beach sediment. To help interpret FIB observations and to improve the use of future monitoring results, a coastal circulation model and a bacteria fate model is being constructed to simulate and predict the FIB transport and distribution at Hobie Cat Beach.

Heavy minerals in the 2011 Tohoku-oki tsunami deposits—insights into sediment sources and hydrodynamics

NASA Astrophysics Data System (ADS)

Jagodziński, Robert; Sternal, Beata; Szczuciński, Witold; Chagué-Goff, Catherine; Sugawara, Daisuke

2012-12-01

The 2011 Tohoku-oki tsunami left sand and mud deposits more than 4 km inland on the coastal plain of Sendai, Japan. The tsunami deposits, pre-tsunami soils and beach sediments were analysed for grain size, and heavy mineral content and assemblages to test the applicability of heavy mineral analyses in the identification of tsunami deposits and interpretation of associated sedimentation processes. Heavy minerals comprised on average 35% of the tsunami deposit in the 0.125-0.25 mm grain size fraction. The most common were orthopyroxenes, clinopyroxenes, amphiboles, limonites and opaque minerals. Heavy mineral concentrations and assemblages were similar in the tsunami deposits, beach and pre-tsunami soils and sediments and thus tsunami deposits could not simply be identified based on their heavy minerals. Sediment provenance analysis revealed that tsunami deposits left within 1.5 km of the shoreline were mostly eroded from the beach, dune and local soils, while deposits farther inland (> 1.5 km) were mostly derived from local soil erosion. No evidence was found for a significant contribution of offshore sediments. Detailed analyses revealed that the lowermost portion of tsunami deposits was mostly of local origin, while the sediment source of the upper portion was variable. A comparison with a previous study of heavy minerals in 2004 IOT deposits confirms that heavy minerals in tsunami deposits are mostly source-dependent and may represent a useful supplementary tool in studies of tsunami deposits. However, the interpretation must always be placed in the local geological context and corroborated with other "tsunami proxies".

Surf Zone Properties and On/Offshore Sediment Transport.

DTIC Science & Technology

1982-06-01

and Random Waves," Proceedings, 14th Coastal Engineering Conference, 1974, pp.558-574. Levi - Civita , T., "Determination Rigoreuse des Ondes...on Beach 2-6 Classification of Normal and Storm Beach 23 Profiles by Dean 2-7 Classification of Normal and Storm Beach 24 Profiles by Author 2-8 Two ...the surface and near bottom, return flow near mid-depth before wave breaking. There were considerable laboratory evidences supporting the two -dimen

The dynamics of fine-grain sediment dredged from Santa Cruz Harbor

USGS Publications Warehouse

Storlazzi, Curt D.; Conaway, Christopher H.; Presto, M. Katherine; Logan, Joshua B.; Cronin, Katherine; van Ormondt, Maarten; Lescinski, Jamie; Harden, E. Lynne; Lacy, Jessica R.; Tonnon, Pieter K.

2011-01-01

In the fall and early winter of 2009, a demonstration project was done at Santa Cruz Harbor, California, to determine if 450 m3/day of predominantly (71 percent) mud-sized sediment could be dredged from the inner portion of the harbor and discharged to the coastal ocean without significant impacts to the beach and inner shelf. During the project, more than 7600 m3 of sediment (~5400 m3 of fine-grain material) was dredged during 17 days and discharged approximately 60 m offshore of the harbor at a depth of 2 m on the inner shelf. The U.S. Geological Survey's Pacific Coastal and Marine Science Center was funded by the U.S. Army Corps of Engineers and the Santa Cruz Port District to do an integrated mapping and process study to investigate the fate of the mud-sized sediment dredged from the inner portion of Santa Cruz Harbor and to determine if any of the fine-grain material settled out on the shoreline and/or inner shelf during the fall and early winter of 2009. This was done by collecting highresolution oceanographic and sediment geochemical measurements along the shoreline and on the continental shelf of northern Monterey Bay to monitor the fine-grain sediment dredged from Santa Cruz Harbor and discharged onto the inner shelf. These in place measurements, in conjunction with beach, water column, and seabed surveys, were used as boundary and calibration information for a three-dimensional numerical circulation and sediment dynamics model to better understand the fate of the fine-grain sediment dredged from Santa Cruz Harbor and the potential consequences of disposing this type of material on the beach and on the northern Monterey Bay continental shelf.

Historical sediment budget and present-day catchment-shoreline coupling at Twofold Bay, southeastern Australia

NASA Astrophysics Data System (ADS)

Tamura, T.; Oliver, T.; Hudson, J.; Woodroffe, C. D.

2017-12-01

Considering projected impacts of sea-level rise in the 21st century on sandy shorelines, an understanding of long-term sediment budget for individual beaches or coastal compartments supports assessments of shoreline stability. We examined a low-lying coastal beach-ridge barrier in Twofold Bay using optically stimulated luminescence (OSL) dating , airborne LiDAR, sedimentological analysis and seismic data to assess changes in rates of sediment supply to this shoreline through time. Calculations of barrier volume, Twofold Bay bay-floor sediment volume and estimates of sediment delivery from a proximal river system provide a broad-scale assessment of past-sediment budget. Between ca. 7500 years ago and 1500 years ago, sources of sediment for shoreline progradation at Boydtown were bay-floor sediments either inherited or moved into the embayment during late-stage transgression. Progradation rate between ca. 7500-1500 years ago was 0.16 m/yr with subaerial barrier volume accumulating at 0.46 m3/m/yr. Between ca. 1500 years and present day, the Towamba River to the south has delivered additional sediment to the Boydtown shoreline more than doubling shoreline progradation rate to 0.65 m/yr and subaerial barrier accumulation has risen to 1.83 m3/m/yr. The delivery of fluvial sediment from the Towamba River was restricted to the past ca. 1500 years as prior to this, estuary infilling prevented floods delivering sediments to the bay. This recent historical coupling of river sand supply and shoreline progradation rate implies that anthropogenic modifications to the Towamba River catchment such as river damming, or climatic changes reducing rainfall or runoff, would negatively impact the Boydtown Beach shoreline. Conversely increased rainfall or deforestation may increase sediment discharge due to upstream erosion. The Boydtown shoreline within Twofold Bay may be able to maintain its current position in the coming century if fluvial sediment delivery continues. The fact that other shorelines within Twofold Bay are seemingly unaffected by the Towamba River, and most shorelines in southeast Australia receive minimal fluvial sediment input, further emphasises the need to consider nearshore sediment reserves in order to accurately determine sea-level rise impacts on sandy shorelines.

Beach morphodynamics and types of foredune erosion generated by storms along the Emilia-Romagna coastline, Italy

NASA Astrophysics Data System (ADS)

Armaroli, Clara; Grottoli, Edoardo; Harley, Mitchell D.; Ciavola, Paolo

2013-10-01

The objectives of this study are to examine the response of a dune and beach system on the Adriatic coastline in northern Italy to the arrival of storms, compare it with seasonal (months) and medium-term (3-year) morphodynamic change, and evaluate results predicted by the numerical model XBeach. The studied coastline stretches 4 km from the Bevano River mouth to the north of the site to the township of Lido di Classe to the south, where the beach is protected by coastal structures. Fieldwork consisted of topographic profile surveys using RTK-DGPS technology (7 times over an approx. 3-year period). 103 samples of surface sediment were collected along 20 of the cross-shore profiles at 6 distinct cross-shore positions, selected on the basis of morphological beach characteristics. Data analyses of dune and beach slopes enabled the study area to be divided into 6 separate morphological zones using the spatial (longshore and cross-shore) variation of morphologies located on the backshore and intertidal beach observed in a preliminary survey of the area. Other criteria were a spatial consistency in beach slopes and/or presence/absence of intertidal morphologies identified in the aerial photographs and Lidar data. The swash zone slope did not show any significant variability for the entire area. A weak seasonal trend in the variability of the mean foredune slope was observed, with steeper slopes typically during winter and flatter slopes during summer. Analysis of grain size revealed that the beach sediment is well-sorted fine sand tending to medium, with a decreasing trend in size from the Bevano River mouth southwards towards Lido di Classe. According to the Masselink and Short (1993) classification, the natural part of the study site has an Intermediate Barred Beach (IBB) and following the Short (1999) classification, results in a modally LBT (longshore bar-trough) or LTT (low tide terrace) with a small section being TBR (transverse bar and rip). Storms are considered the main factor controlling changes in the beach and dune slope. The most significant storm was recorded in March 2010 with a peak significant wave height of 3.91 m. Contrary to the seasonal dune trend, several foredune slopes were observed to flatten following this event, which can be attributed to the action of dune slumping from the already weakened dune state. Modelling of foredune erosion, using a process-based model (XBeach), reproduced the erosion of the upper beach and dune toe reasonably well, but is currently limited by the acceptable slope value for dune stability, which does not account for biotic factors (e.g. plant roots). The comparison between the storm impact categories of Sallenger (2000) and the DSF (Dune Stability Factor) of Armaroli et al. (2012) shows a very good correspondence between the effects of the winter 2008-2009 storms and the vulnerability of the dune system predicted using both classifications.

Mud deposit formation on the open coast of the larger Patos Lagoon-Cassino Beach system

NASA Astrophysics Data System (ADS)

Vinzon, S. B.; Winterwerp, J. C.; Nogueira, R.; de Boer, G. J.

2009-03-01

This paper proposes an explanation of the mud deposits on the inner Shelf of Cassino Beach, South Brazil, by using computational modeling. These mud deposits are mainly formed by sediments delivered from Patos Lagoon, a coastal lagoon connected to the Shelf, next to Cassino Beach. The deposits are characterized by (soft) mud layers of about 1 m thick and are found between the -5 and -20 isobaths. Two hydrodynamic models of the larger Patos Lagoon-Cassino Beach system were calibrated against water elevation measured for a 5 months period, and against currents and salinity measured for a week period. The circulation patterns and water exchange through the mouth were analyzed as a function of local and remote wind effects, and river discharges. The remote wind effect mainly governs the quantity of water exchange with the Lagoon through its effect on mean sea level as a result of Ekman dynamics, while river discharges are important for the salinity of the exchanged water masses. Local winds augment the export-import rates by set-up and set-down within the Lagoon, but their effects are much smaller than those of the remote wind. Currents patterns on the inner Shelf during water outflow revealed a recirculation zone south of the Lagoon, induced by the local geometry and bathymetry of the system. This recirculation zone coincides with observed locations of mud deposition. Water, hence suspended sediment export occurs when remote and local winds are from the N-E, which explains why fine sediment deposits are mainly found south of the Lagoon's breakwater. A sensitivity analysis with the numerical model quantified the contribution of the various mechanisms driving the transport and fate of the fine suspended sediments, i.e. the effects of remote and local wind, of the astronomical tide, of river discharge and fresh-salt water-induced density currents, and of earth rotation. It is concluded that gravitational circulation and earth rotation affects the further dispersion of the deposits largely, whereas the remote wind effect has the largest influence on the amount of sediment released from the Lagoon. It is noted that this paper analyzes the initial deposition patterns induced by current effects only. However, in reality, these deposits are further redistributed over the Shelf by wave effects—these are subject of a next study on the sediment dynamics of the larger Patos Lagoon-Cassino Beach system.

California State Waters Map Series: offshore of Refugio Beach, California

USGS Publications Warehouse

Johnson, Samuel Y.; Dartnell, Peter; Cochrane, Guy R.; Golden, Nadine E.; Phillips, Eleyne L.; Ritchie, Andrew C.; Krigsman, Lisa M.; Dieter, Bryan E.; Conrad, James E.; Greene, H. Gary; Seitz, Gordon G.; Endris, Charles A.; Sliter, Ray W.; Wong, Florence L.; Erdey, Mercedes D.; Gutierrez, Carlos I.; Yoklavich, Mary M.; East, Amy E.; Hart, Patrick E.; Johnson, Samuel Y.; Cochran, Susan A.

2015-01-01

Seafloor habitats in the broad Santa Barbara Channel region consist of significant amounts of soft, unconsolidated sediment interspersed with isolated areas of rocky habitat that support kelp-forest communities nearshore and rocky-reef communities in deep water. The potential marine benthic habitat types mapped in the Offshore of Refugio Beach map area are directly related to its Quaternary geologic history, geomorphology, and active sedimentary processes. These potential habitats, which lie primarily within the Shelf (continental shelf) but also partly within the Flank (basin flank or continental slope) megahabitats, primarily are composed of soft sediment interrupted by a few carbonate mounds. This homogeneous seafloor of sediment and low-relief bedrock provides promising habitat for groundfish, crabs, shrimp, and other marine benthic organisms.

Wrack patches and their influence on upper-shore macrofaunal abundance in an Atlantic Canada sandy beach system

NASA Astrophysics Data System (ADS)

MacMillan, Mitchell R.; Quijón, Pedro A.

2012-08-01

Patches of stranded macrophytes (wrack) are a distinctive feature of sandy beaches worldwide and a potential food subsidy for their resident communities. Despite their relevance, the spatial variation of wrack and its potential influence on upper shore beach organisms remain poorly understood. Wrack and macrofauna were surveyed on seven sandy beaches associated with dunes, till bluffs and sandstone cliffs along the north shore of Prince Edward Island, Atlantic Canada. Wrack patch density, cover, and water content were measured, and their associated macrofauna was compared to the communities inhabiting nearby bare sediments. The survey found among-site spatial differences in wrack characteristics and identified rockweeds (Fucus serratus) and eelgrass (Zostera marina) as the main macrophyte species in the area. Macrofaunal abundances were higher in wrack than in bare sediments but this varied among locations. A field manipulation was then conducted at two sandy beaches to measure macrofauna colonization on patches of fresh and aged rockweed and eelgrass. Regardless of macrophyte's age, macrofaunal organisms preferentially colonized sediments associated with rockweeds. In addition, calculations across treatments detected positive relationships between macrofaunal abundance and wet mass, dry mass and water content of the wrack patches, regardless of macrophyte species or state. Macrophyte preferences were further explored by comparing the nutritional value of the plant tissues and assessing macrofauna feeding rates under laboratory conditions. Rockweed tissues had consistently higher protein, lipid and carbohydrate contents than eelgrass and were affected by higher invertebrate consumption rates. Overall, these results suggest that spatial variation and wrack features and species composition play key roles on the structure of the supralittoral macrofauna.

Field Observations of Swash-Zone Dynamics on a Sea-Breeze Dominated Beach at the Yucatán Peninsula, México

NASA Astrophysics Data System (ADS)

Chardon-Maldonado, P.; Puleo, J. A.; Torres-Freyermuth, A.

2016-02-01

Sea breezes can modify the nearshore processes and alter beach morphology depending on the geographical location. Prior studies have shown that surf zone wave energy intensifies during strong sea-breeze conditions (wind speeds > 10 ms-1) and the impact on the coast can be similar to a small storm. However, few research efforts have investigated the coastal dynamics on sea-breeze dominated beaches (e.g., Masselink and Pattiaratchi, 1998, Mar. Geol.; Pattiaratchi et al., 1997, Cont. Shelf Res.) and, to the authors' knowledge, only one study has focused on swash-zone processes (Sonu et al., 1973, EOS). A field study was performed on a microtidal, low wave energy, sea-breeze dominated sandy beach in order to investigate the effects of local (sea breeze) and synoptic (storm) scale meteorological events on swash-zone dynamics. In-situ measurements of swash-zone hydrodynamics and sediment transport processes were collected from March 31st to April 12th, 2014 in Sisal, Yucatán located on the northern coast of the Yucatán Peninsula. Flow velocities and suspended sediment concentrations were measured concurrently, at multiple cross-shore and alongshore locations, using Vectrino-II profiling velocimeters and optical backscatter sensors, respectively. The high resolution data allowed the quantification of bed shear stress, turbulent dissipation rate, sediment loads and sediment flux during a mesoscale frontal system (cold-front passage referred to as an El Norte) and local sea-breeze cycles. Field observations showed that strong swash-zone bed shear stresses, turbulence intensity and sediment suspension occur during energetic conditions (i.e., El Norte event). On the other hand, despite milder energy conditions during the sea-breeze events, the alongshore component of bed-shear stresses and velocities can be significant owing to the high incidence wave angle associated with the sea-breeze system in the study area. The increased forcing in the swash zone induced sediment suspension, eroding the foreshore and causing accretion in the surf zone. The preliminary analysis demonstrates that strong sea-breeze events induce a significant alongshore swash-zone sediment transport that may be more important than that observed during an El Norte event.

Shoreline changes at the mouths of the Mekong River delta over the last 50 years: fluctuating sediment supply and shoreline cells

NASA Astrophysics Data System (ADS)

Anthony, E.; Besset, M.; Brunier, G.; Dussouillez, P.; Dolique, F.; Nguyen, V. L.; Goichot, M.

2014-12-01

River delta shorelines may be characterized by complex patterns of sediment transport and sequestering at various timescales in response to changes in sediment supply, hydrodynamic conditions, and deltaic self-organization. While being good indicators of delta stability, these changes also have important coastal management and defence implications. These aspects are examined with reference to the mouths of the Mekong River delta, the world's third largest delta, backbone of the Vietnamese economy and home to nearly 20 million people. We conducted an analysis of shoreline fluctuations over the last five decades using low-resolution Landsat (1973-2014), very high-resolution SPOT 5 (2003-2011) satellite imagery, topographic maps (1950, 1965), and field hydrodynamic and shoreline topographic measurements. The results show that the 250 km-long river-mouth sector of the delta shoreline has been characterized by overall accretion but with marked temporal and spatial variations. The temporal pattern is attributed to fluctuations in sediment supply due to both human activities and natural variations in catchment sediment loads (e.g., 2000-2003), and natural adjustments in delta-plain sediment storage and delivery to the coast. The spatial pattern is indicative of discrete sediment cells that may be a response to an overall decreasing sand supply, especially since 2003, following increasingly massive riverbed mining with concomitant losses in channel-bed sand. Field measurements show the prevalence of mesotidal bar-trough beaches characterized by sand migration to the southwest in response to energetic dry-season monsoon waves. Beaches underfed as a result of both wave-energy gradients and possible diminishing sand supply from the adjacent river mouths are eroded to feed accreting beaches. Understanding this cell pattern has important implications in terms of: (1) interpreting past patterns of shoreline translation involved in the construction of successive beach ridges that characterise the prograding mouths sector of the Mekong; (2) linking shoreline stability/instability with coastal sand supply by the Mekong River and the impacts of human activities on this supply; (3) shoreline management and defence planning in the critical sandy river-mouth sector of this densely populated delta.

Folly Beach, South Carolina. Survey Report on Beach Erosion Control and Hurricane Protection. Appendixes.

DTIC Science & Technology

1979-08-01

horseshoe crabs, sand dollars and numerous clams and gastropod mollusks i,, the beach subtidal areas. In addition, several species of fish are conyionly...bacteria and protozoa. Most benthic animals such as crustaceans, bivalve and gastropod mollusks, and burrowing and tube-dwelling polychaete worms are...due to the continual ut :ftil tidal fJ a. . , ted sediment shifting. Inlet inhabitants onsist nos ,y 1 1.., itipods, and polychaetes which are adapted

Constraining pathways of microbial mediation for carbonate concretions of the Miocene Monterey Formation using carbonate-associated sulfate

NASA Astrophysics Data System (ADS)

Loyd, Sean J.; Berelson, William M.; Lyons, Timothy W.; Hammond, Douglas E.; Corsetti, Frank A.

2012-02-01

Carbonate concretions can form as a result of organic matter degradation within sediments. However, the ability to determine specific processes and timing relationships to particular concretions has remained elusive. Previously employed proxies (e.g., carbon and oxygen isotopes) cannot uniquely distinguish among diagenetic alkalinity sources generated by microbial oxidation of organic matter using oxygen, nitrate, metal oxides, and sulfate as electron acceptors, in addition to degradation by thermal decarboxylation. Here, we employ concentrations of carbonate-associated sulfate (CAS) and δ 34S CAS (along with more traditional approaches) to determine the specific nature of concretion authigenesis within the Miocene Monterey Formation. Integrated geochemical analyses reveal that at least three specific organo-diagenetic reaction pathways can be tied to concretion formation and that these reactions are largely sample-site specific. One calcitic concretion from the Phosphatic Shale Member at Naples Beach yields δ 34S CAS values near Miocene seawater sulfate (˜+22‰ VCDT), abundant CAS (ca. 1000 ppm), depleted δ 13C carb (˜-11‰ VPDB), and very low concentrations of Fe (ca. 700 ppm) and Mn (ca. 15 ppm)—characteristics most consistent with shallow formation in association with organic matter degradation by nitrate, iron-oxides and/or minor sulfate reduction. Cemented concretionary layers of the Phosphatic Shale Member at Shell Beach display elevated δ 34S CAS (up to ˜+37‰), CAS concentrations of ˜600 ppm, mildly depleted δ 13C carb (˜-6‰), moderate amounts of Mn (ca. 250 ppm), and relatively low Fe (ca. 1700 ppm), indicative of formation in sediments dominated by sulfate reduction. Finally, concretions within a siliceous host at Montaña de Oro and Naples Beach show minimal CAS concentrations, positive δ 13C values, and the highest concentrations of Fe (ca. 11,300 ppm) and Mn (ca. 440 ppm), consistent with formation in sediments experiencing methanogenesis in a highly reducing environment. This study highlights the promise in combining CAS analysis with more traditional techniques to differentiate among diagenetic reactions as preserved in the geologic record and shows potential for unraveling subsurface biospheric processes in ancient samples with a high degree of specificity.

Radio Frequency Identification (RFID) technology applied to the definition of underwater and subaerial coarse sediment movement

NASA Astrophysics Data System (ADS)

Bertoni, Duccio; Sarti, Giovanni; Benelli, Giuliano; Pozzebon, Alessandro; Raguseo, Gianluca

2010-07-01

In this paper, Radio Frequency Identification technology has been applied to track both underwater and subaerial displacement of pebbles along an artificial coarse beach at Marina di Pisa, Italy. Several preliminary laboratory tests have been performed to adapt the RFID technique for underwater use, which has been the primary impediment to this promising approach to the study of coarse sediment transport and movement. Tests showed the reliability of low frequencies for this kind of work, since they enable good signal transmission and reception through water. Passive ABS plastic transponders were inserted into about 100 pebbles and released onto the beach in March, 2009. A CORE-125 reader was chosen as the operating antenna to continuously transmit low frequency (125 kHz) signals. An acoustic signal toned whenever a pebble was detected while the unambiguous identification code of the pebble is shown immediately on the screen of a laptop connected to the reader. The positions of the pebbles were recorded with a total station. After two months (May, 2009), 74 marked pebbles were retrieved, 77% of the total. The positions of the retrieved pebbles were also recorded with the total station, thus allowing calculation of the coarse sediment transport tendency. About 60% of the recovered pebbles (44 out of 74) were found on the upper shoreface. The analysis of the marked pebble trajectories revealed a divergent transport movement in the northernmost sector of the beach. This movement was probably triggered by an irregularity of the submerged breakwater fronting the shoreline. The southern sector is characterised by chaotic pathways related to the formation and evolution of beach cusps. This outcome highlights and confirms the importance of a complete definition of the beach system, with no separation between the underwater and the subaerial portion of the shore when it comes to sediment transport and movement. This successful application of RFID technology to the underwater environment provides a chance to broaden understanding of a topic in need of further study.

Northeast Florida Regional Sediment Management: Implementation Strategies and Recommendations for Nassau County and Duval County, Florida

DTIC Science & Technology

2016-03-01

51 Figure 21. Mayport beach placement of entrance channel sediment , 1972...................................... 58 Tables Table 1...Entrance Channel dredged sediment placement history by area. ....................... 20 Table 3. Kings Bay Entrance Channel offshore disposal history at...in northeast Florida is beneficial use of sediments dredged from Federal civil works and military navigation channels for shore protection purposes

Assessment of beach and dune erosion and accretion using LiDAR: Impact of the stormy 2013-14 winter and longer term trends on the Sefton Coast, UK

NASA Astrophysics Data System (ADS)

Pye, Kenneth; Blott, Simon J.

2016-08-01

An important question for coastal management concerns the importance of individual storms and clusters of storms on longer term beach sediment budgets, beach and dune erosion, and coastal flood risk. Between October 2013 and March 2014 a series of deep Atlantic low pressure systems crossed the Northeast Atlantic, and strong winds, high waves and high water levels affected many coastal areas in the UK and other parts of western Europe. Net dune recession of up to 12.1 m occurred around Formby Point. On 5 December 2013 the highest water level ever recorded at Liverpool (6.22 m ODN) coincided with waves of Hs of 4.55 m and Tp of 9.3 s in Liverpool Bay. Wave trimming of the dune toe occurred along the entire length of the Sefton coast, but significant dune erosion occurred only where the upper beach (between the mean high water spring tide level and the dune toe) was < 25 m wide. Sediment budget calculations based on LiDAR surveys in October 2013 and May 2014 indicated a net loss of 127 × 103 m3 of sediment from the beach (above 0 m ODN) and a loss of 268 × 103 m3 from the frontal dune system, mostly at Formby Point. However, some parts of the beach to the south of Formby Point gained sediment, indicating net north to south transport over the winter. When considered in a longer term context, the 2013-14 winter represents only a small perturbation on the longer-term coast trend of erosion at Formby Point and progradation to the north and south. Analysis of LiDAR data over a longer time period 1999-2014 indicated upper beach and dune sediment loss of 780 × 103 m3 from the north-central part of Formby Point, with net gains of 806 × 103 m3 and 2116 × 103 m3 in areas to the north and south, respectively. This indicates a net onshore transport of 2142 × 103 m3 from Liverpool Bay towards the coast between Birkdale and Altcar, with a further net total of 210 × 103 m3 transported towards the shore between Altcar and Crosby. In view of the demonstrated value of airborne LiDAR surveys for the quantification of storm impacts and longer term coastal changes, it is recommended that such surveys should be undertaken before and after each winter storm period, covering the area between mean low water spring tide level and a line 200 m landward of the dune toe, of as a part of the regional coastal monitoring programme.

Morphodynamics of an eroding beach and foredune in the Mekong River delta: Implications for deltaic shoreline change

NASA Astrophysics Data System (ADS)

Anthony, E. J.; Dussouillez, P.; Dolique, F.; Besset, M.; Brunier, G.; Nguyen, V. L.; Goichot, M.

2017-09-01

River delta shorelines composed of sand may be characterized by complex spatial and temporal patterns of erosion and accretion even when sand supply is readily available. This is especially the case for deltas with multiple mouths subject to significant wave and tide influence. High-resolution topographical and wave and current measurements were conducted from 2010 to 2012 at Ba Dông beach, a popular resort located on the largest of the multiple inter-distributary plains of the Mekong River delta. Ba Dông beach is a mesotidal, multiple bar-trough system. The upper beach corresponds to the current active beach ridge in the sequence of ridges that have marked the progradation of the inter-distributary delta plains, and is capped by a low foredune that protects villages and agricultural land from marine flooding. During the low river-flow season, the beach is characterized by Northeast monsoon waves and strong longshore currents that transport sediment towards the southwest. Weaker longshore currents towards the northeast are generated by Southwest monsoon waves during the high river-flow season. Ba Dông beach underwent strong erosion between 2010 and 2012, following a phase of massive accretion. In 2012, this erosion resulted in breaching of the foredune, contributing to concerns that the Mekong delta had become vulnerable to retreat. The local erosion at Ba Dông needs to be considered, however, in the broader context of delta shoreline morphodynamics, which involves space- and time-varying patterns of beach accretion and erosion. These patterns are the present expressions of plan-view beach-ridge morphology in the delta, which is characterized by flaring and truncations that reflect changing beach morphodynamics in the course of deltaic progradation. We surmise that these patterns are related to complex interactions involving river water and sediment discharge, waves and wave-generated longshore currents, tidal currents, and shoreline orientation.

Sources and sinks of microplastics in Canadian Lake Ontario nearshore, tributary and beach sediments.

PubMed

Ballent, Anika; Corcoran, Patricia L; Madden, Odile; Helm, Paul A; Longstaffe, Fred J

2016-09-15

Microplastics contamination of Lake Ontario sediments is investigated with the aim of identifying distribution patterns and hotspots in nearshore, tributary and beach depositional environments. Microplastics are concentrated in nearshore sediments in the vicinity of urban and industrial regions. In Humber Bay and Toronto Harbour microplastic concentrations were consistently >500 particles per kg dry sediment. Maximum concentrations of ~28,000 particles per kg dry sediment were determined in Etobicoke Creek. The microplastic particles were primarily fibres and fragments <2mm in size. Both low- and high-density plastics were identified using Raman spectroscopy. We provide a baseline for future monitoring and discuss potential sources of microplastics in terms of how and where to implement preventative measures to reduce the contaminant influx. Although the impacts of microplastics contamination on ecosystem health and functioning is uncertain, understanding, monitoring and preventing further microplastics contamination in Lake Ontario and the other Great Lakes is crucial. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of two sediment types on the fluorescence yield of two Hawaiian scleractinian corals

USGS Publications Warehouse

Piniak, G.A.

2007-01-01

This study used non-invasive pulse-amplitude modulated (PAM) fluorometry to measure the maximum fluorescence yield (Fv/Fm) of two Hawaiian scleractinian coral species exposed to short-term sedimentation stress. Beach sand or harbor mud was applied to coral fragments in a flow-through aquarium system for 0-45 h, and changes in Fv/Fm were measured as a function of sediment type and length of exposure. Corals were monitored for up to 90 h to document recovery after sediment removal. Sediment deposition significantly decreased Fv/Fm in both species and was a function of sediment type and time. Corals that received sediment for 30 h or more had the greatest reduction in yield and exhibited little recovery over the course of the experiment. Harbor mud caused a greater reduction in Porites lobata yield than beach sand, whereas both sediment types had equally deleterious effects on Montipora capitata. Colony morphology and sediment type were important factors in determining yield reduction-P. lobata minimized damage from coarse sand grains by passive sediment rejection or accumulation in depressions in the skeleton, and fluorescence yield decreased most in corals exposed to sticky harbor mud or in colonies with flattened morphologies. Species-specific differences could not be tested due to differences in colony morphology and surface area. ?? 2007.

Distributional patterns in an insect community inhabiting a sandy beach of Uruguay

NASA Astrophysics Data System (ADS)

Mourglia, Virginia; González-Vainer, Patricia; Defeo, Omar

2015-12-01

Most studies of sandy beach macrofauna have been restricted to semiterrestrial species and do not include insects when providing species richness and abundance estimates. Particularly, spatio-temporal patterns of community structure of the entomofauna inhabiting these ecosystems have been scarcely documented. This study assessed spatio-temporal distributional patterns of the night active entomofauna on a beach-dune system of Uruguay, including variations in species richness, abundance and diversity, and their relationship with environmental factors. A deconstructive taxonomic analysis was also performed, considering richness and abundance patterns separately for the most abundant insect Orders (Hymenoptera and Coleoptera) to better understand the factors which drive their patterns. We found clear temporal and across-shore patterns in the insect community inhabiting a land-ocean interface, which matched spatiotemporal variations in the environment. Abundance and species richness were highest in spring and summer, concurrently with high temperatures and low values of sediment moisture and compaction. Multivariate ordinations showed two well-defined species groups, which separated summer, autumn and spring samples from winter ones. Generalized Linear Models allowed us to describe a clear segregation in space of the most important orders of the insect community, with specific preferences for the terrestrial (Hymenoptera) and beach (Coleoptera) fringes. Hymenoptera preferred the dune zone, characterized by high elevation and low sand moisture and compaction levels, whereas Coleoptera preferred gentle slopes and fine and humid sands of the beach. Our results suggest that beach and dune ecosystems operate as two separate components in regard to their physical and biological features. The high values of species richness and abundance of insects reveal that this group has a more significant ecological role than that originally considered so far in sandy beach ecology.

Reconstruction of the coastal morphodynamics of the Fulong-beach dune field in north-eastern Taiwan

NASA Astrophysics Data System (ADS)

Dörschner, Nina; Böse, Margot; Frechen, Manfred

2010-05-01

The Fulong-beach dune field is located at the north-eastern coast of Taiwan. Built up of medium and fine grained quartz rich sand, it represents a unique feature of only few kilometres along the east coast of Taiwan. This unique sedimentological regime makes the area most perfectly suitable for age estimations by optically stimulated luminescence (OSL). The dune field is crossed by the Shuangsi-river, which flows into the Pacific Ocean. The coastal area is subjected to very dynamic conditions in the transition zone between land and sea. Due to the constant force of marine and aeolian processes from tides, weather and sediment accumulation by rivers, it is a continuously changing area. Taiwan is located in a very active tectonic zone with high elevation rates, which reach from 4 mm per year at the east coast up to 7 mm per year in the southern parts of the island. Furthermore Taiwan is affected by medial 3.8 typhoons per year and minor earthquakes nearly occur every day (LIN ET AL. 2006). The consequences are high rates of erosion and sediment transport during very short time periods. The Fulong-beach coastal area is densely populated and proud for being a tourism destination. At the northern end of the dune field the Lungmen nuclear power plant is currently under construction. Four separate dune ridges could be identified from a digital elevation model and from field mapping. During the field campaign in October and November 2009 17 samples were taken for OSL-dating (MURRAY ET AL. 1995) out of the four dune ridges as well as out of a more than 30 m high elevated outcrop cut by the Shuangsi-river. The measurement and the evaluation of the OSL-samples will provide us an insight into the duration and intensity of the processes affecting the coastal area of Taiwan during the Holocene. We will give an outline during the poster presentation of the methodical approach and the morphodynamical processes affecting the Fulong-beach dune field in north-eastern Taiwan. References: LIN, J.C., PETLEY, D., JEN, C.-H. & HSU, M.-L. (2006): Slope movement in a dynamic environment - A case study of Tachia River, Central Taiwan. In: Quaternary International 147, p. 103-112. MURRAY, A.S., OLLEY, J.M. & CAITCHEON, G.G. (1995): Measurement of equivalent doses in quartz from contemporary water-lain sediments using optically stimulated luminescence. In: Quaternary Science Reviews 14, p. 365-371.

Saco River-Camp Ellis Harbor, Saco, Maine. Small Navigation Project, Detailed Project Report and Environmental Assessment.

DTIC Science & Technology

1981-12-01

41294) further evaluation of chemical -biological interactive effects is not necessary because the sediments meet the following evaluation criteria...such release would be predicted at the dredge site. bulk chemical analyses were run on the five samples taken in conjunction with maintenance...material to be dredged is therefore considered to be chemically acceptable for beach nourishment purposes or other disposal methods. 38 1%4* 4J 0 0 * M 0 0

Moving sands along a headland-embayed beach system (Algarve, Southern Portugal)

NASA Astrophysics Data System (ADS)

Oliveira, Sónia; Horta, João; Nascimento, Ana; Gomes, Ana; Veiga-Pires, Cristina; Moura, Delminda

2015-04-01

Resilience of embayed and pocket beaches located at the southernmost coast of Portugal is currently a major question to coastal management of this region. In fact, several among those beaches have been artificially fed aiming to increase the width of the beach allowing people to maintain a safe distance to the unstable rocky cliffs. The sand is dredged from the offshore (ca. 2 miles from the shoreline) representing high costs for the Portuguese government. For how long will the artificial feeding solve the problem? Which beaches are worth being nourished taking into account the morphosedimentary processes? The present work is the result of a field experiment aiming to study the efficiency of the alongshore sedimentary transport between successive embayed beaches. The experiment was performed in the very indented rocky coast of the Algarve region (Southern Portugal) and comprised two field campaigns, both in 2014, during spring tides in March and November. The Algarve coast experiences a semi-diurnal meso-tidal regime ranging from 1.3 m during neap tides to 3.5 m at spring tides and the waves approach from WSW (232°) during 72% of observations along the year, almost normal to the study area shoreline. The wave and current characteristics (significant height-Hs and Period-T for waves, velocity and direction for currents) were measured during three and six tidal cycles respectively for the first and second campaign, using two pressure transducers and one electromagnetic current meter. We used sand painted with orange fluorescent dye (100 kg in March and 200 kg in November) as tracer to track the movement of the sand along the coast. The marked sand was placed on the beach face of the westernmost beach of the study area during the first low tide of each campaign. Following, hundreds of sediment samples were collected during low tide, through the monitored period, in the nodes of a georeferenced square mesh of 10 x 20 m covering three embayed beaches. Later in the laboratory, sediment was characterized concerning the grain size distribution and the marked grains (MG) which were identified and counted with the use of a black light. After statistical analysis, several maps were developed in a Geographical Information System in order to quantify and interpret the direction and velocity of the movement of the sand induced by the observed waves and currents. The results of this work showed that: (i) when the existing shore platforms between adjacent embayed beaches are exposed, their surface is topographically higher than the beach face and strongly dissected by channels (e.g., joints) and karstic cavities, and thus the transference of sand between the adjacent beaches is almost nil, (ii) when a topographic continuity was observed between the beach face and the surface of the shore platforms, the transference of sand between adjacent cells is effective. The two reported situations depend on the beach morphosedimentary processes driven by the angle between the waves and the shoreline. This work is a contribution to the PTDC/GEO-GEO/3981/2012 funded by the Portuguese Foundation for Science and Technology. The authors would like to thank the collaborators of the November campaign: A. Rosa; A. Portugal; A. Silva; C. Correia, J. Cunha e L. Castilho.

Nearshore hydrodynamics at pocket beaches with contrasting wave exposure in southern Portugal

NASA Astrophysics Data System (ADS)

Horta, João; Oliveira, Sónia; Moura, Delminda; Ferreira, Óscar

2018-05-01

Pocket beaches on rocky coasts with headlands that control hydro-sedimentary processes are considered to be constrained sedimentary systems, generally with limited sediment inputs. Pocket beaches face severe changes over time. Under worst-case scenarios, these changes can result in the loss of the beach, causing waves to directly attack adjacent cliffs. Studies of nearshore hydrodynamics can help to understand such changes and optimise sediment nourishment procedures. The present work contributes to the knowledge of hydrodynamic forcing mechanisms at pocket beaches by providing a comprehensive description of the nearshore circulation at two beaches with contrasting wave exposures. Two pocket beaches in southern Portugal were studied by combining field measurements of waves and currents with numerical models (STWAVE and BOUSS-2D). The aim of this analysis was to evaluate nearshore hydrodynamics under different wave exposure forcing conditions (e.g. variable wave heights/directions and different tidal levels). The results show that the beach circulation can rapidly shift from longshore-to rip-dominated depending on changes in both the offshore wave direction and tidal levels. Waves with higher obliquity (for both low and moderate wave energy conditions) tend to generate longshore circulation in all considered tidal stages, while waves with lower obliquity tend to produce rip flow with higher-velocity rip currents during low to intermediate tidal stages. The results indicate that the location and intensity of rip currents strongly depend on geomorphological constraints, that is, the control exerted by shore platforms. A larger morphological control is observed at mean sea level because most platforms are submerged/exposed during high/low tide and therefore exert less control on nearshore circulation.

Evaluation of the quality of coastal bathing waters in Spain through fecal bacteria Escherichia coli and Enterococcus.

PubMed

Aragonés, L; López, I; Palazón, A; López-Úbeda, R; García, C

2016-10-01

Sun. and beach tourism is very important to the economy of Spain, so the control of the quality of the environment on the beaches is essential. Therefore, the analysis and control of the quality of bathing water is necessary, which is defined by the European Directive 2006/7/EC as excellent, good or sufficient depending on the presence of microbiological contamination or other organisms or waste presenting a risk to bathers' health. For that, 1392 beaches of the Iberian Peninsula and its islands were analysed, taking into account: fecal bacteria (Escherichia coli and Enterococcus), physical characteristics of sediment, level of urbanization, climatic and anthropogenic factors, and maritime climate. Thus, it was observed that urban sand beaches located in seas with fewer hours of sunshine and important tide have higher concentrations of E. coli and Enterococcus. There is also an indirect relationship between these microorganisms with salinity (R(2) 0.746 for E. coli and 0.606 for Enterococcus), temperature (R(2) 0.743 for E. coli and 0.604 for Enterococcus) and hours of sunshine (R(2) 0.781 for E. coli and 0.706 for Enterococcus), while this relationship is direct with rainfall (R(2) 0.640 for E. coli and 0.607 for Enterococcus) or wave height (R(2) 0.769 for E. coli and 0.601 for Enterococcus). From all this, it follows that the Directive 2006/7/EC should define more specific criteria as to the place and time of sampling, and take into account the different environment variables that influence the survival of bacteria, so that the results may reflect reality, and avoid staff responsible for sampling freely choose the place and time of sampling. Copyright © 2016 Elsevier B.V. All rights reserved.

Standard operating procedures for collection of soil and sediment samples for the Sediment-bound Contaminant Resiliency and Response (SCoRR) strategy pilot study

USGS Publications Warehouse

Fisher, Shawn C.; Reilly, Timothy J.; Jones, Daniel K.; Benzel, William M.; Griffin, Dale W.; Loftin, Keith A.; Iwanowicz, Luke R.; Cohl, Jonathan A.

2015-12-17

An understanding of the effects on human and ecological health brought by major coastal storms or flooding events is typically limited because of a lack of regionally consistent baseline and trends data in locations proximal to potential contaminant sources and mitigation activities, sensitive ecosystems, and recreational facilities where exposures are probable. In an attempt to close this gap, the U.S. Geological Survey (USGS) has implemented the Sediment-bound Contaminant Resiliency and Response (SCoRR) strategy pilot study to collect regional sediment-quality data prior to and in response to future coastal storms. The standard operating procedure (SOP) detailed in this document serves as the sample-collection protocol for the SCoRR strategy by providing step-by-step instructions for site preparation, sample collection and processing, and shipping of soil and surficial sediment (for example, bed sediment, marsh sediment, or beach material). The objectives of the SCoRR strategy pilot study are (1) to create a baseline of soil-, sand-, marsh sediment-, and bed-sediment-quality data from sites located in the coastal counties from Maine to Virginia based on their potential risk of being contaminated in the event of a major coastal storm or flooding (defined as Resiliency mode); and (2) respond to major coastal storms and flooding by reoccupying select baseline sites and sampling within days of the event (defined as Response mode). For both modes, samples are collected in a consistent manner to minimize bias and maximize quality control by ensuring that all sampling personnel across the region collect, document, and process soil and sediment samples following the procedures outlined in this SOP. Samples are analyzed using four USGS-developed screening methods—inorganic geochemistry, organic geochemistry, pathogens, and biological assays—which are also outlined in this SOP. Because the SCoRR strategy employs a multi-metric approach for sample analyses, this protocol expands upon and reconciles differences in the sample collection protocols outlined in the USGS “National Field Manual for the Collection of Water-Quality Data,” which should be used in conjunction with this SOP. A new data entry and sample tracking system also is presented to ensure all relevant data and metadata are gathered at the sample locations and in the laboratories.

Anthropogenic disruption to the seismic driving of beach ridge formation: The Sendai coast, Japan.

PubMed

Goff, James; Knight, Jasper; Sugawara, Daisuke; Terry, James P

2016-02-15

The expected geomorphic after-effects of the Mw 9.0 Tōhoku-oki earthquake of 11 March 2011 (eastern Japan) are summarized by a schematic model of seismic driving, which details seismogenic disturbances to sediment systems that affect the rate or timing of sediment delivery to coastlines over timescales of 10(2)-10(4)years. The immediate physical environmental responses to this high-magnitude earthquake included a large tsunami and extensive region-wide slope failures. Normally, slope failures within mountain catchments would have significant impacts on Japan's river and coastal geomorphology in the coming decades with, for example, a new beach ridge expected to form within 20-100 years on the Sendai Plain. However, human activity has significantly modified the rate and timing of geomorphic processes of the region, which will have impacts on likely geomorphic responses to seismic driving. For example, the rivers draining into Sendai Bay have been dammed, providing sediment traps that will efficiently capture bedload and much suspended sediment in transit through the river system. Instead of the expected ~1 km of coastal progradation and formation of a ~3m high beach ridge prior to the next large tsunami, it is likely that progradation of the Sendai Plain will continue to slow or even cease as a result of damming of river systems and capture of river sediments behind dams. The resulting reduction of fluvial sediment delivery to the coast due to modification of rivers inadvertently makes seawalls and other engineered coastal structures even more necessary than they would be otherwise. Copyright © 2015 Elsevier B.V. All rights reserved.

Engineering with Nature: Nearshore Berm Placements at Fort Myers Beach and Perdido Key, Florida, USA

DTIC Science & Technology

2015-05-15

may be winnowed from the placement sediment and ideally move offshore. In the case of Fort Myers Beach, this design proved to be successful. The...material and subsequent dredging of material once the undesirable fine fraction has winnowed out. Conclusions Although quite different designs, both

Holocene delta evolution and sediment discharge of the Mekong River, southern Vietnam

NASA Astrophysics Data System (ADS)

Ta, Thi Kim Oanh; Nguyen, Van Lap; Tateishi, Masaaki; Kobayashi, Iwao; Tanabe, Susumu; Saito, Yoshiki

2002-09-01

Evolutionary changes, delta progradation, and sediment discharge of the Mekong River Delta, southern Vietnam, during the late Holocene are presented based on detailed analyses of samples from six boreholes on the lower delta plain. Sedimentological and chronostratigraphic analyses indicate clearly that the last 3 kyr were characterized by delta progradation under increasing wave influence, southeastward sediment dispersal, decreasing progradation rates, beach-ridge formation, and steepening of the face of the delta front. Estimated sediment discharge of the Mekong River for the last 3 kyr, based on sediment-volume analysis, was 144±36 million t yr -1 on average, or almost the same as the present level. The constant rate of delta front migration and stable sediment discharge during the last 3 kyr indicate that a dramatic increase in sediment discharge owing to human activities, as has been suggested for the Yellow River watershed, did not occur. Although Southeast Asian rivers have been considered candidates for such dramatic increases in discharge during the last 2 kyr, the Mekong River example, although it is a typical, large river of this region, does not support this hypothesis. Therefore, estimates of the millennial-scale global pristine sediment flux to the oceans must be revised.

SSMILES.

ERIC Educational Resources Information Center

Sunal, Dennis W.; Tracy, Dyanne M., Eds.

1991-01-01

A learning cycle activity which allows students to practice process skills by sieving different size fractions of sediments is described. Science topics include weathering, erosion, streams, sedimentation, sedimentary rocks, soils, beaches, dunes, or glacial deposits. Mathematics topics include number lines, ordinal numbers, greater than/less…

Sediment unmixing using detrital geochronology

USGS Publications Warehouse

Sharman, Glenn R.; Johnstone, Samuel

2017-01-01

Sediment mixing within sediment routing systems can exert a strong influence on the preservation of provenance signals that yield insight into the influence of environmental forcings (e.g., tectonism, climate) on the earth’s surface. Here we discuss two approaches to unmixing detrital geochronologic data in an effort to characterize complex changes in the sedimentary record. First we summarize ‘top-down’ mixing, which has been successfully employed in the past to characterize the different fractions of prescribed source distributions (‘parents’) that characterize a derived sample or set of samples (‘daughters’). Second we propose the use of ‘bottom-up’ methods, previously used primarily for grain size distributions, to model parent distributions and the abundances of these parents within a set of daughters. We demonstrate the utility of both top-down and bottom-up approaches to unmixing detrital geochronologic data within a well-constrained sediment routing system in central California. Use of a variety of goodness-of-fit metrics in top-down modeling reveals the importance of considering the range of allowable mixtures over any single best-fit mixture calculation. Bottom-up modeling of 12 daughter samples from beaches and submarine canyons yields modeled parent distributions that are remarkably similar to those expected from the geologic context of the sediment-routing system. In general, mixture modeling has potential to supplement more widely applied approaches in comparing detrital geochronologic data by casting differences between samples as differing proportions of geologically meaningful end-member provenance categories.

Sediment unmixing using detrital geochronology

NASA Astrophysics Data System (ADS)

Sharman, Glenn R.; Johnstone, Samuel A.

2017-11-01

Sediment mixing within sediment routing systems can exert a strong influence on the preservation of provenance signals that yield insight into the effect of environmental forcing (e.g., tectonism, climate) on the Earth's surface. Here, we discuss two approaches to unmixing detrital geochronologic data in an effort to characterize complex changes in the sedimentary record. First, we summarize 'top-down' mixing, which has been successfully employed in the past to characterize the different fractions of prescribed source distributions ('parents') that characterize a derived sample or set of samples ('daughters'). Second, we propose the use of 'bottom-up' methods, previously used primarily for grain size distributions, to model parent distributions and the abundances of these parents within a set of daughters. We demonstrate the utility of both top-down and bottom-up approaches to unmixing detrital geochronologic data within a well-constrained sediment routing system in central California. Use of a variety of goodness-of-fit metrics in top-down modeling reveals the importance of considering the range of allowable that is well mixed over any single best-fit mixture calculation. Bottom-up modeling of 12 daughter samples from beaches and submarine canyons yields modeled parent distributions that are remarkably similar to those expected from the geologic context of the sediment-routing system. In general, mixture modeling has the potential to supplement more widely applied approaches in comparing detrital geochronologic data by casting differences between samples as differing proportions of geologically meaningful end-member provenance categories.

Municipal initiatives for managing dunes in coastal residential areas: a case study of Avalon, New Jersey, USA

NASA Astrophysics Data System (ADS)

Nordstrom, Karl F.; Jackson, Nancy L.; Bruno, Michael S.; de Butts, Harry A.

2002-10-01

The characteristics of foredunes created in a municipal management program on a developed barrier island are evaluated to identify how landforms used as protection structures can be natural in appearance and function yet compatible with human values. Shoreline management zones include a naturally evolving, undeveloped segment; a noneroding, developed segment; eroding and noneroding segments of an "improved beach" where dunes have been built by artificial nourishment; and a privately built, artificially nourished dune on the shoreline of an inlet. A disastrous storm in 1962 resulted in an aggressive program for building dunes using sand fences, vegetation plantings, purchase of undeveloped lots, and sediment backpassing to maintain beach widths and dune elevations. The present nourished and shaped foredune in the improved beach is higher, wider, and closer to the berm crest than the natural dune. Restricted inputs of aeolian sand keep the surface flat and poorly vegetated. A stable section of this engineered shore has a wider beach, and sand fences have created a higher foredune with greater topographic diversity. The cross shore zonation of vegetation here is more typical of natural dunes, but the environmental gradient is much narrower. The privately built dune is low, narrow, and located where it could not be created naturally. Foreshore and aeolian sediments in the undeveloped segment and the improved beach are similar in mean grain size (0.16-0.21 mm) and sorting (0.31-0.39 φ), but sediment on the surface of the nourished dune is coarser (28.1% gravel) with a more poorly sorted sand fraction (1.30 φ) representing lag elements on the deflation surface. Willingness to enhance beaches and dunes for protection has reduced insurance premiums and allowed the municipality to qualify for funds from the Federal Emergency Management Agency (FEMA) to replace lost sediment, thus placing an economic value on dunes. Success of the management program is attributed to: (i) timing property-purchase and dune-building programs to periods immediately after storms (causing residents to accept high dunes that restrict access or views); (ii) instituting a vigorous education program (reminding residents of hazards during nonstorm periods); (iii) maintaining control over local sediment supplies (to keep pace with erosion and create new shoreline environments); (iv) investing private and municipal economic resources in landforms (qualifying them for external funds for replacement); and (v) maintaining, augmenting, or simply tolerating biodiversity and natural processes (retaining a natural heritage).

Modelling of sediment transport pattern in the mouth of the Rhone delta: Role of storm and flood events

NASA Astrophysics Data System (ADS)

Boudet, L.; Sabatier, F.; Radakovitch, O.

2017-11-01

The delta of the Rhone River is one of the most important in the Mediterranean Sea. Beach erosion problems along its coasts have developed in recent decades, raising the need for a better understanding of the sediment transport processes at the Rhone mouth and the adjacent beaches. Because field data are very difficult to obtain in such an energetic environment, a high-resolution numerical model (Delft3D) is applied to this area. This model is calibrated by taking into account hydrodynamical and morphological observations. Special attention is given to storm and flood events, which are the major morphological drivers. Therefore, scenarios with different wave and flow conditions are run to estimate the influence of these events on the sediment transport. The analysis of historical hydrological data shows that storms from the southeast represent 70% of the events between 1979 to 2010 and that 20% of them were followed by a flood within a few days. Consequently, specific simulations for such conditions are performed using Delft3D. The model simulates trends in the bedload sediment transport that are consistent with the bedforms observed in the bathymetry data. The total sediment transport at the outlet is only influenced by the river flow, but sediment transport at the mouth-bar depends on an equilibrium between the influence of floods and storms and the succession of these events. A period of 2 or 3 days separating the storm and flood peaks is sufficient to differentiate wave and river flow-induced sediment transport. The waves constrain the total transport on the mouth-bar and shallow mouth-lobe and induce a longshore transfer towards the adjacent beaches. The riverine sediments can be exported seaward only if a flood is energetic enough compared to the storm intensity. Regardless, when a flood is greater than the decadal return period (7800 m3 s-1), the sediment is transported from the outlet across the mouth-bar and is directed offshore.

Deposition of shallow water sponges in response to seasonal changes

NASA Astrophysics Data System (ADS)

Ávila, Enrique; Carballo, José Luis; Vega, Cristina; Camacho, Leonardo; Barrón-Álvarez, José J.; Padilla-Verdín, Claudia; Yáñez-Chávez, Benjamín

2011-08-01

Removal of organisms from the subtidal zone plays an important role in shaping benthic communities in shallow bays. The main objective of this research was to quantify the biomass of sponges washed up on the beach at Mazatlan Bay (Mexico, eastern Pacific Ocean), and to determine its relationship with local weather and oceanographic conditions. To know whether this process has a significant effect on the sponge populations, changes in abundance of the species washed into the beach were also quantified in adjoining sublittoral areas. The sponges that were washed ashore were mainly branching ( Mycale ramulosa), massive ( Haliclona caerulea) and cushion-shaped ( Callyspongia californica) species. Species with high content of spongin in their structure (e.g. Hyattella intestinalis) were common in the subtidal zone but were rarely found on the beach. Encrusting species were never found. Four-year data of sponge deposition on the beach showed that the total annual sponge biomass ranged from 30 to 60 g DW m - 2 with an inter-annual range from 0.1 to 17.3 g DW m - 2 . The highest deposition of sponges was during the spring-summer transition (from April to July), which was associated with a change in wind direction (from NW to WSW). This change also matched with low tides and a high resuspension of bottom sediments, suggesting a high-energy environment during this transition. The increase in sponge biomass washed on the beach coincided with a decrease in the density of adjacent sponge populations. A multiple regression analysis showed that 68.48% of the variation on sponge biomass on the beach could be statistically explained using a combination of environmental factors (wind speed, sediment resuspension and tides). Thus, seasonal changes in wind direction combined with the effect of low tides and sediment resuspension could serve to predict fragmentation/detachment events of benthic organisms in shallow sublittoral areas worldwide. This study also provides insights to explain the predominance of encrusting sponges in the Mexican Pacific Ocean.

The use of time-series LIDAR to understand the role of foredune blowouts in coastal dune dynamics, Sefton, NW England.

NASA Astrophysics Data System (ADS)

O'Keeffe, Nicholas; Delgado-Fernandez, Irene; Aplin, Paul; Jackson, Derek; Marston, Christopher

2017-04-01

Coastal dunes are natural buffers against the threat of climate change-induced sea level rise. Their evolution is largely controlled by sediment exchanges between the geomorphic sub-units of the nearshore, beach, foredune and dune field. Coastlines characterised by multiple blowouts at the beach-dune interface may be more susceptible to coastline retreat through the enhanced landwards transport of beach and foredune sediment. This study, based in Sefton, north-west England, exploits an unprecedented temporal coverage of LIDAR surveys spanning 15 years (1999, 2008, 2010, 2013 and 2014). Established GIS techniques have been utilised to extract both the coastline (foredune toe) and the foredune crest from each LIDAR derived DTM (Digital Terrain Model). Migration of the foredune toe has been tracked over this period. Analysis of differentials between the height of the dune toe and dune crest have been used to locate the alongshore position of blowouts within the foredune. Dune sediment budgets have then been calculated for each DTM and analysis of the budgets conducted, with the coastline being compartmentalised alongshore, based on presence of blowouts within the foredune. Results indicate that sections of the coastline where blowouts are present within the foredune may be most vulnerable to coastline retreat. Temporal changes in the sediment budget within many of these sections also provides evidence that, if blowouts are present, coastline retreat continues to be a possibility even when the dune sediment budget remains positive.

Identification of Challenges and Opportunities for Regional Sediment Management (RSM) and Engineering with Nature (EWN) within Inland USACE Districts

DTIC Science & Technology

2016-07-01

sediment dredging activities in support of navigation channel maintenance with resultant direct beach placement or nearshore placement were common...watershed and stream channel erosion prevention. • Identify sediment resources and flux in and out of the flood plain and create sediment budgets...Regional Sediment Management (RSM) and Engineering With Nature (EWN) within Inland USACE Districts by Katherine Touzinsky, Paul Boyd, and John

CROSS-SHORE TRANSPORT OF BIMODAL SANDS.

USGS Publications Warehouse

Richmond, Bruce M.; Sallenger,, Asbury H.; Edge, Billy L.

1985-01-01

Foreshore sediment level and sediment size were monitored as part of an extensive nearshore processes experiment - DUCK 82. Changes in foreshore texture were compared with computed values of onshore transported material based on current measurements from the surf zone and sediment transport theory. Preliminary results indicate reasonable agreement between predicted size of sediment transported onshore and beach texture changes. It is also demonstrated that coarse sediment may move onshore while finer material may simultaneously move offshore. Refs.

Human impact, geomorphological and bio-environmental indicators for mapping and monitoring of a Mediterranean urban-beach with Posidonia oceanica (Gulf of Cagliari-Sardinia)

NASA Astrophysics Data System (ADS)

De Muro, Sandro; Pusceddu, Nicola; Frongia, Paolo; Buosi, Carla; Passarella, Marinella; Ibba, Angelo

2016-04-01

This work describes the human conditioned evolution (medium term) and the short term dynamics (mainly sediment transport) in southern Sardinia beach (between Giorgino and Cala d'Orri, about 11km), composed of fine to coarse quartz sand, backed by dune ridges and lagoons. The study was founded by NEPTUNE Project, Tender6 (L n. 7/2007). Geomorphological and bio-environmental indicators as: urbanization and coastal defence expansion, dune and beach changes, biotic indices (benthic foraminifera and Posidonia meadow) have been used. Medium-term evolution, over a period of 60 years, was carried out by ortho-images (1954-2015) for reconstructing coastline changes at this temporal scale. The main modifications were the building of the canal harbor, the consequent loss of 2.5km of beach, and the construction of several coastal defense structures, which caused asymmetric accumulations (lee zones) and erosion areas. Short-term variations have been periodically monitored (2014-2015) during 5 different field surveys (DGPS and Echo-sounder data) obtaining topo-bathymetric digital models. Sedimentary and hydrodynamic characteristics have been studied. Wave propagation, coastal currents and sediment transport, have been simulated through numerical models within Delft3D software. The results obtained allowed to visualize the response of the beach to wave stress, forced from SW, S, SE (Cagliari buoy and weather data). The comparison between data collected, thematic maps and models allowed to identify the main controlling factors and distribution mechanisms of the sedimentary paths on the shoreface. Those human modifications (e.g. building of the canal harbour and jetties, lagoon mouths stabilization, the consequent modified hydrodynamics and bottom trawling) have direct influence on the Posidonia oceanica and on its upper limit. In 2002, the Italian Environment Office reported a wide area (between -4m and -20m) of degraded Posidonia and dead matte in front of the study beach. Reflecting the poor state of the Posidonia upper limit, during data collection it has been documented the presence of banquette, mainly composed of Caulerpa prolifera, with which the Posidonia competes for the substrate. The roles of Posidonia oceanica in coastal defence (sediment retainment, hydrodynamics attenuation), fish nursery and water oxygenation have been largely recognized. The health of the Posidonia meadow is also linked to the biotic communities. In order to evaluate the ecosystem quality of the investigated area, living benthic foraminiferal assemblages (Rose Bengal stained) were analysed. Benthic foraminifera are useful as bioindicator proxies for characterization of specific environments in coastal systems, because foraminifera have short life cycles reacting quite quickly to both short and long-term changes in marine and transitional-marine environments on both global and local scale. Results demonstrate, in medium-term scale, the human modification, and in short-term scale, the consequent human conditioning in sediment transport. The benthic foraminiferal biocoenosis and biotic indices decrease in the samples characterized by high environmental stress and are linked to the poor state of the Posidonia upper limit. The low abundance values and the dominance of indicative opportunistic species, such as Ammonia tepida, Haynesina germanica and bolivinids, are the result of these stressed conditions.

New Insights on Coastal Foredune Growth: The Relative Contributions of Marine and Aeolian Processes

NASA Astrophysics Data System (ADS)

Cohn, Nicholas; Ruggiero, Peter; de Vries, Sierd; Kaminsky, George M.

2018-05-01

Coastal foredune growth is typically associated with aeolian sediment transport processes, while foredune erosion is associated with destructive marine processes. New data sets collected at a high energy, dissipative beach suggest that total water levels in the collision regime can cause dunes to accrete—requiring a paradigm shift away from considering collisional wave impacts as unconditionally erosional. From morphologic change data sets, it is estimated that marine processes explain between 9% and 38% of annual dune growth with aeolian processes accounting for the remaining 62% to 91%. The largest wind-driven dune growth occurs during the winter, in response to high wind velocities, but out of phase with summertime beach growth via intertidal sandbar welding. The lack of synchronization between maximum beach sediment supply and wind-driven dune growth indicates that aeolian transport at this site is primarily transport, rather than supply, limited, likely due to a lack of fetch limitations.

Persistence and biodegradation of spilled residual fuel oil on an estuarine beach.

PubMed

Pierce, R H; Cundell, A M; Traxler, R W

1975-05-01

The enrichment of hydrocarbon-degrading bacteria and the persistence of petroleum hydrocarbons on an estuarine beach after a spill of residual fuel oil on 11 April 1973 in Upper Narragansett Bay, R.I. was investigated. A rapid enrichment occurred during days 4 to 16 after the oil spill and a significant population of hydrocarbon-degrading bacteria was maintained in the beach sand for at least a year. The concentration of petroleum hydrocarbons in the mid-tide area declined rapidly during the bacterial enrichment period, remained fairly constant throughout the summer, and then declined to a low concentration after 1 year. An increased concentration of branched and cyclic aliphatic hydrocarbons in the low-tide sediment 128 days after the spill suggested a migration of hydrocarbons during the summer. Hydrocarbon biodegradation was apparent during the winter months at a rate of less than 1 mug of hydrocarbon per g of dry sediment per day.

Regional Similarities and Consistent Patterns of Local Variation in Beach Sand Bacterial Communities throughout the Northern Hemisphere

PubMed Central

Staley, Christopher

2016-01-01

ABSTRACT Recent characterization of the bacterial community structure in beach sands has revealed patterns of biogeography similar to those observed in aquatic environments. Studies to date, however, have mainly focused on subtidal sediments from marine beaches. Here, we investigate the bacterial diversity, using Illumina-based sequencing of the V5-V6 region of the 16S rRNA gene, at 11 beaches representing those next to the Great Lakes, Florida, and the Pacific Ocean. The alpha diversity differed significantly among regions (P < 0.0001), while the within-region diversity was more similar. The beta diversity also differed by region (P < 0.001), where freshwater sands had significantly higher abundances of taxa within the Actinobacteria, Betaproteobacteria, and Verrucomicrobia than marine environments. In contrast, marine sands harbored greater abundances of Gammaproteobacteria and Planctomycetes, and those from Florida had more Deltaproteobacteria and Firmicutes. Marine beaches had significantly different phylogenetic community structures (P ≤ 0.018), but freshwater and Florida beaches showed fewer within-region phylogenetic differences. Furthermore, regionally distinct patterns in taxonomic variation were observed in backshore sands, which had communities distinct from those in nearshore sands (P < 0.001). Sample depth minimally influenced the community composition. The results of this study reveal distinct bacterial community structures in sand on a broad geographic scale but moderate regional similarity and suggest that local variation is primarily related to the distance from the shoreline. This study offers a novel comparison of the bacterial communities in freshwater and marine beach sands and provides an important basis for future comparisons and analyses to elucidate factors affecting microbial ecology in this underexplored environment. IMPORTANCE This study presents a large-scale geographic characterization of the bacterial communities present in beach sands. While previous studies have evaluated how environmental factors influence bacterial community composition, few have evaluated bacterial communities in freshwater sands. Furthermore, the use of a consistent methodology to characterize bacterial communities here allowed a novel comparison of communities across geographic regions. We reveal that while the community composition in sands at individual beaches is distinct, beach sands within the same region harbor similar assemblages of bacteria and these assemblages differ greatly between regions. In addition, moisture, associated with distance from the shoreline, strongly influences the bacteria present in sands and more strongly influences the bacteria present than sample depth does. Thus, the data presented here offer an important basis for a broader characterization of the ecology of bacteria in sands, which may also be relevant to public health and resource management initiatives. PMID:26921429

Beach Ridge Evidence for Regional Tilting and Drainage Reorganization in Central Florida

NASA Astrophysics Data System (ADS)

Adams, P. N.; Jaeger, J. M.; Woo, H. B.; Panning, M. P.

2016-12-01

Beach ridge sets can be constructed by a variety of processes (e.g. swash-built, eolian dune-built), but in all cases their presence represents a sediment supply rate that outpaces the rate of generation of accommodation space, resulting in progradation of the shoreline. The Merritt Island-Cape Canaveral sedimentary complex (MICCSC) consists of a series of adjacent, yet non-conformable, beach ridge sets that suggest a multi-phase constructional history. Previous U/Th, radiocarbon and OSL dating indicates that deposition of the beach ridge sets began at least 40 ka. We show that the duration of time required to accumulate this sedimentary mass, assuming longshore sediment transport (LST) alone, is within the appropriate time frame supplied by the age dates reported, but there is no clear mechanism that explains why LST would be interrupted to cause sedimentary accumulation at this particular location. An alternate explanation for the presence of the MICCSC is that the sedimentary body represents an abandoned paleodelta, whose source provided a sediment supply sufficient for coastal progradation. Although no such source is active today, the St. Johns River is a low-gradient fluvial system that currently empties to the Atlantic Ocean near Jacksonville, Florida, and has a drainage basin area of nearly 23,000 km2, which could satisfy the sediment supply rate required to build a delta the size of the MICCSC. Among several plausible drainage rearrangement mechanisms, we demonstrate that karst-driven, flexural isostatic uplift originating from carbonate dissolution within the central portion of the Florida peninsula has driven northward down-tilting of the landscape, forcing the St. Johns to seek a new coastal exit point, abandoning the MICCSC.

Investigating Coastal Processes Responsible for Large-Scale Shoreline Responses to Human Shoreline Stabilization

NASA Astrophysics Data System (ADS)

Slott, J. M.; Murray, A. B.; Ashton, A. D.

2006-12-01

Human shoreline stabilization practices, such as beach nourishment (i.e. placing sand on an eroding beach), have become more prevalent as erosion threatens coastal communities. On sandy shorelines, recent experiments with a numerical model of shoreline change (Slott, et al., in press) indicate that moderate shifts in storminess patterns, one possible outcome of global warming, may accelerate the rate at which shorelines erode or accrete, by altering the angular distribution of approaching waves (the `wave climate'). Accelerated erosion would undoubtedly place greater demands on stabilization. Scientists and coastal engineers have typically only considered the site-specific consequences of shoreline stabilization; here we explore the coastal processes responsible for large-scale (10's kms) and long-term (decades) effects using a numerical model developed by Ashton, et al. (2001). In this numerical model, waves breaking at oblique angles drive a flux of sediment along the shoreline, where gradients in this flux can shape the coastline into surprisingly complex forms (e.g. cuspate-capes found on the Carolina coast). Wave "shadowing" plays a major role in shoreline evolution, whereby coastline features may block incoming waves from reaching distant parts. In this work, we include beach nourishment in the Ashton, et al. (2001) model. Using a cuspate-cape shoreline as our initial model condition, we conducted pairs of experiments and varied the wave-climate forcing across each pair, each representing different storminess scenarios. Here we report on one scenario featuring increased extra-tropical storm influence. For each experiment-pair we ran a control experiment with no shoreline stabilization and a second where a beach nourishment project stabilized a cape tip. By comparing the results of these two parallel runs, we isolate the tendency of the shoreline to migrate landward or seaward along the domain due solely to beach nourishment. Significant effects from beach nourishment reached several tens of kilometers away from the nourishment project. The magnitude of these effects rivaled the erosion we expect from sea-level rise alone over the coming century. Furthermore, the nature of the effects were unexpected: where we expect beach nourishment sand to spread laterally in the direction of net alongshore sediment transport (e.g. to the right looking off-shore), coastline segments to the right of the cape should tend to migrate seaward, while segments to the left of the cape might naively be expected to feel little effects. We observed, however, that shoreline segments to the left (right) of the stabilized cape tip tended to migrate seaward (landward). Two statistics we collected for each model run--the extent of wave shadowing and the net flux of sediment at each alongshore position--helped explain the surprising behavior. By pinning the location of the cape tip, beach nourishment altered the way in which the cape shadowed adjacent coastlines. The stabilized cape-tip shadowed segments to the left more often, increasing the influence from left-approaching waves. These shoreline segments shifted seaward, relative to the non-nourishment case, through a convergence in alongshore sediment transport from increased transport from the left, rather than from laterally-spreading beach nourishment sand. The stabilized cape-tip shadowed segments to the right less often, increasing the influence of left-approaching waves. These segments shifted landward through a divergence in alongshore sediment transport from increased transport to the right.

Integrating multi-disciplinary field and laboratory methods to investigate the response and recovery of beach-dune systems in Ireland to extreme events

NASA Astrophysics Data System (ADS)

Farrell, E.; Lynch, K.; Wilkes Orozco, S.; Castro Camba, G.; Scullion, A.

2017-12-01

This two year field monitoring project examines the response and recovery of 1.2km of a coastal beach-dune system in the west coast of Ireland (The Maharees, Brandon Bay, Co. Kerry) to storms. The results from this project initiated a larger scale study to assess the long term evolution of Brandon Bay (12km) and patterns of meso-scale rotation. On a bay scale historic shoreline analyses were completed using historic Ordnance Survey maps, aerial photography, and DGPS surveys inputted to the Digital Shoreline Analysis System. These were coupled with a GSTA-wavemeter experiment that collected 410 sediment samples along the beach and nearshore to identify preferred sediment transport pathways along the bay. On a local scale (1.2km) geomorphological changes of the beach and nearshore were monitored using repeated monthly DGPS surveys and drone technology. Topographical data were correlated with atmospheric data obtained from a locally installed automatic weather station, oceanographic data from secondary sources, and photogrammetry using a camera installed at the site collecting pictures every 10 minutes during daylight hours. Changes in surface elevation landward of the foredune from aeolian processes were measured using five pin transects across the dune. The contribution of local blowout dynamics were measured using drone imagery and structure-from-motion technology. The results establish that the average shoreline recession along the 1.2 km site is 72 m during the past 115 years. The topographic surveys illustrate that natural beach building processes initiate system recovery post storms including elevated foreshores and backshores and nearshore sand bar migration across the entire 1.2 km stretch of coastline. In parallel with the scientific work, the local community have mobilized and are working closely with the lead scientists to implement short term coastal management strategies such as signage, information booklets, sand trap fencing, walkways, wooden revetments, dune planting in order to support the end goal of obtaining financial support from government for a larger, long term coastal protection plan.

Intertidal Sandbar Welding as a Primary Source of Sediment for Dune Growth: Evidence from a Large Scale Field Experiment

NASA Astrophysics Data System (ADS)

Cohn, N.; Ruggiero, P.; de Vries, S.

2016-12-01

Dunes provide the first line of defense from elevated water levels in low-lying coastal systems, limiting potentially major flooding, economic damages, and loss of livelihood. Despite the well documented importance of healthy dunes, our predictive ability of dune growth, particularly following erosive storm events, remains poor - resulting in part from traditionally studying the wet and dry beach as separate entities. In fact, however, dune recovery and growth is closely tied to the subtidal morphology and the nearshore hydrodynamic conditions, necessitating treating the entire coastal zone from the shoreface to the backshore as an integrated system. In this context, to further improve our understanding of the physical processes allowing for beach and dune growth during fair weather conditions, a large field experiment, the Sandbar-aEolian Dune EXchange EXperiment, was performed in summer 2016 in southwestern Washington, USA. Measurements of nearshore and atmospheric hydrodynamics, in-situ sediment transport, and morphology change provide insight into the time and space scales of nearshore-beach-dune exchanges along a rapidly prograding stretch of coast over a 6 week period. As part of this experiment, the hypothesis that dune growth is limited by the welding of intertidal sandbars to the shoreline (Houser, 2009) was tested. Using laser particle counters, bed elevation sensors (sonar altimeters and Microsoft Kinect), continuously logging sediment traps, RGB and IR cameras, and repeat morphology surveys (terrestrial lidar, kite based structure from motion, and RTK GPS), spatial and temporal trends in aeolian sediment transport were assessed in relation to the synoptic onshore migration and welding of intertidal sandbars. Observations from this experiment demonstrate that (1) the intertidal zone is the primary source of sediment to the dunes during non-storm conditions, (2) rates of saltation increase during later stages of bar welding but equivalent wind conditions, and (3) alongshore variability in rates of backshore fluxes appear to be related to alongshore variability in intertidal morphology. These observations quantitatively support the Houser (2009) bar welding hypothesis and provide valuable new insights on nearshore-beach-dune sediment exchanges

Integration of seafloor point data in usSEABED

USGS Publications Warehouse

Reid, Jane A.; Williams, S. Jeffress; Zimmermann, Mark; Jenkins, Chris; Golden, Nadine E.

2007-01-01

Sediments of the beach, nearshore, and continental shelves record a complex interplay of processes including wave energy and direction , currents, beach erosion or accretion, bluff or cliff retreat, fluvial input, sediment longshore and cross-shelf transport processes, contaminant content and transport, sediment sources and sinks, and others. In turn, sediments and rocks modify wave patterns, affect recreation and tourism, and provide habitat for fish, epifauna, and infauna. Character of the surficial seafloor also influences navigation, commercial and recreational fishing and gathering of other food sources, communication, piplines, national defense, and provides geologic resources including sand and gravel aggregates, minerals, and real or potential energy sources. The beaches, nearshore, and continental margins fall under overlapping levels of managerial responsibility between Federal, State, regional, and local government agencies and consortia. In addition, universities and other academic institutions investigate these places for pure or applied scientific reasons. Mapping is usually the first step in understanding any issue and is often comprised of remotely gathered geophysical data such as bathymetry and backscatter imagery, and groundtruthing; that is, the collection of physical and virtual samples to tie the remotely gathered data to reality. The physical samples are described and (or) carefully analyzed for grain-size information -- which records both the site's physical conditions and geologic past -- and commonly, for constituent components such as mineral and rock types (to determine onland sources and in situ chemical processes), carbonate and organic content and microfossils (for biological and oceanographic influences), and structure such as layering and bioturbation (for physical influences). The samples may also be subjected to physical tests such as comp[action analyses, liquefaction or plasticity limits, ans other parameters important when considering construction of offshore structures. In recent years, virtual sampling of the seafloor has become popular, through the use of towed video or photographic equipment and the addition of camera to oceanographic equipment such as corers and tripods. Before about ten years ago, most maps were made by hand. Recently, with the advent of desktop GIS packages, map making and resource analysis can be done nearly "on-the-fly" if geographically located data exist. While the problems of projection, scale, and resolution of digitized paper maps are commonly known amongst GIS-users, access to the original underlying point data allows for maps to be regenerated for digital use using statistically proven methods, provides increasing data density by including multiple studies, as well as allows the point data to be used in other ways than just mapping. These point data may be available in raw or refined or in worded descriptions. Raw data such as granulometric analyses can be manipulated through the use of known equations or empirical relationships to provide information about other parameters of the sediment, such as mean grainsize, sorting, erodability, or rugosity. If refined data are presented such as gravel, sand, and mud percentages, the parameter noted earlier may be estimated. In the case of worded descriptions, values for geologic terms can be assigned, for example, "fine sand" equate to 0.2 mm sized particles, to provide numeric terms for GIS or modeling purposes.

Connecting large-scale coastal behaviour with coastal management of the Rhône delta

NASA Astrophysics Data System (ADS)

Sabatier, François; Samat, Olivier; Ullmann, Albin; Suanez, Serge

2009-06-01

The aim of this paper is to connect the Large Scale Coastal Behaviour (LSCB) of the Rhône delta (shoreface sediment budget, river sediment input to the beaches, climatic change) with the impact and efficiency of hard engineering coastal structures. The analysis of the 1895 to 1974 bathymetric maps as well as 2D modelling of the effect of wave blocking on longshore transport allows us to draw up a conceptual model of the LSCB of the Rhône delta. The river sand input, settled in the mouth area (prodeltaic lobe), favours the advance of adjacent beaches. There is however a very weak alongshore sand feeding of the non-adjacent beaches farther off the mouth. After a mouth shift, the prodelta is eroded by aggressive waves and the sand is moved alongshore to build spits. This conceptual model suggests that there is a "timeshift" between the input of river sediments to the sea and the build up of a beach (nonadjacent to the mouth). Nowadays, as the river channels are controlled by dykes and human interventions, a river shift is not possible. It thus appears unlikely that the river sediments can supply the beaches of the Rhône delta coast. Under these conditions, we must expect that the problems of erosion will continue at Saintes-Maries-de-la-Mer and on the Faraman shore, in areas with chronic erosion where the shoreline retreat has been partially stopped by hard engineering practices in the 1980s. Therefore, these artificially stabilised sectors remain potentially under threat because of profile steepening and downdrift erosion evidenced in this paper by bathymetric profile measurements. In the long-term (1905 to 2003), the temporal analysis of the storm surges and the sea level show very weak but reliable increasing trends. Thus, these climatic agents will be more aggressive on the beaches and on the coastal structures calling their efficiency into question. We also evidence that the hard engineering structures were built in a favourable climatic context during the 1980s meanwhile the storm surges and the sea-level rise are stronger since the 1990s. Regarding to the LSCB of the Rhône delta, and the impact of hard engineering coastal structures, we suggest that classical hard coastal protections are not the best option to protect the coast.

Impact of wave action on the structure of material on the beach in Calypsobyen (Spitsbergen)

NASA Astrophysics Data System (ADS)

Mędrek, Karolina; Herman, Agnieszka; Moskalik, Mateusz; Rodzik, Jan; Zagórski, Piotr

2015-04-01

The research was conducted during the XXVI Polar Expedition of Maria Curie-Sklodowska University in Lublin on Spitsbergen. It involved recording water wave action in the Bellsund Strait, and taking daily photographs of the beach on its shore in Calypsobyen. The base of polar expeditions of UMCS, Calypsobyen, is located on the coast of Calypsostranda, developed by raised marine terraces. Weakly resistant Tertiary sandstones occur in the substrate, covered with glacigenic sediments and marine gravels. No skerries are encountered along this section of the accumulation coast. The shore is dominated by gravel deposits. The bottom slopes gently. The recording of wave action was performed from 8 July to 27 August 2014 by means of a pressure based MIDAS WTR Wave and Tide Recorder set at a depth of 10 m at a distance of about 1 km from the shore. The obtained data provided the basis for the calculation of the significant wave height, and the corresponding mean wave period . These parameters reflect wave energy and wave level, having a considerable impact on the dynamics of coastal processes and the type and grain size of sediments accumulated on the beach. Material consisting of medium gravel and seaweed appeared on the beach at high values of significant wave height and when the corresponding mean wave period showed average values. The contribution of fine, gravel-sandy material grew with an increase in mean period and a decrease in significant wave height. At maximum values of mean period and low values of significant wave height, the beach was dominated by well-sorted fine-grained gravel. The lowest mean periods resulted in the least degree of sorting of the sediment (from very coarse sand to medium gravel). The analysis of data from the wave and tide recorder set and their comparison with photographs of the beach suggest that wave action, and particularly wave energy manifested in significant wave height, has a considerable impact on the type and grain size of material occurring on the shore of the fjord. The mean period is mainly responsible for sorting out the sediment, and the size of gravels is associated with significant wave height. Project of National Science Centre no. DEC-2013/09/B/ST10/04141

Effects of sedimentation on soil physical and chemical properties and vegetation characteristics in sand dunes at the Southern Dongting Lake region, China

PubMed Central

Pan, Ying; Zhang, Hao; Li, Xu; Xie, Yonghong

2016-01-01

Sedimentation is recognized as a major factor determining the ecosystem processes of lake beaches; however, the underlying mechanisms, especially in freshwater sand dunes, have been insufficiently studied. To this end, nine belt transects from nine freshwater sand dunes, classified into low (<23.7 m), medium (25.4–26.0 m), and high-elevation groups (>28.1 m) based on their elevations in 1972, were sampled to investigate differences in sedimentation rate and soil and vegetation characteristics in Southern Dongting Lake, China. Sedimentation rate, soil sand content, and soil pH increased, whereas soil clay, fine silt, moisture (MC), organic matter (OM), total N, and total K content, in addition to the growth and biodiversity of sand dune plants generally decreased with decreasing belt transect elevation. Regression analyses revealed that the negative effects of sedimentation on the ecosystem functions of sand dunes could be attributed to higher fine sand content in deposited sediments and stronger inhibition of plant growth. These results are consistent with previous studies performed in coastal sand dunes, which highlights the importance of sedimentation in determining ecological processes. PMID:27808154

Effects of sedimentation on soil physical and chemical properties and vegetation characteristics in sand dunes at the Southern Dongting Lake region, China

NASA Astrophysics Data System (ADS)

Pan, Ying; Zhang, Hao; Li, Xu; Xie, Yonghong

2016-11-01

Sedimentation is recognized as a major factor determining the ecosystem processes of lake beaches; however, the underlying mechanisms, especially in freshwater sand dunes, have been insufficiently studied. To this end, nine belt transects from nine freshwater sand dunes, classified into low (<23.7 m), medium (25.4-26.0 m), and high-elevation groups (>28.1 m) based on their elevations in 1972, were sampled to investigate differences in sedimentation rate and soil and vegetation characteristics in Southern Dongting Lake, China. Sedimentation rate, soil sand content, and soil pH increased, whereas soil clay, fine silt, moisture (MC), organic matter (OM), total N, and total K content, in addition to the growth and biodiversity of sand dune plants generally decreased with decreasing belt transect elevation. Regression analyses revealed that the negative effects of sedimentation on the ecosystem functions of sand dunes could be attributed to higher fine sand content in deposited sediments and stronger inhibition of plant growth. These results are consistent with previous studies performed in coastal sand dunes, which highlights the importance of sedimentation in determining ecological processes.

Numerical simulation of two-phase flow for sediment transport in the inner-surf and swash zones

NASA Astrophysics Data System (ADS)

Bakhtyar, R.; Barry, D. A.; Yeganeh-Bakhtiary, A.; Li, L.; Parlange, J.-Y.; Sander, G. C.

2010-03-01

A two-dimensional two-phase flow framework for fluid-sediment flow simulation in the surf and swash zones was described. Propagation, breaking, uprush and backwash of waves on sloping beaches were studied numerically with an emphasis on fluid hydrodynamics and sediment transport characteristics. The model includes interactive fluid-solid forces and intergranular stresses in the moving sediment layer. In the Euler-Euler approach adopted, two phases were defined using the Navier-Stokes equations with interphase coupling for momentum conservation. The k-ɛ closure model and volume of fluid approach were used to describe the turbulence and tracking of the free surface, respectively. Numerical simulations explored incident wave conditions, specifically spilling and plunging breakers, on both dissipative and intermediate beaches. It was found that the spatial variation of sediment concentration in the swash zone is asymmetric, while the temporal behavior is characterized by maximum sediment concentrations at the start and end of the swash cycle. The numerical results also indicated that the maximum turbulent kinetic energy and sediment flux occurs near the wave-breaking point. These predictions are in general agreement with previous observations, while the model describes the fluid and sediment phase characteristics in much more detail than existing measurements. With direct quantifications of velocity, turbulent kinetic energy, sediment concentration and flux, the model provides a useful approach to improve mechanistic understanding of hydrodynamic and sediment transport in the nearshore zone.

Heavy mineral analysis for assessing the provenance of sandy sediment in the San Francisco Bay Coastal System

USGS Publications Warehouse

Wong, Florence L.; Woodrow, Donald L.; McGann, Mary

2013-01-01

Heavy or high-specific gravity minerals make up a small but diagnostic component of sediment that is well suited for determining the provenance and distribution of sediment transported through estuarine and coastal systems worldwide. By this means, we see that surficial sand-sized sediment in the San Francisco Bay Coastal System comes primarily from the Sierra Nevada and associated terranes by way of the Sacramento and San Joaquin Rivers and is transported with little dilution through the San Francisco Bay and out the Golden Gate. Heavy minerals document a slight change from the strictly Sierran-Sacramento mineralogy at the confluence of the two rivers to a composition that includes minor amounts of chert and other Franciscan Complex components west of Carquinez Strait. Between Carquinez Strait and the San Francisco Bar, Sierran sediment is intermingled with Franciscan-modified Sierran sediment. The latter continues out the Gate and turns southward towards beaches of the San Francisco Peninsula. The Sierran sediment also fans out from the San Francisco Bar to merge with a Sierran province on the shelf in the Gulf of the Farallones. Beach-sand sized sediment from the Russian River is transported southward to Point Reyes where it spreads out to define a Franciscan sediment province on the shelf, but does not continue southward to contribute to the sediment in the Golden Gate area.

Textural Maturity Analysis and Sedimentary Environment Discrimination Based on Grain Shape Data

NASA Astrophysics Data System (ADS)

Tunwal, M.; Mulchrone, K. F.; Meere, P. A.

2017-12-01

Morphological analysis of clastic sedimentary grains is an important source of information regarding the processes involved in their formation, transportation and deposition. However, a standardised approach for quantitative grain shape analysis is generally lacking. In this contribution we report on a study where fully automated image analysis techniques were applied to loose sediment samples collected from glacial, aeolian, beach and fluvial environments. A range of shape parameters are evaluated for their usefulness in textural characterisation of populations of grains. The utility of grain shape data in ranking textural maturity of samples within a given sedimentary environment is evaluated. Furthermore, discrimination of sedimentary environment on the basis of grain shape information is explored. The data gathered demonstrates a clear progression in textural maturity in terms of roundness, angularity, irregularity, fractal dimension, convexity, solidity and rectangularity. Textural maturity can be readily categorised using automated grain shape parameter analysis. However, absolute discrimination between different depositional environments on the basis of shape parameters alone is less certain. For example, the aeolian environment is quite distinct whereas fluvial, glacial and beach samples are inherently variable and tend to overlap each other in terms of textural maturity. This is most likely due to a collection of similar processes and sources operating within these environments. This study strongly demonstrates the merit of quantitative population-based shape parameter analysis of texture and indicates that it can play a key role in characterising both loose and consolidated sediments. This project is funded by the Irish Petroleum Infrastructure Programme (www.pip.ie)

Cattaraugus Creek Harbor, New York General Design Memorandum. Phase II. (Detailed Design). Volume II. Appendix E. Littoral Processes and Sedimentation in the Cattaraugus Embayment, New York. Appendix F. Sediment Transport in Cattaraugus Creek.

DTIC Science & Technology

1976-03-01

beaches than any other part of the southeastern shoreline of Lake Erie . It is the only major sand accumulation zone with the exception of Presque Isle , in...52 20. Photographs of zonal site #10. 54 21. Photograph and map of zonal site #11, Presque Isle , Pa. 57 F22. Photographs and beach profiles at zonal...site #11. 59 23. Photograph of zonal site #12, the recurved spit area on Presque Isle , Pa. 62 24. Block diagram of recurved spit area of Presque Isle

Comprehensive summary of beach renourishment and offshore sand removal impacts for Florida

USGS Publications Warehouse

Demopoulos, A.W.J.; Gualtieri, D.J.; Neils, A.; Huge, D.

2011-01-01

An essential first step in the scope of environmental impacts for a sediment mining project is a formulation of specific purpose, precise needs, and estimated impacts. For each individual project, scope must be described, acceptable alternatives must be determined, critical environmental issues must be identified, and mitigation measures must be resolved. Appropriate Federal and State regulations will often require evidence that sand placement is a reasonable alternative to shoreline protection. If so, material to be extracted from the borrow site must be characterized. Candidates must identify the extent of the potential area for sand resources, complete with screening criteria, and site-specific information must be obtained. Alternatives must be identified, compared, and contrasted. And, importantly, the most cost-effective and environmentally sound approach must be determined for the project to move forward. Florida's beaches and coastlines once provided natural protection against storm damage, while simultaneously supporting aquatic ecosystems and both commercial and recreational fisheries. However, beach erosion associated with regional construction and development of the coastline has reduced the effectiveness of natural storm protection. Coastal beaches are, in geological terms, ever-shifting and evolving through natural processes of erosion and replenishment. With permanent structures in place, such as seawalls, jetties, and revetments, natural shoreline is compartmentalized, dynamics are interrupted, and sediment is no longer replenished. Coastal erosion is often a problem where the natural sediment source is deficient. Many of Florida's beaches are now in need of beach replenishment to reduce the high level of damage caused by coastal flooding. Strategic placement of beach fill is a logical means for improving the stability of a shoreline where such a project is economically and environmentally feasible. Sand placement effectively extends the shoreline and provides protection for coastal developments. Beach nourishment or restoration must, however, be thought of as a continual effort and not a one-time fix. Therefore, a combination of sand placement with other erosion mitigation measures can be an effective way to stabilize a shoreline and extend the life of the beach nourishment. Fill material can be obtained from an offshore borrow site, and its characteristics must match the native material in terms of grain size and structure. Environmental concerns for such an effort include potential for decreased water quality during dredging operations, and disturbance of coastal habitat while removing or depositing dredged material. An in-depth scientific evaluation of deposit sites and potential borrow sites must be executed. Mitigation and monitoring efforts will also be critical for a successful low-impact beach management project. The potential exists for unwanted consequences to develop during dredging operations, all of which must be considered and reduced.-->

Wave Runup on a Frozen Beach Under High Energy Conditions

NASA Astrophysics Data System (ADS)

Didier, D.; Bernatchez, P.; Dumont, D.; Corriveau, M.

2017-12-01

High and mid-latitude beaches have typical morphological characteristics influenced by nearshore processes prevailing under ice conditions during cold season. Nearshore ice complexes (NIC) offer a natural coastal protection by covering beach sediments, while offshore ice-infested waters dissipate incoming waves. Climate change contributes to sea ice shrinking therefore reducing its protection against erosion and flooding. In the Estuary and Gulf of the St. Lawrence (ESL, GSL) (eastern Canada), sea ice cover undergoes an overall shrinking and simulated future projections tend toward a negligible effect on wave climate by 2100. Quantifying the effect of nearshore dynamics on frozen beaches is therefore imperative for coastal management as more wave energy at the coast is expected in the future. To measure the effect of a frozen beach on wave runup elevations, this study employs a continuous video recording of the swash motion at 4Hz. Video-derived wave runup statistics have been extracted during a tidal cycle on a frozen beach, using the Pointe-Lebel beach (ESL) as a test case. Timestack analysis was combined with offshore water levels and wave measurements. A comparison of runup under icy conditions (Dec. 30 2016) with a runup distribution during summer was made under similar high energy wave conditions. Results indicate high runup excursions potentially caused by lowered sediment permeability due to high pore-ice saturation in the swash zone, accentuating the overwash of the eroding coastline and thus the risk of flooding. With projected reduction in coastal sea ice cover and thus higher wave energy, this study suggests that episodes of degradation and weakening could influence the coastal flood risk in mid- and high-latitude cold environments.

Physical criteria for distinguishing sandy tsunami and storm deposits using modern examples

USGS Publications Warehouse

Morton, Robert A.; Gelfenbaum, Guy; Jaffe, Bruce E.

2007-01-01

Modern subaerial sand beds deposited by major tsunamis and hurricanes were compared at trench, transect, and sub-regional spatial scales to evaluate which attributes are most useful for distinguishing the two types of deposits. Physical criteria that may be diagnostic include: sediment composition, textures and grading, types and organization of stratification, thickness, geometry, and landscape conformity. Published reports of Pacific Ocean tsunami impacts and our field observations suggest that sandy tsunami deposits are generally 30 cm thick, generally extend The distinctions between tsunami and storm deposits are related to differences in the hydrodynamics and sediment-sorting processes during transport. Tsunami deposition results from a few high-velocity, long-period waves that entrain sediment from the shoreface, beach, and landward erosion zone. Tsunamis can have flow depths greater than 10 m, transport sediment primarily in suspension, and distribute the load over a broad region where sediment falls out of suspension when flow decelerates. In contrast, storm inundation generally is gradual and prolonged, consisting of many waves that erode beaches and dunes with no significant overland return flow until after the main flooding. Storm flow depths are commonly

Determining the Controlling Factors of Coastal Development along an Active Margin - A Case Study from Aceh, Indonesia

NASA Astrophysics Data System (ADS)

Monecke, Katrin; Meilianda, Ella; Hill, Emma; McAdoo, Brian; Qiang, Qui; Storms, Joep; Walstra, Dirk-Jan; Setiawan, Agus; Masputri, Aisha S.; Mayasari, Cut D.; Riandi, Indra; Nasir, Muhammad

2016-04-01

Understanding the recovery of shorelines after catastrophic events is crucial for sustainable coastal development and future hazard mitigation. Here, we present post-seismic coastal development data from West Aceh, Indonesia, an area that was severely affected by the 2004 Sumatra Andaman earthquake and ensuing Indian Ocean tsunami. Using a combined approach of spatial data analysis, field surveys and numerical modeling, we reconstruct the build-up of a new beach ridge along a 10 kilometer long stretch of the western Acehnese coast after the complete destruction of the beach in 2004. The coastline of West Aceh can be characterized as a microtidal, wave dominated environment with the wave climate being controlled by the monsoon seasons reaching a significant wave height of Hs = 1.2 m during the more energetic West Monsoon from April to September. Waves approach the shoreline at a very low angle resulting in minor and variable longshore sediment transport. The beach has an average foreshore slope of 0.07 and is composed of well sorted medium sand. Recently obtained bathymetric data indicates a steep upper shoreface with a slope of 0.03. Further offshore the slope decreases to 0.01 with 14 m water depth being reached in about 700 m distance to the shoreline. Grab samples obtained in 10 m water depth are composed of fine to medium sand but lenses of medium to coarse sand with abundant shell debris do also occur. Beach ridges can be traced up to 2 km inland and indicate long-term coastal progradation and abundant sediment supply to the littoral zone. The western Acehnese shoreline parallels the Sunda trench and subsided 50 to 100 cm during the 2004 rupture. Modeled land elevation changes as a result of afterslip and viscoelastic mantle relaxation, indicate rapid post-seismic uplift of 4.4 cm/year in the year following the earthquake, but more moderate uplift rates of 1.4 cm/year since mid-2006. In 2004, co-seismic subsidence and tsunami scouring caused the coastline to recede on average 110 m. However, by 2006 a new 22 m wide beach ridge had formed probably due to reworking of sediment transported offshore by the back flow of the tsunami. In the following two years the coast prograded by an additional 30 m, but experienced only minor changes between 2009 and 2011. 2012 and 2013 were characterized by a renewed retreat of up to 41 m, which might be attributed to seasonal hydrodynamic variations. Field surveys in 2015 show that the coastline most recently grew back to its approximate 2011 position. The application of the coastal model UNIBEST allows us to simulate cross-shore profile changes using the acquired field data, to investigate the complex interaction of vertical ground movement, sediment supply, and hydrodynamic parameters and to gain insights into the controlling factors of long-term coastal development and the short-term effects of seismic events on coastal morphology.

Risk Assessment for Children Exposed to Beach Sands Impacted by Oil Spill Chemicals.

PubMed

Black, Jennifer C; Welday, Jennifer N; Buckley, Brian; Ferguson, Alesia; Gurian, Patrick L; Mena, Kristina D; Yang, Ill; McCandlish, Elizabeth; Solo-Gabriele, Helena M

2016-08-27

Due to changes in the drilling industry, oil spills are impacting large expanses of coastlines, thereby increasing the potential for people to come in contact with oil spill chemicals. The objective of this manuscript was to evaluate the health risk to children who potentially contact beach sands impacted by oil spill chemicals from the Deepwater Horizon disaster. To identify chemicals of concern, the U.S. Environmental Protection Agency's (EPA's) monitoring data collected during and immediately after the spill were evaluated. This dataset was supplemented with measurements from beach sands and tar balls collected five years after the spill. Of interest is that metals in the sediments were observed at similar levels between the two sampling periods; some differences were observed for metals levels in tar balls. Although PAHs were not observed five years later, there is evidence of weathered-oil oxidative by-products. Comparing chemical concentration data to baseline soil risk levels, three metals (As, Ba, and V) and four PAHs (benzo[a]pyrene, benz[a]anthracene, benzo[b]fluoranthene, and dibenz[a,h]anthracene) were found to exceed guideline levels prompting a risk assessment. For acute or sub-chronic exposures, hazard quotients, computed by estimating average expected contact behavior, showed no adverse potential health effects. For cancer, computations using 95% upper confidence limits for contaminant concentrations showed extremely low increased risk in the 10(-6) range for oral and dermal exposure from arsenic in sediments and from dermal exposure from benzo[a]pyrene and benz[a]anthracene in weathered oil. Overall, results suggest that health risks are extremely low, given the limitations of available data. Limitations of this study are associated with the lack of toxicological data for dispersants and oil-spill degradation products. We also recommend studies to collect quantitative information about children's beach play habits, which are necessary to more accurately assess exposure scenarios and health risks.

Risk Assessment for Children Exposed to Beach Sands Impacted by Oil Spill Chemicals

PubMed Central

Black, Jennifer C.; Welday, Jennifer N.; Buckley, Brian; Ferguson, Alesia; Gurian, Patrick L.; Mena, Kristina D.; Yang, Ill; McCandlish, Elizabeth; Solo-Gabriele, Helena M.

2016-01-01

Due to changes in the drilling industry, oil spills are impacting large expanses of coastlines, thereby increasing the potential for people to come in contact with oil spill chemicals. The objective of this manuscript was to evaluate the health risk to children who potentially contact beach sands impacted by oil spill chemicals from the Deepwater Horizon disaster. To identify chemicals of concern, the U.S. Environmental Protection Agency’s (EPA’s) monitoring data collected during and immediately after the spill were evaluated. This dataset was supplemented with measurements from beach sands and tar balls collected five years after the spill. Of interest is that metals in the sediments were observed at similar levels between the two sampling periods; some differences were observed for metals levels in tar balls. Although PAHs were not observed five years later, there is evidence of weathered-oil oxidative by-products. Comparing chemical concentration data to baseline soil risk levels, three metals (As, Ba, and V) and four PAHs (benzo[a]pyrene, benz[a]anthracene, benzo[b]fluoranthene, and dibenz[a,h]anthracene) were found to exceed guideline levels prompting a risk assessment. For acute or sub-chronic exposures, hazard quotients, computed by estimating average expected contact behavior, showed no adverse potential health effects. For cancer, computations using 95% upper confidence limits for contaminant concentrations showed extremely low increased risk in the 10−6 range for oral and dermal exposure from arsenic in sediments and from dermal exposure from benzo[a]pyrene and benz[a]anthracene in weathered oil. Overall, results suggest that health risks are extremely low, given the limitations of available data. Limitations of this study are associated with the lack of toxicological data for dispersants and oil-spill degradation products. We also recommend studies to collect quantitative information about children’s beach play habits, which are necessary to more accurately assess exposure scenarios and health risks. PMID:27618904

Sediments from the Boxing Day tsunami on the coasts of southeastern India and Kenya

NASA Astrophysics Data System (ADS)

Weiss, R.; Bahlburg, H.

2006-12-01

On the Boxing Day 2004, the world community experienced a catastrophic tsunami in the Indian Ocean and could also saw how unprepared and unaware countries along the Indian ocean were. Beyond the tragedy of the tremendous loss of lives, the result of this event is an opportunity to study a global tsunami (mega-tsunami) in many regards. Here, we report on tsunami sediments left behind on beaches at the coast of Tamil Nadu (India) and on beaches between Malindi and Lamu (Kenya). Characteristic debris accumulations on the beach surface at Tamil Nadu (India) showed the impact of three tsunami waves. In this area, the tsunami climbed ~5 m up the beach; the last traces of a tsunami wave were found ~580 m away from the shoreline. Palm trees indicated an overland flow depth of 3.5 m, ~50 m from the shoreline. The tsunami deposits were up to 30 cm thick. They had an erosional base to the underlying soil and pre-tsunami beach deposits and were made up of moderately well- to well-sorted coarse and medium sand. The sand sheet thins inland, but without a decrease in grain size. Three distinct layers could be identified within the tsunami deposit. The lower one occasionally displayed cross-bedding with foresets dipping landward indicating deposition during run-up. The two upper layers were graded or parallel-laminated without indicators of flow directions. The boundaries between the different layers were marked by dark laminae, rich in heavy minerals. Also, the presence of benthic foraminifera indicates entrainment of sediment into the water column by the incoming tsunami wave in water depths less than 30 m. On beaches between Malindi and Lamu, Kenya, the traces of only one tsunami wave could be found, which attained a run-up height of about 3 m and traveled ~35 m inland with respect to the tidal stage at tsunami impact. The tsunami sediments consist of one layer of fine sand and are predominantly composed of heavy minerals supplied to the sea by nearby rivers. A slight fining-inland trend could be identified in the thinning- inland sand layer. Benthic foraminifera also indicate an entrainment of sediment by the incoming tsunami wave in a water depth less than 30 m, however there are indications that sediment might be entrained in a water depth of 80 m. The fact that only one sand layer occurs in Kenya as opposed to three at Tamil Nadu might lead to the conclusion that only one wave approached the Kenyan coast. This interpretation is misleading because the Kenyan coast is several thousand kilometers away from source area of the tsunami; the non-linear behavior of the incoming tsunami waves, especially the interaction with the nearby reef, may have resulted in the discovered sedimentologic evidence of the tsunami impact on the Kenyan coast.

Evaluation of submarine strain-gage systems for monitoring coastal sediment migration

NASA Technical Reports Server (NTRS)

Shideler, G. L.; Mcgrath, D. G.

1973-01-01

Single and multiple strain-gage systems were respectively evaluated as in situ point and areal sensors for monitoring sand-height variations in coastal environments. Static loading tests indicate that gage response pressure is linear for sand heights up to 24 inches. Response pressures are a function of both sand height and aggregate density, with density being influenced by both sediment texture and degree of compaction. Poorer sediment sorting and greater compaction result in higher response pressures. Field tests in a beach foreshore environment indicate that the gage systems are effective qualitative instruments for monitoring long-period migration trends of beach sediments; whereas, short-period responses are not sufficiently reliable. The durability and compactness of the gage systems must be substantially increased for effective field operations. It is recommended that the systems' qualitative potentials be further developed, whereas their development as quantitative instruments be terminated. Further development should emphasize the construction of remote recording systems designed for semipermanent installation.

Modern Sedimentation along the SE Bangladesh Coast Reveal Surprisingly Low Accumulation Rates

NASA Astrophysics Data System (ADS)

McHugh, C.; Mustaque, S.; Mondal, D. R.; Akhter, S. H.; Iqbal, M.

2016-12-01

Recent sediments recovered along the SE coast of Bangladesh, from Teknaf to Cox's Bazar and drainage basin analyses reveal sediment sources and very low sedimentation rates of 1mm/year. These low rates are surprisingly low given that this coast is adjacent to the Ganges-Brahmaputra Delta with a yearly discharge of 1GT. The Teknaf anticline (elevation 200 m), part of the western Burma fold-thrust belt dominates the topography extending across and along the Teknaf peninsula. It is thought to have begun evolving since the Miocene (Alam et al. 2003 & Allen et al. 2008). Presently the anticline foothills on the west are flanked by uplifted terraces, the youngest linked to coseismic displacement during the 1762 earthquake (Mondal et al. 2015), and a narrow beach 60-200 m in width. Petrography, semi-quantitative bulk mineralogy and SEM/EDX analyses were conducted on sediments recovered along the west coast from 1-4 m deep trenches and three 4-8 m deep drill holes. GIS mapping of drainage basins and quartz-feldspar-lithic (QFL) ternary plots based on grain counting show mixing of sediments from multiple sources: Himalayan provenance of metamorphic and igneous origin (garnet-mostly almandine, tourmaline, rutile, kyanite, zircon, sillimanite and clinopyroxene) similar to Uddin et al. (2007); Brahmaputra provenance of igneous and metamorphic origin (amphibole, epidote, plagioclase 40% Na and 60% Ca, apatite, ilmenite, magnetite, Cr-spinel and garnet-mostly grossular,) as indicated by Garzanti et al. (2010) & Rahman et al. (2016) and Burmese sources (cassiterite and wolframite) (Zaw 1990 & Searle et al. 2007). Low sedimentation rates are the result of two main factors: 1. Strong longshore currents from the south-east that interact with high tidal ranges as evidenced by the morphology of sand waves and ridge and runnel landforms along the beach. 2. Streams draining the Teknaf anticline are dry during the winter and during summer monsoon rains, the sediments bypass the narrow beach and are washed out offshore. These sedimentation patterns together with the offshore reversing monsoon circulation are shaping the coast by contributing to erosion, mixing of sediments and transporting minerals from the Burma drainage basin in the south.

Performance of a novel multiple-signal luminescence sediment tracing method

NASA Astrophysics Data System (ADS)

Reimann, Tony

2014-05-01

Optically Stimulated Luminescence (OSL) is commonly used for dating sediments. Luminescence signals build up due to exposure of mineral grains to natural ionizing radiation, and are reset when these grains are exposed to (sun)light during sediment transport and deposition. Generally, luminescence signals can be read in two ways, potentially providing information on the burial history (dating) or the transport history (sediment tracing) of mineral grains. In this study we use a novel luminescence measurement procedure (Reimann et al., submitted) that simultaneously monitors six different luminescence signals from the same sub-sample (aliquot) to infer the transport history of sand grains. Daylight exposure experiments reveal that each of these six signals resets (bleaches) at a different rate, thus allowing to trace the bleaching history of the sediment in six different observation windows. To test the feasibility of luminescence sediment tracing in shallow-marine coastal settings we took eight sediment samples from the pilot mega-nourishment Zandmotor in Kijkduin (South-Holland). This site provides relatively controlled conditions as the morphological evolution of this nourishment is densely monitored (Stive et al., 2013). After sampling the original nourishment source we took samples along the seaward facing contour of the spit that was formed from August 2011 (start of nourishment) to June 2012 (sampling). It is presumed that these samples originate from the source and were transported and deposited within the first year after construction. The measured luminescence of a sediment sample was interpolated onto the daylight bleaching curve of each signal to assign the Equivalent Exposure Time (EET) to a sample. The EET is a quantitative measure of the full daylight equivalent a sample was exposed to during sediment transport, i.e. the higher the EET the longer the sample has been transported or the more efficient it has been exposed to day-light during sediment transport. The EET increases with increasing distance from the nourishment source, indicating that our method is capable to quantify sediment transport distances. We furthermore observed that the EET of an aeolian analogue is orders of magnitudes higher than those of the water-lain transported Zandmotor samples, suggesting that our approach is also able to differentiate between different modes of coastal sediment transport. This new luminescence approach offers new possibilities to decipher the sedimentation history of palaeo-environmental archives e.g. in coastal, fluvial or aeolian settings. References: Reimann, T.et al. Quantifying the degreeof bleaching during sediment transport using a polymineral multiple-signalluminescence approach. Submitted. Stive, M.J.F. et al. 2013. A New Alternative to Saving Our Beaches from Sea-Level Rise: The SandEngine. Journal of Coastal research 29, 1001-1008.

Beach morphology monitoring in the Columbia River Littoral Cell: 1997-2005

USGS Publications Warehouse

Ruggiero, Peter; Eshleman, Jodi L.; Kingsley, Etienne; Thompson, David M.; Voigt, Brian; Kaminsky, George M.; Gelfenbaum, Guy

2007-01-01

This report describes methods used, data collected, and results of the Beach Morphology Monitoring Program in the Columbia River Littoral Cell (CRLC) from 1997 to 2005. A collaborative group primarily consisting of the US Geological Survey and the Washington State Department of Ecology performed this work. Beach Monitoring efforts consisted of collecting topographic and bathymetric horizontal and vertical position data using a Real Time Kinematic Differential Global Positioning System (RTK-DGPS). Sediment size distribution data was also collected as part of this effort. The monitoring program was designed to: 1) quantify the short- to medium-term (seasonal to interannual) beach change rates and morphological variability along the CRLC and assess the processes responsible for these changes; 2) collect beach state data (i.e., grain size, beach slope, and dune/sandbar height/position) to enhance the conceptual understanding of CRLC functioning and refine predictions of future coastal change and hazards; 3) compare and contrast the scales of environmental forcing and beach morphodynamics in the CRLC to other coastlines of the world; and 4) provide beach change data in a useful format to land use managers.

Towards increasing the spatial resolution of luminescence chronologies - Portable luminescence reader measurements and standardized growth curves applied to the beach-ridge plain of Phra Thong Island, Thailand

NASA Astrophysics Data System (ADS)

Brill, Dominik; Jankaew, Kruawun; Brückner, Helmut

2016-04-01

Since optically stimulated luminescence (OSL) dating is time consuming and cost intensive, age information available for individual study sites is usually restricted to significantly less than 100 ages. In particular the interpretation of complex depositional systems with temporally and spatially diverse sedimentation histories may suffer from the effects of a poor spatial resolution or an ineffective distribution of chronological data. In these cases, time and cost efficient approaches that provide reasonable dating accuracy are required to substitute or complement full luminescence dating. For the sandy beach-ridge plain of Phra Thong Island, Thailand, which is chronologically constrained by a set of approximately 50 luminescence ages, we evaluated the potential (i) of luminescence profiling using a portable luminescence reader, and (ii) of standardized growth curves (SGCs) to improve the resolution and sampling strategy of OSL dating in coastal settings. Although SGCs are related to some shortcomings in dating accuracy, and luminescence profiling with even the favorable conditions provided by the homogeneous sandy stratigraphy of the beach-ridge plain does not equal full luminescence dating, both approaches are capable of reproducing some of the main chronostratigraphic features of the island. This includes the differentiation between Holocene and last interglacial ridges, as well as the identification of the general east-west progradation and some (but not all) of several 1500-2000 year hiatuses within the Holocene sediment succession. However, while both approaches can successfully identify relative chronological trends, robust absolute age estimates can only be achieved by considering the highly variable dosimetry, which is the main contributing factor to bulk luminescence signals apart from deposition age on Phra Thong Island. At Phra Thong, portable reader signals as a proxy for palaeodoses combined with sample-specific dose rates proved as the best compromise between rapid data acquisition and adequate dating accuracy.

Integrating millennial and interdecadal shoreline changes: Morpho-sedimentary investigation of two prograded barriers in southeastern Australia

NASA Astrophysics Data System (ADS)

Oliver, T. S. N.; Tamura, T.; Hudson, J. P.; Woodroffe, C. D.

2017-07-01

Prograded barriers are distinctive coastal landforms preserving the position of past shorelines as low relief, shore-parallel ridges composed of beach sediments and commonly adorned with variable amounts of dune sand. Prograded barriers have been valued as coastal archives which contain palaeoenvironmental information, however integrating the millennial timescale geological history of barriers with observed inter-decadal modern beach processes has proved difficult. Technologies such as airborne LiDAR, ground penetrating radar (GPR) and optically stimulated luminescence dating (OSL) were utilised at Boydtown and Wonboyn, in southeastern Australia, and combined with previously reported radiocarbon dates and offshore seismic and sedimentological data to reconstruct the morpho-sedimentary history of prograded barrier systems. These technologies enabled reconstruction of geological timescale processes integrated with an inter-decadal model of ridge formation explaining the GPR-imaged subsurface character of the barriers. Both the Boydtown and Wonboyn barriers began prograding 7500-8000 years ago when sea level attained at or near present height along this coastline and continued prograding until the present-day with an initially slower rate of shoreline advancement. Sources of sediment for progradation appear to be the inner shelf and shoreface with a large shelf sand body likely contributing to progradation at Wonboyn. The Towamba River seems to have delivered sediment to Twofold Bay during flood events after transitioning to a mature estuarine system sometime after 4000 cal. yr BP. Some of this material appears to have been reworked onto the Boydtown barrier, increasing the rate of progradation in the seaward 50% of the barrier deposited over the past 1500 years. The GPR imaged beachfaces are shown to have similar geometry to beach profiles following recent storm events and a model of ridge formation involving cut and fill of the beachface, and dune building in the backshore, explains the character of the preserved beachface record and the morphology of the ridges. This model is applicable to future management of individual beaches where such beaches are subject to ongoing cut and fill, dune building processes and inherited sediment budget conditions.

The impact of particle shape on the angle of internal friction and the implications for sediment dynamics at a steep, mixed sand-gravel beach

NASA Astrophysics Data System (ADS)

Stark, N.; Hay, A. E.; Cheel, R.; Lake, C. B.

2014-08-01

The impact of particle shape on the angle of internal friction, and the resulting impact on beach sediment dynamics, is still poorly understood. In areas characterized by sediments of specific shape, particularly non-rounded particles, this can lead to large departures from the expected sediment dynamics. The steep slope (1 : 10) of the mixed sand-gravel beach at Advocate Harbour is stable in large-scale morphology over decades, despite a high tidal range of 10 m or more, and intense shore-break action during storms. The Advocate sand (d < 2 mm) was found to have an elliptic, plate-like shape (Corey Shape Index, CSI ≈ 0.2-0.6). High angles of internal friction of this material were determined using direct shear, ranging from φ ≈ 41 to 49°, while the round to angular gravel was characterized as φ = 33°. The addition of 25% of the elliptic plate-like sand-sized material to the gravel led to an immediate increase in friction angle to φ = 38°. Furthermore, re-organization of the particles occurred during shearing, characterized by a short phase of settling and compaction, followed by a pronounced strong dilatory behavior and an accompanying strong increase of resistance to shear and, thus, shear stress. Long-term shearing (24 h) using a ring shear apparatus led to destruction of the particles without re-compaction. Finally, submerged particle mobilization was simulated using a tilted tray submerged in a water-filled tank. Despite a smooth tray surface, particle motion was not initiated until reaching tray tilt angles of 31° and more, being ≥7° steeper than for motion initiation of the gravel mixtures. In conclusion, geotechnical laboratory experiments quantified the important impact of the elliptic, plate-like shape of Advocate Beach sand on the angles of internal friction of both pure sand and sand-gravel mixtures. The resulting effect on initiation of particle motion was confirmed in tilting tray experiments. This makes it a vivid example of how particle shape can contribute to the stabilization of the beach face.

Evaluating Sediment Mobility for Siting Nearshore Berms

DTIC Science & Technology

2016-04-01

placement of dredged sediment that may contain more fine silts and clays than are allowed for placement directly on the beach. The United States Army...used in the density and viscosity calculations. For this technical note an example study site is selected and the sediment mobility indexes are...acceleration due to gravity, sρ is the sediment density, ρ is the water density, v is the kinematic viscosity of water, crθ is the Shields

Chenier Development within a Prograding Strandplain Complex

NASA Astrophysics Data System (ADS)

FitzGerald, D.; Hein, C. J.; Georgiou, I. Y.

2017-12-01

Strandplains dominate the southern coast of Brazil due to abundant shelf and local sediment and falling sea-level (2-4 m) during the past 6 ka. These plains are composed chiefly of swash-aligned sandy beach and dune ridges deposited in bedrock-framed embayments 2-5 km wide and 3-10 km long. The Tijucas Strandplain developed in a more sheltered and deeply embayed setting fronted by long peninsulas and bedrock islands, which reduce ocean wave energy. The Tijucas River bisects the plain and has provided the primary source of sediment to produce a Holocene basinal fill composed of a seaward-thickening bay mud sequence (10-16 m thick). Long-term gradual shoaling of the basin and attendant lessening wave energy produced upper strandplain foreshore and beach units that transition from landward 8-m thick sand sections to a 3-4-m thick mud unit along the present-day shoreline. The gradual lateral change of the morpho-sedimentary character of the plain is likely a product of climate-induced changes in sediment composition and supply and/or wave regime. For example, the mid-plain is defined by a series of abrupt alterations between sand-dominated beach ridges and mixed sand-and-mud cheniers. This area contains at least four chenier complexes consisting of closely spaced (25-40 m apart) 50-75 m wide ridges composed of 3-4 m thick shelly sand underlain and separated by a cohesive basin-fill clay. The seaward portion of the plain has two sandy chenier ridges each 1 m high and <3 m thick, separated by 100 m of consolidated mud with rare sand beds. Ground-penetrating radar sections show ridges contain numerous seaward-sloping beds having variable dips and multiple truncations, resulting from repeated erosional and depositional events. Expansive, thin (<50 cm) sand sheets composed of flat-lying to shallowly landward-dipping internal radar reflections extend landward from most chenier ridges that overtop inter-ridge mud. The present beach comprises the most current developing chenier. Recent storm-induced landward transport of a thin, sandy overwash fan mimics the proposed mechanism for earlier ridge-swale development. Finally, a future chenier is forming 1 km offshore where breaking waves concentrate sand. Between these two sand deposits is a shallow (< 3 m) muddy region where cores and surface samples indicate an absence of sand.

Lack of physiological responses to hydrocarbon accumulation by Mytilus trossulus after 3-4 years chronic exposure to spilled Exxon Valdez crude oil in Prince William Sound.

PubMed

Thomas, R E; Brodersen, C; Carls, M G; Babcock, M; Rice, S D

1999-01-01

Mussels, Mytilus trossulus, were sampled in 1992 and 1993 from beaches in Prince William Sound that had been oiled by the Exxon Valdez spill of March, 1989. At some of the oiled beaches, mussels were collected from beds overlying oiled sediments, and from bedrock adjacent to these beds. Mussels were also collected from beaches within the Sound that had not been impacted by the spill. Polynuclear aromatic hydrocarbon (PAH) concentrations in mussel tissue, physiological responses (byssal thread production, condition index, clearance rate, and glycogen content), were determined for each group of mussels. Total PAH concentrations in mussel tissue ranged from 0 to 6 micrograms g-1, and were significantly greater in mussels from oiled beds than those from reference beds. No significant differences were noted in byssal thread production, condition index, clearance rate, or glycogen content between oiled sample sites and reference sites. The lack of physiological response was surprising because mussels in this study were chronically exposed to PAH for 3-4 years, and none of the physiological responses measured appeared to be affected by that exposure. The lack of a physiological response suggests that chronically exposed mussels may develop a physiological tolerance to PAH, but we recognize that these measures may not have been sensitive enough to discriminate response from background noise.

Modeling the transport and inactivation of E. coli and enterococci in the near-shore region of Lake Michigan

USGS Publications Warehouse

Liu, L.; Phanikumar, M.S.; Molloy, S.L.; Whitman, R.L.; Shively, D.A.; Nevers, M.B.; Schwab, D.J.; Rose, J.B.

2006-01-01

To investigate the transport and fate of fecal pollution at Great Lakes beaches and the health risks associated with swimming, the near-shore waters of Lake Michigan and two tributaries discharging into it were examined for bacterial indicators of human fecal pollution. The enterococcus human fecal pollution marker, which targets a putative virulence factorthe enterococcal surface protein (esp) in Enterococcus faecium, was detected in 2/28 samples (7%) in the tributaries draining into Lake Michigan and in 6/30 samples (20%) in Lake Michigan beaches. This was indicative of human fecal pollution being transported in the tributaries and occurrence at Lake Michigan beaches. To understand the relative importance of different processes influencing pollution transport and inactivation, a finite-element model of surf-zone hydrodynamics (coupled with models for temperature, E. coli and enterococci) was used. Enterococci appear to survive longer than E. coli, which was described using an overall first-order inactivation coefficient in the range 0.5−2.0 per day. Our analysis suggests that the majority of fecal indicator bacteria variation can be explained based on loadings from the tributaries. Sunlight is a major contributor to inactivation in the surf-zone and the formulation based on sunlight, temperature and sedimentation is preferred over the first-order inactivation formulation.

Heavy metal contamination in sand and sediments near to disposal site of reject brine from desalination plant, Arabian Gulf: Assessment of environmental pollution.

PubMed

Alshahri, Fatimh

2017-01-01

Accumulation of heavy metals in environment may cause series potential risk in the living system. This study was carried out to investigate heavy metal contamination in sand samples and sediments along the beach near to disposal site of reject brine from Alkhobar desalination plant, which is one of the oldest and largest reverse osmosis desalination plants in eastern Saudi Arabia, Arabian Gulf. Fourteen heavy metals (U, Ca, Fe, Al, Ti, Sr, Rb, Ni, Pb, Cd, Cr, Cu, As, and Zr) were measured using gamma-ray spectrometry, atomic absorption spectrometer (AAS) and energy dispersive X-ray fluorescence spectrometer (EDX). The obtained data revealed that the concentrations of these metals were higher than the values in sediment and soil for other studies in Arabian Gulf. Furthermore, the mean values of Fe, Mn, Cr, Cu, As, Sr, and Zr concentrations in sand and sediments were higher than the geochemical background values in shale. The contamination factor (CF), modified degree of contamination (mC d ) and pollution load index (PLI) were assessed. According to contamination factors (CF > 1), the results showed elevated levels of Cu, Cr, Mn, Zr, and As in all samples. The highest value of contamination factor was found for As. Based on PLI (PLI > 1), the values of all sampling sites indicate a localized pollution in the study area. Current study could be useful as baseline data for heavy metals in sand and sediments nearby a desalination plant.

Influence of wave action on the partitioning and transport of unattached and floc-associated bacteria in fresh water.

PubMed

Sousa, Andrew J; Droppo, Ian G; Liss, Steven N; Warren, Lesley; Wolfaardt, Gideon

2015-08-01

The dynamic interaction of bacteria within bed sediment and suspended sediment (i.e., floc) in a wave-dominated beach environment was assessed using a laboratory wave flume. The influence of shear stress (wave energy) on bacterial concentrations and on the partitioning and transport of unattached and floc-associated bacteria was investigated. The study showed that increasing wave energy (0.60 and 5.35 N/s) resulted in a 0.5 to 1.5 log increase in unattached cells of the test bacterium Pseudomonas sp. strain CTO7::gfp-2 in the water column. There was a positive correlation between the bacterial concentrations in water and the total suspended solids, with the latter increasing from values of near 0 to up to 200 mg/L over the same wave energy increase. The median equivalent spherical diameter of flocs in suspension also increased by an order of magnitude in all experimental trials. Under both low (0.60 N/s) and high (5.35 N/s) energy regime, bacteria were shown to preferentially associate with flocs upon cessation of wave activity. The results suggest that collecting water samples during periods of low wave action for the purpose of monitoring the microbiological quality of water may underestimate bacterial concentrations partly because of an inability to account for the effect of shear stress on the erosion and mobilization of bacteria from bed sediment to the water column. This highlights the need to develop a more comprehensive beach analysis strategy that not only addresses presently uncharacterized shores and sediments but also recognizes the importance of eroded flocs as a vector for the transport of bacteria in aquatic environments.

Inner Surf/Swash Zone Morphodynamic Numerical Model Simulation of an Accreting Ridge during Low-Energy Wave Conditions

NASA Astrophysics Data System (ADS)

Song, Youn Kyung; Figlus, Jens; Chardón-Maldonado, Patricia; Puleo, Jack A.

2017-04-01

The inner surf/swash zone of a coastal beach is characterized as an intermittently wet and dry zone in the nearshore that often develops a variety of morphological features including intertidal bars and ridge-runnel (RR) systems. The cross-shore morphodynamic numerical model CSHORE is used to simulate the beach recovery observed during a field experiment carried out at South Bethany Beach, Delaware, a nourished, high-gradient meso-tidal sandy beach along the U. S. Coast. The field campaign was conducted from February 12 to February 25, 2014 to measure bed profile morphology change and sediment characteristics along with detailed hydrodynamic forcing parameters at six cross-shore stations, closely spaced over approximately 50 m in the inner surf and swash zone. On February 13, 2014 a Nor'easter eroded significant portions of the beach leading to formation of a pronounced RR system on the beach face that subsequently accreted in the recovery process after the storm. Bed profile changes, surf and swash velocity profiles, water free surface elevation and suspended sediment concentrations recorded during the recovery at the cross-shore measuring locations on the seaward face of the accreting ridge are compared with CSHORE simulation results. During post-storm recovery, CSHORE demonstrates shoreward migration of the ridge and slight accretion on the beach face by the end of the simulation period on February 25, 2014. This trend was also observed in the field, where accretion at the ridge crest was up to 1.0 m with respect to the post-storm profile. The CSHORE parameters critical to improving model performance in reproducing measured morphodynamics and hydrodynamics during the ridge accretion process are examined and calibrated. Initial results show promise in using this type of efficient, process-based model to reproduce morphological evolution and depth-averaged hydrodynamics as a result of the complex surf and swash zone dynamics associated with beach accretion and RR system mobilization.

On the role of impermeable groins on barred beach morphodynamics: Example of Matalascañas beach, Spain

NASA Astrophysics Data System (ADS)

Sedrati, Mouncef; Morales González, Juan Antonio

2017-04-01

Several studies on barred beaches in settings with mesotidal to macrotidal regimes have focused on cross-shore and alongshore bar mobility. Whereas the general link between hydrodynamics, sediment transport and the response of the intertidal bars and shoreline evolution has been recognized in the literature, the role of coastal defense structures (Breakwaters, groins, seawalls) on bar-trough systems morphodynamics have received more much less attention and the field-based experimental studies of these environments are rare. The main aim of this paper is to highlight the contrasting behavior of a natural and protected barred beach under several hydrodynamics conditions. This paper presents detailed hydrodynamic and morphological data from a field experiment spanning 10 days undertaken in Matalascañas beach, a mesotidal protected vs natural barred beach in the Southern Spanish coast. This mesotidal beach experienced intense erosion in the recent past and therefore it has been partially protected by groins (protection of sea-front touristic residences). During the fieldwork, an intertidal bars in the protected and non-protected areas highlighted contrasting morphological behaviour. The non-protected barred beach shows a less pronounced bar-trough system than the protected zone. Under low energy conditions (significant wave height < 0,6m), onshore bar migration rate in the protected area was more important than the non-protected area. This migration was associated with an onshore sediment transport, resulting from the erosion of the bar's seaward slope. In the same moment, a clear longshore bar migration was observed in the non-protected zone with the absence of this process in the protected zone. During few energetic tides (Significant wave height > 1m), the protected and non-protected zones show a flattening bars processes. The findings of the present study suggest that cross-shore vs longshore bar mobility may even be mitigated by the presence of the groins, which favour onshore than longshore bar migration.

Impact of tsunami on texture and mineralogy of a major placer deposit in southwest coast of India

NASA Astrophysics Data System (ADS)

Babu, N.; Babu, D. S. Suresh; Das, P. N. Mohan

2007-03-01

The great Indonesian earth quake (26 December 2004) triggered a tsunami wave across the Bay of Bengal and Indian Ocean basins and has brought a major havoc in several countries including India. The coastal segment between Thotapalli and Valiazhikal in Kerala state of southwest India, where considerably rich beach placer deposit with ilmenite percentage of more than 70% is concentrated, has been investigated to understand the impact of tsunami on coastal sediments. The grain size analysis flashes out the significant differences between the pre- and post-tsunami littoral environments. While the mineral grains collected during pre-tsunami period show well-sorted nature, the post-tsunami samples represent moderately to poorly sorted nature. Similarly, unimodal and bimodal distributions of the sediments have been recorded for pre- and post-tsunami sediments, respectively. Further, mineral assemblages corresponding to before and after this major wave activity clearly indicate the large-scale redistribution of sediments. The post-tsunami sediments register increasing trends of garnet, sillimanite and rutile. The total heavy mineral percentage of the post-tsunami sediment also shows an improved concentration, perhaps due to the large-scale transport of lighter fraction. Magnetite percentage of post-tsunami samples reflects higher concentration compared to the pre-tsunami samples, indicating the intensity of reworking process. X-ray diffraction patterns of ilmenite grains have confirmed the increased presence of pseduorutile, and pseudobrookite in post-tsunami samples, which could be due to the mixing of more altered grains. SEM examination of grains also confirms the significant alteration patterns on the ubiquitous mineral of placer body, the ilmenite. The reason for these textural, mineralogical and micromorphological changes in heavy minerals particularly in ilmenite, could be due to the churning action on the deeper sediments of onshore region or on the sediments entrapped in the near shelf region of the area, by the ˜ 6 m high tsunami waves.

Balanced sediment fluxes in southern California’s Mediterranean-climate zone salt marshes

USGS Publications Warehouse

Rosencranz, Jordan A.; Ganju, Neil K.; Ambrose, Richard F.; Brosnahan, Sandra M.; Dickhudt, Patrick J.; Guntenspergen, Glenn R.; MacDonald, Glen M.; Takekawa, John Y.; Thorne, Karen M.

2016-01-01

Salt marsh elevation and geomorphic stability depends on mineral sedimentation. Many Mediterranean-climate salt marshes along southern California, USA coast import sediment during El Niño storm events, but sediment fluxes and mechanisms during dry weather are potentially important for marsh stability. We calculated tidal creek sediment fluxes within a highly modified, sediment-starved, 1.5-km2 salt marsh (Seal Beach) and a less modified 1-km2marsh (Mugu) with fluvial sediment supply. We measured salt marsh plain suspended sediment concentration and vertical accretion using single stage samplers and marker horizons. At Seal Beach, a 2014 storm yielded 39 and 28 g/s mean sediment fluxes and imported 12,000 and 8800 kg in a western and eastern channel. Western channel storm imports offset 8700 kg exported during 2 months of dry weather, while eastern channel storm imports augmented 9200 kg imported during dry weather. During the storm at Mugu, suspended sediment concentrations on the marsh plain increased by a factor of four; accretion was 1–2 mm near creek levees. An exceptionally high tide sequence yielded 4.4 g/s mean sediment flux, importing 1700 kg: 20 % of Mugu’s dry weather fluxes. Overall, low sediment fluxes were observed, suggesting that these salt marshes are geomorphically stable during dry weather conditions. Results suggest storms and high lunar tides may play large roles, importing sediment and maintaining dry weather sediment flux balances for southern California salt marshes. However, under future climate change and sea level rise scenarios, results suggest that balanced sediment fluxes lead to marsh elevational instability based on estimated mineral sediment deficits.

Paraiba do Sul river delta, Brazil

NASA Image and Video Library

1996-01-20

STS072-738-019 (11-20 Jan. 1996) --- The Delta of the Paraiba do Sul River, northeast of Rio de Janeiro, Brazil, stands out in this 70mm frame exposed from the Earth-orbiting Space Shuttle Endeavour. The brown color of the river water and offshore sediment plume show that the river is in flood stage. This delta attracts much attention from orbit because of its prominent beach ridges either side of the river mouth. River sediment from inland supplies the material which is redistributed by coastal currents to form the parallel beach ridges. The lower 20 miles of the river appear in this scene. The river flows into the Atlantic in an easterly direction.

Recent scientific advances and their implications for sand management near San Francisco, California: the influences of the ebb tidal delta

USGS Publications Warehouse

Hanes, Daniel M.; Barnard, Patrick L.; Dallas, Kate; Elias, Edwin; Erikson, Li H.; Eshleman, Jodi; Hansen, Jeff; Hsu, Tian Jian; Shi, Fengyan

2011-01-01

Recent research in the San Francisco, California, U.S.A., coastal region has identified the importance of the ebb tidal delta to coastal processes. A process-based numerical model is found to qualitatively reproduce the equilibrium size and shape of the delta. The ebb tidal delta itself has been contracting over the past century, and the numerical model is applied to investigate the sensitivity of the delta to changes in forcing conditions. The large ebb tidal delta has a strong influence upon regional coastal processes. The prominent bathymetry of the ebb tidal delta protects some of the coast from extreme storm waves, but the delta also focuses wave energy toward the central and southern portions of Ocean Beach. Wave focusing likely contributes to a chronic erosion problem at the southern end of Ocean Beach. The ebb tidal delta in combination with non-linear waves provides a potential cross-shore sediment transport pathway that probably supplies sediment to Ocean Beach.

A numerical model investigation of the formation and persistence of an erosion hotspot

USGS Publications Warehouse

Hansen, Jeff E.; Elias, Edwin; List, Jeffrey H.; Barnard, Patrick L.

2011-01-01

A Delft3D-SWAN coupled flow and wave model was constructed for the San Francisco Bight with high-resolution at 7 km-long Ocean Beach, a high-energy beach located immediately south of the Golden Gate, the sole entrance to San Francisco Bay. The model was used to investigate tidal and wave-induced flows, basic forcing terms, and potential sediment transport in an area in the southern portion of Ocean Beach that has eroded significantly over the last several decades. The model predicted flow patterns that were favorable for sediment removal from the area and net erosion from the surf-zone. Analysis of the forcing terms driving surf-zone flows revealed that wave refraction over an exposed wastewater outfall pipe between the 12 and 15 m isobaths introduces a perturbation in the wave field that results in erosion-causing flows. Modeled erosion agreed well with five years of topographic survey data from the area.

Shoreline recovery from storms on the east coast of Southern Africa

NASA Astrophysics Data System (ADS)

Corbella, S.; Stretch, D. D.

2012-01-01

Episodic extreme waves due to sea storms can cause severe coastal erosion. The recovery times of such events are important for the analysis of risk and coastal vulnerability. The recovery period of a storm damaged coastline represents a time when the coastline is most vulnerable and nearby infrastructure is at the greatest risk. We propose that identification of the beach recovery period can be used as a coastal management tool when determining beach usage. As a case study, we analyse 37 yr of beach profile data on the east coast of South Africa. Considering beach length and cross-sectional area, we establish a global recovery period and rate and identify the physical characteristics of the coastlines that either accelerate or retard recovery. The beaches in the case study were found to take an average of two years to recover at a rate of approximately 90 m3 m-1 yr-1. Beach profiles with vegetated dunes recovered faster than urbanized beaches. Perpendicular beach structures have both positive and negative effects on beach recovery. Coastlines with rock outcrops in the surf zone tend to recover slowly and long-term sediment loss was identified in cases where storm damaged beaches have not recovered to pre-erosion levels.

Composite analysis for Escherichia coli at coastal beaches

USGS Publications Warehouse

Bertke, E.E.

2007-01-01

At some coastal beaches, concentrations of fecal-indicator bacteria can differ substantially between multiple points at the same beach at the same time. Because of this spatial variability, the recreational water quality at beaches is sometimes determined by stratifying a beach into several areas and collecting a sample from each area to analyze for the concentration of fecal-indicator bacteria. The average concentration of bacteria from those points is often used to compare to the recreational standard for advisory postings. Alternatively, if funds are limited, a single sample is collected to represent the beach. Compositing the samples collected from each section of the beach may yield equally accurate data as averaging concentrations from multiple points, at a reduced cost. In the study described herein, water samples were collected at multiple points from three Lake Erie beaches and analyzed for Escherichia coli on modified mTEC agar (EPA Method 1603). From the multiple-point samples, a composite sample (n = 116) was formed at each beach by combining equal aliquots of well-mixed water from each point. Results from this study indicate that E. coli concentrations from the arithmetic average of multiple-point samples and from composited samples are not significantly different (t = 1.59, p = 0.1139) and yield similar measures of recreational water quality; additionally, composite samples could result in a significant cost savings.

Evolution of a foredune and backshore river complex on a high-energy, drift-aligned beach

NASA Astrophysics Data System (ADS)

Heathfield, Derek K.; Walker, Ian J.

2015-11-01

This paper examines the multi-decadal evolution of a foredune and backshore river complex on a wave-dominated, drift-aligned coast at Wickaninnish Bay on southwestern Vancouver Island, British Columbia, Canada. Local shoreline positions are generally prograding seaward as fast as + 1.46 m a- 1 in response to rapid regional tectonic uplift and positive onshore sediment budgets. The northern end of the foredune system has extended rapidly alongshore in response to net northward littoral drift. Despite these net accretional responses, the beach-dune system experiences relatively frequent (return interval 1.53 years) erosive events when total water levels exceed a local erosional threshold elevation of 5.5 m above regional chart datum. Geomorphic recovery of the beach-dune system from erosive events is usually rapid (i.e., within a year) by way of high onshore sand transport and aeolian delivery to the upper beach. This response is complicated locally, however, by the influence of a backshore river that alters spatial-temporal patterns of both intertidal and supratidal erosion and deposition. Historic landscape changes and rates of shoreline positional change are derived from several years of aerial photography (1973, 1996, 2007, 2009, 2012) using the USGS Digital Shoreline Analysis System (DSAS). Significant volumetric changes are also estimated from aerial LiDAR-derived DEMs in 2005, 2009 and 2012, and related morphodynamics are interpreted using a statistically constrained geomorphic change detection method. Results suggest that supratidal bar development, overwash deposition and aeolian deposition on a low-lying supratidal platform, combined with alongshore extension of the foredune complex, is forcing Sandhill Creek to migrate northward in the direction of beach drift. In response, the river actively erodes (- 1.24 m a- 1) a bluff system landward of the channel, which generates substantial sediment volumes (- 0.137 m3 m- 2 a- 1) that feed a large intertidal braided channel and delta system. These local responses provide context for a conceptual model of the evolution of a wave-dominated, drift-aligned beach-foredune system that interacts with a backshore river. This model may provide useful information to local park managers as erosion and sedimentation hazards threaten visitor safety and park infrastructure.

Controlling factors of recent clastic coastal sediments (Viransehir, Mersin bay, S Turkey)

NASA Astrophysics Data System (ADS)

Gül, Murat; Özbek, Ahmet; Kurt, Mehmet Ali; Zorlu, Kemal

2009-04-01

The Plio-Quaternary conglomeratic sets within the marine environment of the Viranşehir coast (W Mersin, S Turkey) are responsible for the evolution of sandy and gravely beaches due to their control on various factors such as sea floor irregularity, wave energy, and organic activity. The conglomeratic sets close to the shoreline (50-150 cm) act as wave breakers, creating hard substratum and high energy, well-oxygenated environment for organisms like Patella sp., Phoronida worms and Brachidontes pharaonis (Fischer P. 1870). The boring activities of these organisms have disintegrated the sandy matrix of these sets. Finer-grained matrix sediments have been transported to the interset and open sea, while cobble-pebbles have been carried landwards and have created imbricated gravely beach deposits without matrix. Sandy beach is evolving where the conglomeratic sets away from the shoreline (5.0-10.0 m). In this example, sets form a bar; causing fivefold division as backshore, berm, surf zone, bar and offshore from land to sea. Poorly sorted, cobbles-pebbles cobbles and pebbles are found associated with the high-energy environments of bars, whilst well-sorted sands are observed in low energetic environments on shore. The sets and recent shell fragments are the main sources of coastal sediments in Viranşehir. However, the amount of shell fragments decrease towards the active river mouth. This is due to sediment and fresh water influx from the river causing deteriorated temperature, salinity and light penetration of the marine environment resulting in less organic diversity.

The observed relationship between wave conditions and beach response, Ocean Beach, San Francisco, CA

USGS Publications Warehouse

Hansen, J.E.; Barnard, P.L.

2009-01-01

Understanding how sandy beaches respond to storms is critical for effective sediment management and developing successful erosion mitigation efforts. However, only limited progress has been made in relating observed beach changes to wave conditions, with one of the major limiting factors being the lack of temporally dense beach topography and nearshore wave data in most studies. This study uses temporally dense beach topographic and offshore wave data to directly link beach response and wave forcing with generally good results. Ocean Beach is an open coast high-energy sandy beach located in San Francisco, CA, USA. From April 2004 through the end of 2008, 60 three-dimensional topographic beach surveys were conducted on approximately a monthly basis, with more frequent “short-term surveys during the winters of 2005-06 and 2006-07. Shoreline position data from the short-term surveys show good correlation with offshore wave height, period, and direction averaged over several days prior to the survey (mean R*=0.54 for entire beach). There is, however, considerable alongshore variation in model performance, with R- values ranging from 0.81 to 0.19 for individual sections of the beach. After wave height, the direction of wave approach was the most important factor in determining the response of the shoreline, followed by wave period. Our results indicate that an empirical predictive model of beach response to wave conditions at Ocean Beach is possible with frequent beach mapping and wave data, and that such a model could be useful to coastal managers. 

Observations of transport of bacterial-like microspheres through beach sand

NASA Astrophysics Data System (ADS)

Gast, Rebecca J.; Elgar, Steve; Raubenheimer, Britt

2015-04-01

Often, there is an order of magnitude more fecal indicator bacteria (enterococci) in beach sand than in nearby water. Consequently, sand is considered a reservoir for these bacteria, potentially contributing to poor water quality, and raising questions regarding the human health risks associated with sand exposure. An integral aspect of the distribution and persistence of sand-associated enterococci is the transport of bacteria introduced into the beach environment. Here, plastic microspheres are used as a proxy to examine the wave-induced movement of bacterial-like particles through sand on an ocean beach. Laboratory tests suggest microspheres and bacteria move similarly through sand columns, and have qualitatively similar short-term adsorption-to-sand behavior. Microspheres buried ~0.05 m below the sand surface on an ocean beach moved rapidly [O(10-3) m/s] away from their initial location, both vertically into the ground water below the sand and horizontally seaward within the sediment matrix in response to waves running up the beach face and percolating through the sand.

Coastal processes study at Ocean Beach, San Francisco, CA: summary of data collection 2004-2006

USGS Publications Warehouse

Barnard, Patrick L.; Eshleman, Jodi; Erikson, Li H.; Hanes, Daniel M.

2007-01-01

Ocean Beach in San Francisco, California, contains a persistent erosional section in the shadow of the San Francisco ebb tidal delta and south of Sloat Boulevard that threatens valuable public infrastructure as well as the safe recreational use of the beach. Coastal managers have been discussing potential mediation measures for over a decade, with little scientific research available to aid in decision making. The United States Geological Survey (USGS) initiated the Ocean Beach Coastal Processes Study in April 2004 to provide the scientific knowledge necessary for coastal managers to make informed management decisions. This study integrates a wide range of field data collection and numerical modeling techniques to document nearshore sediment transport processes at the mouth of San Francisco Bay, with emphasis on how these processes relate to erosion at Ocean Beach. The Ocean Beach Coastal Processes Study is the first comprehensive study of coastal processes at the mouth of San Francisco Bay.

Age and morphodynamics of a sandy beach fronted by a macrotidal mud flat along the west coast of Korea: a lateral headland bypass model for beach-dune formation

NASA Astrophysics Data System (ADS)

Chang, Tae Soo; Hong, Seok Hwi; Chun, Seung Soo; Choi, Jeong-Heon

2017-08-01

The Dasari beach-dune system fronted by an intertidal mud flat is a typical example of numerous small beaches found both in embayments and along the open macrotidal west coast of Korea. The beach is frequently exposed to energetic wave action at high tide in winter. Although this coastal dune-sandy beach-intertidal mud flat system has previously been described, its origin and morphodynamic behavior has to date not been firmly established. To clarify these issues, elevation profiles and surficial sediment samples were collected seasonally along five monitoring transects across the tidal flat. In addition, box-cores as well as vibro- and drill-cores were acquired along the middle transect. Optically stimulated luminescence (OSL) and 14C- AMS (accelerator mass spectrometry) dating methods were applied to determine the age of the tidal flat, the beach and the dune deposits. The results show that Dasari beach is topographically composed of two distinct morphological and sedimentological sectors, comprising a high-tide sandy beach that merges seaward into an extensive low-tide tidal flat composed of mud. The transition between the two sectors is marked by a sharp break in slope and change in internal sedimentary structures. At the boundary, the subtle shoreward fining trend in mean grain size on the intertidal flat switches to a pronounced shoreward coarsening trend. Near the transition, mixing between the beach sand and the mud is observed. Another striking feature is a seasonal rotation of the beach system centered on the middle sector, with the northern sector eroding in winter and accreting in summer, and the southern sector accreting in winter and eroding in summer. The spatial grain-size pattern reveals that the beach is fed from the neighboring beach in the north by lateral headland bypassing, rather than onshore transport across the tidal flat, the intermittent lateral supply of sand explaining the seasonal rotation of the beach. Stratigraphically, the beach-dune deposits are underlain by muddy tidal flat deposits, which results in a clear upward coarsening grain-size trend and thus intimates transgressive deposition associated with sea-level rise over the past 7-8 ka. However, a time gap of 4-5 thousand years between the tidal flat and the beach-dune deposits indicates that there is no genetic link between the two depositional systems. As the modern beach-dune system is remote from the former landward limit of the tidal flat, a continuous retreat model must be rejected. Instead, a lateral headland bypassing model, in which sand supplied alongshore progressively encroached the tidal flat, is more plausible. In the light of this interpretation, many of the barrier beach-lagoon models proposed for the macrotidal west coast of Korea need to be reconsidered.

Cobble cam: Grain-size measurements of sand to boulder from digital photographs and autocorrelation analyses

USGS Publications Warehouse

Warrick, J.A.; Rubin, D.M.; Ruggiero, P.; Harney, J.N.; Draut, A.E.; Buscombe, D.

2009-01-01

A new application of the autocorrelation grain size analysis technique for mixed to coarse sediment settings has been investigated. Photographs of sand- to boulder-sized sediment along the Elwha River delta beach were taken from approximately 1??2 m above the ground surface, and detailed grain size measurements were made from 32 of these sites for calibration and validation. Digital photographs were found to provide accurate estimates of the long and intermediate axes of the surface sediment (r2 > 0??98), but poor estimates of the short axes (r2 = 0??68), suggesting that these short axes were naturally oriented in the vertical dimension. The autocorrelation method was successfully applied resulting in total irreducible error of 14% over a range of mean grain sizes of 1 to 200 mm. Compared with reported edge and object-detection results, it is noted that the autocorrelation method presented here has lower error and can be applied to a much broader range of mean grain sizes without altering the physical set-up of the camera (~200-fold versus ~6-fold). The approach is considerably less sensitive to lighting conditions than object-detection methods, although autocorrelation estimates do improve when measures are taken to shade sediments from direct sunlight. The effects of wet and dry conditions are also evaluated and discussed. The technique provides an estimate of grain size sorting from the easily calculated autocorrelation standard error, which is correlated with the graphical standard deviation at an r2 of 0??69. The technique is transferable to other sites when calibrated with linear corrections based on photo-based measurements, as shown by excellent grain-size analysis results (r2 = 0??97, irreducible error = 16%) from samples from the mixed grain size beaches of Kachemak Bay, Alaska. Thus, a method has been developed to measure mean grain size and sorting properties of coarse sediments. ?? 2009 John Wiley & Sons, Ltd.

Correlation of aeolian sediment transport measured by sand traps and fluorescent tracers

NASA Astrophysics Data System (ADS)

Cabrera, Laura L.; Alonso, Ignacio

2010-03-01

Two different methods, fluorescent tracers and vertical sand traps, were simultaneously used to carry out an aeolian sediment transport study designed to test the goodness of fluorescent tracers in aeolian environments. Field experiments were performed in a nebkha field close to Famara beach at Lanzarote Island (Canary Islands, Spain) in a sector where the dunes were between 0.5 and 0.8 m height and 1-2 m wide and the vegetal cover was approximately 22%. In this dune field the sediment supply comes from Famara beach and is blown by trade winds toward the south, where the vegetation acts as natural sediment traps. Wind data were obtained by means of four Aanderaa wind speed sensors and one Aanderaa vane, all them distributed in a vertical array from 0.1 to 4 m height for 27 h. The average velocity at 1 m height during the experiment was 5.26 m s - 1 with the wind direction from the north. The tracer was under wind influence for 90 min at midday. During this period two series of sand traps (T1 and T2) N, S, E and W oriented were used. Resultant transport rates were 0.0131 and 0.0184 kg m - 1 min - 1 respectively. Tracer collection was performed with a sticky tape to sample only surface sediments. Tagged grains were visually counted under UV light. The transport rate was computed from the centroid displacement, that moved 0.875 m southwards, and the depth of the active layer considered was the size of one single grain. Taking into account these data the transport rate was 0.0072 kg m - 1 min - 1 . The discrepancy in results between both methods is related to several factors, such as the thickness of the active layer and the grain size difference between the tagged and the native material.

10Be constrains the sediment sources and sediment yields to the Great Barrier Reef from the tropical Barron River catchment, Queensland, Australia

NASA Astrophysics Data System (ADS)

Nichols, K. K.; Bierman, P. R.; Rood, D. H.

2014-12-01

Estimates of long-term, background sediment generation rates place current and future sediment fluxes to the Great Barrier Reef in context. Without reliable estimates of sediment generation rates and without identification of the sources of sediment delivered to the reef prior to European settlement (c. 1850), determining the necessity and effectiveness of contemporary landscape management efforts is difficult. Using the ~2100-km2 Barron River catchment in Queensland, Australia, as a test case, we use in situ-produced 10Be to derive sediment generation rate estimates and use in situ and meteoric 10Be to identify the source of that sediment, which enters the Coral Sea near Cairns. Previous model-based calculations suggested that background sediment yields were up to an order of magnitude lower than contemporary sediment yields. In contrast, in situ 10Be data indicate that background (43 t km-2 y-1) and contemporary sediment yields (~45 t km-2 y-1) for the Barron River are similar. These data suggest that the reef became established in a sediment flux similar to what it receives today. Since western agricultural practices increased erosion rates, large amounts of sediment mobilized from hillslopes during the last century are probably stored in Queensland catchments and will eventually be transported to the coast, most likely in flows triggered by rare but powerful tropical cyclones that were more common before European settlement and may increase in strength as climate change warms the south Pacific Ocean. In situ and meteoric 10Be concentrations of Coral Sea beach sand near Cairns are similar to those in rivers on the Atherton Tablelands, suggesting that most sediment is derived from the extensive, low-gradient uplands rather than the steep, more rapidly eroding but beach proximal escarpment.

Anthropogenic influences on shoreline and nearshore evolution in the San Francisco Bay coastal system

USGS Publications Warehouse

Dallas, K.L.; Barnard, P.L.

2011-01-01

Analysis of four historical bathymetric surveys over a 132-year period has revealed significant changes to the morphology of the San Francisco Bar, an ebb-tidal delta at the mouth of San Francisco Bay estuary. From 1873 to 2005 the San Francisco Bar vertically-eroded an average of 80 cm over a 125 km2 area, which equates to a total volume loss of 100 ± 52 million m3 of fine- to coarse-grained sand. Comparison of the surveys indicates the entire ebb-tidal delta contracted radially, with the crest moving landward an average of 1 km. Long-term erosion of the ebb-tidal delta is hypothesized to be due to a reduction in the tidal prism of San Francisco Bay and a decrease in coastal sediment supply, both as a result of anthropogenic activities. Prior research indicates that the tidal prism of the estuary was reduced by 9% from filling, diking, and sedimentation. Compilation of historical records dating back to 1900 reveals that a minimum of 200 million m3 of sediment has been permanently removed from the San Francisco Bay coastal system through dredging, aggregate mining, and borrow pit mining. Of this total, ~54 million m3 of sand-sized or coarser sediment was removed from central San Francisco Bay. With grain sizes comparable to the ebb-tidal delta, and its direct connection to the bay mouth, removal of sediments from central San Francisco Bay may limit the sand supply to the delta and open coast beaches. SWAN wave modeling illustrates that changes to the morphology of the San Francisco Bar have altered the alongshore wave energy distribution at adjacent Ocean Beach, and thus may be a significant factor in a persistent beach erosion ‘hot spot’ occurring in the area. Shoreline change analyses show that the sandy shoreline in the shadow of the ebb-tidal delta experienced long-term (1850s/1890s to 2002) and short-term (1960s/1980s to 2002) accretion while the adjacent sandy shoreline exposed to open-ocean waves experienced long-term and short-term erosion. Therefore, the recently observed accelerating rates of bay sediment removal, ebb-tidal delta erosion, and open coast beach erosion are all correlated temporally.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robison, W L; Hamilton, T F; Martinelli, R E

Lawrence Livermore National Laboratory (LLNL) personnel have supported US Air Force (USAF) ballistic missile flight tests for about 15 years for Peacekeeper and Minuteman missiles launched at Vandenberg Air Force Base (VAFB). Associated re-entry vehicles (RV's) re-enter at Regan Test Site (RTS) at the US Army base at Kwajalein Atoll (USAKA) where LLNL has supported scoring, recovery operations for RV materials, and environmental assessments. As part of ongoing USAF ballistic missile flight test programs, LLNL is participating in an updated EA being written for flights originating at VFAB. Marine fauna and sediments (beach-sand samples) were collected by US Fish andmore » Wildlife Service (USFWS), National Marine Fisheries Service (NMFS), and LLNL at Illeginni Island and Boggerik Island (serving as a control site) at Kwajalein Atoll. Data on the concentration of DU (hereafter, U) and Be in collected samples was requested by USFWS and NMFS to determine whether or not U and Be in RV's entering the Illeginni area are increasing U and Be concentrations in marine fauna and sediments. LLNL agreed to do the analyses for U and Be in support of the EA process and provide a report of the results. There is no statistically significant difference in the concentration of U and Be in six species of marine fauna from Illeginni and Boggerik Islands (p - 0.14 for U and p = 0.34 for Be). Thus, there is no evidence that there has been any increase in U and Be concentrations in marine fauna as a result of the missile flight test program. Concentration of U in beach sand at Illeginni is the same as soil and beach sand in the rest of the Marshall Islands and again reflects an insignificant impact from the flight test program. Beach sand from Illeginni has a mean concentration of Be higher than that from the control site, Boggeik Island. Seven of 21 samples from Ileginni had detectable Be. Four samples had a concentration of Be ranging from 4 to 7 ng g {sup -1} (4 to 7 parts per billion (ppb)), one was 17 ppb, one was 0.14 parts per million (ppm), and one was 0.48 ppm. These extremely low concentrations of an insoluble form of Be again indicate no impact on marine life or human health at Illeginni as a result of the missile flight test program. Concentration of Fe in marine fauna muscle tissue is much higher at Illeginni Island than at Boggerik Island (control site) as a result of legacy iron piers, dump sites for iron metal along the island, and scrap iron randomly distributed along extensive portions of the reef line as part of programs conducted in the 1960's through 1980's that were not part of the recent flight test program.« less

Linking macrobenthic communities structure and zonation patterns on sandy shores: Mapping tool toward management and conservation perspectives in Northern France

NASA Astrophysics Data System (ADS)

Rolet, Céline; Spilmont, Nicolas; Dewarumez, Jean-Marie; Luczak, Christophe

2015-05-01

In a context of intensifying anthropogenic pressures on sandy shores, the mapping of benthic habitat appears as an essential first step and a fundamental baseline for marine spatial planning, ecosystem-based management and conservation efforts of soft-sediment intertidal areas. Mapping allows representing intertidal habitats that are basically characterised by abiotic (e.g sediments, exposure to waves…) and biotic factors such as macrobenthic communities. Macrobenthic communities are known to show zonation patterns across sandy beaches and many studies highlighted the existence of three biological zones. We tested this general model of a tripartite biological division of the shore at a geographical scale of policy, conservation and management decisions (i.e. Northern France coastline), using multivariate analyses combined with the Direct Field Observation (DFO) method. From the upper to the lower shores, the majority of the beaches exhibited three macrobenthic communities confirming the existence of the tripartite biological division of the shore. Nevertheless, in some cases, two or four zones were found: (1) two zones when the drying zone located on the upper shore was replaced by littoral rock or engineering constructions and (2) four zones on beaches and estuaries where a muddy-sand community occurred from the drift line to the mid shore. The correspondence between this zonation pattern of macrobenthic communities and the EUNIS habitat classification was investigated and the results were mapped to provide a reference state of intertidal soft-sediment beaches and estuaries. Our results showed evidence of the applicability of this EUNIS typology for the beaches and estuaries at a regional scale (Northern France coastline) with a macroecological approach. In order to fulfil the requirements of the European Directives (WFD and MFSD), this mapping appears as a practical tool for any functional study on these coastal ecosystems, for the monitoring of anthropogenic activities and for the implementation of management plans concerning effective conservation strategies.

USGS Coastal and Marine Geology Survey Data in Google Earth

NASA Astrophysics Data System (ADS)

Reiss, C.; Steele, C.; Ma, A.; Chin, J.

2006-12-01

The U.S. Geological Survey (USGS) Coastal and Marine Geology (CMG) program has a rich data catalog of geologic field activities and metadata called InfoBank, which has been a standard tool for researchers within and outside of the agency. Along with traditional web maps, the data are now accessible in Google Earth, which greatly expands the possible user audience. The Google Earth interface provides geographic orientation and panning/zooming capabilities to locate data relative to topography, bathymetry, and coastal areas. Viewing navigation with Google Earth's background imagery allows queries such as, why areas were not surveyed (answer presence of islands, shorelines, cliffs, etc.). Detailed box core subsample photos from selected sampling activities, published geotechnical data, and sample descriptions are now viewable on Google Earth, (for example, M-1-95-MB, P-2-95-MB, and P-1-97- MB box core samples). One example of the use of Google Earth is CMG's surveys of San Francisco's Ocean Beach since 2004. The surveys are conducted with an all-terrain vehicle (ATV) and shallow-water personal watercraft (PWC) equipped with Global Positioning System (GPS), and elevation and echo sounder data collectors. 3D topographic models with centimeter accuracy have been produced from these surveys to monitor beach and nearshore processes, including sand transport, sedimentation patterns, and seasonal trends. Using Google Earth, multiple track line data (examples: OB-1-05-CA and OB-2-05-CA) can be overlaid on beach imagery. The images also help explain the shape of track lines as objects are encountered.

Macrodebris and microplastics from beaches in Slovenia.

PubMed

Laglbauer, Betty J L; Franco-Santos, Rita Melo; Andreu-Cazenave, Miguel; Brunelli, Lisa; Papadatou, Maria; Palatinus, Andreja; Grego, Mateja; Deprez, Tim

2014-12-15

The amount of marine debris in the environment is increasing worldwide, which results in an array of negative effects to biota. This study provides the first account of macrodebris on the beach and microplastics in the sediment (shoreline and infralittoral) in relation to tourism activities in Slovenia. The study assessed the quality and quantity of macrodebris and the quality, size and quantity of microplastics at six beaches, contrasting those under the influences of tourism and those that were not. Beach cleanliness was estimated using the Clean Coast Index. Tourism did not seem to have an effect on macrodebris or microplastic quantity at beaches. Over 64% of macrodebris was plastic, and microplastics were ubiquitous, which calls for classification of plastics as hazardous materials. Standard measures for marine debris assessment are needed, especially in the form of an all-encompassing debris index. Recommendations for future assessments are provided for the Adriatic region. Copyright © 2014 Elsevier Ltd. All rights reserved.

Impacts of Off-Road Vehicles (ORVs) on Burrow Architecture of Ghost Crabs (Genus Ocypode) on Sandy Beaches

NASA Astrophysics Data System (ADS)

Lucrezi, Serena; Schlacher, Thomas A.

2010-06-01

Recreational beach use with off-road vehicles is popular, but potentially harmful from an environmental perspective. Beaches are important habitats to invertebrates such as ghost crabs of the genus Ocyopde, which excavate extensive and elaborate burrows. Ghost crabs are sensitive to human pressures and changes in burrow architecture may thus be a consequence of disturbance by vehicles—the predictive hypothesis of this article. This was tested during the austral spring and summer by comparing 305 burrow casts between beaches open and closed to vehicles in Eastern Australia. Traffic influenced burrow architecture: there were smaller crabs on vehicle-impacted beaches, and after the peak traffic period (Christmas and New Year holidays), these crabs had tunnelled deeper into the sediment on shores rutted by cars. Crabs constructed all types of previously described burrows, but, significantly, smaller crabs from vehicle-impacted beaches simplified their shapes following heavy traffic disturbance from four (I, J, Y, M) to only two types (I, Y). These data support a model of active behavioural responses to disturbance from vehicles, extending the known effects of beach traffic to impacts on behavioural traits of the beach fauna.

Assessment of gamma-emitting radionuclides in sediment cores from the Gulf of Aqaba, Red Sea.

PubMed

Ababneh, Zaid Q; Al-Omari, Husam; Rasheed, Mohamad; Al-Najjar, Tariq; Ababneh, Anas M

2010-10-01

The Gulf of Aqaba is the only seaport in Jordan which currently has intense activities such as industrial development, phosphate ore exportation, oil importation, shipping, commercial and sport fishing. Most of these activities, especially the phosphate ore exportation, could cause serious radiological effects to the marine environment. Thus, it is essential to investigate the level of the radioactivity concentrations to establish a baseline database, which is not available yet in the Gulf of Aqaba. Radioactivity concentrations of gamma-emitting radionuclides in core and beach sediments of the Gulf of Aqaba were investigated. Core sediments were collected from five representative locations for three different water column depths (5, 15 and 35 m). The results showed that the activity concentrations of 238U, 235U and 226Ra for both seafloor and beach sediments from the phosphate loading berth (PLB) location to be higher than those from other investigated locations and more than twice as high as the worldwide average; the 238U activity concentration was found to vary from 57 to 677 Bq kg(-1). The results also showed that there is little variation of radioactivity concentrations within the core length of 15 cm. The calculated mean values of the radium equivalent activity Ra(eq), the external hazard index, H(ex), the absorbed dose rate and the annual effective dose for the beach sediment in PLB location were 626 Bq kg(-1), 1.69, 263 nGy h(-1) and 614 µSv y(-1), respectively. These values are much higher than the recommended limits that impose potential health risks to the workers in this location. As for other studied locations, the corresponding values were far below the maximum recommended limit and lies within the worldwide range.

Qualitative and quantitative composition of microplastics particles during the expeditionary measurement program in the South-Eastern Baltic Sea

NASA Astrophysics Data System (ADS)

Esiukova, Elena; Bagaeva, Margarita; Chubarenko, Natalia

2016-04-01

According to the tasks of the Russian Science Foundation project "Physical and dynamical properties of marine microplastics particles and their transport in a basin with vertical and horizontal salinity gradient on the example of the Baltic Sea" number 15-17-10020, a comprehensive expeditionary program of measurements in the South-Eastern Baltic started. The project is aimed at finding solutions for a number of problems caused by superfluous plastic pollution in the World Ocean and, in particular, in the Baltic Sea. This pollution has been accumulating for years and just recently it has become obvious that only multidisciplinary approach (geographical, biological, chemical, etc.) to the issues related to the processes of transformation of properties and propagation of plastic particles will allow the study of physical aspects of the problem. During the first stage of the study samples should be selected from the water surface, water column at various horizons, bottom sediments in the Baltic Sea, from different areas at the beaches - in order to further examine the qualitative and quantitative composition of microplastic particles in different seasons for different hydrophysical situations. Reconnaissance survey was begun to choose the fields for research close to point and distributed sources of microplastics. Preference is given to those beaches that are exposed to maximum anthropogenic pollution: areas around the town of Baltiysk, the northern part of the Vistula Spit (near the settlement of Kosa), and the Sambia peninsula coast (settlements of Yantarny, Donskoye, Primorye, Kulikovo, towns of Svetlogorsk, Pionersky, Zelenogradsk). Locations for experimental sites were found in order to assess time for formation of microplastics (Vistula Spit, Kosa settlement). In June-November, 2015 there were 5 expeditions in the waters of the South-Eastern Baltic, 7 expeditions along the coast line of the Baltic Sea (in Kaliningrad Oblast), and 5 expeditions to the Vistula lagoon to take samples and collect experimental materials. Altogether, 61 samples were taken from the surface of the beaches, water and bottom sediments in the Baltic Sea. The primary examination of those samples revealed abundant microplastic particles of the required sizes (0.5 - 5 mm) shaped as pellet of various configurations, spheres, threads, fragments, as well as particles of amber and small fractions of paraffin. The research is supported by the Russian Science Foundation grant number 15-17-10020.

Benson Beach Demonstration Project: Composition and Abundance of Biota at Three Alternative Sump Sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Greg D.; Pearson, Walter H.; Evans, Nathan R.

2004-01-15

The Portland District of the U.S. Army Corps of Engineers is investigating plans to provide sediment to nourish beaches north of the Mouth of the Columbia River (MCR). Under the currently designed proposal, sediment dredged from the MCR will be temporarily stored at one of three proposed areas south of the North Jetty before being redredged and moved by a cutterhead pipeline dredge over the jetty to nourish Benson Beach. Resulting potential impacts to resident Dungeness crab (Cancer magister) and fishes represent one of the criteria for evaluating each of the alternative locations. To establish the species composition and relativemore » abundance of crabs and fishes associated with each of the three proposed sump areas, researchers from the Pacific Northwest National Laboratory Marine Sciences Division completed nine field sampling trips from July 8, 2003, to November 1, 2003, for a total of 113 successful trawls comprising an area of over 7.4 ha (74,156 m2). This report documents the results of that effort. To understand the relative risk of losses to crab populations associated with dredging impacts at the sump alternative areas, it is recommended that a modified dredge impact model be developed using the data collected in this study. This model should estimate crab adult equivalent loss and associated error rates to gain a population-level perspective on the potential entrainment impacts at each of the three alternative sump areas. As well, a sustained survey of Dungeness crab distribution and movement within the Columbia River estuary would clarify the relative value of the sump areas as a migratory corridor for crab populations, and support management decisions relative to issues associated with dredged material handling and disposal.« less

Evaluation of the use of Olivella minuta (Gastropoda, Olividae) and Hastula cinerea (Gastropoda, Terebridae) as TBT sentinels for sandy coastal habitats.

PubMed

Petracco, Marcelo; Camargo, Rita Monteiro; Berenguel, Thayana Amorim; de Arruda, Noelle C L Patrício; del Matto, Lygia A; Amado, Lílian Lund; Corbisier, Thais Navajas; Castro, Ítalo Braga; Turra, Alexander

2015-07-01

Tributyltin (TBT) contamination is still recorded in the environment even after its ban in antifouling paints. Since most biomonitors of TBT contamination, through imposex evaluation, are hard-bottom gastropods, the identification of soft-bottom sentinels has become useful for regions where rocky shores and coral reefs are absent. Thus, an evaluation of Olivella minuta and Hastula cinerea as monitors of TBT contamination was performed in two sandy beaches located under influence area of São Sebastião harbor (São Paulo state, Brazil), where previous and simultaneous studies have reported environmental contamination by TBT. In addition, the imposex occurrence in H. cinerea was assessed in an area with low marine traffic (Una beach), also located in São Paulo State. A moderate imposex incidence in O. minuta was detected in Pernambuco (% I = 9.36, RPLI = 4.49 and RPLIstand = 4.27) and Barequeçaba (% I = 2.42, RPLI = 0.36 and RPLIstand = 0.81) beaches, indicating TBT contamination. In contrast, more severe levels of imposex were recorded for H. cinerea in Una beach (% I = 12.45) and mainly in Barequeçaba beach (% I = 98.92, RPLI = 26.65). Our results suggest that O. minuta and H. cinerea have good potential as biomonitors for TBT based on their wide geographical distribution, common occurrence in different coastal sediment habitats, easy collection, and association with TBT-contaminated sediments.

Coastal geomorphic conditions and styles of storm surge washover deposits from Southern Thailand

NASA Astrophysics Data System (ADS)

Phantuwongraj, Sumet; Choowong, Montri; Nanayama, Futoshi; Hisada, Ken-Ichiro; Charusiri, Punya; Chutakositkanon, Vichai; Pailoplee, Santi; Chabangbon, Akkaneewut

2013-06-01

The characteristics of tropical storm washover deposits laid down during the years 2007 to 2011 along the southern peninsular coast of the Gulf of Thailand (GOT) were described in relation to their different geomorphic conditions, including perched fan, washover terrace and sheetwash lineations preserved behind the beach zone within 100 m of the shoreline. As a result, washover terrace and sheetwash lineations were found where the beach configuration was uniform and promoted an unconfined flow. Non-uniform beach configurations that promoted a confined flow resulted in a perched fan deposit. Washover sediments were differentiated into two types based on sedimentary characteristics, including (i) a thick-bedded sand of multiple reverse grading layers and (ii) a medium-bedded sand of multiple normal grading layers. In the case of thick-bedded washover deposits, the internal sedimentary structures were characterized by the presence of sub-horizontal bedding, reverse grading, lamination, foreset bedding and wavy bedding, whereas, horizontal bedding, normal grading, and dunes were the dominant structures in the medium-bedded washover sand. Rip-up clasts were rare and recognized only in the washover deposits in the bottom unit, which reflects the condition when a mud supply was available. All washover successions were found in the landward inclined-bedding with a basal sharp contact. A high elevated beach ridge associated with a large swale at the backshore proved suitable for a thick-bedded washover type, whereas a small beach ridge with uniformly flat backshore topography promoted a medium-bedded washover sediment.

The Performance of Nearshore Dredge Disposal at Ocean Beach, San Francisco, California, 2005-2007

USGS Publications Warehouse

Barnard, Patrick L.; Erikson, Li H.; Hansen, Jeff E.; Elias, Edwin

2009-01-01

Ocean Beach, California, contains an erosion hot spot in the shadow of the San Francisco ebb tidal delta that threatens valuable public infrastructure as well as the safe recreational use of the beach. In an effort to reduce the erosion at this location a new plan for the management of sediment dredged annually from the main shipping channel at the mouth of San Francisco Bay was implemented in May 2005 by the United States Army Corps of Engineers, San Francisco District (USACE). The USACE designated a temporary nearshore dredge disposal site for the annual disposal of about 230,000 m3 (300,000 yd3) of sand about 750 m offshore and slightly south of the erosion hot spot, in depths between approximately 9 and 14 m. The site has now been used three times for a total sediment disposal of about 690,000 m3 (about 900,000 yds3). The disposal site was chosen because it is in a location where strong tidal currents and open-ocean waves can potentially feed sediment toward the littoral zone in the reach of the beach that is experiencing critical erosion, as well as prevent further scour on an exposed outfall pipe. The onshore migration of sediment from the target disposal location might feed the primary longshore bar or the nearshore zone, and provide a buffer to erosion that peaks during winter months when large waves impact the region. The United States Geological Survey (USGS) has been monitoring and modeling the bathymetric evolution of the test dredge disposal site and the adjacent coastal region since inception in May 2005. This paper reports on the first 2.5 years of this monitoring program effort (May 2005 to December 2007) and assesses the short-term coastal response. Here are the key findings of this report: *Approximately half of the sediment that has been placed in the nearshore dredge-disposal site during the 2.5 years of this study remains within the dredge focus area. *In the winter of 2006-7, large waves transported the dredge-mound material onshore. *High rates of seasonal cross-shore sediment transport mask any potential profile change in the Coastal Profiling System data due to dredge placement. *Pockets of accretion have been recorded by topographic surveying adjacent to the dredge site, but it is unclear if the accretion is linked to the nourishment. *Cross-shore profile modeling suggests that dredge material must be placed in water depths no greater than 5 m to drive a positive shoreline response. *Area modeling demonstrates that the new dredge site increases wave dissipation and modifies local sediment-transport patterns, although the effect on the nearshore morphology is largely negligible. *Any increase in beach width or wave energy-dissipation related to the nourishment is likely to be realized only in the vicinity directly onshore of the nourishment site, which is several hundred meters south of the area of critical erosion. *Larger waves from the northwest and smaller waves from the west or southwest contribute most to the sediment transport from the dredge mound onshore.

Reading Ombrone river delta evolution through beach ridges morphology

NASA Astrophysics Data System (ADS)

Mammi, Irene; Piccardi, Marco; Pranzini, Enzo; Rossi, Lorenzo

2017-04-01

The present study focuses on the evolution of the Ombrone River delta (Southern Tuscany, Italy) in the last five centuries, when fluvial sediment input was huge also as a consequence of the deforestation performed on the watershed. The aim of this study is to find a correlation between river input and beach ridges morphology and to explain the different distribution of wetlands and sand deposits on the two sides of the delta. Visible, NIR and TIR satellite images were processed to retrieve soil wetness associated to sand ridges and interdune silty deposits. High resolution LiDAR data were analysed using vegetation filter and GIS enhancement algorithms in order to highlight small morphological variations, especially in areas closer to the river where agriculture has almost deleted these morphologies. A topographic survey and a very high resolution 3D model obtained from a set of images acquired by an Unmanned Aerial Vehicle (UAV) were carried out in selected sites, both to calibrate satellite LiDAR 3D data, and to map low relief areas. Historical maps, aerial photography and written documents were analysed for dating ancient shorelines associated to specific beach ridges. Thus allowing the reconstruction of erosive and accretive phases of the delta. Seventy beach ridges were identified on the two wings of the delta. On the longer down-drift side (Northern wing) beach ridges are more spaced at the apex and gradually converge to the extremity, where the Bruna River runs and delimits the sub aerial depositional area of the Ombrone River. On the shorter up-drift lobe (Southern wing), beach ridges are closer, but run almost parallel each other. In this case, a rocky headland called Collelungo promontory closes and cuts the beach ridges sequence but shallow water depth allows sediment by pass. One kilometre to the south a more pronounced promontory encloses a small pocket beach (Cala di Forno) and identifies the limit of the subaerial depositionary area. Beach ridges heights were analysed through LiDAR data and some of them were found higher than average. Conceptual models in literature allowed us to explain higher beach ridges as periods of stability or a very initial erosion stage interesting the beach. The high resolution DTM produced from LiDAR and UAV data permitted a better reconstruction of the last five centuries of delta evolution and to characterize the difference of beach ridges morphology of the up-drift and the down-drift sides of the delta. Within this framework the presence of interdune swales in the down-drift side has been explained.

Developing a Sand Management Plan for Galveston Island

DTIC Science & Technology

2015-10-16

Engineer Coastal & Hydraulics Laboratory Engineer Research & Development Center On behalf of the Project Team: Andrew Morang, David King, and Robert...Budget Objectives • Identify sources and sinks of sediment in coastal system  Beach fills  Littoral and offshore sources  Dredge data...more than 100 ft of erosion After 10 years After 50 years Innovative solutions for a safer, better world BUILDING STRONG® Beach Fills (West End

Monitoring toxicity of polycyclic aromatic hydrocarbons in intertidal sediments for five years after the Hebei Spirit oil spill in Taean, Republic of Korea.

PubMed

Lee, Chang-Hoon; Lee, Jong-Hyeon; Sung, Chan-Gyoung; Moon, Seong-Dae; Kang, Sin-Kil; Lee, Ji-Hye; Yim, Un Hyuk; Shim, Won Joon; Ha, Sung Yong

2013-11-15

Ecotoxicological monitoring of intertidal sediments was performed for 5 years after the Hebei Spirit oil spill in Taean, Korea. Sediment toxicity was observed on most of the beaches 4 months after the spill and later decreased rapidly to nontoxic levels 8 months after the spill. The concentrations of total polycyclic aromatic hydrocarbons (TPAHs) in the sediments ranged from 2 to 530,000 ng/g during the monitoring. More than half of the samples exhibited significant toxicity 5 years after the Hebei Spirit oil spill. Using a logistic regression model, the median lethal concentration of TPAHs to amphipod Monocorophium uenoi was estimated to be 36,000 ng/g. From the 63 chemistry and toxicity data, the effect range-low, effect range median, threshold effect level, and probable effect level were derived to be 3190, 54,100, 2480, and 29,000 ng/g, respectively. The relative compositions of the PAH groups indicated that the weathering process is still ongoing. Copyright © 2013 Elsevier Ltd. All rights reserved.

Shipboard magnetic field "noise" reveals shallow heavy mineral sediment concentrations in Chesapeake Bay

USGS Publications Warehouse

Shah, Anjana K.; Vogt, Peter R.; Rosenbaum, Joseph G.; Newell, Wayne L.; Cronin, Thomas M.; Willard, Debra A.; Hagen, Rick A.; Brozena, John; Hofstra, Albert

2012-01-01

Shipboard magnetic field data collected over Chesapeake Bay exhibit low-amplitude, short-wavelength anomalies that most likely indicate shallow concentrations of heavy mineral sediments. Piston core layers and black sand beach samples exhibit enhanced magnetic susceptibilities and carry remanent magnetization, with mineralogical analyses indicating ilmenite and trace magnetite and/or maghemite and hematite. The anomalies are subtle and would be filtered as noise using traditional approaches, but can instead be highlighted using spectral methods, thus providing nearly continuous coverage along survey tracks. The distribution of the anomalies provides constraints on relevant sorting mechanisms. Comparisons to sonar data and previous grab samples show that two of three areas surveyed exhibit short-wavelength anomalies that are clustered over sand-covered areas, suggesting initial sorting through settling mechanisms. This is supported by a correlation between core magnetic susceptibility and grain size. Near the Choptank River, where sediment resuspension is wave-dominated, anomalies show a sharp decrease with seafloor depth that cannot be explained by signal attenuation alone. In Pocomoke Sound, where both tidal currents and wave-action impact sediment resuspension, anomalies show a more gradual decrease with depth. Near the mouth of the bay, where there is a higher influx of sediments from the continental shelf, short-wavelength anomalies are isolated and do not appear to represent heavy mineral sand concentrations. These combined observations suggest the importance of further sorting by erosional processes in certain parts of the bay. Additionally, comparisons of these data to cores sampling pre-Holocene sediments suggest that the sorting of heavy minerals in higher energy, shallow water environments provides a mechanism for correlations between core magnetic susceptibility and sea-level changes.

Geotechnical Impacts of Hurricane Harvey Along the Texas, USA Coast

NASA Astrophysics Data System (ADS)

Smallegan, S. M.; Stark, N.; Jafari, N.; Ravichandran, N.; Shafii, I.; Bassal, P.; Figlus, J.

2017-12-01

As part of the NSF-funded Geotechnical Extreme Events Reconnaissance (GEER) Association response to Hurricane Harvey, a team of engineers and scientists mobilized to the coastal cities of Texas, USA from 1 to 5 September 2017. Damage to coastal and riverine structures due to erosion by storm surge, waves, and coastal and riverine flooding was assessed in a wide coastal zone between Corpus Christi and Galveston. Making initial landfall near Rockport, Texas on 26 August 2017, Hurricane Harvey was classified as a category 4 hurricane on the Saffir-Simpson scale with wind speeds exceeding 130 mph and an atmospheric pressure of 938 mbar. The storm stalled over the Houston area, pouring 40 inches of rain on an area encompassing more than 3,000 square miles. Hurricane Harvey, which remained a named storm for 117 hours after initial landfall, slowly moved east into the Gulf of Mexico and made final landfall near Cameron, Louisiana on 30 August. The GEER team surveyed sixteen main sites, extending from Mustang Island in the southwest to Galveston in the northeast and as far inland as Rosenburg. In Port Aransas, beach erosion and undercutting along a beach access road near Aransas Pass were observed. Due to several tide gauge failures in this area, the nearest NOAA tide gauge (#8775870 near Corpus Christi) was used to estimate water levels of 1.35 m, approximately 1.0 m above the predicted tide. In Holiday Beach, anchored retaining walls were inundated, causing backside scour along the entire length and exposing the sheetpile wall anchors. Along the Colorado River at the Highway 35 bridge near Bay City, active riverbank failure was observed and a sheet pile wall was found collapsed. Significant sediment deposits lined the vegetated riverbanks. A USGS stream gage recorded gage heights greater than 45 ft, exceeding the flood stage of 44 ft. Fronting a rubblemound seawall in Surfside Beach, a runnel and ridge formation was observed. Nearby at San Luis Pass, infilled scour around bridge piers and beach erosion were observed. Sediment samples, penetrometer, and mini torvane data were collected at most of these sites and data analysis is being conducted. The presentation will provide an overview of the findings of the GEER team. The preliminary report may be found at www.geerassociation.org.

Beach nourishment alternative assessment to constrain cross-shore and longshore sediment transport

USGS Publications Warehouse

Karasu, Servet; Work, Paul A.; Uzlu, Ergun; Kankal, Murat; Yuksek, Omer

2016-01-01

A combined field and laboratory investigation was conducted to assess five options for creation of a recreational beach on a steep, armored shoreline on the eastern Black Sea coast. All designs incorporated a beach nourishment project placed between two existing, shore-normal, rubble-mound groins. Alternatives included the placement of a nearshore berm, longshore extensions added to the existing groins, and shore-parallel breakwaters. Several alternatives are reviewed for quantifying the performance of each design, including assessment of the change in shoreline position and project volume retained between the groins. Dimensionless benefits and benefit-cost ratios are quantified, and recommendations made on how to select the best outcome from a benefit-to-cost standpoint when options including hard structures are incorporated into a beach nourishment project design.

Close-range airborne Structure-from-Motion Photogrammetry for high-resolution beach morphometric surveys: Examples from an embayed rotating beach

NASA Astrophysics Data System (ADS)

Brunier, Guillaume; Fleury, Jules; Anthony, Edward J.; Gardel, Antoine; Dussouillez, Philippe

2016-05-01

The field of photogrammetry has seen significant new developments essentially related to the emergence of new computer-based applications that have fostered the growth of the workflow technique called Structure-from-Motion (SfM). Low-cost, user-friendly SfM photogrammetry offers interesting new perspectives in coastal and other fields of geomorphology requiring high-resolution topographic data. The technique enables the construction of topographic products such as digital surface models (DSMs) and orthophotographs, and combines the advantages of the reproducibility of GPS surveys and the high density and accuracy of airborne LiDAR, but at very advantageous cost compared to the latter. Three SfM-based photogrammetric experiments were conducted on the embayed beach of Montjoly in Cayenne, French Guiana, between October 2013 and 2014, in order to map morphological changes and quantify sediment budgets. The beach is affected by a process of rotation induced by the alongshore migration of mud banks from the mouths of the Amazon River that generate spatial and temporal changes in wave refraction and incident wave angles, thus generating the reversals in longshore drift that characterise this process. Sub-vertical aerial photographs of the beach were acquired from a microlight aircraft that flew alongshore at low elevation (275 m). The flight plan included several parallel flight axes with an overlap of 85% between pictures in the lengthwise direction and 50% between paths. Targets of 40 × 40 cm, georeferenced by RTK-DGPS, were placed on the beach, spaced 100 m apart. These targets served in optimizing the model and in producing georeferenced 3D products. RTK-GPS measurements of random points and cross-shore profiles were used to validate the photogrammetry results and assess their accuracy. We produced dense point clouds with 150 to 200 points/m², from which we generated DSMs and orthophotos with respective resolutions of 10 cm and 5 cm. Compared to the GPS control points, we obtained a mean vertical accuracy less than ± 10 cm, with a maximum of 20 cm in marginal sectors with sparse vegetation and in the lower intertidal zone where water-saturated surfaces generated lower-resolution data as a result of a lack of coherence between photographs. The overall results show that SfM photogrammetry is a robust tool for beach morphological and sediment budget surveys. Our SfM workflow enabled the discrimination of beach surface features at a scale of a few tens of centimetres despite the low textural contrasts exhibited by the quartz beach sand and the relatively uniform upper beach topography, as well as the calculation of beach sediment budgets. 66,000 m³ of sand were removed from the northern sector of the beach, of which 22,000 m³ were transferred to the southern sector in the course of rotation. Finally, we briefly highlight: (1) the advantages of SfM photogrammetry compared to other high-resolution survey methods, (2) the advantages and disadvantages of, respectively, a microlight aircraft and an unmanned aerial vehicle (UAV) in undertaking SfM photogrammetry, and (3) areas of potential future improvement of the SfM workflow technique. These concern more extensive cross-shore deployment of ground control points to reduce possible tilt, and oblique cross-shore photography to improve parallax.

Stability of a very coarse-grained beach at Carmel, California

USGS Publications Warehouse

Dingler, J.R.

1981-01-01

Monastery Beach at Carmel, California, is a pocket beach composed of very coarse to granular sediment. In profile, the beach has a well-defined berm crest; a steep foreshore; and a gently sloping, barless offshore covered by large, long-crested oscillation ripples. Carmel Submarine Canyon heads a few hundred meters offshore of the beach, and San Jose Creek, a small ephemeral steam, ponds onshore of the central part of the berm. Wave conditions vary greatly during a year because the beach lies open to the Pacific Ocean for azimuths between 270??-322??N whence come a variety of wave types. Even with a variable wave climate, Monastery Beach has maintained a swell profile for almost three years. Aperiodic beach surveys show that the beach responds little to seasonal changes in wave climate. Four survey lines maintained the same swell profile throughout the study period. The fifth line maintained a stable profile only across the foreshore; the berm was twice artificially breached during storms to prevent upstream flooding along San Jose Creek. In comparison, Carmel Beach, a nearby beach composed of medium sand, commonly alternates between swell and storm profiles. The increased stability of Monastery Beach relative to Carmel Beach is attributed to two factors: grain size differences and location within Carmel Bay. Rebuilding proceeded very slowly along the breached part of the berm at Monastery Beach. The probable cause of such a low recovery rate is that oscillation ripples trapped the sand that was carried offshore when San Jose Creek eroded the beach. The ripples, which are active under high-energy conditions, approach dormancy under low-energy conditions. Each ripple, therefore, acts like a reservoir, retaining sand during most swell conditions. ?? 1981.

Tracing the origin of dissolved organic matter (DOM) in subterranean estuaries using colored DOM and amino acids

NASA Astrophysics Data System (ADS)

Kim, T.; Kwon, E.; Kim, G.

2011-12-01

In order to determine the origin of dissolved organic matter (DOM) in the subterranean estuary (STE), the mixing zone of fresh terrestrial groundwater and recirculating seawater in a coastal permeable aquifer, we conducted water sampling from two STEs with different geological settings: (1) Jeju Island beaches (Hwasun and Samyang), which are composed of volcanic rocks and sandy sediments, and (2) Hampyeong beach, which is located in a large intertidal, sandy flat zone. The distributions of salinity, total hydrolysable amino acids (THAA), dissolved organic carbon (DOC), and colored DOM (CDOM) were measured for groundwater samples in these STEs. In the Hwasun STE, the humic-like peak decreases with increasing salinity, whereas the protein-like peak does not show a clear relationship with salinity. In contrast, in the Samyang STE, both humic-like peak and protein-like peak increase with increasing salinity. These contrasting results indicate that DOM in the Hwasun STE originates mainly from terrestrial inputs, while that in the Samyang STE originates mainly from biological and/or microbial activities. In the Hampyeong STE, we observed good correlations among the biodegradation index, alanine D/L ratios, THAA concentrations, DOC, and CDOM index (both humic-like and protein-like). Together with their geographical distribution patterns, these correlations indicate that DOM in the Hampyeong STE is mainly derived from marine sediments in the course of seawater recirculation. Our study shows that CDOM and amino acids are excellent tracers of DOM in the STE where DOM is derived from diverse sources.

Strategic Placement of Mixed Sediment in the Form of a Nearshore Berm along Fort Myers Beach, Florida

DTIC Science & Technology

2017-03-28

reusable and sustainable placement site. 6. The nearshore berm will allow increased shore protection from large waves breaking and attenuating on the berm...maintenance in 1986, 1996, and 2001 (Florida Department of Environmental Protection 2009). In the past, as part of regional sediment management, sediment...Environmental Protection 2009). Figure 1. Study area and survey line locations. Sanibel Island (to the northwest of Estero Island) shelters Fort

Lidar observations of wind- and wave-driven morphological evolution of coastal foredunes

NASA Astrophysics Data System (ADS)

Spore, N.; Brodie, K. L.; Kershner, C. M.

2016-02-01

Coastal foredunes are continually evolving geomorphic features that are slowly built up by wind-blown sand and rapidly eroded during storms by large waves and swash. Landward aeolian transport removes sediment from the active beach and surf-zone, trapping it in the dune, where as coastal erosion both removes sediment from the dune and can decrease the overall fetch and sediment supply available to the dune. Understanding how wave and wind-driven process interact with each other and the dune-beach system itself is a critical component of improving predictions of coastal evolution. To investigate these processes, two 50 m alongshore by 25 m cross-shore patches of dune along an open coast beach fronting the Atlantic Ocean in Duck, NC were scanned with a high resolution terrestrial lidar scanner ( 5000 points per m^2) every three weeks over the last year to observe detailed morphological evolution of the dune and upper beach. Sequential scans were co-registered to each other using fixed objects in the field of view, significantly increasing precision and accuracy of the observations. The north study site featured a 7.5 m tall scarped foredune system, where as the southern study site featured a 6 m tall, hummocky, prograding foredune. Initial analyses show large accretion events on the southern prograding site. For example, during one three week period in February, portions of the site accreted over 40 cm. In contrast, during the same three week period at the northern site (less than 1 km away), response was alongshore variable with erosion and accretion of roughly 10 cm on the foredune face. Further analysis will focus on separating wind vs. wave driven evolution of these sites. Funded by the USACE Coastal Inlets Research Program.

GPR studies over the tsunami affected Karaikal beach, Tamil Nadu, south India

NASA Astrophysics Data System (ADS)

Loveson, V. J.; Gujar, A. R.; Barnwal, R.; Khare, Richa; Rajamanickam, G. V.

2014-08-01

In this study, results of GPR profiling related to mapping of subsurface sedimentary layers at tsunami affected Karaikal beach are presented . A 400 MHz antenna was used for profiling along 262 m stretch of transect from beach to backshore areas with penetration of about 2.0 m depth (50 ns two-way travel time). The velocity analysis was carried out to estimate the depth information along the GPR profile. Based on the significant changes in the reflection amplitude, three different zones are marked and the upper zone is noticed with less moisture compared to other two (saturated) zones. The water table is noticed to vary from 0.5 to 0.75 m depth (12-15 ns) as moving away from the coastline. Buried erosional surface is observed at 1.5 m depth (40-42 ns), which represents the limit up to which the extreme event acted upon. In other words, it is the depth to which the tsunami sediments have been piled up to about 1.5 m thickness. Three field test pits were made along the transect and sedimentary sequences were recorded. The sand layers, especially, heavy mineral layers, recorded in the test pits indicate a positive correlation with the amplitude and velocity changes in the GPR profile. Such interpretation seems to be difficult in the middle zone due to its water saturation condition. But it is fairly clear in the lower zone located just below the erosional surface where the strata is comparatively more compact. The inferences from the GPR profile thus provide a lucid insight to the subsurface sediment sequences of the tsunami sediments in the Karaikal beach.

Coastal monitoring of the May 2005 dredge disposal offshore of Ocean Beach, San Francisco, Calif.

USGS Publications Warehouse

Barnard, Patrick L.; Hanes, Daniel M.

2006-01-01

Ocean Beach, California, contains an erosion hot spot in the shadow of the San Francisco ebb tidal delta south of Sloat Boulevard that threatens valuable public infrastructure as well as the safe recreational use of the beach. In an effort to reduce the erosion at this location and avoid hazardous navigation conditions at the current disposal site (SF-8), a new plan for the management of sediment dredged annually from the main shipping channel at the mouth of Francisco Bay was implemented in May 2005 by the United States Army Corps of Engineers, San Francisco District (COE). The objective for COE was to perform a test dredge disposal of ~230,000 m3 (300,000 yd3) of sand just offshore of the erosion hot spot, in depths between approximately 9 and 14 m. This disposal site was chosen because it is in a location where the strong tidal currents associated with the mouth of San Francisco Bay and waves can potentially feed sediment toward the littoral zone in the reach of the beach that is experiencing critical erosion. The onshore migration of sediment from the target disposal location might feed the primary longshore bar or the nearshore zone, and provide a buffer to erosion that peaks during winter months when large waves impact the region. The U.S. Geological Survey (USGS), in collaboration with the Sea Floor Mapping Lab (SFML) of California State University, Monterey Bay, monitored the initial bathymetric evolution of the test dredge disposal site and the adjacent coastal region from May 2005 to November 2005. This paper reports on this monitoring effort and assesses the short-term coastal response.

Heavy Minerals in Palaeotsunami Deposits: Assemblages, Spatial Distribution and Microtextural Imprints

NASA Astrophysics Data System (ADS)

Costa, P. J.; Andrade, C.; Cascalho, J.; Dawson, A. G.; Freitas, M. C.; Dawson, S.; Mahaney, W. C.

2013-12-01

The sedimentological record provides a database useful to characterize and evaluate recurrence of tsunamis, which contributes to assessing the vulnerability of any coastal area to this natural hazard. Thus, the enhancement of our ability to recognize signatures specific of tsunami activity imprinted in coastal sediments is of unquestionable interest. The aim of this study is to discuss and further contribute to the improvement of the characterization of (palaeo)tsunami deposits, and of their source materials. With that purpose the vertical and horizontal distribution of heavy mineral (HM) assemblages in sand-sized tsunamigenic deposits from six locations exhibiting a varied suite of coastal contexts and corresponding to three inundation events -(8200yrs BP - Scotland, 1500yrs BP - Scotland, AD 1755 - Portugal) were studied. In general, results from paleotsunami sediments show that site-specific effects prevent 'blind' extrapolations; instead, the bulk of the HM assemblages reflect local specificities related with the regional geology. In the Portuguese sediments (Martinhal, Boca do Rio and Salgados) ca. 90% of the non-opaque HM population consists of tourmaline, andalusite and staurolite, whereas amphiboles are dominant (> 90% of the assemblage) in the Scottish sediments (Scasta Voe, Basta Voe and Whale Firth). Principal Components Analyses revealed that the first 2 components explain more than 2/3 of the total variance found in each site. Horizontal and vertical variations in the HM were observed and especially in the heavier mineral species. Although, in some of the studied cases, the deposit was macroscopically massive, data on HM allowed the distinction of backwash layer(s), related with incorporation of inland materials. In what concerns sources, results indicate that palaeotsunami sediments share fewer compositional similarities with present-day inshore and offshore materials and more resemblances with dune and beach sediment, thus indicating these as the more likely source areas. In addition, preliminary results of SEM analysis of microtextural features imprinted in the surface of heavy minerals indicate an increase in the number of mechanical marks in the surface of palaeotsunami grains when compared with potential source materials (beach, dune, inshore and offshore samples). This work further reveals the potential to use heavy minerals as a complementary sedimentological tool in the study of palaeotsunami deposits.

Beach Erosional Hot Spots: Types, Causes, and Solutions

DTIC Science & Technology

2001-09-01

Pope, and McClung (1999) showed that variable erosion rates along a beach nourishment project on Presque Isle , Pennsylvania (Lake Erie ) were related to...and McClung, J. K. (1999). “Coastal response to a detached breakwater system: Presque Isle , Erie , PA, U.S.A,” Proc. Coastal Sediments ’99, ASCE...borrow pits located too close to shore at Grand Isle , LA. The resultant cuspate shoreline was subsequently predicted by refraction analysis

New method for estimating bacterial cell abundances in natural samples by use of sublimation

NASA Technical Reports Server (NTRS)

Glavin, Daniel P.; Cleaves, H. James; Schubert, Michael; Aubrey, Andrew; Bada, Jeffrey L.

2004-01-01

We have developed a new method based on the sublimation of adenine from Escherichia coli to estimate bacterial cell counts in natural samples. To demonstrate this technique, several types of natural samples, including beach sand, seawater, deep-sea sediment, and two soil samples from the Atacama Desert, were heated to a temperature of 500 degrees C for several seconds under reduced pressure. The sublimate was collected on a cold finger, and the amount of adenine released from the samples was then determined by high-performance liquid chromatography with UV absorbance detection. Based on the total amount of adenine recovered from DNA and RNA in these samples, we estimated bacterial cell counts ranging from approximately 10(5) to 10(9) E. coli cell equivalents per gram. For most of these samples, the sublimation-based cell counts were in agreement with total bacterial counts obtained by traditional DAPI (4,6-diamidino-2-phenylindole) staining.

Coastal monitoring solutions of the geomorphological response of beach-dune systems using multi-temporal LiDAR datasets (Vendée coast, France)

NASA Astrophysics Data System (ADS)

Le Mauff, Baptiste; Juigner, Martin; Ba, Antoine; Robin, Marc; Launeau, Patrick; Fattal, Paul

2018-03-01

Three beach and dune systems located in the northeastern part of the Bay of Biscay in France were monitored over 5 years with a time series of three airborne LiDAR datasets. The three study sites illustrate a variety of morphological beach types found in this region. Reproducible monitoring solutions adapted to basic and complex beach and dune morphologies using LiDAR time series were investigated over two periods bounded by the three surveys. The first period (between May 2008 and August 2010) is characterized by a higher prevalence of storm events, and thus has a greater potential for eroding the coast, than the second period (between August 2010 and September 2013). During the first period, the central and northeastern part of the Bay of Biscay was notably impacted by Storm Xynthia, with water levels and wave heights exceeding the 10-year return period and 1-year return period, respectively. Despite differences in dune morphology between the sites, the dune crest (Dhigh) and the dune base (Dlow) are efficiently extracted from each DEM. Based on the extracted dune base, an original shoreline mobility indicator is built displaying a combination of the horizontal and vertical migrations of this geomorphic indicator between two LiDAR datasets. A 'Geomorphic Change Detection' is also completed by computing DEMs of Difference (DoD) resulting in segregated maps of erosion and deposition and sediment budgets. Accounting for the accuracy of LiDAR datasets, a probabilistic approach at a 95% confidence interval is used as a threshold for the Geomorphic Change Detection showing more reliable results. However, caution should be taken when interpreting thresholded maps of changes and sediment budgets because some beach processes may be masked, especially on wide tidal beaches, by only keeping the most significant changes. The results of the shoreline mobility and Geomorphic Change Detection show a high variability in the beach responses between and within the three study sites, explained mainly by beach orientation and local factors. Despite variable site-specific mechanisms, the recovery processes redistribute the available sand more on the upper parts of the beach, producing significant deposition generally in the form of embryo dunes. The monitoring of the beach and dune systems with airborne LiDAR datasets reveals that the three study sites show diverse behaviours during the first period likely associated with storms, while the analysis show more homogenous beach responses during the second period likely associated with a recovery phase.

Field studies of beach cones as coastal erosion control/reversal devices for areas with significant oil and gas activities. Final report, February 24, 1992--September 18, 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Law, V.J.

1995-09-18

The primary objective of this project was to evaluate the utility of a device called the {open_quotes}beach cone{close_quotes} in combating coastal erosion. Seven initial sites were selected for testing beach cones in a variety of geometric configurations. Permits were obtained from the State of Louisiana and the U.S. Army Corps of Engineers to perform the work associated with this study. Six hundred beach cones were actually installed at six of the sites in late July and early August, 1992. Findings indicate that beach cones accreted significant amounts of materials along the beach of a barrier island, and they might havemore » been instrumental in repairing an approximately 200 meter gap in the island. At the eighth installation the amount of accreted material was measured by surveys to be 2200 cubic meters (2900 cubic yards) in February of 1993, when the cones were found to have been completely covered by the material. At other test sites, accretion rates have been less dramatic but importantly, no significant additional erosion has occurred, which is a positive result. The cost of sediment accretion using beach cones was found to be about $13.72 per cubic yard, which would be much lower if the cones were mass produced (on the order of $3.00 per cubic yard). The survival of the cones through the fringes of Hurricane Andrew indicates that they can be anchored sufficiently to survive significant storms. The measurements of the cones settling rates indicate that this effect is not significant enough to hinder their effectiveness. A subcontract to Xavier University to assess the ecological quality of the experimental sites involved the study of the biogeochemical cycle of trace metals. The highest concentration of heavy metals were near a fishing camp while the lowest levels were in the beach sand of a barrier island. This suggests that the metals do not occur naturally in these areas, but have been placed in the sediments by man`s activities.« less

Comment on “On AGU's Position Statement, ‘Human Impacts on Climate’”

NASA Astrophysics Data System (ADS)

Evans, Rob

2009-08-01

Regarding the Forum by Cyril Galvin (Eos, 89(46), 459, 2008), while I understand AGU's willingness to present both sides of the coin, as it were, I am disappointed that this Forum appeared in Eos. One major point in question is the assertion by Galvin that “nowhere on the sandy ocean shores of the world is there a beach whose erosion has been documented to be caused by sea level rise.” This point disregards the fact that coastal barrier systems have been moving landward for the last several thousand years, driven by rising sea level. Yes, the picture is complex, and yes, wave action and storms, in addition to constraints on sediment supply—many of them heavily influenced in the present day by societal actions—are also important: Some beaches will erode without rising sea level if they are starved of new sediment to replace that removed by wave-driven, alongshore currents, and it is of course the waves that move the sediment around.

A quantitative analysis of microplastic pollution along the south-eastern coastline of South Africa.

PubMed

Nel, H A; Froneman, P W

2015-12-15

The extent of microplastic pollution (<5mm) in the southern hemisphere, particularly southern Africa, is largely unknown. This study aimed to evaluate microplastic pollution along the south-eastern coastline of South Africa, looking at whether bays are characterised by higher microplastic densities than open stretches of coastline in both beach sediment and surf-zone water. Microplastic (mean ± standard error) densities in the beach sediment ranged between 688.9 ± 348.2 and 3308 ± 1449 particles · m(-2), while those in the water column varied between 257.9 ± 53.36 and 1215 ± 276.7 particles · m(-3). With few exceptions there were no significant spatial patterns in either the sediment or water column microplastic densities; with little differences in density between bays and the open coast (P>0.05). These data indicate that the presence of microplastics were not associated with proximity to land-based sources or population density, but rather is governed by water circulation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Hydrodynamics of a small trained tidal inlet (Currumbin Creek, Australia)

NASA Astrophysics Data System (ADS)

Shaeri, S.; Tomlinson, R. B.; Etemad-Shahidi, A.; Strauss, D.; Hughes, L. P.

2014-04-01

Small tidal inlets are important features of coastal areas, in terms of provision of access from a back barrier water-body to the ocean as well as periodic circulation of fresh nutrients for the local ecology. Usually, dimensional and geometrical characteristics contribute significantly to morphological stability or instability of a particular inlet and necessitate an individual investigation of any desired location. In other words, generalized usage of previous empirical and experimental research of a different position can hardly be used for other places. In this regard, one of the powerful tools to understand the physical processes of a particular region is to collect as much field data as possible. Such a dataset is used to further analyse and explore the governing processes and can also be used for building a numerical computer model for supplementary studies. In this research, the results of a comprehensive field measurement at Currumbin Creek, Queensland, Australia are presented. This study is part of broader research to investigate the long term evolution of the Currumbin entrance and its adjacent beaches. Currently, an annual dredging campaign is needed to reduce the risk of flooding due to excess rainfall inundations and to maintain water quality. The majority of data were collected over a three month period consistent with the time of the 2012 dredging operation. However, due to the loss of some instrumentation, data collection for some of the parameters was repeated till the middle of May 2013. All collected data included: (1) nearshore waves and tide; (2) creek tidal variation; (3) creek flow discharge and velocity; (4) bathymetric survey of the creek; (5) beach profile evolution survey; and (6) sediment sampling. The measurement showed that the creek entrance is tidally dominated, with flood events having a major role in sediment transport into the creek. The nearshore stations' wave data illustrated the marginal effect of the beach curvature between updrift and downdrift stations. Thus, the historical dataset available from the updrift wave rider buoy will be selected to be used for future numerical modelling. Although changes of some beach profiles were comparatively insignificant, the dramatic changes of the profile lines nearby the inlet channel and also rapid bathymetric change of the flood shoal following the dredging completion are valuable information to better calibrate and interpret a local sediment modelling study for the next phase. Essentially, this evaluation needs to be considered for proposing any alternative maintenance activities.

Morphosedimentary evolution of carbonate sandy beaches at decadal scale : case study in Reunion Island , Indian Ocean

NASA Astrophysics Data System (ADS)

Mahabot, Marie-Myriam; Pennober, Gwenaelle; Suanez, Serge; Troadec, Roland; Delacourt, Christophe

2017-04-01

Global change introduce a lot of uncertainties concerning future trajectory of beaches by directly or indirectly modifying major driving factors. An improved understanding of the past shoreline evolution may help for anticipate future coastline response. However, in tropical environment, studies concerning carbonate beaches dynamics are scarce compared to open sandy beaches. Consequently, coral reef protected beaches morphological adjustment is still poorly understood and long-term evolution rate are poorly quantified in these specific environment. In this context, La Reunion Island, insular department of France located in Indian Ocean, constitute a favoured laboratory. This high volcanic island possesses 25 km of carbonate beaches which experience hydrodynamic forcing specific from tropical environment: cyclonic swell during summer and long period swell during winter. Because of degraded coral reef health and high anthropogenic pressure, 50% of the beaches are in erosion since 1970s. Beach survey has been conducted since 1990s by scientist and are now encompassed as pilot site within a French observatory network which guarantee long-term survey with high resolution observational techniques. Thus, La Reunion Island is one of the rare carbonate beach to be surveyed since 20 years. This study aims to examined and quantify beach response at decadal scale on carbonate sandy beaches of Reunion Island. The study focus on 12 km of beaches from Cap Champagne to the Passe de Trois-Bassins. The analyze of 15 beach profile data originated from historical and DGPS beach topographic data confirm long term trend to erosion. Sediment lost varies between 0.5 and 2 m3.yr-1 since 1998. However longshore current have led to accretion of some part of beach compartment with rate of 0.7 to 1.6 m3.yr-1. Wave climate was examined from in-situ measurement over 15 years and show that extreme waves associated with tropical cyclones and long period swell play a major role in beach dynamics. Swell frequency and intensity are both determinant for beach evolution.

Submarine groundwater discharge and solute transport under a transgressive barrier island

NASA Astrophysics Data System (ADS)

Evans, Tyler B.; Wilson, Alicia M.

2017-04-01

Many recent investigations of groundwater dynamics in beaches employed groundwater models that assumed isotropic, numerically-convenient hydrogeological conditions. Real beaches exhibit local variability with respect to stratigraphy, sediment grain size and associated topographic profile, so that groundwater flow may diverge significantly from idealized models. We used a combination of hydrogeologic field methods and a variable-density, saturated-unsaturated, transient groundwater flow model to investigate SGD and solute transport under Cabretta Beach, a small transgressive barrier island seaward of Sapelo Island, Georgia. We found that the inclusion of real beach heterogeneity drove important deviations from predictions based on theoretical beaches. Cabretta Beach sustained a stronger upper saline plume than predicted due to the presence of a buried silty mud layer beneath the surface. Infiltration of seawater was greater for neap tides than for spring tides due to variations in beach slope. The strength of the upper saline plume was greatest during spring tides, contrary to recent model predictions. The position and width of the upper saline plume was highly dynamic through the lunar cycle. Our results suggest that field measurements of salinity gradients may be useful for estimating rates of tidally and density driven recirculation through the beach. Finally, our results indicate that several important biogeochemical cycles recently studied at Cabretta Beach were heavily influenced by groundwater flow and associated solute transport.

Plastic debris and microplastics along the beaches of the Strait of Hormuz, Persian Gulf.

PubMed

Naji, Abolfazl; Esmaili, Zinat; Khan, Farhan R

2017-01-30

Currently little is known about the prevalence of plastics and microplastics (MPs) in the Persian Gulf. Five sampling stations were selected along the Strait of Hormuz (Iran) that exhibited different levels of industrialization and urbanization, and included a marine protected area. Debris was observed and sediments were collected for MPs extraction via fluidization/floatation methodology. The order of MP abundance (par/kg) generally reflected the level of anthropogenic activity: Bostanu (1258±291)>Gorsozan (122±23)>Khor-e-Yekshabeh (26±6)>Suru (14±4)>Khor-e-Azini (2±1). Across all sites fibers dominated (83%, 11% film, 6% fragments). FT-IR analysis showed polyethylene (PE), nylon, and PET (polyethylene terephthalate) were the commonly recovered polymers. Likely sources include beach debris, discarded fishing gear, and urban and industrial outflows that contain fibers from clothes. This study provides a 'snapshot' of MP pollution and longitudinal studies are required to fully understand plastic contamination in the region. Copyright © 2016 Elsevier Ltd. All rights reserved.

Spatial and Temporal Variation in Enterococcal Abundance and Its Relationship to the Microbial Community in Hawaii Beach Sand and Water

PubMed Central

Cui, Henglin; Yang, Kun; Pagaling, Eulyn

2013-01-01

Recent studies have reported high levels of fecal indicator enterococci in marine beach sand. This study aimed to determine the spatial and temporal variation of enterococcal abundance and to evaluate its relationships with microbial community parameters in Hawaii beach sand and water. Sampling at 23 beaches on the Island of Oahu detected higher levels of enterococci in beach foreshore sand than in beach water on a mass unit basis. Subsequent 8-week consecutive samplings at two selected beaches (Waialae and Kualoa) consistently detected significantly higher levels of enterococci in backshore sand than in foreshore/nearshore sand and beach water. Comparison between the abundance of enterococci and the microbial communities showed that enterococci correlated significantly with total Vibrio in all beach zones but less significantly with total bacterial density and Escherichia coli. Samples from the different zones of Waialae beach were sequenced by 16S rRNA gene pyrosequencing to determine the microbial community structure and diversity. The backshore sand had a significantly more diverse community and contained different major bacterial populations than the other beach zones, which corresponded to the spatial distribution pattern of enterococcal abundance. Taken together, multiple lines of evidence support the possibility of enterococci as autochthonous members of the microbial community in Hawaii beach sand. PMID:23563940

Bioremediation of the Exxon Valdez oil in Prince William Sound beaches.

PubMed

Boufadel, Michel C; Geng, Xiaolong; Short, Jeff

2016-12-15

Oil from the Exxon Valdez laden with polycyclic aromatic hydrocarbons (PAH) has persisted on some beaches in Prince William Sound, Alaska, >20years after these beaches became contaminated. The degradation rate of the total PAH (TPAH) is estimated at 1% per year. Low oxygen concentrations were found to be the major factor causing oil persistence, and bioremediation through the injection of hydrogen peroxide and nutrients deep into four beaches in PWS were conducted in the summers of 2011 and 2012. It was found that due to the treatment, the TPAH biodegradation rate was between 13% and 70% during summer 2011 and summer 2012. The results also showed high efficiency in the delivery of oxygen and nutrient to the contaminated areas of the beach. However, the approach has an environmental cost associated with it, and stakeholders would need to conduct a rigorous net environmental benefit analysis (NEBA) for pursuing the bioremediation of submerged contaminated sediments, especially in higher latitudes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Measurement uncertainties in quantifying aeolian mass flux: evidence from wind tunnel and field site data

PubMed Central

Keijsers, Joep G.S.; Maroulis, Jerry; Visser, Saskia M.

2014-01-01

Aeolian sediment traps are widely used to estimate the total volume of wind-driven sediment transport, but also to study the vertical mass distribution of a saltating sand cloud. The reliability of sediment flux estimations from such measurements are dependent upon the specific configuration of the measurement compartments and the analysis approach used. In this study, we analyse the uncertainty of these measurements by investigating the vertical cumulative distribution and relative sediment flux derived from both wind tunnel and field studies. Vertical flux data was examined using existing data in combination with a newly acquired dataset; comprising meteorological data and sediment fluxes from six different events, using three customized catchers at Ameland beaches in northern Netherlands. Fast-temporal data collected in a wind tunnel shows that the median transport height has a scattered pattern between impact and fluid threshold, that increases linearly with shear velocities above the fluid threshold. For finer sediment, a larger proportion was transported closer to the surface compared to coarser sediment fractions. It was also shown that errors originating from the distribution of sampling compartments, specifically the location of the lowest sediment trap relative to the surface, can be identified using the relative sediment flux. In the field, surface conditions such as surface moisture, surface crusts or frozen surfaces have a more pronounced but localized effect than shear velocity. Uncertainty in aeolian mass flux estimates can be reduced by placing multiple compartments in closer proximity to the surface. PMID:25071984

Sediment Management Options for Galveston Island, Texas

DTIC Science & Technology

2015-06-15

Galveston Island is a major tourist and commercial center on the Gulf of Mexico at the mouth of Galveston Bay, Texas, USA. The shoreline along the...experience various rates of erosion, but Reach 1 is the highest priority since it is the part of the beach where most tourists visit and is...1.12 m/yr. It is assumed that all remaining littoral material not accounted for in beach growth enters San Luis Pass. All morphologic evidence shows

Potential for gulls to transport bacteria from human waste sites to beaches.

PubMed

Alm, Elizabeth W; Daniels-Witt, Quri R; Learman, Deric R; Ryu, Hodon; Jordan, Dustin W; Gehring, Thomas M; Santo Domingo, Jorge

2018-02-15

Contamination of recreational beaches due to fecal waste from gulls complicates beach monitoring and may pose a risk to public health. Gulls that feed at human waste sites may ingest human fecal microorganisms associated with that waste. If these gulls also visit beaches, they may serve as vectors, transporting fecal microorganisms to the beach where they may subsequently contaminate sand and water. In this study, samples collected from landfills, treated wastewater storage lagoons, and public beaches demonstrated a spatial and temporal overlap of markers for gull and human-associated microorganisms. In addition, markers for gull, fecal indicator bacteria, and the human-associated marker, HF183, were detected in gull feces and cloacae samples. Further, HF183 was detected in cloacae samples from gulls that were documented by radio-telemetry traveling between human waste sites and public beaches. This study highlights the potential for gulls that visit human waste sites to disperse human-associated microorganisms in the beach landscape. Copyright © 2017 Elsevier B.V. All rights reserved.

Chemical Data for Rock, Sediment, Biological, Precipitate, and Water Samples from Abandoned Copper Mines in Prince William Sound, Alaska

USGS Publications Warehouse

Koski, Randolph A.; Munk, LeeAnn

2007-01-01

In the early 20th century, approximately 6 million metric tons of copper ore were mined from numerous deposits located along the shorelines of fjords and islands in Prince William Sound, Alaska. At the Beatson, Ellamar, and Threeman mine sites (fig. 1), rocks containing Fe, Cu, Zn, and Pb sulfide minerals are exposed to chemical weathering in abandoned mine workings and remnant waste piles that extend into the littoral zone. Field investigations in 2003 and 2005 as well as analytical data for rock, sediment, precipitate, water, and biological samples reveal that the oxidation of sulfides at these sites is resulting in the generation of acid mine drainage and the transport of metals into the marine environment (Koski and others, 2008; Stillings and others, 2008). At the Ellamar and Threeman sites, plumes of acidic and metal-enriched water are flowing through beach gravels into the shallow offshore environment. Interstitial water samples collected from beach sediment at Ellamar have low pH levels (to ~3) and high concentrations of metals including iron, copper, zinc, cobalt, lead, and mercury. The abundant precipitation of the iron sulfate mineral jarosite in the Ellamar gravels also signifies a low-pH environment. At the Beatson mine site (the largest copper mine in the region) seeps containing iron-rich microbial precipitates drain into the intertidal zone below mine dumps (Foster and others, 2008). A stream flowing down to the shoreline from underground mine workings at Beatson has near-neutral pH, but elevated levels of zinc, copper, and lead (Stillings and others, 2008). Offshore sediment samples at Beatson are enriched in these metals. Preliminary chemical data for tissue from marine mussels collected near the Ellamar, Threeman, and Beatson sites reveal elevated levels of copper, zinc, and lead compared to tissue in mussels from other locations in Prince William Sound (Koski and others, 2008). Three papers presenting results of this ongoing investigation of sulfide oxidation in Prince William Sound are in press. Koski and others (2008) provide an overview of rock alteration, surface water chemistry, and the distribution of metals at the Ellamar, Threeman, and Beatson mine sites. Based on a 60-day, stream-discharge experiment at Beatson in 2005, Stillings and others (2008) analyze changes in water chemistry during storm events and the flux of metals to the shoreline. Foster and others (2008) investigate the biomass and diversity of microbial communities present in surface waters (streams, seeps, pore waters) using fatty acid methyl ester (FAMES) data and principal component analysis. The publications cited above contain a subset of the total chemical data for rock, sediment, biological, precipitate, and water samples collected from the three mine sites in 2003 and 2005. The purpose of this report is the presentation of complete chemical data sets for all samples collected during the two field periods of fieldwork. Data for a small number of samples collected at two other mines (Schlosser and Fidalgo, fig. 1), visited in 2003, are also included in the tables.

Chemical Data for Rock, Sediment, Biological, Precipitate, and Water Samples from Abandoned Copper Mines in Prince William Sound, Alaska

USGS Publications Warehouse

Koski, Randolph A.; Munk, LeeAnn

2007-01-01

Introduction In the early 20th century, approximately 6 million metric tons of copper ore were mined from numerous deposits located along the shorelines of fjords and islands in Prince William Sound, Alaska. At the Beatson, Ellamar, and Threeman mine sites (fig. 1), rocks containing Fe, Cu, Zn, and Pb sulfide minerals are exposed to chemical weathering in abandoned mine workings and remnant waste piles that extend into the littoral zone. Field investigations in 2003 and 2005 as well as analytical data for rock, sediment, precipitate, water, and biological samples reveal that the oxidation of sulfides at these sites is resulting in the generation of acid mine drainage and the transport of metals into the marine environment (Koski and others, 2008; Stillings and others, 2008). At the Ellamar and Threeman sites, plumes of acidic and metal-enriched water are flowing through beach gravels into the shallow offshore environment. Interstitial water samples collected from beach sediment at Ellamar have low pH levels (to ~3) and high concentrations of metals including iron, copper, zinc, cobalt, lead, and mercury. The abundant precipitation of the iron sulfate mineral jarosite in the Ellamar gravels also signifies a low-pH environment. At the Beatson mine site (the largest copper mine in the region) seeps containing iron-rich microbial precipitates drain into the intertidal zone below mine dumps (Foster and others, 2008). A stream flowing down to the shoreline from underground mine workings at Beatson has near-neutral pH, but elevated levels of zinc, copper, and lead (Stillings and others, 2008). Offshore sediment samples at Beatson are enriched in these metals. Preliminary chemical data for tissue from marine mussels collected near the Ellamar, Threeman, and Beatson sites reveal elevated levels of copper, zinc, and lead compared to tissue in mussels from other locations in Prince William Sound (Koski and others, 2008). Three papers presenting results of this ongoing investigation of sulfide oxidation in Prince William Sound are in press. Koski and others (2008) provide an overview of rock alteration, surface water chemistry, and the distribution of metals at the Ellamar, Threeman, and Beatson mine sites. Based on a 60-day, stream-discharge experiment at Beatson in 2005, Stillings and others (2008) analyze changes in water chemistry during storm events and the flux of metals to the shoreline. Foster and others (2008) investigate the biomass and diversity of microbial communities present in surface waters (streams, seeps, pore waters) using fatty acid methyl ester (FAMES) data and principal component analysis. The publications cited above contain a subset of the total chemical data for rock, sediment, biological, precipitate, and water samples collected from the three mine sites in 2003 and 2005. The purpose of this report is the presentation of complete chemical data sets for all samples collected during the two field periods of fieldwork. Data for a small number of samples collected at two other mines (Schlosser and Fidalgo, fig. 1), visited in 2003, are also included in the tables.

Application of Kite Based Aerial Photography to Resolve Short Term Sediment Exchanges Between a Dissipative Beach and Densely Vegetated Dunes

NASA Astrophysics Data System (ADS)

Conlin, M.; Cohn, N.; Ruggiero, P.

2016-12-01

Sand dunes provide coastal communities critical protection from flooding and erosion, as well as a habitat for a range of species- some threatened or endangered. As such, it is of importance to develop a quantitative understanding of the processes through which these systems evolve at a variety of temporal and spatial scales. During summer 2016, a large field campaign in southwest Washington called the Sandbar-aEolian Dune EXchange EXperiment (SEDEX2) focused on developing a suite of data sets fundamental to improving our understanding of the ways in which beaches and dunes grow during fair weather conditions. As part of this experiment, daily to bi-weekly measurements of upper-beach and vegetated dune morphology were collected by post-processing images acquired using a consumer grade kite-based aerial photography system with low-cost Agisoft Photoscan Structure from Motion (SfM) software. Under the appropriate environmental conditions (e.g., sufficient wind, no precipitation, and minimal fog), kite-based SfM techniques minimize survey effort and time as compared to traditional coastal surveying methods such as RTK DGPS and Terrestrial Laser Scanning (TLS), making this approach ideally suited for frequent surveys of small ( < 5 km2) coastal areas. However, while the dominant grass in the area, A. breviligulta (American Beachgrass), is critical for perturbing the wind field, impacting sediment transport processes, and partially dictating dune morphology, it grows densely and therefore complicates the development of aerial photography derived bare-earth digital elevation models. Here we document daily-to-weekly-scale upper beach and dune evolution using kite-based SfM techniques, focusing particularly on improving the efficacy of this technology both in vegetated areas and over short timescales. Our kite-based SfM approach, validated by concurrent RTK DGPS surveys, TLS scans, and dune vegetation surveys, is allowing us to develop quantitative estimates of the sediment exchange between the back-beach and dunes. Other data collected during SEDEX2 are being utilized to determine the primary drivers of these observed changes.

Centennial-scale human alterations, unintended natural-system responses, and event-driven mitigation within a coupled fluvial-coastal system: Lessons for collective management and long-term coastal change planning

NASA Astrophysics Data System (ADS)

Hein, C. J.; Hoagland, P.; Huang, J. C.; Canuel, E. A.; Fitzsimons, G.; Rosen, P.; Shi, W.; Fallon, A. R.; Shawler, J. L.

2017-12-01

On decadal to millennial timescales, human modifications of linked riparian and coastal landscapes have altered the natural transport of sediments to the coast, causing time-varying sediment fluxes to estuaries, wetlands, and beaches. This study explored the role of historical changes in land use and river/coastal engineering on patterns of coastal erosion in the coupled system comprising the Merrimack River and the Plum Island barrier beach (northern Massachusetts, USA). Recreational values of the beach, attendant impacts on the local housing market, human perceptions of future beach utilization, and collective management options were investigated. Key historical changes included the installation of dams to benefit industry and control flooding in the early 19th century; river-mouth jetties to maintain navigation and allow for the residential development of a more stable barrier in the early 20th century; and the progressive hardening of the shoreline in response to multi-decadal cyclical erosion and house losses throughout the latter 20th and 21st centuries. The tools of sedimentology, shoreline-change analysis, historic documentation, population surveys, and economic modeling were used to examine these changes and the dynamic linked responses of the natural system and human populations. We found cascading effects of human alterations to the river that changed sediment fluxes to the coastal zone, driving a need for mitigation over centennial timescales. More recently, multidecadal erosion-accretion cycles of the beach have had little impact on the housing market, which is instead more responsive to public shoreline stabilization efforts in response to short-term (< 5 years) erosion threats. General perceptions about the need to plan for long-term coastal changes are associated with sea-level rise and enhanced storminess, but real-time mitigation, such as shoreline hardening, has been reactive, lacking a collective consensus for best management and a longer-term perspective for adaptation. Together, these findings suggest that approaches which consider a range of timescales and balance the natural processes of barrier islands, associated ecosystems, and local communities are needed for sustainable management of coupled fluvial-coastal systems.

A molecular stable carbon isotope study of organic matter in immature Miocene Monterey sediments, Pismo basin

NASA Astrophysics Data System (ADS)

Schouten, Stefan; Schoell, Martin; Rijpstra, W. Irene C.; Sinninghe Damsté, Jaap S.; de Leeuw, Jan W.

1997-05-01

The 300 m section of the Miocene Monterey Formation outcropping at Shell Beach (Pismo basin; ca. 15-11 Ma) is composed of calcareous phosphatic (15.1-14.5 Ma) and siliceous facies (14.5-11.0 Ma). An objective of this paper is to document lateral paleoenvironmental changes in the Miocene Moneterey Formation by comparing the Shell Beach (SB) profile with the Naples Beach (NB) section in the Santa Barbara-Ventura basin (Schouten et al., 1997) which is ˜80 km to the south. Eight samples (one sample representing, on average, a time period of ca. 2000 y) from this section were analyzed for variations of extractable biomarkers and their carbon isotopic signatures as indicators for paleoenvironmental change during the Miocene. Saturated hydrocarbons present include 28,30-dinorhopane, phytane, n-alkanes (C 17sbnd C 31), lycopane, and 17β,21β(H)-homohopane. The biomarkers released after desulfurization of the polar fractions predominantly consist of phytane, 2,6,10,14-tetramethyl-7-(3-methylpentyl)pentadecane, C 17sbnd C 31n-alkanes, regular 5α- and 5β-steranes, dinosteranes, and (22R)-17β,21β(H)-pentakishomohopane. Steranes have similar carbon isotopic compositions (-25 to -27‰) throughout the section and are isotopically similar at both sites, indicating laterally similar and vertically stable environmental conditions for algae living in the upper part of the photic zone. Free and S-bound n-alkanes at SB mainly originate from marine organisms and not from terrestrial sources as in the NB section. S-bound pentakishomohopane is ca. 1-4‰ depleted compared to the steranes and is thought to be derived from the deeper water dwelling cyanobacteria. These findings are consistent with stable carbon isotopic data obtained for these compounds from Middle Miocene Monterey sediments at Naples Beach and indicates similar environmental conditions in the depositional environments of the Santa Barbara-Ventura and the Pismo basin. S-bound highly branched isoprenoids have, at both sites, different isotopic compositions indicating the presence of different diatom species, special growth conditions, or different bloom periods in the Pismo basin. The carbon isotopic composition of 28,30-dinorhopane shifts to more depleted values up section, suggesting that the dinorhopane-synthesizing organism or organisms live on CO 2, which is isotopically influenced by methane production and oxidation. The C 31 hopane is enriched by 1-4‰ in 13C compared to other hopanes and steranes. Specific bacteria, possibly heterotrophs, may have been the organisms producing this compound.

A mega-nourishment creates novel habitat for intertidal macroinvertebrates by enhancing habitat relief of the sandy beach

NASA Astrophysics Data System (ADS)

van Egmond, E. M.; van Bodegom, P. M.; Berg, M. P.; Wijsman, J. W. M.; Leewis, L.; Janssen, G. M.; Aerts, R.

2018-07-01

Globally, sandy beaches are subject to coastal squeeze due to erosion. Soft-sediment strategies, such as sand nourishment, are increasingly applied to mitigate effects of erosion, but have long-term negative impacts on beach flora and fauna. As a more ecologically and sustainable alternative to regular beach nourishments, a mega-nourishment has been constructed along the Dutch coast by depositing 21.5 Mm3 of sand, from which sand is gradually redistributed along the coast by natural physical processes. The 'Sand Motor' mega-nourishment was constructed as a long-term management alternative for coastal protection and is the first large-scale experiment of its kind. We evaluated the development of intertidal macroinvertebrate communities in relation to this mega-nourishment, and compared it to species composition of beaches subject to regular beach or no nourishment. We found that a mega-nourishment resulted initially in a higher macroinvertebrate richness, but a lower macroinvertebrate abundance, compared to regular beach nourishment. As there was no effect of year after nourishment, this finding suggests that colonization and/or local extinction were not limiting macroinvertebrate richness at the mega-nourishment. In addition, a mega-nourishment does not converge to an intertidal macroinvertebrate community similar to those on unnourished beaches within a time scale of four years. Beach areas at the mega-nourishment sheltered from waves harbored a distinct macroinvertebrate community compared to typical wave-exposed sandy beach communities. Thus, a mega-nourishment temporally creates new habitat for intertidal macroinvertebrates by enhancing habitat relief of the sandy beach. We conclude that a mega-nourishment may be a promising coastal defense strategy for sandy shores in terms of the macroinvertebrate community of the intertidal beach.

No geochemical evidence for an asteroidal impact at late Devonian mass extinction horizon

NASA Astrophysics Data System (ADS)

McGhee, G. R., Jr.; Gilmore, J. S.; Orth, C. J.; Olsen, E.

1984-04-01

Three sedimentary sequences in New York State (Dunkirk Beach, Walnut Creek Gorge, and Mills Mills) and one sedimentary sequence in Belgium (Sinsin), that cross the Devonian Frasnian-Famennian boundary, were examined for an iridium (Ir) anomaly to determine whether the biotic extinctions at the end of the Cretaceous could have been caused by an asteroidal impact. The sampling at three of the four areas was on 2-cm center points, and 15 to 20 g of sample were collected. The instrumental neutron activation method required 5 g samples, and consequently the distance between samples was less than 1 cm. Though the Devonian samples studied had a high probability of locating an Ir anomaly, none was found. The highest Ir values were between 0.2 and 2 percent of those reported for the marine and terrestrial Ir analyses at the Cretaceous-Tertiary boundary, and Devonian pyrite-rich sediments did not exhibit high Ir concentrations.

Role of light and heavy minerals on natural radioactivity level of high background radiation area, Kerala, India.

PubMed

Ramasamy, V; Sundarrajan, M; Suresh, G; Paramasivam, K; Meenakshisundaram, V

2014-02-01

Natural radionuclides ((238)U, (232)Th and (40)K) concentrations and eight different radiological parameters have been analyzed for the beach sediments of Kerala with an aim of evaluating the radiation hazards. Activity concentrations ((238)U and (232)Th) and all the radiological parameters in most of the sites have higher values than recommended values. The Kerala beach sediments pose significant radiological threat to the people living in the area and tourists going to the beaches for recreation or to the sailors and fishermen involved in their activities in the study area. In order to know the light mineral characterization of the present sediments, mineralogical analysis has been carried out using Fourier transform infrared (FTIR) spectroscopic technique. The eight different minerals are identified and they are characterized. Among the various observed minerals, the minerals such as quartz, microcline feldspar, kaolinite and calcite are major minerals. The relative distribution of major minerals is determined by calculating extinction co-efficient and the values show that the amount of quartz is higher than calcite and much higher than microcline feldspar. Crystallinity index is calculated to know the crystalline nature of quartz present in the sediments. Heavy mineral separation analysis has been carried out to know the total heavy mineral (THM) percentage. This analysis revealed the presence of nine heavy minerals. The minerals such as monazite, zircon, magnetite and illmenite are predominant. Due to the rapid and extreme changes occur in highly dynamic environments of sandy beaches, quantities of major light and heavy minerals are widely varied from site to site. Granulometric analysis shows that the sand is major content. Multivariate statistical (Pearson correlation, cluster and factor) analysis has been carried out to know the effect of mineralogy on radionuclide concentrations. The present study concluded that heavy minerals induce the (238)U and (232)Th concentrations. Whereas, light mineral (calcite) controls the (40)K concentration. In addition to the heavy minerals, clay content also induces the important radioactive variables. © 2013 Published by Elsevier Ltd.

Mixed response in bacterial and biochemical variables to simulated sand mining in placer-rich beach sediments, Ratnagiri, West coast of India.

PubMed

Fernandes, Christabelle E G; Das, Anindita; Nath, B N; Faria, Daphne G; Loka Bharathi, P A

2012-05-01

We investigated the influence on bacterial community and biochemical variables through mechanical disturbance of sediment-akin to small-scale mining in Kalbadevi beach, Ratnagiri, a placer-rich beach ecosystem which is a potential mining site. Changes were investigated by comparing three periods, namely phase I before disturbance, phase II just after disturbance, and phase III 24 h after disturbance as the bacterial generation time is ≤7 h. Cores from dune, berm, high-, mid-, and low-tide were examined for changes in distribution of total bacterial abundance, total direct viability (counts under aerobic and anaerobic conditions), culturability and biochemical parameters up to 40 cm depth. Results showed that bacterial abundance decreased by an order from 10(6) cells g(-1) sediment, while, viability reduced marginally. Culturability on different-strength nutrient broth increased by 155% during phase II. Changes in sedimentary proteins, carbohydrates, and lipids were marked at berm and dune and masked at other levels by tidal influence. Sedimentary ATP reduced drastically. During phase III, Pearson's correlation between these variables evolved from non-significant to significant level. Thus, simulated disturbance had a mixed effect on bacterial and biochemical variables of the sediments. It had a negative impact on bacterial abundance, viability and ATP but positive impact on culturability. Viability, culturability, and ATP could act as important indicators reflecting the disturbance in the system at short time intervals. Culturability, which improved by an order, could perhaps be a fraction that contributes to restoration of the system at bacterial level. This baseline information about the potential mining site could help in developing rational approach towards sustainable harnessing of resources with minimum damage to the ecosystem.

Investigating sea bed morphology of an estuary located in the western coast of India

NASA Astrophysics Data System (ADS)

Chowdhury, P.; Behera, M. R.; Ranjan, P.

2016-02-01

Estuaries and tidal inlets are complex natural systems. They form a vital ecosystem and host a plethora of diverse flora and fauna. The major problem associated with them is that they experience both climate effects and human interference in different spatial and temporal scales. The increasing threats of sea level variability and changes in the other ocean parameters like currents, waves, winds and tidal ranges may cause these inlets to behave differently. Mandovi - Zuari is one such complex inlet situated in the western coast of India. It is a major tourist attraction and a home to dense mangrove forest. It experiences mixed tides (mainly semi-diurnal in nature). Also the salinity of this region tends to change seasonally. The annual evolution in morphology of this region is of importance as the sediment transport in this area plays an important role in determining the beach morphology of the adjacent beaches. Tourism being the most important economic driver of this state, it is important to assess the possible changes in the beach morphology over the coming decades. A state-of-the-art process based model, Delft 3D, is used to calculate the annual sediment transport with a focus to understand the morphological evolution history of this inlet. In this regard a hydrodynamic analysis of the region is carried out by forcing a composite tide at the offshore boundary of the model domain to obtain the tidal levels and currents. The sea bed contours are obtained with the help of admiralty charts. For estimating the sediment transport, Van Rijn formula is used as found in the sediment module of Delft 3D. The morphological changes along the coast of Goa, India is estimated and the locations of accretion and erosion are identified.

Barrier Island Morphology and Sediment Characteristics Affect the Recovery of Dune Building Grasses following Storm-Induced Overwash

PubMed Central

Brantley, Steven T.; Bissett, Spencer N.; Young, Donald R.; Wolner, Catherine W. V.; Moore, Laura J.

2014-01-01

Barrier islands are complex and dynamic systems that provide critical ecosystem services to coastal populations. Stability of these systems is threatened by rising sea level and the potential for coastal storms to increase in frequency and intensity. Recovery of dune-building grasses following storms is an important process that promotes topographic heterogeneity and long-term stability of barrier islands, yet factors that drive dune recovery are poorly understood. We examined vegetation recovery in overwash zones on two geomorphically distinct (undisturbed vs. frequently overwashed) barrier islands on the Virginia coast, USA. We hypothesized that vegetation recovery in overwash zones would be driven primarily by environmental characteristics, especially elevation and beach width. We sampled species composition and environmental characteristics along a continuum of disturbance from active overwash zones to relict overwash zones and in adjacent undisturbed environments. We compared species assemblages along the disturbance chronosequence and between islands and we analyzed species composition data and environmental measurements with Canonical Correspondence Analysis to link community composition with environmental characteristics. Recovering and geomorphically stable dunes were dominated by Ammophila breviligulata Fernaud (Poaceae) on both islands while active overwash zones were dominated by Spartina patens (Aiton) Muhl. (Poaceae) on the frequently disturbed island and bare sand on the less disturbed island. Species composition was associated with environmental characteristics only on the frequently disturbed island (p = 0.005) where A. breviligulata was associated with higher elevation and greater beach width. Spartina patens, the second most abundant species, was associated with larger sediment grain size and greater sediment size distribution. On the less frequently disturbed island, time since disturbance was the only factor that affected community composition. Thus, factors driving the abundance of dune-building grasses and subsequent recovery of dunes varied between the two geomorphically distinct islands. PMID:25148028

Neogene paleoceanographic events recorded in an active-margin setting: Humboldt basin, California

USGS Publications Warehouse

McCrory, P.A.

1990-01-01

Recognition of North Pacific paleoceanographic events in the marginal Humboldt (Eel River) basin of northern California enables correlation of stratigraphic sections and development of a chronostratigraphy. Paleoclimatically related coiling shifts in Neogloboquadrina pachyderma (Ehrenberg) and benthic foraminiferal datums form the basis of the chronostratigraphy. Benthic foraminiferal datums are defined by the occurrence of selected benthic species and abundance maxima of benthic biofacies. The compiled chronostratigraphy is used to refine reconstructions of the depositional history of Humboldt basin. Paleoceanographic events, recognized by the distribution of benthic foraminiferal biofacies, are used to infer paleoceanographic history along the northeastern Pacific margin. The similarity in coiling curves of N. pachyderma from the marine sequence at DSDP Site 173 and the coastal Centerville Beach section of Humboldt basin and at other independently dated sites along the northeastern Pacific margin demonstrates that matching records of climatic oscillations is a reliable method of correlating marine sequences. Benthic fauna from the Centerville Beach section vary in phase with climatically related coiling shifts in N. pachyderma. In particular these data show an increase in displaced neritic fauna during inferred warm intervals and resurgence of deeper bathyal fauna during inferred cool events. Similar data are observed from the inland Eel River section, demonstrating that benthic foraminiferal trends recognized at Centerville Beach can be identified elsewhere in Humboldt basin. This in-phase benthic response to climatic fluctuations probably results from changes in vertical depth range of many benthic species in response to paleoclimatically related vertical changes in water-mass position. Depositional histories reconstructed for two key sites in southern Humboldt basin indicate low rates of sediment accumulation during early basin filling with hemipelagic sediments. Initiation of turbidite sedimentation in the early Pliocene resulted in a sharp increase in rate of sediment accumulation. This increase in rate of sediment accumulation is partially a response to tectonic uplift in the northern Coast Ranges and may be an effect of realignment of motion between the Pacific and North American plates at about this time. The inland site shoaled more rapidly during turbidite sedimentation as a result of a higher rate of sediment accumulation. The rate of sediment accumulation increased again at this site in the late Pliocene during deposition of shelf and nearshore facies. The Eel River region subsided concurrent with deposition of these shallow-water deposits. ?? 1990.

Organic contaminants, trace and major elements, and nutrients in water and sediment sampled in response to the Deepwater Horizon oil spill

USGS Publications Warehouse

Nowell, Lisa H.; Ludtke, Amy S.; Mueller, David K.; Scott, Jonathon C.

2012-01-01

Beach water and sediment samples were collected along the Gulf of Mexico coast to assess differences in contaminant concentrations before and after landfall of Macondo-1 well oil released into the Gulf of Mexico from the sinking of the British Petroleum Corporation's Deepwater Horizon drilling platform. Samples were collected at 70 coastal sites between May 7 and July 7, 2010, to document baseline, or "pre-landfall" conditions. A subset of 48 sites was resampled during October 4 to 14, 2010, after oil had made landfall on the Gulf of Mexico coast, called the "post-landfall" sampling period, to determine if actionable concentrations of oil were present along shorelines. Few organic contaminants were detected in water; their detection frequencies generally were low and similar in pre-landfall and post-landfall samples. Only one organic contaminant--toluene--had significantly higher concentrations in post-landfall than pre-landfall water samples. No water samples exceeded any human-health benchmarks, and only one post-landfall water sample exceeded an aquatic-life benchmark--the toxic-unit benchmark for polycyclic aromatic hydrocarbons (PAH) mixtures. In sediment, concentrations of 3 parent PAHs and 17 alkylated PAH groups were significantly higher in post-landfall samples than pre-landfall samples. One pre-landfall sample from Texas exceeded the sediment toxic-unit benchmark for PAH mixtures; this site was not sampled during the post-landfall period. Empirical upper screening-value benchmarks for PAHs in sediment were exceeded at 37 percent of post-landfall samples and 22 percent of pre-landfall samples, but there was no significant difference in the proportion of samples exceeding benchmarks between paired pre-landfall and post-landfall samples. Seven sites had the largest concentration differences between post-landfall and pre-landfall samples for 15 alkylated PAHs. Five of these seven sites, located in Louisiana, Mississippi, and Alabama, had diagnostic geochemical evidence of Macondo-1 oil in post-landfall sediments and tarballs. For trace and major elements in water, analytical reporting levels for several elements were high and variable. No human-health benchmarks were exceeded, although these were available for only two elements. Aquatic-life benchmarks for trace elements were exceeded in 47 percent of water samples overall. The elements responsible for the most exceedances in post-landfall samples were boron, copper, and manganese. Benchmark exceedances in water could be substantially underestimated because some samples had reporting levels higher than the applicable benchmarks (such as cobalt, copper, lead and zinc) and some elements (such as boron and vanadium) were analyzed in samples from only one sampling period. For trace elements in whole sediment, empirical upper screening-value benchmarks were exceeded in 57 percent of post-landfall samples and 40 percent of pre-landfall samples, but there was no significant difference in the proportion of samples exceeding benchmarks between paired pre-landfall and post-landfall samples. Benchmark exceedance frequencies could be conservatively high because they are based on measurements of total trace-element concentrations in sediment. In the less than 63-micrometer sediment fraction, one or more trace or major elements were anthropogenically enriched relative to national baseline values for U.S. streams for all sediment samples except one. Sixteen percent of sediment samples exceeded upper screening-value benchmarks for, and were enriched in, one or more of the following elements: barium, vanadium, aluminum, manganese, arsenic, chromium, and cobalt. These samples were evenly divided between the sampling periods. Aquatic-life benchmarks were frequently exceeded along the Gulf of Mexico coast by trace elements in both water and sediment and by PAHs in sediment. For the most part, however, significant differences between pre-landfall and post-landfall samples were limited to concentrations of PAHs in sediment. At five sites along the coast, the higher post-landfall concentrations of PAHs were associated with diagnostic geochemical evidence of Deepwater Horizon Macondo-1 oil.

Self-organising of wave and beach relief in storm: field experiments

NASA Astrophysics Data System (ADS)

Kuznetsova, Olga; Saprykina, Yana; Kuznetsov, Sergey; Stremel, Margarita; Korsinin, Dmitry; Trifonova, Ekaterina; Andreeva, Natalia

2017-04-01

This paper presents results of waves and morfodynamics observation carried out in frame of complex field experiments "Shkorpilowtsy-2016" and "Shkorpilowtsy-2007", which were made in order to understand how bottom deformations depend on wave parameters and how wave-bottom self-organisation process runs during storm events. Sediment transport and profile deformations were analysed taking into account the presence of underwater bar (data 2007) and without it (data 2016). Experiments were made on field base of Institute of Oceanology "Fridtjof Nansen" (Bulgarian Academy of Sciences) in Shkorpilowtsy settlement, that is locates on Black Sea coast, 40 km from Varna. The base is equipped with 253 m research pier that provide measuring until 5 m depth on distance 200 m from shore. During filed works synchronous observations on wave parameters and bottom changes were made on average three times a day for one month: 18.09-08.10.2007 and 07.10-02.11.2016. Morphological observations involved cross-shore beach profile deformations measuring along the scientific pier from shore to sea through each 2 m using metal pole in 2007 and metal or rope lot in 2016. Wave measurements included visual observations of breaking and surf zones location, wave type (wind or swell wave) and direction as well as free surface deviation (wave chronogram) registrations using high-frequency capacitive or resistance sensors mounted along the pier. In 2007 registration of free surface elevation was carried out with 7 capacitance and 8 resistant wire gauges, in 2016 - with 18 capacitance wire gauges. Sampling frequency was 5 Hz in 2007 and 20 Hz in 2016, duration of the records varied from 20 min up to one hour in 2007 and between 10 min and one hour in 2016. Wave spectra computed from chronogram allowed to estimate wave spectral (significant wave height, spectral peak and mean periods and complex) and integral parameters (Irribaren and Ursell numbers) to analyse dependence bottom deformations on it. Self-organising of bottom relief and waves were studied on a scale of several storms. Results of investigations show that increase of significant wave height and spectral peak period of wave entering in coastal zone as well as Ursell number lead to erosion, which was localised in first 100 m near on barred profile and covered whole observed profile in case without bar. Features of sediment transport by forming a mobile temporal underwater bar were examined for cases of flat sloping and barred underwater beach profiles. On timescale of one storm type of wave breaking affect sediment transport: plunging wave breaking is responsible for formation and evolution of underwater sand bar as well as decreasing of sediment amount in upper part of beach profile and shoreline regression, while spilling do not lead to significant bottom deformations. The work was supported by Russian Foundation of Basic Research (grants 16-55-76002 (ERA-a), 16-35-00542 (mol_a), 15-05-08239, 15-05-04669).

The presence of radioactive materials in soil, sand and sediment samples of Potenga sea beach area, Chittagong, Bangladesh: Geological characteristics and environmental implication

NASA Astrophysics Data System (ADS)

Yasmin, Sabina; Barua, Bijoy Sonker; Uddin Khandaker, Mayeen; Kamal, Masud; Abdur Rashid, Md.; Abdul Sani, S. F.; Ahmed, H.; Nikouravan, Bijan; Bradley, D. A.

2018-03-01

Accurate quantification of naturally occurring radioactive materials in soil provides information on geological characteristics, possibility of petroleum and mineral exploration, radiation hazards to the dwelling populace etc. Of practical significance, the earth surface media (soil, sand and sediment) collected from the densely populated coastal area of Chittagong city, Bangladesh were analysed using a high purity germanium γ-ray spectrometer with low background radiation environment. The mean activities of 226Ra (238U), 232Th and 40K in the studied materials show higher values than the respective world average of 33, 36 and 474 Bq/kg reported by the UNSCEAR (2000). The deduced mass concentrations of the primordial radionuclides 238U, 232Th and 40K in the investigated samples are corresponding to the granite rocks, crustal minerals and typical rocks respectively. The estimated mean value of 232Th/238U for soil (3.98) and sediment (3.94) are in-line with the continental crustal average concentration of 3.82 for typical rock range reported by the National Council on Radiation Protection and Measurements (NCRP). But the tonalites and more silicic rocks elevate the mean value of 232Th/238U for sand samples amounting to 4.69. This indicates a significant fractionation during weathering or associated with the metasomatic activity in the investigated area of sand collection.

Distribution of living larger benthic foraminifera in littoral environments of the United Arab Emirates

NASA Astrophysics Data System (ADS)

Fiorini, Flavia; Lokier, Stephen W.

2015-04-01

The distribution of larger benthic foraminifera in Recent littoral environment of the United Arab Emirates (Abu Dhabi and Western regions) was investigated with the aim of understanding the response of those foraminifera to an increase in water salinity. For this purpose, 100 sediment samples from nearshore shelf, beach-front, channel, lagoon, and intertidal environment were collected. Sampling was undertaken at a water depth shallower than 15 m in water with a temperature of 22 to 35˚C, a salinity ranging from 40 to 60‰ and a pH of 8. Samples were stained with rose Bengal at the moment of sample collection in order to identify living specimens. The most abundant epiphytic larger benthic foraminifera in the studied area were Peneroplis pertusus and P. planatus with less common Spirolina areatina, S. aciculate and Sorites marginalis. The living specimens of the above mentioned species with normal test growing were particularly abundant in the nearshore shelf and lagoonal samples collected on seaweed. Dead specimens were concentrated in the coarser sediments of the beach-front, probably transported from nearby environments. Shallow coastal ponds are located in the upper intertidal zone and have a maximum salinity of 60‰ and contain abundant detached seagrass. Samples collected from these ponds possess a living foraminifera assemblage dominated by Peneroplis pertusus and P. planatus. High percentages (up to 50% of the stained assemblage) of Peneroplis presented abnormality in test growth, such as the presence of multiple apertures with reduced size, deformation in the general shape of the test, irregular suture lines and abnormal coiling. The high percentage of abnormal tests reflects natural environmental stress mainly caused by high and variable salinity. The unique presence of living epiphytic species, suggests that epiphytic foraminifera may be transported into the pond together with seagrass and continued to live in the pond. This hypothesis is supported by the fact that all of the foraminifera with abnormal test growth were adults and exhibiting a normal proloculus and normal growth of the earlier chambers.

Nearshore Coastal Dynamics on a Sea-Breeze Dominated Micro-Tidal Beach (NCSAL)

NASA Astrophysics Data System (ADS)

Torres-Freyermuth, A.; Puleo, J. A.; Ruiz de Alegría-Arzaburu, A.; Figlus, J.; Mendoza, T.; Pintado-Patino, J. C.; Pieterse, A.; Chardon-Maldonado, P.; DiCosmo, N. R.; Wellman, N.; Garcia-Nava, H.; Palemón-Arcos, L.; Roberts, T.; López-González, J.; Bravo, M.; Ojeda, E.; Medellín, G.; Appendini, C. M.; Figueroa, B.; González-Leija, M.; Enriquez, C.; Pedrozo-Acuña, A.; Salles, P.

2014-12-01

A comprehensive field experiment devoted to the study of coastal processes on a micro-tidal beach was conducted from March 30th to April 12th 2014 in Sisal, Yucatán México. Wave conditions in the study area are controlled by local (i.e., sea-breezes) and meso-scale (i.e., Nortes) meteorological events. Simultaneous measurements of waves, tides, winds, currents, sediment transport, runup, and beach morphology were obtained in this experiment. Very dense nearshore instrumentation arrays allow us the study of the cross-/along- shore variability of surf/swash zone dynamics during different forcing conditions. Strong sea-breeze wind events produced a diurnal cycle with a maximum wind speed of 14 m/s. The persistent sea-breeze system forces small-amplitude (Hs<1 m) short-period (Tp<4 s) NE waves approaching with a high incidence wave angle. These wave conditions drive westward alongshore currents of up to 0.6 m/s in the inner surf zone and hence produce an active sediment transport in the swash zone. On the other hand, the more energetic (Hs>1 m) Norte event, lasting 48 hours, reached the coast on April 8th generating a long-period swell (Tp>10 s) arriving from the NNW. This event induced an eastward net sediment transport across a wide surf zone. However, long-term observations of sand impoundment at a groin located near the study area suggests that the net sediment transport in the northern Yucatan peninsula is controlled by sea-breeze events and hence swash zone dynamics play an important role in the net sediment budget of this region. A comparative study of surf and swash zone dynamics during both sea-breeze and Norte events will be presented. The Institute of Engineering of UNAM, throughout an International Collaborative Project with the University of Delaware, and CONACYT (CB-167692) provided financial support. The first author acknowledges ONR Global for providing financial support throughout the Visiting Scientist Program.

An integrated methodology to forecast the efficiency of nourishment strategies in eroding deltas.

PubMed

Bergillos, Rafael J; López-Ruiz, Alejandro; Principal-Gómez, Daniel; Ortega-Sánchez, Miguel

2018-02-01

Many deltas across the globe are retreating, and nearby beaches are undergoing strong erosion as a result. Among soft and prompt solutions, nourishments are the most heavily used. This paper presents an integrated methodology to forecast the efficiency of nourishment strategies by means of wave climate simulations, wave propagations with downscaling techniques, computation of longshore sediment transport rates and application of the one-line model. It was applied to an eroding deltaic beach (Guadalfeo, southern Spain), where different scenarios as a function of the nourished coastline morphology, input volume and grain size were tested. For that, the evolution of six scenarios of coastline geometry over a two-year period (lifetime of nourishment projects at the study site) was modelled and the uncertainty of the predictions was also quantified through Monte Carlo techniques. For the most efficient coastline shape in terms of gained dry beach area, eight sub-scenarios with different nourished volumes were defined and modelled. The results indicate that an input volume around 460,000m 3 is the best strategy since nourished morphologies with higher volumes are more exposed to the prevailing storm directions, inducing less efficient responses. After setting the optimum coastline morphology and input sediment volume, eleven different nourished grain sizes were modelled; the most efficient coastline responses were obtained for sediment sizes greater than 0.01m. The availability of these sizes in the sediment accumulated upstream of a dam in the Guadalfeo River basin allows for the conclusion that this alternative would not only mitigate coastal erosion problems but also sedimentation issues in the reservoir. The methodology proposed in this work is extensible to other coastal areas across the world and can be helpful to support the decision-making process of artificial nourishment projects and other environmental management strategies. Copyright © 2017 Elsevier B.V. All rights reserved.

Our Dynamic Coastline.

ERIC Educational Resources Information Center

Aubrey, David G.

1980-01-01

Discusses mechanisms which influence both rapid and gradual modifications of ocean beaches. Among factors described are storms, waves, currents, tides, sediment transport, and climate. Some effects of these forces upon coastline configurations are also presented. (WB)

Quantifying the effects of European beach grass on aeolian sand transport over the last century: Bodega Marine Reserve, California

NASA Astrophysics Data System (ADS)

Cesmat, R.; Werner, S.; Smith, M. E.; Riedel, T.; Best, R.; Olyarnik, S.

2012-12-01

Introduction of European beach grass (Ammophila arenaria) to coastal dune systems of western North America induced significant changes to the transport and storage of sediment, and consequently the nesting habitat of the western snowy plover (Charadrius alexandrinus nivosus). At the Bodega Marine Reserve and Sonoma Coast State Park, Ammophila was introduced within the ~0.5 km2 dune area in the 1920's to limit the flux of sand through Bodega Harbor and agricultural land. To assess the potential impact of restoration efforts (Ammophila removal) on aeolian sediment flux, we measured sediment flux as a function of wind speeds and ground cover, and used these measurements to parameterize a spatial model for historical sand deposition Fine- to coarse-grained lithic to sub-lithic sand is delivered to the Bodega dune system from Salmon Creek beach, the down-shore terminus of a littoral system fed by the 3846 km2 Russian River catchment, several small (<100 km2) coastal catchments, and seacliff erosion. Littoral sediment traverses the 1.8 km wide dune system from NW to SE via aeolian transport. Ammophila colonization occurred initially adjacent to the shoreface, inducing deposition of a ~10 meter-high foredune and has subsequently encroached the ~0.5 km2 region between the foredune and Bodega Harbor. Comparison of historical topographic maps via raster subtraction indicates rapid construction of both the foredune and a ~15 meter-high transverse dune (Gaffney ridge) at the edge of the planted region. An average accumulation rate of ~4,000 m3/yr is indicated within the study swath by the preserved sediment volumes. Within the modern dune system, unvegetated areas exhibit 2-3 meter wavelength, ~1/2 meter amplitude mega-ripples, and the uppermost 2-10 cm consists of coarse-sand to granule-sized armor layer. In contrast, grain-sizes in vegetated areas are largely vertically homogenous. Open areas are typically 2-8 meters lower than adjacent vegetated areas, and show evidence for net lowering of the land surface (i.e., exposed fence posts, roots). Conversely, vegetated areas appear prone to sediment accumulation, particularly downwind of unvegetated areas. We measured sand transport using 0.5 m high traps deployed at 18 sites throughout the dune field, and used a linear mixed effects model to predict transport rate as a function of wind and ground cover class, taking into account random effects of sampling date and repeated measurements at each site. The analysis indicates up to 450-times higher transport rates in unvegetated areas relative to vegetated areas at peak wind conditions. We then used these results to parameterize a simple raster-based sediment flux model for the 0.5 km wide study area, using LIDAR-based topography and aerial orthophotography to classify ground cover. Due to the nearly complete compartmentalization of sediment flux by vegetative baffling, the model suggests that proposed restoration (removal of vegetative cover) of the seaward 1 km of the dune system would lead to significant increases in sediment transport in the treated area accompanied by accumulation along its vegetated downwind edge, but little to no change in sand flux within Ammophila-covered areas >0.2 km downwind of restored areas.

Surficial sediments along the inner Continental shelf of Maine

USGS Publications Warehouse

Kelley, J.T.; Dickson, S.M.

1999-01-01

Through 10 years of support from the Minerals Management Service-Association of American State Geologists' Continental Margins Program we have mapped along the Maine coast, seaward to the 100 m isobath. In all, 1,773 bottom sample stations were occupied, 3,358 km of side-scan sonar and 5,011 km of seismic reflection profiles were gathered. On the basis of these data, a surficial sediment map was created for the Maine inner continental shelf during the Year 8 project, and cores and seismic data were collected to evaluate sand thickness during Years 9 and 10. Sand covers only 8% of the Maine shelf, and is concentrated seaward of beaches off southern Maine in water depths less than 60 m. Sand occurs in three depositional settings: (1) in shoreface deposits connected dynamically to contemporary beaches; (2) in submerged deltas associated with lower sea-level positions; and (3) in submerged lowstand shoreline positions between 50 and 60 m. Seismic profiles over the shoreface off Saco Bay, Wells Embayment, and off the Kennebec River mouth each imaged a wedge-shaped acoustic unit which tapered off between 20 and 30 m. Cores determined that this was sand that was underlain by a variable but thin (commonly < 1 m) deposit of estuarine muddy sand and a thick deposit of glacial-marine mud. Off Saco Bay, more than 55 million m3 of sand exists in the shoreface, compared with about 22 million m3 on the adjacent beach and dunes. Seaward of the Kennebec River, a large delta deposited between 13 ka and the present time holds more than 300 million m3 of sand and gravel. The best sorted sand is on the surface nearshore, with increasing amounts of gravel offshore and mud beneath the surficial sand sheet. Bedforms indicate that the surficial sand is moved by waves to at least 55 m depth. Seaward of the Penobscot River, no significant sand or gravel was encountered. Muddy estuarine sediments overlie muddy glacial-marine sediment throughout the area offshore area of this river. No satifactory explanation is offered for lack of a sandy delta seaward of Maine's largest river. Lowstand-shoreline deposits were cored in many places in Saco Bay and off the Kennebec River mouth. Datable materials from cores indicated that the lowstand occurred around 10.5 ka off the Kennebec. Cores did not penetrate glacial-marine sediment in the lowstand deposits, and seismic profiles were ambiguous about the vertical extent of sand in these units. For these reasons, no total thickness of sand was determined from the lowstand deposits, but given the area of the surficial sand, the volume is probably in the hundreds of millions of cubic meters.Through 10 years of support from the Minerals Management Service, the Association of American State Geologists' Continental Margins Program have mapped along the Maine coast, seaward to the 100 m isobath. In all, 1,773 bottom samples stations were occupied, 3,358 km of side-scan sonar and 5,011 km of seismic reflection profiles were gathered. On the basis of these data, a surficial sediment map was created for the Maine inner continental shelf during the year 8 project, and cores and seismic data were collected to evaluate sand thickness during year 9 and year 10.

Assessment of Rip-Current Hazards Using Alongshore Topographic Anisotropy at Bondi Beach, Australia

NASA Astrophysics Data System (ADS)

Hartman, K.; Trimble, S. M.; Bishop, M. P.; Houser, C.

2016-12-01

Rip currents are a relatively high-velocity flow of water away from the beach common in coastal environments. As beach morphology adapts to sediment fluxes and wave climate, it is essential to be able to assess rip-current hazard conditions. Furthermore, it is essential to be able to characterize the scale-dependent bathymetric morphology that governs the extent and magnitude of a rip current. Consequently, our primary objective is to assess the alongshore distribution of topographic anisotropy, in order to identify rip-current hazard locations. Specifically, we utilized multi-band satellite imagery to generate a bathymetric digital elevation model (DEM) for Bondi Beach Australia, and collected field data to support our analysis. Scale-dependent spatial analysis of the DEM was conducted to assess the directional dependence of topographic relief, the magnitude of topographic anisotropy, and the degree of anisotropic symmetry. We displayed anisotropy parameters as images and false-color composites to visualize morphological conditions associated with rip channels. Our preliminary results indicate that rip channels generally have a higher anisotropy index and orthogonal orientation compared to dissipative or reflective beach anisotropy and orientation. Scale-dependent variations in anisotropy can be used to assess the spatial extent of rip currents. Furthermore, well-defined rip channels exhibit positive symmetry, while variations in the distribution of symmetry reflect sediment-flux variations alongshore. These results clearly reveal that a well-developed rip channel can be identified and assessed using topographic anisotropy, as scale-dependent anisotropy patterns are unique when compared to the surrounding bathymetry and terrain. In this way, it is possible to evaluate the alongshore distribution of rip currents. Alongshore topographic anisotropy data will be extremely important as input into hazard assessment studies and the development of hazard decision support systems.

Liquefaction along Late Pleistocene to early Holocene Faults as Revealed by Lidar in Northwest Tasmania, Australia

NASA Astrophysics Data System (ADS)

Webb, J.; Gardner, T.

2016-12-01

In northwest Tasmania well-preserved mid-Holocene beach ridges with maximum radiocarbon ages of 5.25 ka occur along the coast; inland are a parallel set of lower relief beach ridges of probable MIS 5e age. The latter are cut by northeast-striking faults clearly visible on LIDAR images, with a maximum vertical displacement (evident as difference in topographic elevation) of 3 m. Also distinct on the LIDAR images are large sand boils along the fault lines; they are up to 5 m in diameter and 2-3 m high and mostly occur on the hanging wall close to the fault traces. Without LIDAR it would have been almost impossible to distinguish either the fault scarps or the sand boils. Excavations through the sand boils show that they are massive, with no internal structure, suggesting that they formed in a single event. They are composed of well-sorted, very fine white sand, identical to the sand in the underlying beach ridges. The sand boils overlie a peaty paleosol; this formed in the tea-tree swamp that formerly covered the area, and has been offset along the faults. Radiocarbon dating of the buried organic-rich paleosol gave ages of 14.8-7.2 ka, suggesting that the faulting is latest Pleistocene to early Holocene in age; it occurred prior to deposition of the mid-Holocene beach ridges, which are not offset. The beach ridge sediments are up to 7 m thick and contain an iron-cemented hard pan 1-3 m below the surface. The water table is very shallow and close to the ground surface, so the sands of the beach ridges are mostly saturated. During faulting these sands experienced extensive liquefaction. The resulting sand boils rose to a substantial height of 2-3 m, probably possibly reflecting the elevation of the potentiometric surface within the confined part of the beach ridge sediments below the iron-cemented hard pan. Motion on the faults was predominantly dip slip (shown by an absence of horizontal offset) and probably reverse, which is consistent with the present-day northwest-southeast compressive stress in this area.

Beach Resilience to Coastal Structures on a Natural Beach

NASA Astrophysics Data System (ADS)

Torres-Freyermuth, A.; Medellín, G.; Hofman, A.; Tereszkiewicz, P.; Palemón-Arcos, L.; López-González, J.

2016-12-01

Beach resilience plays an important role on reducing coastal risk associated to either natural or human induced perturbations affecting the coast. Field experiments were conducted in order to investigate beach resilience in Sisal, Yucatán. Both impermeable and permeable 14-m groins were designed to asses the impact of coastal structures on the beach morphology during a 24-hour period. The experiments were conducted in the spring of 2015 and 2016, allowing the assessment of both structures under similar forcing conditions. Intense sea breeze events (W>12 m/s) generated high-angle short-waves, driving alongshore transport in the swash zone. Wind, waves, tides, and currents were measured concurrently and are correlated with beach morphology evolution data derived from intense monitoring conducted during the structure deployment. The impermeable structure induced a significant beach accretion (>60 m3/day) in the updrift side of the structure causing a tremendous impact downdrift. On the other hand, the permeable groin induced a smaller but still significant accretion (40 m3/day), allowing sediment bypass throughout the structure. Furthermore, the beach surveying continued after structures removal in order to estimate the beach recovery capability. Field observations show that the impact of the structure on the morphology is negligible six days after structure removal for the impermeable groin and only one day for the permeable structure. The latter suggests the high beach resilience of the study area. We acknowledge field support provided by researchers and students at the LIPC-UNAM. Financial support was provided by CONACYT (Projects LN271544 and Cátedras 1146), DGAPA-UNAM (PAPIIT-IN107315) and Grupo BARI.

USACE Regional Sediment Management and Engineering with Nature 2013 Workshop Summary

DTIC Science & Technology

2014-08-01

Tools into HEC-RAS St. Louis Kaskaskia River Navigation Channel Mobile Biodegradable Containment Structures for RSM Honolulu Hawaii RSM – Haleiwa...sediment from USACE to private entities for use. Share successes and lessons learned.  Increase the use of vegetation and other biodegradable ...beaches, and submerged mounds) and construction materials (e.g., reef balls, combination of rock sills and oyster bags , native plants, and

Dramatic beach and nearshore morphological changes due to extreme flooding at a wave-dominated river mouth

USGS Publications Warehouse

Barnard, P.L.; Warrick, J.A.

2010-01-01

Record flooding on the Santa Clara River of California (USA) during January 2005 injected ∼ 5 million m3 of littoral-grade sediment into the Santa Barbara Littoral Cell, approximately an order of magnitude more than both the average annual river loads and the average annual alongshore littoral transport in this portion of the cell. This event appears to be the largest sediment transport event on record for a Southern California river. Over 170 m of local shoreline (mean high water (MHW)) progradation was observed as a result of the flood, followed by 3 years of rapid local shoreline recession. During this post-flood stage, linear regression-determined shoreline change rates are up to −45 m a− 1 on the subaerial beach (MHW) and − 114 m a− 1 on the submarine delta (6 m isobath). Starting approximately 1 km downdrift of the river mouth, shoreline progradation persisted throughout the 3-year post-flood monitoring period, with rates up to + 19 m a− 1. Post-flood bathymetric surveys show nearshore (0 to 12 m depth) erosion on the delta exceeding 400 m3/m a− 1, more than an order of magnitude higher than mean seasonal cross-shore sediment transport rates in the region. Changes were not constant with depth, however; sediment accumulation and subsequent erosion on the delta were greatest at − 5 to − 8 m, and accretion in downdrift areas was greatest above –2 m. Thus, this research shows that the topographic bulge (or “wave”) of sediment exhibited both advective and diffusive changes with time, although there were significant variations in the rates of change with depth. The advection and diffusion of the shoreline position was adequately reproduced with a simple “one line” model, although these modeling techniques miss the important cross-shore variations observed in this area. This study illustrates the importance of understanding low-frequency, high volume coastal discharge events for understanding short- and long-term sediment supply, littoral transport, and beach and nearshore evolution in coastal systems adjacent to river mouths.

Presence of Campylobacter and Salmonella in sand from bathing beaches.

PubMed

Bolton, F J; Surman, S B; Martin, K; Wareing, D R; Humphrey, T J

1999-02-01

The purpose of this study was to determine the presence of thermophilic Campylobacter spp. and Salmonella spp. in sand from non-EEC standard and EEC standard designated beaches in different locations in the UK and to assess if potentially pathogenic strains were present. Campylobacter spp. were detected in 82/182 (45%) of sand samples and Salmonella spp. in 10/182 (6%). Campylobacter spp. were isolated from 46/92 (50%) of samples from non-EEC standard beaches and 36/90 (40%) from EEC standard beaches. The prevalence of Campylobacter spp. was greater in wet sand from both types of beaches but, surprisingly, more than 30% of samples from dry sand also contained these organisms. The major pathogenic species C. jejuni and C. coli were more prevalent in sand from non-EEC standard beaches. In contrast, C. lari and urease positive thermophilic campylobacters, which are associated with seagulls and other migratory birds, were more prevalent in sand from EEC standard beaches. Campylobacter isolates were further characterized by biotyping and serotyping, which confirmed that strains known to be of types associated with human infections were frequently found in sand on bathing beaches.

Stable carbon and oxygen isotope record of central Lake Erie sediments

USGS Publications Warehouse

Tevesz, M.J.S.; Spongberg, A.L.; Fuller, J.A.

1998-01-01

Stable carbon and oxygen isotope data from mollusc aragonite extracted from sediment cores provide new information on the origin and history of sedimentation in the southwestern area of the central basin of Lake Erie. Sediments infilling the Sandusky subbasin consist of three lithologic units overlying glacial deposits. The lowest of these is a soft gray mud overlain by a shell hash layer containing Sphaerium striatinum fragments. A fluid mud unit caps the shell hash layer and extends upwards to the sediment-water interface. New stable isotope data suggest that the soft gray mud unit is of postglacial, rather than proglacial, origin. These data also suggest that the shell hash layer was derived from erosional winnowing of the underlying soft gray mud layer. This winnowing event may have occurred as a result of the Nipissing flood. The Pelee-Lorain moraine, which forms the eastern boundary of the Sandusky subbasin, is an elevated area of till capped by a sand deposit that originated as a beach. The presence of both the shell hash layer and relict beach deposit strengthens the interpretation that the Nipissing flood was a critical event in the development of the southwestern area of the central basin of Lake Erie. This event, which returned drainage from the upper lakes to the Lake Erie basin, was a dominant influence on regional stratigraphy, bathymetry, and depositional setting.

Quantitative mineralogy of the Yukon River system: Changes with reach and season, and determining sediment provenance

USGS Publications Warehouse

Eberl, D.D.

2004-01-01

The mineralogy of Yukon River basin sediment has been studied by quantitative X-ray diffraction. Bed, beach, bar, and suspended sediments were analyzed using the RockJock computer program. The bed sediments were collected from the main stem and from selected tributaries during a single trip down river, from Whitehorse to the Yukon River delta, during the summer of 2001. Beach and bar sediments were collected from the confluence region of the Tanana and Yukon Rivers during the summer of 2003. Suspended sediments were collected at three stations on the Yukon River and from a single station on the Tanana River at various times during the summers of 2001 through 2003, with the most complete set of samples collected during the summer of 2002. Changes in mineralogy of Yukon River bed sediments are related to sediment dilution or concentration effects from tributary sediment and to chemical weathering during transport. Carbonate minerals compose about 2 wt% of the bed sediments near Whitehorse, but increase to 14 wt% with the entry of the White River tributary above Dawson. Thereafter, the proportion of carbonate minerals decreases downstream to values of about 1 to 7 wt% near the mouth of the Yukon River. Quartz and feldspar contents of bed sediments vary greatly with the introduction of Pelly River and White River sediments, but thereafter either increase irregularly (quartz from 20 to about 50 wt%) or remain relatively constant (feldspar at about 35 wt%) with distance downstream. Clay mineral content increases irregularly downstream from about 15 to about 30 wt%. The chief clay mineral is chlorite, followed by illite + smectite; there is little to no kaolinite. The total organic carbon content of the bed sediments remains relatively constant with distance for the main stem (generally 1 to 2 wt%, with one exception), but fluctuates for the tributaries (1 to 6 wt%). The mineralogies of the suspended sediments and sediment flow data were used to calculate the amount of mineral dissolution during transport between Eagle and Pilot Station, a distance of over 2000 km. We estimate that approximately 3 wt% of the quartz, 15 wt% of the feldspar (1 wt% of the alkali and 25 wt% of the plagioclase), and 26 wt% of the carbonates (31 wt% of the calcite and 15 wt% of the dolomite) carried by the river dissolve in this reach. The mineralogies of the suspended sediments change with the season. For example, during the summer of 2002 the quartz content varied by 20 wt%, with a minimum in mid-summer. The calcite content varied by a similar amount, and had a maximum corresponding to the quartz minimum. These modes are related to the relative amount of sediment flowing from the White River system, which is relatively poor in quartz, but rich in carbonate minerals. Suspended total clay minerals varied by as much as 25 wt%, with maxima in mid July, and suspended feldspar varied up to 10 wt%. Suspended sediment data from the summers of 2001 and 2003 support the 2002 trends. A calculation technique was developed to determine theproportion of various sediment sources in a mixed sediment by unmixing its quantitative mineralogy. Results from this method indicate that at least three sediment sources can be identified quantitatively with good accuracy. With this technique, sediment mineralogies can be used to calculate the relative flux of sediment from different tributaries, thereby identifying sediment provenance.

Beach Erosion and Accretion: Comparison of the Seasonal Influence of Suspended- and Bedload-Sediment Transport at Grays Harbor, Washington, U. S. A.

NASA Astrophysics Data System (ADS)

Sherwood, C. R.; Lacy, J. R.; Ruggiero, P.; Kerr, L. A.; Gelfenbaum, G.; Wilson, D. J.

2001-12-01

We conducted field studies on the ebb-tidal delta near the entrance to Grays Harbor, Washington in Autumn, 1999 and Spring 2001, with the objectives of 1) providing directional wave data to validate a shoaling and refraction model for the ebb-tidal delta, and 2) measuring forcing (wave- and current-induced near-bottom velocities, accelerations, and shear stresses) and responses (bedforms, suspended-sediment profiles, and sediment fluxes) associated with intervals of beach erosion and accretion. In the Autumn experiment (October - December), tripods were deployed at shallow ( ~14-m) and deep ( ~24-m) sites on the northern, middle, and southern flanks of the ebb tidal. In the Spring experiment (May - mid-July), tripods were redeployed at four sites and a new inshore site ( ~9-m depth), and pressures, current velocities, and suspended-sediment concentrations were measured with 5-MHz acoustic Doppler velocimeters (ADVs), optical backscatterance sensors, upward-looking acoustic Doppler current profilers (ADCPs), a downward-looking pulse-coherent acoustic Doppler profiler (PCADP), and an acoustic backscatterance sensor (ABS). We also measured bedforms with profiling and imaging sonars and estimated Reynolds stresses with a pair of 10-MHz ADVs at the inshore site. Incident waves, nearshore circulation patterns, statistics of near-bottom wave- and current-induced velocities, and sediment fluxes were distinctly different in the two experiments. During the Autumn measurements, the general direction of wave approach shifted from WNW to WSW as the North Pacific weather pattern shifted from summer to winter, and we observed a large storm (offshore significant wave heights Hs of ~8 m) and a sequence of about 8 smaller events with ~4 to 5-m waves. Sediment transport was dominated by storm-induced, downwelling-favorable circulation that transported suspended sediments northward and offshore. Inferred bedload fluxes were directed shoreward, but were much smaller. In contrast, Spring wave conditions were much milder (maximum Hs of ~4 m), and waves approached mostly from the WNW. There were long periods of upwelling-favorable circulation interrupted by intervals of storm-induced northward flow. Net suspended-sediment transport was directed northward at the deeper sites and southward at the inshore sites. Near-bottom transport remained offshore at the deeper sites, but was lower, with negligible net cross-shore component at the shallow sites. The relative contribution of shoreward bedload transport was much larger. These changes in sediment transport outside the breaker zone are consistent with measured changes in beach and bar morphology.

Understanding coastal processes to assist with coastal erosion management in Darwin Harbour, Northern Territory, Australia

NASA Astrophysics Data System (ADS)

Tonyes, S. G.; Wasson, R. J.; Munksgaard, N. C.; Evans, K. G.; Brinkman, R.; Williams, D. K.

2017-02-01

Sand transport pathways in Darwin Harbour, Northern Territory, Australia, are being investigated to assist with coastal management. Coastal erosion, which threatens public and private infrastructure, is one of the major problems along the harbour beaches. A study of sediment transport is essential to identify the challenges encountered by the stakeholders in coastal management. Darwin Harbour, located in the tropical, cyclone prone area of Australia, was, until recently, considered a near pristine estuary. A semi-diurnal macro-tidal embayment, the tidal variation in the harbour reaches up to 8 m with a mean tidal range of 3.7 m. The beach morphology consists of sandy pocket beaches between coastal cliffs, sandbars, rocky shore platforms, tidal flats and mangrove fringes. A two-dimensional depth averaged finite-element hydrodynamic model (RMA-2), coupled with a sediment transport model (RMA-11) from Resource Modelling Associates, has been used to infer the sources and the depositional areas of sand in the harbour. Grain size distributions and geochemical analysis are also used to characterize the sand and its source(s). Initial results show that the beach sand is mostly of offshore origin with small sand input from the rivers. Potential supplementary sand sources are the eroded materials from the shore platforms and the rocky cliffs. Due to the rapid development in Darwin Harbour, this study is fundamental in understanding coastal processes to support decision making in coastal management, particularly in a macro-tidal, tropical estuary.

Effects of elevated temperatures and rising sea level on Arctic Coast

USGS Publications Warehouse

Barnes, Peter W.

1990-01-01

Ice is a major agent on the inner shelf, gouging the bottom, increasing hydraulic scour, transporting sediment, and influencing river flood patterns. Rapid coastal retreat is common and low barrier islands and beaches are constantly changing due to the influence of permafrost, ice-push, waves, and currents. Coastal processes are presently a balance between the influence of ice and the action of waves and currents. Quantitative values for processes are poorly known, however our qualitative understanding is nearly complete. Climatic warming and rising sea levels would decrease the temporal and aerial extent of coastal ice thereby expanding the role of waves and currents. As a result, shoreline retreat rates would increase, producing a transgressive erosional surface on the low coastal plain. With increased wave activity, beaches and barrier islands presently nourished by ice push processes would decay and disappear. Increased sediment supply from a deeply thawed, active layer would release more sediments to rivers and coasts. Additional research should be focused on permafrost and sea ice processes active during freeze up and breakup; the two seasons of most vigorous activity and change.

Coastal erosion and accretion rates in Greece

NASA Astrophysics Data System (ADS)

Foteinis, Spyros; Papadopoulos, Costas; Koutsogiannaki, Irini; Synolakis, Costas

2010-05-01

Erosion threatens many coastal regions of Greece. Anthropogenic changes of landforms such as coastal roads built on even narrow beaches, sand mining for construction, poor design of coastal structures that interfere with sediment, and dams without sediment bypasses have significantly reduced beach widths. We present erosion rates for different beaches, some of which are in sensitive ecosystems, otherwise "protected" by local and EU ordinances. By comparing inferences of beach widths in varying intervals from 1933 to 2006, we infer that the construction of dams in Acheloos river in western Greece, built in a faraonic attempt to partially divert its flows to eastern Greece, this is responsible for up to 20m/year erosion rates observed in certain locales in the Acheloos delta. More characteristic erosion rates in the region are ~ 2m/year. By contrast, there appears rapid accretion of up to 4m/year in the beaches around the Nestos delta in northern Greece (Papadopoulos, 2009). In beaches that are not near large river deltas, erosion rates range from 0.5m/year to 1m/year. While we have not done comprehensive comparisons among coastlines with different levels of coastal development, it does appear that rapid coastal development correlates well with erosion rates. The underlying problem is the complete lack of any semblance of coastal zone management in Greece and substandard design of coastal structures, which are often sited without any measurements of waves and currents offshore (Synolakis et al, 2008). Beach maintenance remains an exotic concept for most local authorities, who invariably prefer to build hard coastal structures to "protect" versus nourish, siting lack of experience with nourishment and "environmental" concerns. In certain cases, choices are dictated by costs, the larger the cost the easier the project gets approved by regulatory authorities, hence the preference for concrete or rubble structures. We conclude that, unless urgent salvage measures are initiated to protect the coastal zone and educate government and local authorities on sustainable management, several beaches will disappear within the next two decades. References Papadopoulos, C., 2009, Comperative assessment of coastal erosion in the regions of north Amvrakikos gulf, Acheloos delta, Nestos delta, Kos, Limnos, and Kitros, Diploma Thesis, Technical Univerity of Crete, Chanea, Greece, 130 p.( In greek). Synolakis, C.E., Kalligeris, N., Foteinis, S., Voukouvalas, E., 2008, The Plight of the Beaches of Crete, Solutions to Coastal Disasters 2008, Conference Proceedings ASCE, pp. 495-506, (doi 10.1061/40968(312)45)

Physical and chemical changes in the foreshore of an estuarine beach: Implications for viability and development of horseshoe crab Limulus polyphemus eggs

USGS Publications Warehouse

Jackson, N.L.; Smith, D.R.; Nordstrom, K.F.

2008-01-01

Knowledge of conditions that favor development of eggs is important for management of species whose population growth is sensitive to early life history survival. Viability and development of the eggs of horseshoe crabs Limulus polyphemus on a sand and gravel beach were evaluated using data gathered on Delaware Bay, USA, from 18 May to 19 June 2004. Eggs were transplanted to pouches and buried in the foreshore for up to 6 wk. Viability and developmental stage were estimated as a function of oxygen and temperature gradients across the foreshore. These gradients were related to the characteristics of the intertidal foreshore sediments, beach water table changes, and frequency of inundation due to tide and swash/backwash processes. Results demonstrate the importance of interstitial temperature for development to larvae and the passive role of sediment characteristics on moisture retention and temperature. Percentage of eggs remaining in egg stage was similar across the foreshore, but more eggs developed to embryos at 0.45 of foreshore width, where moisture and gravel content were greater and interstitial temperature was lower. More eggs developed to larvae at 0.60 and 0.75 of foreshore width, where moisture and gravel content were less but interstitial temperature was higher. The beach above 0.75 of foreshore width came under the influence of wave action or full tidal inundation only during high wave heights or spring tides, and pouches at 0.75 of foreshore width were inundated only 19% of the time. Periodic wetting at this elevation did not reduce overall viability of the eggs. High wave energy events resulted in sediment activation depths to pouches at 0.30 of foreshore width, where loss of eggs due to wave activation was the most important control on the development of eggs. ?? Inter-Research 2008.

Acoustic measurement of sediment dynamics in the coastal zones using wireless sensor networks

NASA Astrophysics Data System (ADS)

Sudhakaran, A., II; Paramasivam, A.; Seshachalam, S.; A, C.

2014-12-01

Analyzing of the impact of constructive or low energy waves and deconstructive or high energy waves in the ocean are very much significant since they deform the geometry of seashore. The deformation may lead to productive result and also to the end of deteriorate damage. Constructive waves results deposition of sediment which widens the beach where as deconstructive waves results erosion which narrows the beach. Validation of historic sediment transportation and prediction of the direction of movement of seashore is essential to prevent unrecoverable damages by incorporating precautionary measurements to identify the factors that influence sediment transportation if feasible. The objective of this study is to propose a more reliable and energy efficient Information and communication system to model the Coastal Sediment Dynamics. Various factors influencing the sediment drift at a particular region is identified. Consequence of source depth and frequency dependencies of spread pattern in the presence of sediments is modeled. Property of source depth and frequency on sensitivity to values of model parameters are determined. Fundamental physical reasons for these sediment interaction effects are given. Shallow to deep water and internal and external wave model of ocean is obtained intended to get acoustic data assimilation (ADA). Signal processing algorithms are used over the observed data to form a full field acoustic propagation model and construct sound speed profile (SSP). The inversions of data due to uncertainties at various depths are compared. The impact of sediment drift over acoustic data is identified. An energy efficient multipath routing scheme Wireless sensor networks (WSN) is deployed for the well-organized communication of data. The WSN is designed considering increased life time, decreased power consumption, free of threats and attacks. The practical data obtained from the efficient system to model the ocean sediment dynamics are evaluated with remote sensing data and the reasons of deviations and uncertainties are unbiased. The probability of changes and impact of sediment drift over ocean dynamic model over the long running of years is estimated.

Converting old shore protection structures into softer defence

NASA Astrophysics Data System (ADS)

Pranzini, Enzo

2010-05-01

Beach erosion has been affecting several developed countries since the middle of 19th century, which led to the construction of many different protection structures. These frequently proved to be ineffective locally, while being negative for downdrift coastal segments. In addition, such defence structures modified the coastal morphology, often transforming a sandy beach into a rocky coast. Softer shore protection projects have been developed in the past years, mostly accompanied by beach nourishment that uses quarried material or shelf sediments. This proved to be efficient in defending the beach, without negative fallouts on unprotected sectors. These techniques can be easily applied to beaches where no "archeaostructures" had been realized before. On the other hand, difficulties arise when such "old style" structures are to be replaced with softer techniques, since traditional hard defences usually cause such changes to beach profile that innovative ones become "too soft". Due to profile deepening in front of reflective structures, wave shoaling is reduced and energy dissipation concentrated in a narrow beach band. Restoring a milder profile needs a large amount of sediments and fine sands are not stable under those conditions. The new challenge for coastal engineers, coastal geomorphologists and coastal planners is managing the transition from old archaeostructures to new soft shore protection techniques. This process requires years of progressive adaptation - an unsuitable timing for politicians who demand fast results to be sold during the next elections. In Italy, along the Tuscany coast, where more than two kilometres of breakwaters protect each kilometre of coast, such a process has been initiated after a long phase of stakeholder participation in order to overcome public scepticism towards "invisible" defences. Detached breakwaters were lowered below sea level at Follonica and Marina di Pisa, while the number of groins is to be reduced at Marina di Massa in the near future. At Follonica, no beach nourishment has so far been realised along with such works, whereas at Marina di Pisa a gravel beach has been created for absorbing the higher energy that overpasses the lowered structure. At Marina di Massa submerged structures (groins and detached breakwaters) will be realized to counterbalance the demolition of the emerged groins. Beach evolution is being presently monitored in all these sites. This will help evaluate the efficiency of projects, providing data and results that will be useful when beach profile becomes milder and height/number of defences may need to be further reduced. Preliminary results at Follonica suggest that some beaches were overprotected, and redimensioning of structures did not result in beach erosion, since decrease in protection was accompanied by reduction in negative side-effects of the original defence, such as piling up. In Marina di Pisa, where detached breakwaters were lowered and a gravel beach realized, there was an increase in water quality and users got the possibility of using a new beach suitable for recreational activity, without any reduction in coastal protection. Project execution at Marina di Massa has just started a few months ago and monitoring results are not yet significative - however, 3D physical model experiments, carried out to optimize the design, have been encouraging. These and further results will guide additional projects to be realized in other parts of Tuscany, as well as in other Italian coastal segments presently undergoing the negative effects of past widespread archaeostructure construction.

Beach monitoring criteria: reading the fine print

USGS Publications Warehouse

Nevers, Meredith B.; Whitman, Richard L.

2011-01-01

Beach monitoring programs aim to decrease swimming-related illnesses resulting from exposure to harmful microbes in recreational waters, while providing maximum beach access. Managers are advised by the U.S. EPA to estimate microbiological water quality based on a 5-day geometric mean of fecal indicator bacteria (FIB) concentrations or on a jurisdiction-specific single-sample maximum; however, most opt instead to apply a default single-sample maximum to ease application. We examined whether re-evaluation of the U.S. EPA ambient water quality criteria (AWQC) and the epidemiological studies on which they are based could increase public beach access without affecting presumed health risk. Single-sample maxima were calculated using historic monitoring data for 50 beaches along coastal Lake Michigan on various temporal and spatial groupings to assess flexibility in the application of the AWQC. No calculation on either scale was as low as the default maximum (235 CFU/100 mL) that managers typically use, indicating that current applications may be more conservative than the outlined AWQC. It was notable that beaches subject to point source FIB contamination had lower variation, highlighting the bias in the standards for these beaches. Until new water quality standards are promulgated, more site-specific application of the AWQC may benefit beach managers by allowing swimmers greater access to beaches. This issue will be an important consideration in addressing the forthcoming beach monitoring standards.

Erosion and sedimentation from the 17 July, 1998 Papua New Guinea tsunami

USGS Publications Warehouse

Gelfenbaum, G.; Jaffe, B.

2003-01-01

This paper describes erosion and sedimentation associated with the 17 July 1998 Papua New Guinea tsunami. Observed within two months of the tsunami, distinct deposits of a layer averaging 8-cm thick of gray sand rested on a brown muddy soil. In most cases the sand is normally graded, with more coarse sand near the base and fine sand at the top. In some cases the deposit contains rip-up clasts of muddy soil and in some locations it has a mud cap. Detailed measurements of coastal topography, tsunami flow height and direction indicators, and deposit thickness were made in the field, and samples of the deposit were collected for grain-size analysis in the laboratory. Four shore-normal transects were examined in detail to assess the shore-normal and along shore distribution of the tsunami deposit. Near the shoreline, the tsunami eroded approximately 10-25 cm of sand from the beach and berm. The sandy layer deposited by the tsunami began 50-150 m inland from the shoreline and extended across the coastal plain to within about 40 m of the limit of inundation; a total distance of up to 750 m from the beach. As much as 2/3 of the sand in the deposit originated from offshore. Across most of the coastal plain the deposit thickness and mean grain size varied little. In the along-shore direction the deposit thickness varied with the tsunami wave height; both largest near the entrance to Sissano Lagoon.

Wave Attenuation on Muddy Bottoms Offshore Cassino Beach

DTIC Science & Technology

2006-10-01

D.Sc Principal Investigator Laboratory for the Dynamics of Cohesive Sediments Federal University of Rio de Janeiro Rio de Janeiro , Brazil...5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Federal University of Rio de Janeiro ,Laboratory for the...Dynamics of Cohesive Sediments, Rio de Janeiro , Brazil, 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES

Linking human impacts within an estuary to ebb-tidal delta evolution

USGS Publications Warehouse

Dallas, Kate L.; Barnard, Patrick L.

2009-01-01

San Francisco Bay, California, USA is among the most anthropogenically altered estuaries in the entire United States, but the impact on sediment transport to the coastal ocean has not been quantified. Analysis of four historic bathymetric surveys has revealed large changes to the morphology of the San Francisco Bar, an ebb-tidal delta at the mouth of the San Francisco Bay. From 1873 to 2005 the bar eroded an average of 80 cm, which equates to a total volume loss of 100 + 65 x 106 m3 of sediment. Comparison of the surveys indicates the entire ebb delta has contracted radially while its crest has moved landward an average of 1 km. Compilation of historic records reveals that 130 x 106 m3 of sediment has been permanently removed from the San Francisco Bay and adjacent coastal ocean. Constriction of the bar is hypothesized to be from a decrease in sediment supply from San Francisco Bay, a reduction in the tidal prism of the estuary, and/or a reduction in the input of hydraulic mining debris. Changes to the morphology of the San Francisco Bar have likely altered wave refraction and focusing patterns on adjacent beaches and may be a factor in persistent beach erosion occurring in the area.

Spatio-temporal scaling effects on longshore sediment transport pattern along the nearshore zone

NASA Astrophysics Data System (ADS)

Khorram, Saeed; Ergil, Mustafa

2018-03-01

A measure of uncertainties, entropy has been employed in such different applications as coastal engineering probability inferences. Entropy sediment transport integration theories present novel visions in coastal analyses/modeling the application and development of which are still far-reaching. Effort has been made in the present paper to propose a method that needs an entropy-power index for spatio-temporal patterns analyses. Results have shown that the index is suitable for marine/hydrological ecosystem components analyses based on a beach area case study. The method makes use of six Makran Coastal monthly data (1970-2015) and studies variables such as spatio-temporal patterns, LSTR (long-shore sediment transport rate), wind speed, and wave height all of which are time-dependent and play considerable roles in terrestrial coastal investigations; the mentioned variables show meaningful spatio-temporal variability most of the time, but explanation of their combined performance is not easy. Accordingly, the use of an entropy-power index can show considerable signals that facilitate the evaluation of water resources and will provide an insight regarding hydrological parameters' interactions at scales as large as beach areas. Results have revealed that an STDDPI (entropy based spatio-temporal disorder dynamics power index) can simulate wave, long-shore sediment transport rate, and wind when granulometry, concentration, and flow conditions vary.

Beach disturbance caused by off-road vehicles (ORVs) on sandy shores: relationship with traffic volumes and a new method to quantify impacts using image-based data acquisition and analysis.

PubMed

Schlacher, Thomas A; Morrison, Jennifer M

2008-09-01

Vehicles cause environmental damage on sandy beaches, including physical displacement and compaction of the sediment. Such physical habitat disturbance provides a relatively simple indicator of ORV-related impacts that is potentially useful in monitoring the efficacy of beach traffic management interventions; such interventions also require data on the relationship between traffic volumes and the resulting levels of impact. Here we determined how the extent of beach disturbance is linked to traffic volumes and tested the utility of image-based data acquisition to monitor beach surfaces. Experimental traffic application resulted in disturbance effects ranging from 15% of the intertidal zone being rutted after 10 vehicle passes to 85% after 100 passes. A new camera platform, specifically designed for beach surveys, was field tested and the resulting image-based data compared with traditional line-intercept methods and in situ measurements using quadrats. All techniques gave similar results in terms of quantifying the relationship between traffic intensity and beach disturbance. However, the physical, in situ measurements, using quadrats, generally produced higher (+4.68%) estimates than photos taken with the camera platform coupled with off-site image analysis. Image-based methods can be more costly, but in politically and socially sensitive monitoring applications, such as ORV use on sandy beaches, they are superior in providing unbiased and permanent records of environmental conditions in relation to anthropogenic pressures.

INFORMATION MANAGEMENT AND RELATED QUALITY ASSURANCE FOR A LARGE SCALE, MULTI-SITE RESEARCH PROJECT

EPA Science Inventory

During the summer of 2000, as part of a U.S. Environmental Protection Agency study designed to improve microbial water quality monitoring protocols at public beaches, over 11,000 water samples were collected at five selected beaches across the country. At each beach, samples wer...

Beach Volume Change Using Uav Photogrammetry Songjung Beach, Korea

NASA Astrophysics Data System (ADS)

Yoo, C. I.; Oh, T. S.

2016-06-01

Natural beach is controlled by many factors related to wave and tidal forces, wind, sediment, and initial topography. For this reason, if numerous topographic data of beach is accurately collected, coastal erosion/acceleration is able to be assessed and clarified. Generally, however, many studies on coastal erosion have limitation to analyse the whole beach, carried out of partial area as like shoreline (horizontal 2D) and beach profile (vertical 2D) on account of limitation of numerical simulation. This is an important application for prevention of coastal erosion, and UAV photogrammetry is also used to 3D topographic data. This paper analyses the use of unmanned aerial vehicles (UAV) to 3D map and beach volume change. UAV (Quadcopter) equipped with a non-metric camera was used to acquire images in Songjung beach which is located south-east Korea peninsula. The dynamics of beach topography, its geometric properties and estimates of eroded and deposited sand volumes were determined by combining elevation data with quarterly RTK-VRS measurements. To explore the new possibilities for assessment of coastal change we have developed a methodology for 3D analysis of coastal topography evolution based on existing high resolution elevation data combined with low coast, UAV and on-ground RTK-VRS surveys. DSMs were obtained by stereo-matching using Agisoft Photoscan. Using GCPs the vertical accuracy of the DSMs was found to be 10 cm or better. The resulting datasets were integrated in a local coordinates and the method proved to be a very useful fool for the detection of areas where coastal erosion occurs and for the quantification of beach change. The value of such analysis is illustrated by applications to coastal of South Korea sites that face significant management challenges.

Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) at ambient freshwater beaches

USGS Publications Warehouse

Fogarty, Lisa R.; Haack, Sheridan K.; Johnson, Heather E.; Brennan, Angela K.; Isaacs, Natasha M.; Spencer, Chelsea

2015-01-01

Methicillin-resistant Staphylococcus aureus (MRSA) are a threat to human health worldwide, and although detected at marine beaches, they have been largely unstudied at freshwater beaches. Genes indicating S. aureus (SA; femA) and methicillin resistance (mecA) were detected at 11 and 12 of 13 US Great Lakes beaches and in 18% or 27% of 287 recreational water samples, respectively. Eight beaches had mecA + femA (potential MRSA) detections. During an intensive study, higher bather numbers, staphylococci concentrations, and femA detections were found in samples collected after noon than before noon. Local population density, beach cloud cover, and beach wave height were significantly correlated with SA or MRSA detection frequency. The Panton-Valentine leukocidin gene, associated with community-acquired MRSA, was detected in 12 out of 27 potential MRSA samples. The femA gene was detected less frequently at beaches that met US enterococci criteria or EU enterococci ‘excellent’ recreational water quality, but was not related to Escherichia coli-defined criteria. Escherichia coli is often the only indicator used to determine water quality at US beaches, given the economic and healthcare burden that can be associated with infections caused by SA and MRSA, monitoring of recreational waters for non-fecal bacteria such as staphylococci and/or SA may be warranted.

Storms in the deep: tempestite- and beach-like deposits in pelagic sequences (Middle-Upper Jurassic, Subbetic, South of Spain)

NASA Astrophysics Data System (ADS)

Pomar, Luis; Molina, Jose M.; Ruiz-Ortiz, Pedro A.; Vera, Juan A.

2017-04-01

Fine-peloidal- to coarse oolitic-bioclastic grainstones with hummocky cross stratification (HCS) occur interbedded in Middle-Upper Jurassic pelagic lime-mudstone successions (Betic ranges, Southern Spain). These strata were deposited in pelagic troughs and swells, away from continental areas, in the Southern Iberian Continental Margin of the Western Tethys. Previously interpreted as tempestites, mainly due to the attribution of the HCS to surface storm waves, they are now reinterpreted as the product of turbulence in deeper conditions. Among many, some selected examples are here presented. All of them share: 1) Grainstone beds are interbedded with pelagic mudstones and marls 2) Grainstone components were reworked by oscillatory flows superimposed to unidirectional tractive flows (unidirectional ripple lamination and HCS). 3) Components were either derived from shallow-water environments (e.g., ooids), or produced in pelagic conditions (e.g., radiolarians, Saccocoma, peloids, etc). 4) Although surface-storm tempestite flows can be required to bring downslope components from shallow-water settings, the grainstone beds reflect sediment reworking at a depth dominated by fine pelagic sedimentation. 5) Internal waves propagating along a pycnocline and breaking against a sloping surface are the best candidate to induce the sedimentary structures and sediment organization that characterize these grainstone beds. The examples here presented (Middle-Upper Jurassic of the Subbetic) include: a) Peloid grainstones interbedded with radiolarite marls deposited on the flanks of volcanic guyots. The interbedded lime muds and marls contain 'filaments', sponge spicules and radiolarians. b) Peloid-bioclastic (radiolarians, Saccocoma, etc.) grainstone beds with HCS, interbedded with pelagic lime muds. c) Coarse oolitic grainstone unit, encased in pelagic marls, with wedge-shaped crossbed-sets with gently seaward-dipping parallel lamination, and sets of low-angle up-slope dipping parallel lamination. These oolitic grainstones hold characteristics similar to the ridge-berm-swash zone of modern beaches and are here interpreted to represent an "internal beach". d) Crossbedded peloidal-skeletal (Saccocoma) grainstones with HCS and wave ripples on top, interbedded with pelagic mudstones and wackestones with abundant bioturbation and ammonites (Ammonitico Rosso facies). All these grainstones are reinterpreted as the product of breaking internal waves. This breaking produces episodic high-turbulence events and remobilizes sediments at the depth where the pycnocline intersects the sea floor. The swash run-up produces erosion and the backwash return flow can bypass the breaker and travel downdip where the oscillatory-flow component of the IWs become dominant and form the characteristic HCS bedforms. Coarser sediments "trapped" at the breaker zone form sediment accumulations similar to the sediments caught by the "littoral fence" in the surface beach. This scenario evidences the HCS not to be necessarily linked to the surface storms but to the bathymetry of the pycnocline, solving the problem of having HCS in pelagic zones where the storm and hurricanes wave action can be considered "out-of-context". Acknowledgments: fundings from projet CGL2014-52096-P and Research Group RNM-200 (PAIDI-JA)

The Early Shorebird Will Catch Fewer Invertebrates on Trampled Sandy Beaches

PubMed Central

Schlacher, Thomas A.; Carracher, Lucy K.; Porch, Nicholas; Connolly, Rod M.; Olds, Andrew D.; Gilby, Ben L.; Ekanayake, Kasun B.; Maslo, Brooke; Weston, Michael A.

2016-01-01

Many species of birds breeding on ocean beaches and in coastal dunes are of global conservation concern. Most of these species rely on invertebrates (e.g. insects, small crustaceans) as an irreplaceable food source, foraging primarily around the strandline on the upper beach near the dunes. Sandy beaches are also prime sites for human recreation, which impacts these food resources via negative trampling effects. We quantified acute trampling impacts on assemblages of upper shore invertebrates in a controlled experiment over a range of foot traffic intensities (up to 56 steps per square metre) on a temperate beach in Victoria, Australia. Trampling significantly altered assemblage structure (species composition and density) and was correlated with significant declines in invertebrate abundance and species richness. Trampling effects were strongest for rare species. In heavily trafficked plots the abundance of sand hoppers (Amphipoda), a principal prey item of threatened Hooded Plovers breeding on this beach, was halved. In contrast to the consistently strong effects of trampling, natural habitat attributes (e.g. sediment grain size, compactness) were much less influential predictors. If acute suppression of invertebrates caused by trampling, as demonstrated here, is more widespread on beaches it may constitute a significant threat to endangered vertebrates reliant on these invertebrates. This calls for a re-thinking of conservation actions by considering active management of food resources, possibly through enhancement of wrack or direct augmentation of prey items to breeding territories. PMID:27564550

The Early Shorebird Will Catch Fewer Invertebrates on Trampled Sandy Beaches.

PubMed

Schlacher, Thomas A; Carracher, Lucy K; Porch, Nicholas; Connolly, Rod M; Olds, Andrew D; Gilby, Ben L; Ekanayake, Kasun B; Maslo, Brooke; Weston, Michael A

2016-01-01

Many species of birds breeding on ocean beaches and in coastal dunes are of global conservation concern. Most of these species rely on invertebrates (e.g. insects, small crustaceans) as an irreplaceable food source, foraging primarily around the strandline on the upper beach near the dunes. Sandy beaches are also prime sites for human recreation, which impacts these food resources via negative trampling effects. We quantified acute trampling impacts on assemblages of upper shore invertebrates in a controlled experiment over a range of foot traffic intensities (up to 56 steps per square metre) on a temperate beach in Victoria, Australia. Trampling significantly altered assemblage structure (species composition and density) and was correlated with significant declines in invertebrate abundance and species richness. Trampling effects were strongest for rare species. In heavily trafficked plots the abundance of sand hoppers (Amphipoda), a principal prey item of threatened Hooded Plovers breeding on this beach, was halved. In contrast to the consistently strong effects of trampling, natural habitat attributes (e.g. sediment grain size, compactness) were much less influential predictors. If acute suppression of invertebrates caused by trampling, as demonstrated here, is more widespread on beaches it may constitute a significant threat to endangered vertebrates reliant on these invertebrates. This calls for a re-thinking of conservation actions by considering active management of food resources, possibly through enhancement of wrack or direct augmentation of prey items to breeding territories.

Beach profile modification and sediment transport by ice: an overlooked process on Lake Michigan

USGS Publications Warehouse

Barnes, P.W.; Kempema, E.W.; Reimnitz, E.; McCormick, M.; Weber, W.S.; Hayden, E.C.

1993-01-01

Coastal lake ice includes a belt of mobile crash and slush ice and a stable nearshore-ice complex (NIC). Sediment concentrations indicate that the NIC and the belt of brash and slush contains 180 to 280 t (113 to 175m3) of sand per kilometer of coast. This static sediment load is roughly equivalent to the average amount of sand eroded from the bluffs and to the amount accumulating in the deep lake basin each year. Sediment is being rafted alongshore in the mobile brash and slush at rates of 10 to 30 cm/sec. -from Authors

Presence of Campylobacter and Salmonella in sand from bathing beaches.

PubMed Central

Bolton, F. J.; Surman, S. B.; Martin, K.; Wareing, D. R.; Humphrey, T. J.

1999-01-01

The purpose of this study was to determine the presence of thermophilic Campylobacter spp. and Salmonella spp. in sand from non-EEC standard and EEC standard designated beaches in different locations in the UK and to assess if potentially pathogenic strains were present. Campylobacter spp. were detected in 82/182 (45%) of sand samples and Salmonella spp. in 10/182 (6%). Campylobacter spp. were isolated from 46/92 (50%) of samples from non-EEC standard beaches and 36/90 (40%) from EEC standard beaches. The prevalence of Campylobacter spp. was greater in wet sand from both types of beaches but, surprisingly, more than 30% of samples from dry sand also contained these organisms. The major pathogenic species C. jejuni and C. coli were more prevalent in sand from non-EEC standard beaches. In contrast, C. lari and urease positive thermophilic campylobacters, which are associated with seagulls and other migratory birds, were more prevalent in sand from EEC standard beaches. Campylobacter isolates were further characterized by biotyping and serotyping, which confirmed that strains known to be of types associated with human infections were frequently found in sand on bathing beaches. PMID:10098779

Geological and hydrogeological investigations in west Malaysia

NASA Technical Reports Server (NTRS)

Ahmad, J. B. (Principal Investigator); Khoon, S. Y.

1977-01-01

The author has identified the following significant results. Large structures along the east coast of the peninsula were discovered. Of particular significance were the circular structures which were believed to be associated with mineralization and whose existence was unknown. The distribution of the younger sediments along the east coast appeared to be more widespread than previously indicated. Along the Pahang coast on the southern end, small traces of raised beach lines were noted up to six miles inland. The existence of these beach lines was unknown due to their isolation in large coastal swamps.

Coastal geomorphological study of pocket beaches in Crete, with the use of planview indices.

NASA Astrophysics Data System (ADS)

Alexandrakis, George; Karditsa, Aikaterini; Poulos, Serafim; Kampanis, Nikos

2013-04-01

The formation of pocket beaches is a result of a large number of processes and mechanisms that vary on space and time scales. This study aims in defining the planform characteristics of pocket beaches in Crete Isl. and to determine their sheltering effect, embaymentization and their status of equilibrium. Thus, data from 30 pocket beaches along the coastline of Crete, with different geomorphological and hydrodynamical setting, were collected. Planform parameters were applied and coastal planview indices from the bibliography were applied. The parameters included: length and orientation of the headlands between the pocket beach; length between the bay entrance and the center of the beach; lengths of the i) embayed shoreline, ii) embayed beach, iii) beach segment located at the shadow of a headland; linear distance and orientation between the edges of the embayed beach; direction of the incident wave energy flux; wave crest obliquity to the control line; beach area, maximum beach width and headland orientation and river/ torrent catchment areas in beach zones that an active river system existed (Bowman et al.2009). For the morphological mapping of the study areas, 1:5000 orthophoto maps were used. Wave regime has been calculated with the use of prognostic equations and utilising local wind data (mean annual frequency of wind speed and direction), provided by the Wind and Wave Atlas of the Eastern Mediterranean Sea. The diffraction and refraction of the waves has been simulated with the use of numerical models. The study shows that Cretan pocket beaches display a wide range of indentation, suggesting that is the result of several parameters that include tectonics, coastal hydrodynamics and river catchment areas. The more indented bays are, the shorter their beaches become, while low-indented pocket beaches are the widest and the longest ones. Beaches with headland with large length appear to be more protected and receive smaller amount of wave energy. Most of the Cretan pocket beaches have limited sediment supply for the mainland, while they appear to be in an unstable status. D. Bowman, J. Guillén, L. López, V. Pellegrino (2009), Planview Geometry and morphological characteristics of pocket beaches on the Catalan coast (Spain). Geomorphology, 108, 191-199

Comparison of the Immunomagnetic Separation/Adenosine Triphosphate Rapid Method and the Modified mTEC Membrane-Filtration Method for Enumeration of Escherichia coli

USGS Publications Warehouse

Brady, Amie M.G.; Bushon, Rebecca N.; Bertke, Erin E.

2009-01-01

Water quality at beaches is monitored for fecal indicator bacteria by traditional, culture-based methods that can take 18 to 24 hours to obtain results. A rapid detection method that provides estimated concentrations of fecal indicator bacteria within 1 hour from the start of sample processing would allow beach managers to post advisories or close the beach when the conditions are actually considered unsafe instead of a day later, when conditions may have changed. A rapid method that couples immunomagnetic separation with adenosine triphosphate detection (IMS/ATP rapid method) was evaluated through monitoring of Escherichia coli (E. coli) at three Lake Erie beaches in Ohio (Edgewater and Villa Angela in Cleveland and Huntington in Bay Village). Beach water samples were collected between 4 and 5 days per week during the recreational seasons (May through September) of 2006 and 2007. Composite samples were created in the lab from two point samples collected at each beach and were shown to be comparable substitutes for analysis of two individual samples. E. coli concentrations in composite samples, as determined by the culture-based method, ranged from 4 to 24,000 colony-forming units per 100 milliliters during this study across all beaches. Turbidity also was measured for each sample and ranged from 0.8 to 260 neophelometric turbidity ratio units. Environmental variables were noted at the time of sampling, including number of birds at the beach and wave height. Rainfall amounts were measured at National Weather Service stations at local airports. Turbidity, rainfall, and wave height were significantly related to the culture-based method results each year and for both years combined at each beach. The number of birds at the beach was significantly related to the culture-based method results only at Edgewater during 2006 and during both years combined. Results of the IMS/ATP method were compared to results of the culture-based method for samples by year for each beach. The IMS/ATP method underwent several changes and refinements during the first year, including changes in reagents and antibodies and alterations to the method protocol. Because of the changes in the method, results from the two years of study could not be combined. Kendall's tau correlation coefficients for relations between the IMS/ATP and culture-based methods were significant except for samples collected during 2006 at Edgewater and for samples collected during 2007 at Villa Angela. Further, relations were stronger for samples collected in 2006 than for those collected in 2007, except at Edgewater where the reverse was observed. The 2007 dataset was examined to identify possible reasons for the observed difference in significance of relations by year. By dividing the 2007 data set into groups as a function of sampling date, relations (Kendall's tau) between methods were observed to be stronger for samples collected earlier in the season than for those collected later in the season. At Edgewater and Villa Angela, there were more birds at the beach at time of sampling later in the season compared to earlier in the season. (The number of birds was not examined at Huntington.) Also, more wet days (when rainfall during the 24 hours prior to sampling was greater than 0.05 inch) were sampled later in the season compared to earlier in the season. Differences in the dominant fecal source may explain the change in the relations between the culture-based and IMS/ATP methods.

BACTERIA, BEACHES AND SWIMMABLE WATERS: INTRODUCING VIRTUAL BEACH

EPA Science Inventory

Safe beaches meet water quality standards and are valued for their aesthetics and the recreational opportunities that they afford. In the United States recreational water quality assessments and beach closure decisions are presently based on samples of enterococci or Escherichia ...

Change in Sediment Provenance Near the Current Estuary of Yellow River Since the Holocene Transgression

NASA Astrophysics Data System (ADS)

Song, Sheng; Feng, Xiuli; Li, Guogang; Liu, Xiao; Xiao, Xiao; Feng, Li

2018-06-01

Sedimentary sequence and sediment provenance are important factors when it comes to the studies on marine sedimentation. This paper studies grain size distribution, lithological characteristics, major and rare earth elemental compositions, micropaleontological features and 14C ages in order to examine sedimentary sequence and sediment provenance of the core BH6 drilled at the mouth of the Yellow River in Bohai Sea. According to the grain size and the micropaleontological compositions, 4 sedimentary units have been identified. Unit 1 (0-8.08 mbsf) is of the delta sedimentary facies, Unit 2 (8.08-12.08 mbsf) is of the neritic shelf facies, Unit 3 (12.08-23.85 mbsf) is of near-estuary beach-tidal facies, and Unit 4 (23.85 mbsf-) is of the continental lake facies. The deposits from Unit 1 to Unit 3 have been found to be marine strata formed after the Holocene transgression at about 10 ka BP, while Unit 4 is continental lacustrine deposit formed before 10 ka BP. The provenances of core BH6 sediments show properties of the continental crust and vary in different sedimentary periods. For Unit 4 sediments, the source regions are dispersed while the main provenance is not clear, although the parent rock characteristics of a few samples are similar to the Luanhe River sediments. For Unit 3, sediments at 21.1-23.85 mbsf have been mainly transported from the Liaohe River, while sediments above 21.1 mbsf are mainly from the Yellow River and partially from the Liaohe River. For Unit 2, the sediments have been mainly transported from the Yellow River, with a small amount from other rivers. For Unit 1, the provenance is mainly the Yellow River catchment. These results help in better understanding the evolution of the Yellow River Delta.

Distribution and sources of surfzone bacteria at Huntington Beach before and after disinfection on an ocean outfall-- a frequency-domain analysis.

PubMed

Noble, M A; Xu, J P; Robertson, G L; Rosenfeld, L K

2006-06-01

Fecal indicator bacteria (FIB) were measured approximately 5 days a week in ankle-depth water at 19 surfzone stations along Huntington Beach and Newport Beach, California, from 1998 to the end of 2003. These sampling periods span the time before and after treated sewage effluent, discharged into the coastal ocean from the local outfall, was disinfected. Bacterial samples were also taken in the vicinity of the outfall during the pre- and post-disinfection periods. Our analysis of the results from both data sets suggest that land-based sources, rather than the local outfall, were the source of the FIB responsible for the frequent closures and postings of local beaches in the summers of 2001 and 2002. Because the annual cycle is the dominant frequency in the fecal and total coliform data sets at most sampling stations, we infer that sources associated with local runoff were responsible for the majority of coliform contamination along wide stretches of the beach. The dominant fortnightly cycle in enterococci at many surfzone sampling stations suggests that the source for these relatively frequent bacteria contamination events in summer is related to the wetting and draining of the land due to the large tidal excursions found during spring tides. Along the most frequently closed section of the beach at stations 3N-15N, the fortnightly cycle is dominant in all FIBs. The strikingly different spatial and spectral patterns found in coliform and in enterococci suggest the presence of different sources, at least for large sections of beach. The presence of a relatively large enterococci fortnightly cycle along the beaches near Newport Harbor indicates that contamination sources similar to those found off Huntington Beach are present, though not at high enough levels to close the Newport beaches.

Laboratory Observations of Dune Erosion

NASA Astrophysics Data System (ADS)

Maddux, T. B.; Ruggiero, P.; Palmsten, M.; Holman, R.; Cox, D. T.

2006-12-01

Coastal dunes are an important feature along many coastlines, owing to their input to the sediment supply, use as habitat, and ability to protect onshore resources from wave attack. Correct predictions of the erosion and overtopping rates of these features are needed to develop improved responses to coastal dune damage events, and to determining the likelihood and magnitude of future erosion and overtopping on different beaches. We have conducted a large-scale laboratory study at Oregon State University's O.H. Hinsdale Wave Research Laboratory (HWRL) with the goal of producing a comprehensive, near prototype-scale, physical model data set of hydrodynamics, sediment transport, and morphological evolution during extreme dune erosion events. The two goals of this work are (1) to develop a better understanding of swash/dune dynamics and (2) to evaluate and guide further development of dune erosion models. We present initial results from the first phase of the experimental program. An initial beach and dune profile was selected based on field LIDAR-based observations of various U.S. east coast and Gulf coast dune systems. The laboratory beach was brought to equilibrium with pre-storm random wave conditions. It was subsequently subjected to attack from steadily increasing water level and offshore wave heights. Observations made include inner surf zone and swash free surface and velocities as well as wave-by-wave estimates of topographical change at high spatial resolution through the use of stereo video imagery. Future work will include studies of fluid overtopping of the dune and sediment overwash and assessment of the resilience of man-made "push-up" dunes to wave attack in comparison with their more-compacted "natural" cousins.

Sand and gravel resources of Puerto Rico

USGS Publications Warehouse

Rodriguez, Rafael W.

Many of Puerto Rico's beaches are eroding, and though rates of erosion vary, it is a major concern for the tourism and residential development industries. More than 85 percent of the population lives within 7 kilometers of the coast and they are heavily dependent on tourists that are attracted by the island's beaches and coral reefs. High-quality scientific data are needed to help formulate public policy regarding residential and commercial construction along the coast, beach replenishment, and future use of marine resources. Scientists have long recognized that the causes of coastal land loss are not limited to a relative rise in sea level, but can be manmade as well. For example, sediment supply to beaches especially along the north shore of Puerto Rico has been strongly affected by upstream river channeling, dam construction, various agricultural practices, paving and urbanization, as well as shallow-water oceanographic processes. The response to coastal erosion in Puerto Rico has been mostly crisis based leading to engineered solutions that have a negative effect on the coastal environment.

Adsorption of trace metals to plastic resin pellets in the marine environment.

PubMed

Holmes, Luke A; Turner, Andrew; Thompson, Richard C

2012-01-01

Plastic production pellets collected from beaches of south west England contain variable concentrations of trace metals (Cr, Co, Ni, Cu, Zn, Cd and Pb) that, in some cases, exceed concentrations reported for local estuarine sediments. The rates and mechanisms by which metals associate with virgin and beached polyethylene pellets were studied by adding a cocktail of 5 μg L(-1) of trace metals to 10 g L(-1) pellet suspensions in filtered seawater. Kinetic profiles were modelled using a pseudo-first-order equation and yielded response times of less than about 100 h and equilibrium partition coefficients of up to about 225 ml g(-1) that were consistently higher for beached pellets than virgin pellets. Adsorption isotherms conformed to both the Langmuir and Freundlich equations and adsorption capacities were greater for beached pellets than for virgin pellets. Results suggest that plastics may represent an important vehicle for the transport of metals in the marine environment. Copyright © 2011 Elsevier Ltd. All rights reserved.

A Molecular MST Approach to Investigate Fecal Indicator Bacteria in Bioaerosols, Bathing Water, Seaweed Wrack, and Sand at Recreational Beaches

NASA Astrophysics Data System (ADS)

Thoren, K. M.; Sinigalliano, C. D.

2016-02-01

Despite numerous cases of beach bacteria affecting millions of people worldwide, the persistence of the bacteria populations in coastal areas is still not well understood. The purpose of this study was to test the levels of persistence of Fecal Indicating Bacteria (FIB) of enterococci, Escherichia coli, and Human-source Bacteroidales, within the intertidal "swash zone" and the deeper waist zone in which people commonly bathe and play. In addition, the study sought to determine if these bacterial contaminants may also be found in aerosols at the beach. Measuring solar insolation in relation to bacterial persistence in seaweed wrack was used to determine if sunlight plays a role in modifying concentrations of FIB at the beach. Light intensity measured by a solar photometer and air quality measured by aerosol plate counts and qPCR Microbial Source Tracking (MST) was compared to varying locations where the beach samples were collected. Results from water samples demonstrate that bacteria measured using plate counts and qPCR were indeed higher within the swash zone than in the waist zone. This is in contrast with the way that the EPA currently measures and determines the public safety of beach waters. They commonly measure the waist zone, but disregard the swash zone. Results from beach bio-aerosol samples showed a wide variety of fungi and bacteria in the beach air, and qPCR MST analysis of these bio-aerosols showed the presence of FIBs such as enterococci on several of the aerosol collection plates. This emphasizes the need to collect samples from the entire beach instead of just measuring at an isolated area, and that exposure to microbial contaminants may include bathing water, beach sand, seaweed wrack, and bio-aerosols. Thus, the data reveals a potential way to identify harmful levels of bacteria and dangerous levels of poor air quality at recreational beaches. These results expound the need for broader assessment of potential beach contamination, not only the swimming water, but also the beach air, shoreline, and also varying depths of water, which can be extremely beneficial to reduce people's risk from microbial contamination exposure.

Determining the presence of dipropylene glycol n-butyl ether (DPnB) in sediments and sands contaminated by the Deepwater Horizon (DWH) oil spill

NASA Astrophysics Data System (ADS)

Boehman, B.; Lyons, S. L.; Geng, Z.; White, H. K.

2016-02-01

In an attempt to mitigate the impact of the oil released from the Deepwater Horizon (DWH) oil spill, chemical dispersants (Corexit 9527 and Corexit 9500A, from Nalco Co.) were applied to the surface and subsurface waters of the Gulf of Mexico. Over the past five years studies have investigated the fate of oil from the spill and the applied dispersants, although significantly less is known about the latter. To determine the presence of dispersant in environmental samples, dioctyl sodium sulfosuccinate (DOSS), a component of both Corexit mixtures, has previously been examined in samples taken from the water column, coastal beaches and deep-sea sediments. This study expands upon this work by developing a method to extract dipropylene glycol n-butyl ether (DPnB), an additional compound present in Corexit, from sand and sediment samples contaminated with oil from the DWH spill. Controls spiked with a known quantity of DPnB were extracted with a range of organic solvents of different polarities to optimize the extraction of DPnB. Total organic extracts were then subjected to silica gel chromatography to isolate DPnB from any oil that was co-extracted. All samples were concentrated prior to analysis via gas chromatography mass spectrometry (GC/MS) using selected ion monitoring (SIM). The analysis and quantification of DPnB, which has different chemical properties than DOSS, will provide additional insight into the mechanisms that control the fate of oil and dispersant mixtures in the marine environment.

Geologic framework studies of South Carolina's Long Bay from Little River Inlet to Winyah Bay, 1999-2003: geospatial data release

USGS Publications Warehouse

Baldwin, W.E.; Denny, J.F.; Schwab, W.C.; Gayes, P.T.; Morton, R.; Driscoll, N.W.

2007-01-01

The northern South Carolina coast is a heavily developed region that supports a thriving tourism industry, large local populations and extensive infrastructure (Figure 1). The economic stability of the region is closely tied to the health of its beaches: primarily in providing support for local tourism and protection from storm events. Despite relatively low long-term shoreline erosion rates, and the implied stability of the beaches, the economic impact of storm events to coastal communities has been costly. For example, Hurricane Hugo made landfall on the central South Carolina coast in 1989. High winds and storm surge inflicted roughly $6 billion in property loss and damages, and Hugo remains the costliest storm event in South Carolina history. Localized erosion, commonly occurring around tidal inlets and erosion "hot spots", has also proved costly. Construction and maintenance of hard structures and beach nourishment, designed to mitigate the effects of erosion, have become annual or multi-annual expenditures. Providing a better understanding of the physical processes controlling coastal erosion and shoreline change will allow for more effective management of coastal resources. In 1999, the U.S. Geological Survey (USGS), in partnership with the South Carolina Sea Grant Consortium (SCSGC), began a study to investigate inner continental shelf and shoreface processes. The objectives of the USGS/SCSGC cooperative program are: 1) to provide a regional synthesis of the shallow geologic framework underlying the shoreface and inner continental shelf, and to define its role in coastal evolution and modern beach behavior; 2) to identify and model the physical processes affecting coastal ocean circulation and sediment transport, and to define their role in shaping the modern shoreline; and 3) to identify sediment sources and transport pathways in order to develop a regional sediment budget. This report contains the geospatial data used to define the geologic framework offshore of the northern South Carolina coast. The digital data presented herein accompany USGS Open-File Reports OFR 2004-1013 and OFR 2005-1345, describing the stratigraphic framework and modern sediment distribution within Long Bay, respectively. Direct on-line links to these publications are available within 'References' on the navigation bar to the left. Additional links to other publications and web sites are also available.

The Purisima Formation at Capitola Beach, Santa Cruz County, CA: A Deeper Examination of Pliocene Fossils

NASA Astrophysics Data System (ADS)

White, L. D.; Brooks, K.; Chen, R.; Chen, T.; James, T.; Gonzales, J.; Schumaker, D.; Williams, D.

2005-12-01

Fossil samples from the Pliocene Purisima Formation at Capitola Beach in Santa Cruz County, CA were collected in July-August 2005. The Purisima Formation composes the bulk of the cliffs exposed at Capitola Beach and a rich assemblage of well-preserved fossils occur in gray to brown sandstone and siltstone. Erosion of the cliff face averages 0.3 meter/year and fresh cliff falls in the winter and spring months of 2005 provided an excellent opportunity to resample the Capitola Beach section of the Purisima Formation previously documented by Perry (1988). Organisms were identified from information in Perry (1988) and were compared with collections at the California Academy of Sciences. The most abundant fossils found are from the phylum Mollusca, classes Bivalvia and Gastropoda. Abundant bivalve taxa are: Anadara trilineata, Clinocardium meekianum, Macoma sp., Protothaca staleyi, and Tresus pajaroanus. Also common are the gastropods, Calyptraea fastigata, Crepdiula princeps, Mitrella gausapata, Nassarius grammatus, Nassarius californianus, Natica clausa, and Olivella pedroana. Less common invertebrate fossils are from the phylum Echinodermata ( Dendraster sp., the extinct fossil sand dollar) and from the phylum Arthropoda ( Crustacea), crab fragments ( Cancer) and barnacles ( Balanus). Because numerous fossils are concentrated as fragments in shell beds, Norris (1986) and Perry (1988) believe many were redeposited as storm beds during strong current events that promoted rapid burial. In contrast, whale and other vertebrate bones are common in certain horizons and their presence may be related to the conditions that promoted phosphate mineralization, such as episodes of low sedimentation rates and prolonged exposure on the seafloor (Föllmi and Garrison, 1991). The bone beds, together with the rich infaunal and epifaunal invertebrate assemblages, represent a community of invertebrate organisms that thrived in a shallow marine sea during the Pliocene epoch, approximately 3-5 million years ago.

Holocene Depositional History of the Southern New Jersey Barrier and Backbarrier Regions

DTIC Science & Technology

1990-02-01

1954) that the continental shelf is a source for beach sediment. 25. Biederman (1962) and Charlesworth (1968) compared sediments along- shore and...perpendicular to the coast in a number of barrier and backbarrier environments. Biederman (1962) found that mean grain size decreased from north to south...Geology and Stratigraphic Preser- vation Potential and Evolution of Delaware’s Barrier Systems," Marine Geology. Vol 63, pp 235-262. Biederman , E. W

Indicators of microbial beach water quality: preliminary findings from Teluk Kemang beach, Port Dickson (Malaysia).

PubMed

Praveena, Sarva Mangala; Chen, Kwan Soo; Ismail, Sharifah Norkhadijah Syed

2013-11-15

This study aims to determine the concentrations of total coliforms and Escherichia coli (E. coli) in beach water, Teluk Kemang beach. This study was also aimed to determine relationship between total coliforms, E. coli and physicochemical parameters. As perceived health symptoms among beach visitors are rarely incorporated in beach water studies, this element was also assessed in this study. A total of eight water sampling points were selected randomly along Teluk Kemang beach. Total coliforms concentrations were found between 20 and 1940 cfu/100ml. E. coli concentrations were between 0 and 90 cfu/100ml. Significant correlations were found between total coliforms and E. coli with pH, temperature and oxidation reduction potential. Skin and eyes symptoms were the highest reported though in small numbers. Microbiological water quality in Teluk Kemang public beach was generally safe for recreational activities except sampling location near with sewage outfall. Copyright © 2013 Elsevier Ltd. All rights reserved.

Piping Plover Habitat Loss at the Nature Conservancy's John E. Williams Preserve, Central North Dakota: an Interdisciplinary Study of Alkaline Prairie Pothole Glacial Lakes, Groundwater, Gravel Beaches and Vegetation Encroachment

NASA Astrophysics Data System (ADS)

Sciamanda, M.; Kellner, J. R.; Lamb, M. A.; Clotts, R.; Pastika, D. W.; Welter, D. J.; Brown, J. M.; Schuweiler, T. K.; Mohanty, R. B.; Vang, K. M.; Nichols, K. S.; Lorah, P. A.; Robinson, D. O.

2016-12-01

The Piping Plover (Charadrius melodus) is a threatened migratory bird that nests along shores of alkaline lakes, the Great Lakes, and the Atlantic Ocean. John Williams Preserve, in central North Dakota, houses one of the largest breeding populations in the world. Over the past eighty years, vegetation has encroached and caused variable habitat loss from lake to lake (Root and Ryan, 2004). Processes operating on different time scales affect lake, beach and vegetation changes: long-term global climate changes, decadal drought cycles, and seasonal and local weather. To determine how these processes interact to affect vegetation growth, soil salinity and habitat loss, we began a multidisciplinary field study. Sampled lake cores provide a chemical record of historical events and possible habitat changes. Water chemistry samples taken in different months inform groundwater flow patterns and core interpretation. Spatial analyses of local and regional groundwater systems informed placement of piezometers to determine groundwater flow. Aerial drone imagery builds on previous ground studies and allows for a quantitative spatial analysis of vegetation encroachment and geomorphic analyses. The three main lakes in our study show a general increase in concentration of major ions from east to west —from Pelican to Peterson to Williams—that mirrors westerly groundwater flow. Geochemical data from sediment cores, including LOI, XRD and XRF data, show that Williams is the most variable chemically, Pelican the least. Williams contains the most evaporate minerals, including thernardite and burkeite. Land use changes in the last 120 years may have changed lake chemistry: at 60 cm depth in cores, there are changes in the organic matter concentration and major ion chemistry, suggesting an increase in runoff and sediment input. Historical research points to changing agricultural practices as a possible cause of these changes. Initial ArcGIS analyses of detailed drone topographic data compared to historical ground studies of habitat loss suggests that topography and westerly winds that move water and ice sheets both play a role: there is more habitat on the east side of lakes and where there is a gently sloping beach. We aim to understand the interplay of these geological and biological factors to help inform conservation practices.

Microbial diversity and ecotoxicity of sediments 3 years after the Jiaozhou Bay oil spill.

PubMed

Gao, Wei; Yin, Xiaofei; Mi, Tiezhu; Zhang, Yiran; Lin, Faxiang; Han, Bin; Zhao, Xilong; Luan, Xiao; Cui, Zhisong; Zheng, Li

2018-05-09

In 2013, the "Qingdao oil pipeline explosion" released an estimated 2000 tons of oil into the environment. Sediment samples were collected from ten sites in Jiaozhou Bay and Shilaoren Beach to evaluate the influence of the spilled oil on the benthic environment 3 years after the oil spill accident. The compositions of oil, bacterial diversity and biotoxicity were examined in this study. The results showed that the concentration of total petroleum hydrocarbons (TPHs) peaked near the oil leak point and gradually decreased along the coastline, ranging from 21.5 to 133.2 μg/g. The distribution of polycyclic aromatic hydrocarbons (PAHs) was correlated with TPH, and naphthalenes were dominant in the 20 detected PAHs. The bacterial diversities in seriously polluted and slightly polluted sediments were completely different. As degrading bacteria, Alcanivorax and Lutibacter were the main genera at the oil-polluted sites. The analysis of biotoxicity by the luminescent bacteria method showed great differences among the polluted sites, the control site in Jiaozhou Bay, and the non-polluted site outside of Jiaozhou Bay. The biotoxicity also peaked at the site near the oil leak point. These results indicate that the oil spill that occurred 3 years ago still affects the environment and impacts the bacterial communities in the sediments.

Ancient Clam Gardens Increased Shellfish Production: Adaptive Strategies from the Past Can Inform Food Security Today

PubMed Central

Groesbeck, Amy S.; Rowell, Kirsten; Lepofsky, Dana; Salomon, Anne K.

2014-01-01

Maintaining food production while sustaining productive ecosystems is among the central challenges of our time, yet, it has been for millennia. Ancient clam gardens, intertidal rock-walled terraces constructed by humans during the late Holocene, are thought to have improved the growing conditions for clams. We tested this hypothesis by comparing the beach slope, intertidal height, and biomass and density of bivalves at replicate clam garden and non-walled clam beaches in British Columbia, Canada. We also quantified the variation in growth and survival rates of littleneck clams (Leukoma staminea) we experimentally transplanted across these two beach types. We found that clam gardens had significantly shallower slopes than non-walled beaches and greater densities of L. staminea and Saxidomus giganteus, particularly at smaller size classes. Overall, clam gardens contained 4 times as many butter clams and over twice as many littleneck clams relative to non-walled beaches. As predicted, this relationship varied as a function of intertidal height, whereby clam density and biomass tended to be greater in clam gardens compared to non-walled beaches at relatively higher intertidal heights. Transplanted juvenile L. staminea grew 1.7 times faster and smaller size classes were more likely to survive in clam gardens than non-walled beaches, specifically at the top and bottom of beaches. Consequently, we provide strong evidence that ancient clam gardens likely increased clam productivity by altering the slope of soft-sediment beaches, expanding optimal intertidal clam habitat, thereby enhancing growing conditions for clams. These results reveal how ancient shellfish aquaculture practices may have supported food security strategies in the past and provide insight into tools for the conservation, management, and governance of intertidal seascapes today. PMID:24618748

Field studies of beach cones as coastal erosion control/reversal devices for areas with significant oil and gas activities. Annual report, February 24, 1993--February 23, 1994

DOE Office of Scientific and Technical Information (OSTI.GOV)

Law, V.J.

1994-07-07

The primary objective of this project was to evaluate the utility of a device called the ``beach cone`` in combating coastal erosion. Seven initial sites were selected for testing beach cones in a variety of geometric configurations, and six sites were actually used. Six hundred beach cones were installed at the six sites in late July and early August, 1992. An additional 109 cones were installed at an eighth site in December of 1992. Findings indicate that beach cones accreted significant amounts of materials along the beach of a barrier island. At the eighth installation the amount of accreted materialmore » was measured by surveys to be 2200 cubic meters (2900 cubic yards) in February of 1993, when the cones were found to have been completely covered by the material. The average increase in elevation was about 7 inches (0. 18 in) with a maximum buildup of 3 ft. (I in). At other test sites, accretion rates have been less dramatic but importantly, no significant additional erosion has occurred, which is a positive result. The cost of sediment accretion using beach cones was found to be about $13.72 per cubic yard of sand or approximately $500,000 per mile of beach, which would be much lower if the cones were mass produced. The survival of the cones through the fringes of Hurricane Andrew indicates that they can be anchored sufficiently to survive significant storms. The measurements of the cones settling rates indicate that this effect is negligible, does not hinder their effectiveness. We do not yet have sufficient data to state the categorical success of the beach cones, but results to date are encouraging.« less

Microbes in Beach Sands: Integrating Environment, Ecology and Public Health

PubMed Central

Whitman, Richard; Harwood, Valerie J.; Edge, Thomas A.; Nevers, Meredith; Byappanahalli, Muruleedhara; Vijayavel, Kannappan; Brandão, João; Sadowsky, Michael J.; Alm, Elizabeth Wheeler; Crowe, Allan; Ferguson, Donna; Ge, Zhongfu; Halliday, Elizabeth; Kinzelman, Julie; Kleinheinz, Greg; Przybyla-Kelly, Kasia; Staley, Christopher; Staley, Zachery; Solo-Gabriele, Helena M.

2014-01-01

SUMMARY Beach sand is a habitat that supports many microbes, including viruses, bacteria, fungi and protozoa (micropsammon). The apparently inhospitable conditions of beach sand environments belie the thriving communities found there. Physical factors, such as water availability and protection from insolation; biological factors, such as competition, predation, and biofilm formation; and nutrient availability all contribute to the characteristics of the micropsammon. Sand microbial communities include autochthonous species/phylotypes indigenous to the environment. Allochthonous microbes, including fecal indicator bacteria (FIB) and waterborne pathogens, are deposited via waves, runoff, air, or animals. The fate of these microbes ranges from death, to transient persistence and/or replication, to establishment of thriving populations (naturalization) and integration in the autochthonous community. Transport of the micropsammon within the habitat occurs both horizontally across the beach, and vertically from the sand surface and ground water table, as well as at various scales including interstitial flow within sand pores, sediment transport for particle-associated microbes, and the large-scale processes of wave action and terrestrial runoff. The concept of beach sand as a microbial habitat and reservoir of FIB and pathogens has begun to influence our thinking about human health effects associated with sand exposure and recreational water use. A variety of pathogens have been reported from beach sands, and recent epidemiology studies have found some evidence of health risks associated with sand exposure. Persistent or replicating populations of FIB and enteric pathogens have consequences for watershed/beach management strategies and regulatory standards for safe beaches. This review summarizes our understanding of the community structure, ecology, fate, transport, and public health implications of microbes in beach sand. It concludes with recommendations for future work in this vastly under-studied area. PMID:25383070

Predator Diet and Trophic Position Modified with Altered Habitat Morphology

PubMed Central

Tewfik, Alexander; Bell, Susan S.; McCann, Kevin S.; Morrow, Kristina

2016-01-01

Empirical patterns that emerge from an examination of food webs over gradients of environmental variation can help to predict the implications of anthropogenic disturbance on ecosystems. This “dynamic food web approach” is rarely applied at the coastal margin where aquatic and terrestrial systems are coupled and human development activities are often concentrated. We propose a simple model of ghost crab (Ocypode quadrata) feeding that predicts changing dominant prey (Emerita talpoida, Talorchestia sp., Donax variablis) along a gradient of beach morphology and test this model using a suite of 16 beaches along the Florida, USA coast. Assessment of beaches included quantification of morphological features (width, sediments, slope), macrophyte wrack, macro-invertebrate prey and active ghost crab burrows. Stable isotope analysis of carbon (13C/12C) and nitrogen (15N/14N) and the SIAR mixing model were used to determine dietary composition of ghost crabs at each beach. The variation in habitat conditions displayed with increasing beach width was accompanied by quantifiable shifts in ghost crab diet and trophic position. Patterns of ghost crab diet were consistent with differences recorded across the beach width gradient with respect to the availability of preferred micro-habitats of principal macro-invertebrate prey. Values obtained for trophic position also suggests that the generalist ghost crab assembles and augments its diet in fundamentally different ways as habitat morphology varies across a highly dynamic ecosystem. Our results offer support for a functional response in the trophic architecture of a common food web compartment (ghost crabs, macro-invertebrate prey) across well-known beach morphologies. More importantly, our “dynamic food web approach” serves as a basis for evaluating how globally wide-spread sandy beach ecosystems should respond to a variety of anthropogenic impacts including beach grooming, beach re-nourishment, introduction of non-native or feral predators and human traffic on beaches. PMID:26824766

Post-storm evolution a high-energy remote sandy beach backed by a high and wide coastal dune

NASA Astrophysics Data System (ADS)

Castelle, Bruno; Bujan, Stéphane; Ferreira, Sophie

2016-04-01

During the winter 2013/2014, the high-energy meso-macrotidal remote beach of Truc Vert (SW France) was exposed to the most energetic wave conditions over at least the last 65 years with, for instance, the 2-month averaged significant wave height at the coast exceeding 3.6 m. Unprecedented beach and dune erosion was observed with the notable presence of a 700-m long localized megacusp embayment with the erosion scarp height exceeding 6 m in its centre where the dune retreat reached 30 m. Both the beach and the coastal dune eroded by about 90 m3/m within 3 months of severe storm activity, that is, a total beach-dune system sediment loss reaching 180m3/m. Beach and dune evolution after the winter 2013/2014 was inspected from March 2014 to November 2015 using bimonthly topographic surveys covering 1500+ m alongshore. 1.5 years after the winter 2014/2015, the beach-dune system did not fully recover to its pre-winter 2014/2015 level. The dune accreted by only a few m3/m while the beach accreted by an impressive amount of approximately 150m3/m, to reach a total volume that was only exceeded in 2012 within our full 10-year time series. Despite little volumetric changes, the dune showed significant morphological change through slumping and onshore wave- and wind-driven sediment transport. Seasonal natural revegetation was observed with large dune grass growth into the summer berm and within the erosion scarp with slumped clots of dune grass re-establishing their growth during the winter 2014/2015. In late 2015, the onset of morphological foredune development was observed. It is anticipated that, if Truc Vert is not exposed to a cluster of severe storms during the winter 2015/2016, the coastal dune will increase in volume within 2016 at a much higher rate than during 2015. Last but not least, starting in late 2015, the coastal dune of Truc Vert is now intensively monitored through regular 4-km long UAV photogrammetric surveys. Given that, nowadays, some scientists advocate that dunes maintained as dynamic systems retaining diversity and complexity not only provide more ecosystem services but can even be more resistant to marine erosion and more resilient than actively managed dunes, it is the objective to test different dune management strategies at Truc Vert, including no dune maintenance.

A Pilot Study of Microbial Contamination of Subtropical Recreational Waters

PubMed Central

Fleming, Lora E; Solo, Gabriele H.; Elmir, Samir; Shibata, Tomoyuki; Squicciarini, Dominick; Quirino, Wendy; Arguello, Margia; Van de Bogart, Gayl

2009-01-01

Microbial water quality indicators are used to determine whether a water body is safe for recreational purposes. There have been concerns raised about the appropriate use of microbial indicators to regulate recreational uses of water bodies, in particular those located in tropical and sub-tropical environments. This prospective cohort pilot study evaluated the relationship between microbial water quality indicators and public health within two public beaches without known sewage discharge, but with historically high microbial levels for one beach, in subtropical Miami-Dade County (Florida). Monitoring was conducted in three phases: daily water monitoring, beach sand sampling, and spatially intense water sampling. An epidemiological questionnaire from a Los Angeles recreational beach-goer study was used to assess the self-reported swimming-related symptoms and exposures. There was no significant association between the number nor the type of reported symptoms and the different sampling months or beach sites, although persons who returned repeatedly to the beach were more likely to report symptoms. The number of indicator organisms correlated negatively with the frequency of symptoms reported by recreational beach goers. Results of the daily monitoring indicated that different indicators provided conflicting results concerning beach water quality. Larger epidemiologic studies with individual exposure monitoring are recommended to further evaluate these potentially important associations in subtropical recreational waters. PMID:20151031

Carpinteria Coastal Processes Study, 2005-2007; Final Report

USGS Publications Warehouse

Barnard, Patrick L.; Revell, David L.; Eshleman, Jodi L.; Mustain, Neomi

2008-01-01

PROJECT SUMMARY The United States Geological Survey (USGS), in collaboration with the University of California, Santa Cruz (UCSC), conducted a two-year study of the beach and nearshore coastal processes for the City of Carpinteria and adjacent beaches. The work was performed in response to and worked directly with the United States Army Corps of Engineers (USACE) Project Management Plan (PMP) for the City of Carpinteria: * Carpinteria Shoreline, Santa Barbara County, California PMP (June 2003) www.spl.usace.army.mil/cms/index.php?option=com_content&task=view&id=487&Itemid=31 The City of Carpinteria has experienced significant erosion and storm damage over the last decade (Figure 1.1). A USACE reconnaissance survey has shown shoreline retreat rates that approach 2 m/yr in some locations. The goals of this project are to analyze historical trends/changes in the beach and nearshore environment, document local wave and tidal currents, and assess current beach and nearshore conditions in terms of grain size, beach size and shape, seasonal changes, and nearshore bathymetry. In summary, this work serves to quantify sediment sources, transport and sinks throughout the study area to support USACE and the City of Carpinteria coastal management activities.

Morphological characteristics and medium-term evolution of the beaches between Ceuta and Cabo Negro (Morocco)

NASA Astrophysics Data System (ADS)

Anfuso, G.; Martínez Del Pozo, J. A.; Nachite, D.; Benavente, J.; Macias, A.

2007-05-01

This work presents the results of a combined study on the beach morphology and the evolution at short- and medium-term of the littoral between Ceuta and Cabo Negro (Morocco). It is an interesting sector showing a great increase of human occupation and coastal structures. The monitoring program allowed for the reconstruction of the beach morphological behavior and the seasonal changes. The studied beaches presented reflective profiles recording little seasonality, with the most notable morphological changes being strictly related to storms. Surf Similarity and Surf Scaling parameters highlighted the existence of intermediate and reflective beach states, characterized by plunging breakers. Aerial photographs and a satellite image have been geo-referenced and elaborated with GIS tools to reconstruct the short- and medium-term evolution of the littoral and the sediment transport pathways. The littoral showed important erosion at short- and medium-term related to a negative sedimentary budget because of offshore transport. Sand accumulation was recorded close to the main ports, i.e., Marina Smir and Marina Kabila. These port structures constituted impermeable, fixed limits, which divided the studied area into littoral cells. Other free, transit limits were also observed.

Disturbance of beach sediment by off-road vehicles

NASA Astrophysics Data System (ADS)

Anders, Fred J.; Leatherman, Stephen P.

1987-10-01

A three-year investigation was undertaken to examine the effects of off-road vehicles (ORVs) on the beach at Fire Island, New York. Within the National Seashore over 45,000 vehicle trips per year are concentrated in the zone seaward of the dune toe. The experimental approach was adopted in order to assess the environmental effects of ORVs. Specially developed instrumentation was used to measure the direct displacement of sand by vehicles traversing the beach. Direct displacement data were reduced graphically and analyzed by stepwise linear regression. The results of 89 field experiments (788 cases) showed that slope, sand compaction, and number of vehicle passes in the same track were the principal factors controlling the measured net seaward displacement of sand. The data suggest that ORV use levels within the National Seashore could be contributing to the overall erosion rate by delivering large quantities of sand to the swash zone (max. of 119,300 m3/yr). However, with proper management downslope movement of sand could be reduced by an order of magnitude. While vehicular passage over the open beach displaces sand seaward, it is not known if such activity actually increases the amount of erosion, measured as net loss to the beach face.

A Sr-Nd isotopic study of sand-sized sediment provenance and transport for the San Francisco Bay coastal system

USGS Publications Warehouse

Rosenbauer, Robert J.; Foxgrover, Amy C.; Hein, James R.; Swarzenski, Peter W.; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.

2013-01-01

A diverse suite of geochemical tracers, including 87Sr/86Sr and 143Nd/144Nd isotope ratios, the rare earth elements (REEs), and select trace elements were used to determine sand-sized sediment provenance and transport pathways within the San Francisco Bay coastal system. This study complements a large interdisciplinary effort (Barnard et al., 2012) that seeks to better understand recent geomorphic change in a highly urbanized and dynamic estuarine-coastal setting. Sand-sized sediment provenance in this geologically complex system is important to estuarine resource managers and was assessed by examining the geographic distribution of this suite of geochemical tracers from the primary sources (fluvial and rock) throughout the bay, adjacent coast, and beaches. Due to their intrinsic geochemical nature, 143Nd/144Nd isotopic ratios provide the most resolved picture of where sediment in this system is likely sourced and how it moves through this estuarine system into the Pacific Ocean. For example, Nd isotopes confirm that the predominant source of sand-sized sediment to Suisun Bay, San Pablo Bay, and Central Bay is the Sierra Nevada Batholith via the Sacramento River, with lesser contributions from the Napa and San Joaquin Rivers. Isotopic ratios also reveal hot-spots of local sediment accumulation, such as the basalt and chert deposits around the Golden Gate Bridge and the high magnetite deposits of Ocean Beach. Sand-sized sediment that exits San Francisco Bay accumulates on the ebb-tidal delta and is in part conveyed southward by long-shore currents. Broadly, the geochemical tracers reveal a complex story of multiple sediment sources, dynamic intra-bay sediment mixing and reworking, and eventual dilution and transport by energetic marine processes. Combined geochemical results provide information on sediment movement into and through San Francisco Bay and further our understanding of how sustained anthropogenic activities which limit sediment inputs to the system (e.g., dike and dam construction) as well as those which directly remove sediments from within the Bay, such as aggregate mining and dredging, can have long-lasting effects

Anthropogenic effects on shoreface and shoreline changes: Input from a multi-method analysis, Agadir Bay, Morocco

NASA Astrophysics Data System (ADS)

Aouiche, Ismail; Daoudi, Lahcen; Anthony, Edward J.; Sedrati, Mouncef; Ziane, Elhassane; Harti, Abderrazak; Dussouillez, Philippe

2016-02-01

In many situations, the links between shoreline fluctuations and larger-scale coastal change embracing the shoreface are not always well understood. In particular, meso-scale (years to decades) sand exchanges between the shoreface and the shoreline, considered as important on many wave-dominated coasts, are rather poorly understood and difficult to identify. Coastal systems where sediment transport is perturbed by engineering interventions on the shoreline and shoreface commonly provide fine examples liable to throw light on these links. This is especially so where shoreface bathymetric datasets, which are generally lacking, are collected over time, enabling more or less fine resolution of the meso-scale coastal sediment budget. Agadir Bay and the city of Agadir together form one of the two most important economic development poles on the Atlantic coast of Morocco. Using a combined methodological approach based on wave-current modelling, bathymetric chart-differencing, determination of shoreline fluctuations, and beach topographic surveying, we highlight the close links between variations in the bed of the inner shoreface and the bay shoreline involving both cross-shore and longshore sand transport pathways, sediment budget variations and new sediment cell patterns. We show that the significant changes that have affected the bay shoreline and shoreface since 1978 clearly reflect anthropogenic impacts, notably blocking of alongshore sand transport by Agadir harbour, completed in 1988, and the foundations of which lie well beyond the depth of wave closure. Construction of the harbour has led to the creation of a rapidly accreting beach against an original portion of rocky shoreline updrift and to a net sand loss exceeding 145,000 m3/year between 1978 and 2012 over 8.5 km2of the bay shoreface downdrift. Shoreline retreat has been further exacerbated by sand extraction from aeolian dunes and by flattening of these dunes to make space for tourist infrastructure. Digital elevation models of part of the bay beach between 2012 and 2014 confirm this on-going sand loss. These changes have involved the establishment of two divergent longshore bay sediment cells instead of the original single unidirectional cell. A prospective view of these changes suggests that perturbation of longshore drift and the on-going bay sediment budget deficit will eventual directly pose threats to the harbour access and to coastal tourism on which the economic growth of Agadir has been built.

Sandy beaches: state of the art of nematode ecology.

PubMed

Maria, Tatiana F; Vanaverbeke, Jan; Vanreusel, Ann; Esteves, André M

2016-01-01

In this review, we summarize existing knowledge of the ecology of sandy-beach nematodes, in relation to spatial distribution, food webs, pollution and climate change. We attempt to discuss spatial scale patterns (macro-, meso- and microscale) according to their degree of importance in structuring sandy-beach nematode assemblages. This review will provide a substantial background on current knowledge of sandy-beach nematodes, and can be used as a starting point to delineate further investigations in this field. Over decades, sandy beaches have been the scene of studies focusing on community and population ecology, both related to morphodynamic models. The combination of physical factors (e.g. grain size, tidal exposure) and biological interactions (e.g. trophic relationships) is responsible for the spatial distribution of nematodes. In other words, the physical factors are more important in structuring nematodes communities over large scale of distribution while biological interactions are largely important in finer-scale distributions. It has been accepted that biological interactions are assumed to be of minor importance because physical factors overshadow the biological interactions in sandy beach sediments; however, the most recent results from in-situ and ex-situ experimental investigations on behavior and biological factors on a microscale have shown promise for understanding the mechanisms underlying larger-scale patterns and processes. Besides nematodes are very promising organisms used to understand the effects of pollution and climate changes although these subjects are less studied in sandy beaches than distribution patterns.

Beach and dune building processes: Linking nearshore to backshore and events to decades

NASA Astrophysics Data System (ADS)

Ruggiero, P.; Cohn, N.; Hacker, S.; Moore, L. J.; Duran Vinent, O.; de Vries, S.

2016-12-01

Due to the wide range of complex processes in the active coastal zone, individual studies have tended to focus on specific time scales (e.g., event-scale erosion) and/or specific morphological units, (e.g., the nearshore bar zone). As a result, the wet and dry portions of the beach have typically been studied independently. In nature, however, the nearshore and the backshore are highly interdependent and understanding the linkages between these units is critical to characterizing coastal evolution. For example, during periods of intense storm conditions (e.g., major El Niños on the U.S. West Coast), elevated water levels and large waves commonly lead to the scarping, or even destruction, of wind formed dunes. Given that dunes act as a form of green infrastructure and are a major asset to the coastal zone, it is critical to be able to forecast backshore evolution. Existing models for backshore recovery, however, are typically based on local historical trends rather than a mechanistic understanding including onshore sediment transport, dune growth, and the role of ecomorphodynamic feedbacks. Therefore, most likely as a result of the historical academic separation of wave and wind driven processes, geomorphology and ecology, and short- and long-term processes, our understanding of beach and dune building is still in its infancy. Here we describe SEDEX2, the Sandbar-aEolian-Dune EXchange Experiment, a comprehensive summer 2016 field campaign in which measurements of waves, currents, wind, dune ecology, subaqueous and aeolian sediment transport, and subsequent morphological changes were collected along the Long Beach Peninsula, WA. The data collected during the six-week experiment are contextualized by nearly two decades of focused research on the seasonal-centennial scale evolution of this rapidly prograding system. The findings of this study, actively bridging across disciplines, morphometric units, and temporal scales are informing conceptual and numerical models of beach-dune interaction and helping to improve management of vital backshore resources.

Results From a Microbial Source-Tracking Study at Villa Angela Beach, Cleveland, Ohio, 2007

USGS Publications Warehouse

Bushon, Rebecca N.; Stelzer, Erin A.; Stoeckel, Donald M.

2009-01-01

During the 2007 recreational season at Villa Angela Beach in Cleveland, Ohio, scientists with the U.S. Geological Survey (USGS) and the Northeast Ohio Regional Sewer District (NEORSD) found high Escherichia coli (E. coli) concentrations that were not easily explained by results obtained to date in ongoing investigations of recreational water quality at the beach. To help understand the sources behind these elevated E. coli concentrations, the USGS and NEORSD sampled beach-area water for Bacteroides DNA markers. Bacteroides are a group of enteric bacteria that are being used in microbial source tracking, in hope that host-associated DNA markers could be used to indicate potential sources of E. coli in the Villa Angela environment. The USGS Ohio Water Microbiology Laboratory analyzed a total of 13 source samples (sewage and waterfowl feces) and 33 beach-area water and sand samples for three Bacteroides DNA markers. This report lists the results of those analyses, along with environmental conditions at Villa Angela on the dates that samples were collected.

Policies and practices of beach monitoring in the Great Lakes, USA: a critical review

USGS Publications Warehouse

Nevers, Meredith B.; Whitman, Richard L.

2010-01-01

Beaches throughout the Great Lakes are monitored for fecal indicator bacteria (typically Escherichia coli) in order to protect the public from potential sewage contamination. Currently, there is no universal standard for sample collection and analysis or results interpretation. Monitoring policies are developed by individual beach management jurisdictions, and applications are highly variable across and within lakes, states, and provinces. Extensive research has demonstrated that sampling decisions for time, depth, number of replicates, frequency of sampling, and laboratory analysis all influence the results outcome, as well as calculations of the mean and interpretation of the results in policy decisions. Additional shortcomings to current monitoring approaches include appropriateness and reliability of currently used indicator bacteria and the overall goal of these monitoring programs. Current research is attempting to circumvent these complex issues by developing new tools and methods for beach monitoring. In this review, we highlight the variety of sampling routines used across the Great Lakes and the extensive body of research that challenges comparisons among beaches. We also assess the future of Great Lakes monitoring and the advantages and disadvantages of establishing standards that are evenly applied across all beaches.

Historical Sediment Budget (1860s to Present) for the United States Shoreline of Lake Erie

DTIC Science & Technology

2016-08-01

B. Monroe, and D. E. Guy, Jr. 1986. Lake Erie shore erosion: The effect of beach width and shore protection structures. Journal of Coastal Research...2005. Concepts in sediment budgets. Journal of Coastal Research 21(2):307–322. Stewart, C. J. 1999. A revised geomorphic, shore protection , and...Engineer District, Buffalo 1776 Niagara Street Buffalo, NY 14207 Andrew Morang and Ashley E. Frey Coastal and Hydraulics Laboratory U.S. Army

Comparison of empirical and numerical methods for the assessment of coastal vulnerability to erosion

NASA Astrophysics Data System (ADS)

Kokkinos, Dimitris; Prinos, Panagiotis

2017-04-01

Assessing the vulnerability to erosion is an important step in order to identify the prone areas and propose an adaptation policy to climate change in coastal areas. In this paper two coastal areas at the Northern part of the Aegean Sea are selected to examine their vulnerability to erosion. The first case is Lesbos Island where the most common feature is pocket beaches and the second one is the coast of Thrace composed by long sandy beaches. In both case studies, the same simplified methodology proposed by Mendoza and Jimenez (2009) is used, which links the vulnerability to erosion with morphodynamic parameters such as beach retreat and beach width. The key parameter for the vulnerability assessment is the beach retreat. For its calculation two different approaches are used and compared. The first approach divides the eroded volume with the eroded depth and it is based on an empirical formula, derived for the Greek seas from the CCSEAWAVS project (Kokkinos et al, 2014), which links the eroded volume with JA parameter, a beach erosion predictor proposed by Jimenez (1993). The sediment fall velocity, the beach slope and the wave characteristics are the only necessary parameters to calculate JA. The second approach is based on the results derived from the numerical model Xbeach (Roelvink et al., 2009), which is an open source, state-of the-art, two-dimensional model including the hydrodynamic processes of short and long wave transformation, wave-induced setup, overwash, inundation, as well as the morphodynamic processes of bed load and suspended sediment transport, dune face avalanching, bed update and breaching. The results indicate that the area of Thrace is very prone to erosion at the eastern and western part of the study area, while the Island of Lesbos appears to have very low vulnerability. The application of this methodology with the two different approaches aims to generate useful information about the vulnerability to erosion, to examine the reliability of the empirical approach and to support studies for an adaptation policy to climate change. References: Jiménez, J.A., Sánchez-Arcilla, A., Stive, M.J.F., (1993), "Discussion on prediction of storm/normal beach profiles" Journal of Waterway Port, Coast. & Oc. Eng., 19(4): 466-468. Kokkinos D., Prinos P., Galiatsatou G., Jimenez J.A. (2014), "Estimation of Erosion Potential and Erosion Vulnerability Indices in the study sites" CCSEAWAVS, Report-Deliverable 4.2, THALES research project (In Greek) Mendoza, E.T. and Jiménez, J.A, (2009) "Regional geomorphic vulnerability analysis to storms for Catalan beaches", P. I. Civil Eng-Mar. En., 162(3): 127-135 Roelvink D., Reniers A., Van Dongeren A., De Vries J.T., McCall R., Lescinski J. (2009), "Modelling storm impacts on beaches, dunes and barrier islands", Coast. Eng., 56: 1133-1152

Cape Baleia, Caravelas, Brazil

NASA Image and Video Library

1993-01-19

STS054-86-001 (13-19 Jan. 1993) --- This 70mm view shows a spectacular multiple spit on the coast of Brazil, about halfway between Rio de Janeiro and the mouth of the Amazon River. Over a few thousand years, according to NASA scientists, shifting regimes of wave and current patterns piled up sand onto a series of beach ridges and tidal lagoons. The present swirls of sediment along the coast evidently were derived from beach erosion, because streams flowing into the Atlantic contain dark, clear water. Offshore, reefs and sandbanks parallel the coast. The largest is the Recife da Pedra Grande (Big Rocks Reef).

California State Waters Map Series: offshore of Santa Barbara, California

USGS Publications Warehouse

Johnson, Samuel Y.; Dartnell, Peter; Cochrane, Guy R.; Golden, Nadine E.; Phillips, Eleyne L.; Ritchie, Andrew C.; Greene, H. Gary; Krigsman, Lisa M.; Kvitek, Rikk G.; Dieter, Bryan E.; Endris, Charles A.; Seitz, Gordon G.; Sliter, Ray W.; Erdey, Mercedes D.; Gutierrez, Carlos I.; Wong, Florence L.; Yoklavich, Mary M.; Draut, Amy E.; Hart, Patrick E.; Conrad, James E.; Cochran, Susan A.; Johnson, Samuel Y.; Cochran, Susan A.

2013-01-01

In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow (to about 100 m) subsurface geology. The Offshore of Santa Barbara map area lies within the central Santa Barbara Channel region of the Southern California Bight. This geologically complex region forms a major biogeographic transition zone, separating the cold-temperate Oregonian province north of Point Conception from the warm-temperate California province to the south. The map area is in the southern part of the Western Transverse Ranges geologic province, which is north of the California Continental Borderland. Significant clockwise rotation—at least 90°—since the early Miocene has been proposed for the Western Transverse Ranges province, and geodetic studies indicate that the region is presently undergoing north-south shortening. Uplift rates (as much as 2.2 mm/yr) that are based on studies of onland marine terraces provide further evidence of significant shortening. The city of Santa Barbara, the main coastal population center in the map area, is part of a contiguous urban area that extends from Carpinteria to Goleta. This urban area was developed on the coalescing alluvial surfaces, uplifted marine terraces, and low hills that lie south of the east-west-trending Santa Ynez Mountains. Several beaches line the actively utilized Santa Barbara coastal zone, including Arroyo Burro Beach Park, Leadbetter Beach, East Beach, and “Butterfly Beach.” There are ongoing coastal erosion problems associated with both development and natural processes; between 1933–1934 and 1998, cliff erosion in the map area occurred at rates of about 0.1 to 1 m/yr, the largest amount (63 m) occurring at Arroyo Burro in the western part of the map area. In addition, development of the Santa Barbara Harbor, which began in 1928, lead to shoaling west of the harbor as the initial breakwater trapped sand, as well as to coastal erosion east of the harbor. Since 1959, annual harbor dredging has mitigated at least some of the downcoast erosion problems. The Offshore of Santa Barbara map area lies in the central part of the Santa Barbara littoral cell, which is characterized by littoral drift to the east-southeast. Drift rates have been estimated to be about 400,000 tons/yr at Santa Barbara Harbor. Sediment supply to the western and central parts of the littoral cell, including the map area, is largely from relatively small transverse coastal watersheds. Within the map area, these coastal watersheds include (from east to west) San Ysidro Creek, Oak Creek, Montecito Creek, Sycamore Creek, Mission Creek, Arroyo Burro, and Atascadero Creek. The Ventura and Santa Clara Rivers, the mouths of which are about 40 to 50 km southeast of Santa Barbara, are much larger sediment sources. Still farther east, eastward-moving sediment in the littoral cell is trapped by Hueneme and Mugu Canyons and then transported to the deep-water Santa Monica Basin. The offshore part of the map area consists of a relatively flat and shallow continental shelf, which dips gently seaward (about 0.4° to 0.8°) so that water depths at the 3-nautical-mile limit of California’s State Waters are about 45 m in the east and about 75 m in the west. This part of the Santa Barbara Channel is relatively well protected from large Pacific swells from the north and northwest by Point Conception and from the south and southwest by offshore islands and banks. The shelf is underlain by variable amounts of upper Quaternary shelf, estuarine, and fluvial sediments deposited as sea level fluctuated in the late Pleistocene. Seafloor habitats in the broad Santa Barbara Channel region consist of significant amounts of soft sediment and isolated areas of rocky habitat that support kelp-forest communities nearshore and rocky-reef communities in deep water. The potential marine benthic habitat types mapped in the Offshore of Santa Barbara map area are directly related to its Quaternary geologic history, geomorphology, and active sedimentary processes. These potential habitats, which lie within the Shelf (continental shelf) megahabitat, range from soft, unconsolidated sediment to hard sedimentary bedrock. This heterogeneous seafloor provides promising habitat for rockfish, groundfish, crabs, shrimp, and other marine benthic organisms.

Coastal Studies in a Comprehensive Summer Field Geology Course.

ERIC Educational Resources Information Center

Cameron, Barry; Jones, Richard J.

1979-01-01

Describes a college geology course that incorporates a coastal segment. Field studies are done on Plum Island and include examining beaches, dune fields, and an adjacent marsh and spit. Topics include sedimentation, coastal geomorphology, botanical effects, and coastal studies methodology. (MA)

INVESTIGATION OF AMENDMENTS TO REDUCE METALS LEACHABILITY IN CONTAMINATED SEDIMENTS

EPA Science Inventory

Dredged material can be a valuable resource for environmental ehnacement projects such as restoring or establishing new wetlands for beach restoration and stabilization, and fill material for flood rotection and new developments Few studies have addressed both the ecological and ...

Path analyses of the influence of substrate composition on nematode numbers and on decomposition of stranded seaweed at an Antarctic coast

NASA Astrophysics Data System (ADS)

Alkemade, R.; Van Rijswijk, P.

Large amounts of seaweed are deposited along the coast of Admiralty Bay, King George Island, Antarctica. The stranded seaweed partly decomposes on the beach and supports populations of meiofauna species, mostly nematodes. The factors determining the number of nematodes found in the seaweed packages were studied. Seaweed/sediment samples were collected from different locations, along the coast near Arctowski station, covering gradients of salinity, elevation and proximity of Penguin rookeries. On the same locations decomposition rate was determined by means of permeable containers with seaweed material. Models, including the relations between location, seaweed and sediment characteristics, number of nematodes and decomposition rates, were postulated and verified using path analysis. The most plausible and significant models are presented. The number of nematodes was directly correlated with the height of the location, the carbon-to-nitrogen ratio, and the salinity of the sample. Nematode numbers were apparently indirectly dependent on sediment composition and water content. We hypothesize that the different influences of melt water and tidal water, which affect both salinity and water content of the deposits, are important phenomena underlying these results. Analysis of the relation between decomposition rate and abiotic, location-related characteristics showed that decomposition rate was dependent on the water content of the stranded seaweed and sediment composition. Decomposition rates were high on locations where water content of the deposits was high. There the running water from melt water run-off or from the surf probably increased weight losses of seaweed.

Distribution and sources of surfzone bacteria at Huntington Beach before and after disinfection on an ocean outfall - A frequency-domain analysis

USGS Publications Warehouse

Noble, M.A.; Xu, J. P.; Robertson, G.L.; Rosenfeld, L.K.

2006-01-01

Fecal indicator bacteria (FIB) were measured approximately 5 days a week in ankle-depth water at 19 surfzone stations along Huntington Beach and Newport Beach, California, from 1998 to the end of 2003. These sampling periods span the time before and after treated sewage effluent, discharged into the coastal ocean from the local outfall, was disinfected. Bacterial samples were also taken in the vicinity of the outfall during the pre- and post-disinfection periods. Our analysis of the results from both data sets suggest that land-based sources, rather than the local outfall, were the source of the FIB responsible for the frequent closures and postings of local beaches in the summers of 2001 and 2002. Because the annual cycle is the dominant frequency in the fecal and total coliform data sets at most sampling stations, we infer that sources associated with local runoff were responsible for the majority of coliform contamination along wide stretches of the beach. The dominant fortnightly cycle in enterococci at many surfzone sampling stations suggests that the source for these relatively frequent bacteria contamination events in summer is related to the wetting and draining of the land due to the large tidal excursions found during spring tides. Along the most frequently closed section of the beach at stations 3N-15N, the fortnightly cycle is dominant in all FIBs. The strikingly different spatial and spectral patterns found in coliform and in enterococci suggest the presence of different sources, at least for large sections of beach. The presence of a relatively large enterococci fortnightly cycle along the beaches near Newport Harbor indicates that contamination sources similar to those found off Huntington Beach are present, though not at high enough levels to close the Newport beaches. ?? 2006 Elsevier Ltd. All rights reserved.

Dynamic changes in the population structure of Escherichia coli in the Yeongsan River basin of South Korea.

PubMed

Jang, Jeonghwan; Di, Doris Y W; Han, Dukki; Unno, Tatsuya; Lee, Jeom-Ho; Sadowsky, Michael J; Hur, Hor-Gil

2015-11-01

Although Escherichia coli has been used as an indicator to examine fecal contamination of aquatic environment, it also has been reported to become naturalized to secondary habitats, including soil, water and beach sand. A total of 2880 E. coli isolates obtained from surface water and sediment samples from the Yeongsan River in 2013 were genotyped by using the horizontal fluorophore-enhanced rep-PCR DNA fingerprinting technique. Although different E. coli genotypic groups were observed between surface water and sediments in the dry season, they were mingled and undifferentiated from each other in the rainy season. This indicates that there are frequent sediment resuspension events in the river basin. Moreover, the genotypic composition of the E. coli population in the Yeongsan River basin changes over months and years, implying that genotypic structure of E. coli populations dynamically fluctuates in the river environment. Consequently, our data suggests that the use of E. coli libraries for fecal source tracking needs to be reassessed to account for the changing structure of riverine E. coli populations. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The application of microtextural and heavy mineral analysis to discriminate between storm and tsunami deposits

USGS Publications Warehouse

Costa, Pedro J.M.; Gelfenbaum, Guy R.; Dawson, Sue; La selle, Seanpaul; Milne, F; Cascalho, J.; Ponte Lira, C.; Andrade, C.; Freitas, M. C.; Jaffe, Bruce E.

2017-01-01

Recent work has applied microtextural and heavy mineral analyses to sandy storm and tsunami deposits from Portugal, Scotland, Indonesia and the USA. We looked at the interpretation of microtextural imagery (scanning electron microscopy) of quartz grains and heavy mineral compositions. We consider inundation events of different chronologies and sources (the AD 1755 Lisbon and 2004 Indian Ocean tsunamis, the Great Storm of 11 January 2005 in Scotland, and Hurricane Sandy in 2012) that affected contrasting coastal and hinterland settings with different regional oceanographic conditions. Storm and tsunami deposits were examined along with potential source sediments (alluvial, beach, dune and nearshore sediments) to determine provenance.Results suggest that tsunami deposits typically exhibit a significant spatial variation in grain sizes, microtextures and heavy minerals. Storm deposits show less variability, especially in vertical profiles. Tsunami and storm quartz grains had more percussion marks and fresh surfaces compared to potential source material. Moreover, in the studied cases, tsunami samples had fewer fresh surfaces than storm deposits.Heavy mineral assemblages are typically site-specific. The concentration of heavy minerals decreases upwards in tsunamigenic units, whereas storm sediments show cyclic concentrations of heavy minerals, reflected in the laminations observed macroscopically in the deposits.

Recreational water quality response to a filtering barrier at a Great Lakes beach

USGS Publications Warehouse

Przybyla-Kelly, Kasia; Nevers, Meredith; Breitenbach, Cathy; Whitman, Richard L.

2013-01-01

Recent research has sought to determine the off- or onshore origin of fecal indicator bacteria (FIB) in order to improve local recreational water quality. In an effort to reduce offshore contamination, a filtering barrier (FB) was installed at Calumet Beach, Lake Michigan, Chicago, IL. A horseshoe-shaped curtain (146 m long, 0.18 mm apparent opening size, 1.5–1.6 m deepest point) was designed to exclude FIB containing or promoting debris and thus reduce the number of swimming advisories during the examination period of July through September 2012. Mean water Escherichia coli concentrations were significantly lower at southern transects (S; outside FB) than at transects within the FB (WN) and at northern transects (N; outside FB) (1.45 log (MPN)/100 ml vs. 1.74 and 1.72, respectively, p < 0.05, n = 234). Turbidity was significantly higher at the WN transects (p < 0.001, n = 233), but it tended to increase throughout the sampling season within and outside the FB. E. coli in adjacent foreshore sand was significantly lower at the WN transects. A combination of factors might explain higher E. coli and turbidity within the FB including increased sediment resuspension, trapped algae, shallowing within the FB, and large lake hydrodynamic processes. This remediation approach may find better use in a different hydrodynamic setting, but the results of this experiment provide insight on sources of contamination and nearshore dynamics that may direct future beach management strategies.

Provenance of Holocene calcareous beach-dune sediments, Western Eyre Peninsula, Great Australian Bight, Australia

NASA Astrophysics Data System (ADS)

James, Noel P.; Bone, Yvonne

2017-07-01

Much of western Eyre Peninsula adjacent to the Great Australian Bight is veneered with siliceous and calcareous Quaternary aeolian dunes. The lengthy coastline adjacent to this cool-water carbonate factory is a series of Precambrian crystalline bedrock-Pleistocene aeolianite headlands that separate many long, sweeping, Holocene carbonate sand beaches and their backbeach dunes. Incessant SW waves, rolling swells, and onshore winds have resulted in > 350 km of semi-continuous calcareous strandline aeolian sands. The sediment is composed of quartz grains, Cenozoic limestone clasts, and relict particles (extraclasts) but the deposits are overwhelmingly dominated by contemporaneous biofragments from offshore. These skeletal grains are, in order of relative abundance, molluscs > benthic foraminifers > coralline algae > bryozoans, and echinoids. Benthic foraminifers are mostly small (especially rotaliids and miliolids) but the large relict symbiont-bearing protistMarginopora vertebralis, which grew in the latter stages of MIS 2, is present locally. There are no significant onshore-offshore trends within individual beach-dune complexes. There is, however, a prominent spatial partitioning, with extraclast-rich sediments in the north and biofragment-rich deposits in the south. This areal trend is interpreted to result from more active seafloor carbonate production in the south, an area of conspicuous seasonal nutrient upwelling and profound nektic and benthic biological productivity. The overall system is strikingly similar to Holocene and Pleistocene aeolianites along the inboard margin of the Lacepede Shelf and Bonney Coast some 500 km to the southeast, implying a potential universality to the nature of cool-water carbonate aeolianite deposition. The composition of these cool-water aeolianites is more multifaceted than those formed on warm-water, shallow flat-topped platforms, largely because of the comparatively deep, temperate shelf, the high-energy wave and swell climate impacting the shoreline, and thus the different geohistory during sea level change.

Modelling of sediment transport and morphological evolution under the combined action of waves and currents

NASA Astrophysics Data System (ADS)

Franz, Guilherme; Delpey, Matthias T.; Brito, David; Pinto, Lígia; Leitão, Paulo; Neves, Ramiro

2017-09-01

Coastal defence structures are often constructed to prevent beach erosion. However, poorly designed structures may cause serious erosion problems in the downdrift direction. Morphological models are useful tools to predict such impacts and assess the efficiency of defence structures for different scenarios. Nevertheless, morphological modelling is still a topic under intense research effort. The processes simulated by a morphological model depend on model complexity. For instance, undertow currents are neglected in coastal area models (2DH), which is a limitation for simulating the evolution of beach profiles for long periods. Model limitations are generally overcome by predefining invariant equilibrium profiles that are allowed to shift offshore or onshore. A more flexible approach is described in this paper, which can be generalised to 3-D models. The present work is based on the coupling of the MOHID modelling system and the SWAN wave model. The impacts of different designs of detached breakwaters and groynes were simulated in a schematic beach configuration following a 2DH approach. The results of bathymetry evolution are in agreement with the patterns found in the literature for several existing structures. The model was also tested in a 3-D test case to simulate the formation of sandbars by undertow currents. The findings of this work confirmed the applicability of the MOHID modelling system to study sediment transport and morphological changes in coastal zones under the combined action of waves and currents. The same modelling methodology was applied to a coastal zone (Costa da Caparica) located at the mouth of a mesotidal estuary (Tagus Estuary, Portugal) to evaluate the hydrodynamics and sediment transport both in calm water conditions and during events of highly energetic waves. The MOHID code is available in the GitHub repository.

Process based modeling of total longshore sediment transport

USGS Publications Warehouse

Haas, K.A.; Hanes, D.M.

2004-01-01

Waves, currents, and longshore sand transport are calculated locally as a function of position in the nearshore region using process based numerical models. The resultant longshore sand transport is then integrated across the nearshore to provide predictions of the total longshore transport of sand due to waves and longshore currents. Model results are in close agreement with the I1-P1 correlation described by Komar and Inman (1970) and the CERC (1984) formula. Model results also indicate that the proportionality constant in the I1-P1 formula depends weakly upon the sediment size, the shape of the beach profile, and the particular local sediment flux formula that is employed. Model results indicate that the various effects and influences of sediment size tend to cancel out, resulting in little overall dependence on sediment size.

The influence of wave-, wind- and tide-forced currents on headland sand bypassing - Study case: Santa Catarina Island north shore, Brazil

NASA Astrophysics Data System (ADS)

Vieira da Silva, Guilherme; Toldo, Elírio E., Jr.; Klein, Antonio H. da F.; Short, Andrew D.

2018-07-01

Investigations of headland sand bypassing are still an under-reported subject in the literature. This paper aims to understand the contribution of currents forced by different mechanisms such as tides, winds (i.e. local wind acting over the ocean surface generating currents, without considering wave generation) and waves (as they approach/break on the coast) to headland sand bypassing. The study was carried out in an area comprising a series of seven headlands with varying wave exposure due to changes in shoreline orientation and increasing tidal influence close to a relatively large bay. This paper uses a calibrated and validated process-based model (Delft3D) to simulate a series of scenarios including spring and neap tides during flood and ebb conditions and a range of wind and wave scenarios that encompass both average and extreme conditions. The results indicate that waves are the main driving force for the headland bypassing as they transport sand at rates two orders of magnitude higher than tide- or wind-driven sediment transport. The tide-driven currents can only transport sediment during spring tides in locations where the currents are intensified. It is also demonstrated that the wave direction plays an important role in sediment transport. In exposed areas with larger headlands a combination of wave directions is required to first transport sediment offshore (out of the beach) and secondly to transport sediment alongshore and back to the next beach. Whereas in areas with little variation in wave direction exposure, the same oblique wave direction is responsible for the entire headland bypassing process. This is the first time the contribution of tide-, winds- and wave-generated sediment transport to headland bypassing have been studied.

The South Carolina Coastal Erosion Study: Numerical modeling of circulation and sediment transport in Long Bay, SC

NASA Astrophysics Data System (ADS)

Warner, J. C.; Sullivan, C.; Voulgaris, G.; Work, P.; Haas, K.; Hanes, D. M.

2004-12-01

Long Bay, South Carolina, is a heavily populated coastal region that supports a large tourism industry. Sand resources are important for both recreation and coastal habitat. Earlier geological framework studies have identified a large sand deposit oblique to the shoreline, oriented clockwise in the offshore direction. This sand feature is ~ 10 km long, 2 km wide, and in excess of 3m thick, possibly providing a source for beach nourishment material. Objectives of this study are to describe the physical processes that control the transport of sediment in Long Bay, specifically off the coast of Myrtle Beach, South Carolina. Specifically we seek to 1) measure and model the oceanographic circulation in the region, 2) identify the processes that maintain the presence of the offshore sand feature, 3) quantify the control that the shoal exerts on the nearshore through changes in wave energy propagation, and 4) identify consequences of removal of the offshore sand feature. Both observational and numerical experiments are used to study the oceanographic circulation and transport of sediment. The observational study is described in an accompanying poster and consists of eight sites that measured tides, surface waves, currents, salinity, temperature, suspended sediment concentrations, and bed forms from October 2003 to April 2004. Numerical modeling for circulation and sediment transport in the study region uses a new version of ROMS (v2.1) that now includes transport of multiple grain sizes, coupling of sediment transport to wave bottom boundary layer models, and evolution of the bottom morphology. The SWAN model is used to compute wave propagation. Results indicate that currents in the study area are strongly influenced by both tidal motion and wind driven setup / setdown. The presence of the offshore sand feature alters the residual flows in the region. Sediment transport is more significant during periods of sustained strong winds that generate local waves. Wind direction plays a key role in determining the direction and magnitude of sediment transport.

Beach recovery capabilities after El Niño 2015–2016 at Ensenada Beach, Northern Baja California

NASA Astrophysics Data System (ADS)

Ruiz de Alegría-Arzaburu, Amaia; Vidal-Ruiz, Jesús Adrián

2018-06-01

This study investigates the recovery capabilities of a single-barred beach in the Pacific Mexican coast before and after the 2015-2016 El Niño winter. Concurrent hydrodynamic and morphological data collected over a 3-year period (August 2014-2017) were analysed to determine the subaerial-subtidal volumetric exchange and cross-shore subtidal sandbar migrations, in relation to the incident wave forcing. The beach presented a seasonal seaward and landward sandbar migration cycle. The sandbar migrated offshore during the energetic waves between November and February, and onshore during the milder wave period in spring, until welding to the subaerial beach around May. The transfer of sediment towards the subaerial section continued over the summer, reaching a complete recovery by September/October. Prior to El Niño, the subaerial beach successfully recovered by the end of summer 2015 through the landward sandbar migration process. The 2015-2016 energetic winter waves caused a subaerial volume loss of 140 m3 m-1 (from October 2015 to March 2016), more than twice the amount eroded in the other winters, and the sandbar moved further offshore and to deeper depths (3-4 m) than the winter before. In addition, the energetic 2015-2016 winter waves lasted for 2 months longer than in other years, making the 2016 spring shorter. Consequently, during the onshore migration, the sandbar was unable of reaching shallow depths, and a large portion of sand remained in the subtidal beach. The subaerial beach recovered 60 and 65% of the loss in the 2016 and 2017 summers, respectively. It is concluded that the landward migration process of the sandbar during the spring is critical to ensure a full subaerial beach recovery over the mild wave period in summer. The recovery capabilities of the subaerial beach will depend on the cross-shore distance and depth where the sandbar is located, and on the duration of mild wave conditions required for the sandbar to migrate onshore.

Beach recovery capabilities after El Niño 2015-2016 at Ensenada Beach, Northern Baja California

NASA Astrophysics Data System (ADS)

Ruiz de Alegría-Arzaburu, Amaia; Vidal-Ruiz, Jesús Adrián

2018-05-01

This study investigates the recovery capabilities of a single-barred beach in the Pacific Mexican coast before and after the 2015-2016 El Niño winter. Concurrent hydrodynamic and morphological data collected over a 3-year period (August 2014-2017) were analysed to determine the subaerial-subtidal volumetric exchange and cross-shore subtidal sandbar migrations, in relation to the incident wave forcing. The beach presented a seasonal seaward and landward sandbar migration cycle. The sandbar migrated offshore during the energetic waves between November and February, and onshore during the milder wave period in spring, until welding to the subaerial beach around May. The transfer of sediment towards the subaerial section continued over the summer, reaching a complete recovery by September/October. Prior to El Niño, the subaerial beach successfully recovered by the end of summer 2015 through the landward sandbar migration process. The 2015-2016 energetic winter waves caused a subaerial volume loss of 140 m3 m-1 (from October 2015 to March 2016), more than twice the amount eroded in the other winters, and the sandbar moved further offshore and to deeper depths (3-4 m) than the winter before. In addition, the energetic 2015-2016 winter waves lasted for 2 months longer than in other years, making the 2016 spring shorter. Consequently, during the onshore migration, the sandbar was unable of reaching shallow depths, and a large portion of sand remained in the subtidal beach. The subaerial beach recovered 60 and 65% of the loss in the 2016 and 2017 summers, respectively. It is concluded that the landward migration process of the sandbar during the spring is critical to ensure a full subaerial beach recovery over the mild wave period in summer. The recovery capabilities of the subaerial beach will depend on the cross-shore distance and depth where the sandbar is located, and on the duration of mild wave conditions required for the sandbar to migrate onshore.

The influence of fluvial dynamics and North Atlantic swells on the beach habitat of leatherback turtles at Grande Riviere Trinidad.

PubMed

Darsan, Junior; Jehu, Adam; Asmath, Hamish; Singh, Asha; Wilson, Matthew

2016-09-15

Grande Riviere beach, located on the north coast of Trinidad, West Indies, is internationally recognised as a critical habitat/nesting ground for the endangered leatherback turtles (Dermochelys coriacea). Episodic extreme flooding of the Grande Riviere River led to the shifting of the river mouth and resulted in backshore beach erosion, with the most recent recorded event occurring in 2012. Following this event, the construction of a sand dam to arrest further erosion which threatened coastal infrastructure, precipitated a host of new problems ranging from beach instability to public health threats. In January 2013, high energy swell waves naturally in-filled the erosion channel, and the beach recovery continued over the successive months, thereby rendering the intervention in the previous year questionable. This paper presents a geomorphological analysis of beach dynamics for Grande Riviere, within the context of this erosion event. Data on beach profiles, sediment and coastal processes were collected using standard geomorphological techniques. Beach topographic analysis and water quality tests on impounded water in the erosion channel were conducted. Results indicate that the event created an erosion channel of 4843.42 m(3) over a contiguous area of 2794.25 m(2). While swell waves were able to naturally infill the channel, they also eroded 17,762 m(3) of sand overall across the beach. Water quality tests revealed that the impounded water was classified as a pollutant, and created challenges for remediation. Hydrologic and coastal geomorphologic interplay is responsible for the existence and sustainability of this coastal system. It is also evident that the beach system is able to recover naturally following extreme events. Our results demonstrate that effective and integrated management of such critical habitats remains dependent upon continuous monitoring data which should be used to inform policy and decision making. Copyright © 2016 Elsevier Ltd. All rights reserved.

The effect of off-road vehicles on barrier beach invertebrates at Cape Cod and Fire Island National Seashores

USGS Publications Warehouse

Kluft, J. M.; Ginsberg, Howard S.

2009-01-01

The effects of off-road vehicles (ORVS) on invertebrates inhabiting seaweed debris (wrack) and supratidal sands on energetic beaches in the northeastern United States were studied at Cape Cod National Seashore, MA, and Fire Island, NY. Cores, wrack quadrats, and pitfall traps were used to sample four beaches, which all had vehicle-free sections in close proximity to ORV corridors, allowing for paired traffic/no-traffic samples at these sites. A manipulative experiment was also performed by directly driving over nylon-mesh bags filled with eelgrass (Zostera marina) wrack that had been colonized by beach invertebrates, then subjected to treatments of high-, low-, and no-traffic. Pitfall trap samples had consistently higher overall invertebrate abundances in vehicle-free than in high-traffic zones on all four beaches. In contrast, both wrack quadrats (with intact wrack clumps) and the cores taken directly beneath them did not show consistent differences in overall invertebrate abundances in areas open and closed to vehicles. Overall abundance of wrack was lower on beaches with vehicle traffic. The talitrid amphipod Talorchestia longicornis and the lycosid spider Arctosa littoralis, both of which roam widely on the beach and burrow in supratidal bare sands as adults, were always less abundant in beach sections open to vehicle traffic, regardless of the sampling method used. Other invertebrates, such as oligochaetes (family Enchytraeidae) and Tethinid flies (Tethina parvula), both of which spend most of their lives within/beneath wrack detritus, showed either no response or a positive response to traffic disturbance. In the drive-over experiment, different species responded differently to traffic. The tenebrionid beetle Phaleria testacea (85% larvae) was significantly less abundant in disturbed wrack bags than in controls, while Tethina parvula (90% larvae) showed the reverse trend. Therefore, ORVs adversely affected beach invertebrates, both by killing or displacing some species, and by lowering wrack abundance, thus lowering overall abundance of wrack dwellers. However, for some interstitial detritivores vehicle disturbance apparently facilitated mechanical breakdown of wrack and increased observed abundances. Our results suggest that alternating opening and closing of adjacent beaches to vehicle traffic allows recolonization of wrack clumps in newly-closed beaches from two sources: wrack-dwelling species from intact wrack clumps that remain on the disturbed beach and wide-ranging species from adjacent undisturbed beaches. Research on rapidity of recolonization from these sources is needed to optimize schedules of beach opening and closing for conservation of supratidal invertebrates.

A baseline record of trace elements concentration along the beach placer mining areas of Kanyakumari coast, South India.

PubMed

Simon Peter, T; Chandrasekar, N; John Wilson, J S; Selvakumar, S; Krishnakumar, S; Magesh, N S

2017-06-15

Trace element concentration in the beach placer mining areas of Kanyakumari coast, South India was assessed. Sewage and contaminated sediments from mining sites has contaminated the surface sediments. Enrichment factor indicates moderately severe enrichment for Pb, minor enrichment for Mn, Zn, Ni, Fe and no enrichment for Cr and Cu. The Igeo values show higher concentration of Pb ranging in the scale of 3-4, which shows strong contamination due to high anthropogenic activity such as mining and terrestrial influences into the coastal regions. Correlation coefficient shows that most of the elements are associated with each other except Ni and Pb. Factor analysis reveals that Mn, Zn, Fe, Cr, Pb and Cu are having a significant loading and it indicates that these elements are mainly derived from similar origin. The cluster analysis clearly indicated that the mining areas are grouped under cluster 2 and non-mining areas are clustered under group 1. Copyright © 2017 Elsevier Ltd. All rights reserved.

Depositional setting and early diagenesis of the dinosaur eggshell-bearing Aren Fm at Bastus, Late Campanian, south-central Pyrenees

NASA Astrophysics Data System (ADS)

Díaz-Molina, Margarita; Kälin, Otto; Benito, M. Isabel; Lopez-Martinez, Nieves; Vicens, Enric

2007-07-01

The Late Cretaceous Aren Fm exposed north of Bastus in the Tremp Basin (south-central Pyrenees) preserves an excellent record of dinosaur eggs laid in a marine littoral setting. Different from other cases reported in literature, at the Bastus site the preferential nesting ground was original beach sand. The coastal deposits of Aren Fm can be grouped into four facies assemblages, representing respectively shoreface, beachface, beach ridge plain and backbarrier lagoon environments. Shoreface deposits include fine- to coarse-grained hybrid arenites and subordinate quartz-dominated conglomerates with ripple structures of wave and wave-current origin. Beachface deposits are mainly storm beach conglomerates, but parallel-laminated foreshore arenites locally occur. Backbarrier lagoon deposits comprise of washover sandy conglomerates that grade laterally into sandy lime mudstones, biomicrites and marls. Beach ridge sediment, wherein the bulk of dinosaur eggs and eggshell debris occurs, predominantly is a reddish hybrid arenite that has undergone a complex early diagenetic evolution, including marine and meteoric cementation followed by soil development. The reddish arenites overlie wave-dominated shoreface deposits and in places pass laterally into lagoonal deposits. They originally formed shore ridges, that became stabilized during progradational episodes by pedogenesis (beach ridge, sensu [Otvos, E.G., 2000. Beach ridges—definitions and significance. Geomorphology 32, 83-108.]), which also affected the dinosaur eggs. The eggshell-bearing beach ridge arenites are typically preserved at the top of parasequences forming the systems tracts of a third-order sequence. Thick packages of this facies resulted from aggradation of barrier/beach ridge deposits, whose preservation below surfaces of transgressive erosion was favoured by incipient lithification.

Field Guide to Beaches. Early Science Curriculum Project Pamphlet Series PS-7.

ERIC Educational Resources Information Center

Hoyt, John H.

The study of beaches and their capacity as an interface between land, air, and water is presented. Students investigate shore phenomena to better understand the beach's history and possible future. Also discussed is the interaction between man and the beach, from weather effects to pollution. Laboratory investigations of samples collected from the…

Hurricane Ike: Observations and Analysis of Coastal Change

USGS Publications Warehouse

Doran, Kara S.; Plant, Nathaniel G.; Stockdon, Hilary F.; Sallenger, Asbury H.; Serafin, Katherine A.

2009-01-01

Understanding storm-induced coastal change and forecasting these changes require knowledge of the physical processes associated with the storm and the geomorphology of the impacted coastline. The primary physical processes of interest are the wind field, storm surge, and wave climate. Not only does wind cause direct damage to structures along the coast, but it is ultimately responsible for much of the energy that is transferred to the ocean and expressed as storm surge, mean currents, and large waves. Waves and currents are the processes most responsible for moving sediments in the coastal zone during extreme storm events. Storm surge, the rise in water level due to the wind, barometric pressure, and other factors, allows both waves and currents to attack parts of the coast not normally exposed to those processes. Coastal geomorphology, including shapes of the shoreline, beaches, and dunes, is equally important to the coastal change observed during extreme storm events. Relevant geomorphic variables include sand dune elevation, beach width, shoreline position, sediment grain size, and foreshore beach slope. These variables, in addition to hydrodynamic processes, can be used to predict coastal vulnerability to storms The U.S. Geological Survey's (USGS) National Assessment of Coastal Change Hazards Project (http://coastal.er.usgs.gov/hurricanes), strives to provide hazard information to those interested in the Nation's coastlines, including residents of coastal areas, government agencies responsible for coastal management, and coastal researchers. As part of the National Assessment, observations were collected to measure coastal changes associated with Hurricane Ike, which made landfall near Galveston, Texas, on September 13, 2008. Methods of observation included aerial photography and airborne topographic surveys. This report documents these data-collection efforts and presents qualitative and quantitative descriptions of hurricane-induced changes to the shoreline, beaches, dunes, and infrastructure in the region that was heavily impacted by Hurricane Ike.

Lidar Observations of Wave Shape

NASA Astrophysics Data System (ADS)

Brodie, K. L.; Raubenheimer, B.; Spore, N.; Gorrell, L.; Slocum, R. K.; Elgar, S.

2016-02-01

As waves propagate across the inner-surf zone, through a shorebreak, to the swash, their shapes can evolve rapidly, particularly if there are large changes in water depth over a wavelength. As wave shapes evolve, the time history of near-bed wave-orbital velocities also changes. Asymmetrical near-bed velocities result in preferential directions for sediment transport, and spatial variations in asymmetries can lead to morphological evolution. Thus, understanding and predicting wave shapes in the inner-surf and swash zones is important to improving sediment transport predictions. Here, rapid changes in wave shape, quantified by 3rd moments (skewness and asymmetry) of the sea-surface elevation time series, were observed on a sandy Atlantic Ocean beach near Duck, NC using terrestrial lidar scanners that measure the elevation of the water surface along a narrow cross-shore transect with high spatial [O(1 cm)] and temporal [O(0.5 s)] resolution. The terrestrial lidar scanners were mounted on a tower on the beach dune (about 8 m above the water surface) and on an 8-m tall amphibious tripod [the Coastal Research Amphibious Buggy (CRAB)]. Observations with the dune lidar are used to investigate how bulk wave shape parameters such as wave skewness and asymmetry, and the ratio of wave height to water depth (gamma) vary with beach slope, tide level, and offshore wave conditions. Observations with the lidar mounted on the CRAB are used to investigate the evolution of individual waves propagating across the surf zone and shorebreak to the swash. For example, preliminary observations from the CRAB include a wave that appeared to shoal and then "pitch" backwards immediately prior to breaking and running up the beach. Funded by the USACE Coastal Field Data Collection Program, ASD(R&E), and ONR.

Wave-induced coherent turbulence structures and sediment resuspension in the nearshore of a prototype-scale sandy barrier beach

NASA Astrophysics Data System (ADS)

Kassem, Hachem; Thompson, Charlotte E. L.; Amos, Carl L.; Townend, Ian H.

2015-10-01

The suspension of sediments by oscillatory flows is a complex case of fluid-particle interaction. The aim of this study is to provide insight into the spatial (time) and scale (frequency) relationships between wave-generated boundary layer turbulence and event-driven sediment transport beneath irregular shoaling and breaking waves in the nearshore of a prototype sandy barrier beach, using data collected through the Barrier Dynamics Experiment II (BARDEX II). Statistical, quadrant and spectral analyses reveal the anisotropic and intermittent nature of Reynolds' stresses (momentum exchange) in the wave boundary layer, in all three orthogonal planes of motion. The fractional contribution of coherent turbulence structures appears to be dictated by the structural form of eddies beneath plunging and spilling breakers, which in turn define the net sediment mobilisation towards or away from the barrier, and hence ensuing erosion and accretion trends. A standing transverse wave is also observed in the flume, contributing to the substantial skewness of spanwise turbulence. Observed low frequency suspensions are closely linked to the mean flow (wave) properties. Wavelet analysis reveals that the entrainment and maintenance of sediment in suspension through a cluster of bursting sequence is associated with the passage of intermittent slowly-evolving large structures, which can modulate the frequency of smaller motions. Outside the boundary layer, small scale, higher frequency turbulence drives the suspension. The extent to which these spatially varied perturbation clusters persist is associated with suspension events in the high frequency scales, decaying as the turbulent motion ceases to supply momentum, with an observed hysteresis effect.

Fine-Scale Volume Heterogeneity in a Mixed Sand/Mud Sediment Off Fort Walton Beach, FL

DTIC Science & Technology

2010-07-01

by Vaughan et al. [4]. Subsequent to the mud drape, wind-wave activity mobilized sediment and some of the mud layer was resuspended, and sand from...hardening effects, which is a common issue with polychromatic energy sources, such as the HD-500 and medical CT systems. Beam hardening is a process...provides a convenient characterization of levels of heterogeneity. The CV is defined as the standard devi - ation divided by the mean and multiplied by

A Paradigm for Developing Sediment Toxicity Bioassays for the Regulatory Evaluation of Dredged Material

DTIC Science & Technology

1994-06-01

sediment-associated toxicant in the lower Fox River and Green Bay , Wisconsin," Environ. Toxicol. Chem. 9, 313-322. Burton, G. A., Jr., Stemmer, B. L...Barton, J. ¶ USEPA, Region X, Seatle, WA Bay . S. It So. CA Coastal Water Research Project, Long Beach, CA Black, J. t EA Engineering, Science and...Umbeck F. I USAGE, Seattle District, Seattle, WA Ward, J. f Battelle Northwest Pacific Laboratory, Sequim , WA Weber, C.¶ USEPA, Cincinnati, OH Welch, T

Saco Bay, Maine: Sediment Budget for Late Twentieth Century to Present

DTIC Science & Technology

2016-02-01

determined that sediment flux was variable, depending on bathymetry and input wave conditions. Despite these variations in conditions, there is no obvious...DETAILS, SACO BAY, MAINE V3. Last update: 11 September 2014 Units are yd3/year. Source1 = bluffs, river influx, wind . Sink1 = wind -blown loss or...Beach05 (B05), Pine Point QSource1 1,600 Wind transport (from Kelley et al. 2005). DeltaV 1,600 Dune accumulation 1859–1991 (from Kelley et al. 2005

Hydraulics and geology related to beach restoration in Lee County, Florida. [Captiva Island

NASA Technical Reports Server (NTRS)

Winton, T. (Principal Investigator); Brooks, H. K.; Degner, J.; Ruth, B.

1981-01-01

The erosion problem on Captiva Island is discussed. It is due to a deficit in the sand budget of the littoral drift system; a system with losses due to attrition of the particles and mass losses into the lagoons, to offshore, and to lateral transport. The effect that reopening Blind Pass would have, and the placement of sediment retaining structures in the surf zone at the northern and southern limits of the Captiva beach system, wave examined. A geological approach was used to study the origin and dynamic changes that have occurred. Through hydraulic modeling, changes that will occur by reopening and stabilizing Blind Pass are predicted. It is concluded that if the island is to be stabilized, beach nourishment with proper amounts and particle size is a necessity and that jetties adequate to restrict lateral and offshore losses are essential. It is shown that the reopening of Blind Pass would have minimal effects on the passes to the north and south, and would improve the environmental conditions in the sound with no adverse effects on the beach system.

Association of Fecal Indicator Bacteria with Human Viruses and Microbial Source Tracking Markers at Coastal Beaches Impacted by Nonpoint Source Pollution

PubMed Central

McQuaig, Shannon; Griffith, John

2012-01-01

Water quality was assessed at two marine beaches in California by measuring the concentrations of culturable fecal indicator bacteria (FIB) and by library-independent microbial source tracking (MST) methods targeting markers of human-associated microbes (human polyomavirus [HPyV] PCR and quantitative PCR, Methanobrevibacter smithii PCR, and Bacteroides sp. strain HF183 PCR) and a human pathogen (adenovirus by nested PCR). FIB levels periodically exceeded regulatory thresholds at Doheny and Avalon Beaches for enterococci (28.5% and 31.7% of samples, respectively) and fecal coliforms (20% and 5.8%, respectively). Adenoviruses were detected at four of five sites at Doheny Beach and were correlated with detection of HPyVs and human Bacteroides HF183; however, adenoviruses were not detected at Avalon Beach. The most frequently detected human source marker at both beaches was Bacteroides HF183, which was detected in 27% of samples. Correlations between FIBs and human markers were much more frequent at Doheny Beach than at Avalon Beach; e.g., adenovirus was correlated with HPyVs and HF183. Human sewage markers and adenoviruses were routinely detected in samples meeting FIB regulatory standards. The toolbox approach of FIB measurement coupled with analysis of several MST markers targeting human pathogens used here demonstrated that human sewage is at least partly responsible for the degradation of water quality, particularly at Doheny Beach, and resulted in a more definitive assessment of recreational water quality and human health risk than reliance on FIB concentrations alone could have provided. PMID:22773625

Is Kissamos Bay in NW Crete, Greece worth to be exploited as a marine aggregates deposit? An integrated approach

NASA Astrophysics Data System (ADS)

Anastasatou, Marianthi; Tsoutsia, Antonia; Petrakis, Stelios; Rousakis, Grigoris; Karditsa, Aikaterini; Hasiotis, Thomas; Kapsimalis, Vasilios; Poulos, Serafim; Stamatakis, Michael

2017-04-01

This study uses an integrated approach to investigate the offshore area of Kissamos Bay, NW Crete Island, Greece, as a prospective marine aggregate (MA) deposit. Non-fuel marine minerals and especially marine aggregates (sand and gravel) are reviewed from the perspective of resources during the last decades. The possible MA deposit of Kissamos Bay was explored during the implementation of the research project THALES-MARE, considering existing information of previous extraction activities in the wider area. Kissamos Bay is located at the inner continental shelf off NW Crete. The onshore basement rocks are composed of Mesozoic to Eocene limestones, shale and sandstone units, along with Neogene sediments such as marls, sandstones and claystones, which locally host Messinian gypsum layers. Sixteen sea-bottom sediment samples were collected with a Smith-McIntyretype grab along four transects, vertical to the shoreline, at water depths of 11 to 44m. A sub-bottom acoustic profiler survey was conducted in order to quantitatively determine the deposit (dimensions and structure). Mineralogical, geochemical, sedimentological and benthic analyses of the samples were carried out, in order to determine the quality of the reservoir and the environmental impact of a potential exploitation. Mineralogical results indicated that the bulk samples consist predominantly of quartz, while calcite occurs as a second significant phase. Chemical analysis of major and trace elements revealed that the average SiO2 content is around 55% with samples closer to the beach (depths <15m) reaching 70%. SO3 content, attributed to the presence of gypsum, is lower than 1%. The Cl- content of the unwashed material reflected mainly the presence of halite and is approximately 0.2%. The results of the benthic analysis indicated that no pressure will occur at the local ecosystem due to a potential exploitation of the deposit. Granulometric analysis of the sediments indicated that the main particle size composition is sand with extended spots of coarser material (gravel) in the western part of the bay, while the finer fraction (mud) increases in greater depths ( 40m). After the analysis of the seismic profiles, it was estimated that the surface area of the deposit is approximately 12.25 km2 and the volume of the sand and gravels is about 0.4 km3, whereas the average specific weight of the sediments in the study area is 2.5-3 g/cm3. The aforementioned results support the idea that Kissamos Bay can be a promising area for marine aggregate exploitation, regarding beach replenishment and the wider construction industry. However, with respect to silica content, a better quality (quartz sand) is required for cement applications. Acknowledgments: This work was supported by the research program THALES-MARE (MIS: 375655), funded by the Operational Programme "Education and lifelong learning, 2007-2013" of the Ministry of Education and Religious Affairs, Culture and Sports.

Confirmation of putative stormwater impact on water quality at a Florida beach by microbial source tracking methods and structure of indicator organism populations.

PubMed

Brownell, M J; Harwood, V J; Kurz, R C; McQuaig, S M; Lukasik, J; Scott, T M

2007-08-01

The effect of a stormwater conveyance system on indicator bacteria levels at a Florida beach was assessed using microbial source tracking methods, and by investigating indicator bacteria population structure in water and sediments. During a rain event, regulatory standards for both fecal coliforms and Enterococcus spp. were exceeded, contrasting with significantly lower levels under dry conditions. Indicator bacteria levels were high in sediments under all conditions. The involvement of human sewage in the contamination was investigated using polymerase chain reaction (PCR) assays for the esp gene of Enterococcus faecium and for the conserved T antigen of human polyomaviruses, all of which were negative. BOX-PCR subtyping of Escherichia coli and Enterococcus showed higher population diversity during the rain event; and higher population similarity during dry conditions, suggesting that without fresh inputs, only a subset of the population survives the selective pressure of the secondary habitat. These data indicate that high indicator bacteria levels were attributable to a stormwater system that acted as a reservoir and conduit, flushing high levels of indicator bacteria to the beach during a rain event. Such environmental reservoirs of indicator bacteria further complicate the already questionable relationship between indicator organisms and human pathogens, and call for a better understanding of the ecology, fate and persistence of indicator bacteria.

Equilibrium shoreline response of a high wave energy beach

USGS Publications Warehouse

Yates, M.L.; Guza, R.T.; O'Reilly, W. C.; Hansen, J.E.; Barnard, P.L.

2011-01-01

Four years of beach elevation surveys at Ocean Beach, San Francisco, California, are used to extend an existing equilibrium shoreline change model, previously calibrated with fine sand and moderate energy waves, to medium sand and higher-energy waves. The shoreline, characterized as the cross-shore location of the mean high water contour, varied seasonally by between 30 and 60 m, depending on the alongshore location. The equilibrium shoreline change model relates the rate of horizontal shoreline displacement to the hourly wave energy E and the wave energy disequilibrium, the difference between E and the equilibrium wave energy that would cause no change in the present shoreline location. Values for the model shoreline response coefficients are tuned to fit the observations in 500 m alongshore segments and averaged over segments where the model has good skill and the estimated effects of neglected alongshore sediment transport are relatively small. Using these representative response coefficients for 0.3 mm sand from Ocean Beach and driving the model with much lower-energy winter waves observed at San Onofre Beach (also 0.3 mm sand) in southern California, qualitatively reproduces the small seasonal shoreline fluctuations at San Onofre. This consistency suggests that the shoreline model response coefficients depend on grain size and may be constant, and thus transportable, between sites with similar grain size and different wave climates. The calibrated model response coefficients predict that for equal fluctuations in wave energy, changes in shoreline location on a medium-grained (0.3 mm) beach are much smaller than on a previously studied fine-grained (0.2 mm) beach. Copyright ?? 2011 by the American Geophysical Union.

Geographic setting influences Great Lakes beach microbiological water quality

USGS Publications Warehouse

Haack, Sheridan K.; Fogarty, Lisa R.; Stelzer, Erin A.; Fuller, Lori M.; Brennan, Angela K.; Isaacs, Natasha M.; Johnson, Heather E.

2013-01-01

Understanding of factors that influence Escherichia coli (EC) and enterococci (ENT) concentrations, pathogen occurrence, and microbial sources at Great Lakes beaches comes largely from individual beach studies. Using 12 representative beaches, we tested enrichment cultures from 273 beach water and 22 tributary samples for EC, ENT, and genes indicating the bacterial pathogens Shiga-toxin producing E. coli (STEC), Shigella spp., Salmonella spp, Campylobacter jejuni/coli, and methicillin-resistant Staphylococcus aureus, and 108–145 samples for Bacteroides human, ruminant, and gull source-marker genes. EC/ENT temporal patterns, general Bacteroides concentration, and pathogen types and occurrence were regionally consistent (up to 40 km), but beach catchment variables (drains/creeks, impervious surface, urban land cover) influenced exceedances of EC/ENT standards and detections of Salmonella and STEC. Pathogen detections were more numerous when the EC/ENT Beach Action Value (but not when the Geometric Mean and Statistical Threshold Value) was exceeded. EC, ENT, and pathogens were not necessarily influenced by the same variables. Multiple Bacteroides sources, varying by date, occurred at every beach. Study of multiple beaches in different geographic settings provided new insights on the contrasting influences of regional and local variables, and a broader-scale perspective, on significance of EC/ENT exceedances, bacterial sources, and pathogen occurrence.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burch, T.L.; Sherwood, C.R.

Large changes in the distribution of sediment near the entrance to Grays Harbor, Washington, have occurred since the long rock jetties were built to confine flow. Spits to the north and south of the entrance have grown, the entrance channel has deepened, and the outer bar has eroded and moved offshore. The shorelines of North Beach and South Beach have experienced significant amounts of both erosion and accretion since the jetties were constructed around the turn of the century. Recently, the erosion rate at South Beach has increased and, because Half Moon Bay is growing at the expense of themore » shoreward side of Point Chehalis, the vegetated portion of the spit is now less than 350 ft wide at the narrowest section. The US Army Corps of Engineers, Seattle District, requested that Battelle/Marine Sciences Laboratory evaluate long-term trends in erosion near the entrance to Grays Harbor.« less

Modes and emergent time scales of embayed beach dynamics

NASA Astrophysics Data System (ADS)

Ratliff, Katherine M.; Murray, A. Brad

2014-10-01

In this study, we use a simple numerical model (the Coastline Evolution Model) to explore alongshore transport-driven shoreline dynamics within generalized embayed beaches (neglecting cross-shore effects). Using principal component analysis (PCA), we identify two primary orthogonal modes of shoreline behavior that describe shoreline variation about its unchanging mean position: the rotation mode, which has been previously identified and describes changes in the mean shoreline orientation, and a newly identified breathing mode, which represents changes in shoreline curvature. Wavelet analysis of the PCA mode time series reveals characteristic time scales of these modes (typically years to decades) that emerge within even a statistically constant white-noise wave climate (without changes in external forcing), suggesting that these time scales can arise from internal system dynamics. The time scales of both modes increase linearly with shoreface depth, suggesting that the embayed beach sediment transport dynamics exhibit a diffusive scaling.

Storm-induced inner-continental shelf circulation and sediment transport: Long Bay, South Carolina

USGS Publications Warehouse

Warner, John C.; Armstrong, Brandy N.; Sylvester, Charlene S.; Voulgaris, George; Nelson, Tim; Schwab, William C.; Denny, Jane F.

2012-01-01

Long Bay is a sediment-starved, arcuate embayment located along the US East Coast connecting both South and North Carolina. In this region the rates and pathways of sediment transport are important because they determine the availability of sediments for beach nourishment, seafloor habitat, and navigation. The impact of storms on sediment transport magnitude and direction were investigated during the period October 2003–April 2004 using bottom mounted flow meters, acoustic backscatter sensors and rotary sonars deployed at eight sites offshore of Myrtle Beach, SC, to measure currents, water levels, surface waves, salinity, temperature, suspended sediment concentrations, and bedform morphology. Measurements identify that sediment mobility is caused by waves and wind driven currents from three predominant types of storm patterns that pass through this region: (1) cold fronts, (2) warm fronts and (3) low-pressure storms. The passage of a cold front is accompanied by a rapid change in wind direction from primarily northeastward to southwestward. The passage of a warm front is accompanied by an opposite change in wind direction from mainly southwestward to northeastward. Low-pressure systems passing offshore are accompanied by a change in wind direction from southwestward to southeastward as the offshore storm moves from south to north.During the passage of cold fronts more sediment is transported when winds are northeastward and directed onshore than when the winds are directed offshore, creating a net sediment flux to the north–east. Likewise, even though the warm front has an opposite wind pattern, net sediment flux is typically to the north–east due to the larger fetch when the winds are northeastward and directed onshore. During the passage of low-pressure systems strong winds, waves, and currents to the south are sustained creating a net sediment flux southwestward. During the 3-month deployment a total of 8 cold fronts, 10 warm fronts, and 10 low-pressure systems drove a net sediment flux southwestward. Analysis of a 12-year data record from a local buoy shows an average of 41 cold fronts, 32 warm fronts, and 26 low-pressure systems per year. The culmination of these events would yield a cumulative net inner-continental shelf transport to the south–west, a trend that is further verified by sediment textural analysis and bedform morphology on the inner-continental shelf.

The influence of ice on southern Lake Michigan coastal erosion

USGS Publications Warehouse

Barnes, P.W.; Kempema, E.W.; Reimnitz, E.; McCormick, M.

1994-01-01

Coastal ice does not protect the coast but enhances erosion by displacing severe winter wave energy from the beach to the shoreface and by entraining and transporting sediment alongshore and offshore. Three aspects of winter ice in Lake Michigan were studied over a 3-year period and found to have an important influence on coastal sediment dynamics and the coastal sediment budget: (1) the influence of coastal ice on shoreface morphology, (2) the transport of littoral sediments by ice, and (3) the formation of anchor and underwater ice as a frequent and important event entraining and transporting sediment. The nearshore ice complex contains a sediment load (0.2 - 1.2 t/m of coast) that is roughly equivalent to the average amount of sand eroded from the coastal bluffs and to the amount of sand ice- rafted offshore to the deep lake basin each year. -from Authors

PROTECTING HEALTH WITH SAME DAY WATER QUALITY MONITORING RESULTS FOR BATHING BEACHES

EPA Science Inventory

Current US Environmental Protection Agency guidelines recommend the use of cultural methods for E. coli and enterococci to monitor beach water quality. The guidelines recommend a single sample value or a geometric mean value from at least five samples. The single sample guideli...

Some problems associated with the analysis and interpretation of mixed carbonate and quartz beach sands, illustrated by examples from North-West Ireland

NASA Astrophysics Data System (ADS)

Carter, R. W. G.

1982-09-01

Mixes of carbonate and quartz sands, which are commonly encountered in Recent coastal sediments, require careful analysis if they are to be correctly interpreted. Grain-size data fall into multimodal or segmented zig-zag distributions which may require some kind of component separation if they are to be summarised by conventional statistics, and before they can be assigned to a particular hydrodynamic depositional process or environment. Unfortunately, separation techniques are only spasmodically applied, usually without due regard to the consequences. Such artificially filtered or truncated distributions are of little subsequent use. Using a range of samples from two beaches in NW Ireland, where carbonate proportions range from nearly zero to over sixty percent, the interrelationships of the two dominant components were examined. Where only a small carbonate proportion is incorporated into a large quartz one, predictable modifications of the size-curve are apparent. However, the components are more independent if mixtures are near equal. The occurrence of a number of distinctive combinations of simple straight lines and complex zig-zag curves probably reflects the relatively dynamic nature of the carbonate fraction.

Population biology of the gastropod Olivella minuta (Gastropoda, Olividae) on two sheltered beaches in southeastern Brazil

NASA Astrophysics Data System (ADS)

Petracco, Marcelo; Camargo, Rita Monteiro; Tardelli, Daniel Teixeira; Turra, Alexander

2014-10-01

The structure, dynamics and production of two populations of the olivid gastropod Olivella minuta were analyzed through monthly sampling from November 2009 through October 2011 on two sandy beaches, Pernambuco (very sheltered) and Barequeçaba (sheltered) in São Paulo state (23°48'S), southeastern Brazil. On both beaches, samples were taken along five transects established perpendicular to the waterline. Parameters of the von Bertalanffy growth function were estimated for both populations from monthly length-frequency distributions. The production and turnover ratios were determined using the mass-specific growth rate method. The population on the less-sheltered Barequeçaba Beach was less abundant (120.02 ± 22.60 ind m-1) than on Pernambuco Beach (3295.30 ± 504.86 ind m-1 (±SE)), which we attribute to the greater environmental stability of the latter. Conversely, the mean length, size of the largest individual, and body mass were higher at Barequeçaba than at Pernambuco. The significant differences in the growth of individuals and the mortality rate (Z) between the beaches suggest that density-dependent processes were operating at Pernambuco Beach. The production and P/B ratio at Pernambuco (12.12 g AFDM m-1 year-1 and 1.91 year-1) were higher than at Barequeçaba (0.82 g AFDM m-1 year-1 and 1.06 year-1). The difference in production can be attributed to the higher abundance on Pernambuco, while the higher P/B ratio resulted from the scarcity of smaller individuals in the intertidal zone of Barequeçaba. The P/B ratio estimated for the Pernambuco population is the highest found so far for sandy-beach gastropods. This study reinforces the theory that biological interactions are important regulators of sheltered sandy-beach populations. Future studies with multi-beach sampling are needed to better understand the life-history variations of O. minuta along gradients of degree of exposure of sandy beaches.

Fine-grained sediment dispersal along the California coast

USGS Publications Warehouse

Warrick, Jonathan A.; Storlazzi, Curt D.

2013-01-01

Fine-grained sediment (silt and clay) enters coastal waters from rivers, eroding coastal bluffs, resuspension of seabed sediment, and human activities such as dredging and beach nourishment. The amount of sediment in coastal waters is an important factor in ocean ecosystem health, but little information exists on both the natural and human-driven magnitudes of fine-grained sediment delivery to the coastal zone, its residence time there, and its transport out of the system—information upon which to base environmental assessments. To help fill these information gaps, the U.S. Geological Survey has partnered with Federal, State, and local agencies to monitor fine-grained sediment dispersal patterns and fate in the coastal regions of California. Results of these studies suggest that the waves and currents of many of the nearshore coastal settings of California are adequately energetic to transport fine-grained sediment quickly through coastal systems. These findings will help with the management and regulation of fine-grained sediment along the U.S. west coast.

Bathymetric Changes Shaped by Longshore Currents on a Natural Beach

NASA Astrophysics Data System (ADS)

Reilly, W. L.; Slinn, D.; Plant, N.

2004-12-01

The goal of the project is to simulate beach morphology on time scales of hours to days. Our approach is to develop finite difference solutions from a coupled modeling system consisting of existing nearshore circulation, wave, and sediment flux models. We initialize the model with bathymetry from a dense data set north of the pier at the Field Research Facility (FRF) in Duck, NC. We integrate the model system forward in time and compare the results of the hind-cast of the beach evolution with the field observations. The model domain extends 1000 meters in the alongshore direction and 500 meters in the cross-shore direction with 5 meter grid spacing. The bathymetry is interpolated and filtered from CRAB transects. A second-degree exponential smoothing method is used to return the cross-shore beach profile near the edges of the modeled domain back to the mean alongshore profile, because the circulation model implements periodic boundary conditions in the alongshore direction. The offshore wave height and direction are taken from the 8-meter bipod at the FRF and input to the wave-model, SWAN (Spectral Wave Nearshore), with a Gaussian-shaped frequency spectrum and a directional spreading of 5 degrees. A constant depth induced wave breaking parameter of 0.73 is used. The resulting calculated wave induced force per unit surface area (gradient of the radiation stress) output from SWAN is used to drive the currents in the circulation model. The circulation model is based on the free-surface non-linear shallow water equations and uses the fourth order compact scheme to calculate spatial derivatives and a third order Adams-Bashforth time discretization scheme. Free slip, symmetry boundary conditions are applied at both the shoreline and offshore boundaries. The time averaged sediment flux is calculated at each location after one hour of circulation. The sediment flux model is based on the approach of Bagnold and includes approximations for both bed-load and suspended load. The bathymetry is then updated by computing the divergence of the time averaged sediment fluxes. The process is then repeated using the updated bathymetry in both SWAN and the circulation model. The cycle continues for a simulation of 10 hours. The results of bathymetric change vary for different time-dependent wave conditions and initial bathymetric profiles. Typical results indicate that for wave heights on the order of one meter, shoreline advancement and sandbar evolution is observed on the order of tens of centimeters.

Assessment of offshore New Jersey sources of Beach replenishment sand by diversified application of geologic and geophysical methods

USGS Publications Warehouse

Waldner, J.S.; Hall, D.W.; Uptegrove, J.; Sheridan, R.E.; Ashley, G.M.; Esker, D.

1999-01-01

Beach replenishment serves the dual purpose of maintaining a source of tourism and recreation while protecting life and property. For New Jersey, sources for beach sand supply are increasingly found offshore. To meet present and future needs, geologic and geophysical techniques can be used to improve the identification, volume estimation, and determination of suitability, thereby making the mining and managing of this resource more effective. Current research has improved both data collection and interpretation of seismic surveys and vibracore analysis for projects investigating sand ridges offshore of New Jersey. The New Jersey Geological Survey in cooperation with Rutgers University is evaluating the capabilities of digital seismic data (in addition to analog data) to analyze sand ridges. The printing density of analog systems limits the dynamic range to about 24 dB. Digital acquisition systems with dynamic ranges above 100 dB can permit enhanced seismic profiles by trace static correction, deconvolution, automatic gain scaling, horizontal stacking and digital filtering. Problems common to analog data, such as wave-motion effects of surface sources, water-bottom reverberation, and bubble-pulse-width can be addressed by processing. More than 160 line miles of digital high-resolution continuous profiling seismic data have been collected at sand ridges off Avalon, Beach Haven, and Barnegat Inlet. Digital multichannel data collection has recently been employed to map sand resources within the Port of New York/New Jersey expanded dredge-spoil site located 3 mi offshore of Sandy Hook, New Jersey. Multichannel data processing can reduce multiples, improve signal-to-noise calculations, enable source deconvolution, and generate sediment acoustic velocities and acoustic impedance analysis. Synthetic seismograms based on empirical relationships among grain size distribution, density, and velocity from vibracores are used to calculate proxy values for density and velocity. The seismograms are then correlated to the digital seismic profile to confirm reflected events. They are particularly useful where individual reflection events cannot be detected but a waveform generated by several thin lithologic units can be recognized. Progress in application of geologic and geophysical methods provides advantages in detailed sediment analysis and volumetric estimation of offshore sand ridges. New techniques for current and ongoing beach replenishment projects not only expand our knowledge of the geologic processes involved in sand ridge origin and development, but also improve our assessment of these valuable resources. These reconnaissance studies provide extensive data to the engineer regarding the suitability and quantity of sand and can optimize placement and analysis of vibracore samples.Beach replenishment serves the dual purpose of maintaining a source of tourism and recreation while protecting life and property. Research has improved both data collection and interpretation of seismic surveys and vibracore analysis for projects investigating sand ridges offshore of New Jersey. The New Jersey Geological Survey in cooperation with Rutgers University is evaluating the capabilities of digital seismic data to analyze sand ridges. The printing density of analog systems limits the dynamic range to about 24 dB. Digital acquisition systems with dynamic ranges about 100 dB can permit enhanced seismic profiles by trace static correction, deconvolution, automatic gain scaling, horizontal stacking and digital filtering.

Storm impacts on a high energy sandy beach system, northwest Ireland: short (event) to long term (decadal) behaviour

NASA Astrophysics Data System (ADS)

Guisado-Pintado, Emilia; Jackson, Derek; Cooper, Andrew; O'Connor, Marianne

2017-04-01

Long-term monitoring of beach dynamics is an important element in risk prevention and management of both natural and human resources at the coast. The predicted intensification in storminess (frequency, duration and magnitude), partly associated with climate change, represents a pressing concern for coastal communities globally and has undoubtedly led to an improvement in available techniques and technologies for observation and analysis. Here we examine a high energy Atlantic beach system at Five Fingers strand (NW Ireland) to help understand hydrodynamic forcing on beach response under various wave energy scenarios. The system, which has been modally attuned to a large swell wave environment, periodically undergoes significant morphological changes over various spatial and temporal scales manifest in the development and movements of dynamic nearshore bars and a nearshore ebb-tide delta. A combination of field and laboratory techniques (GPS, Terrestrial Laser Scanning (TLS) Instrumentation, Drone surveys) implemented from the shoreface to the beach, captures the response and evolution of the system over the short (event), medium (weeks to months) and long-term (multiyear) timescale. Numerical modelling of nearshore wave hydrodynamics (using SWAN wave simulation model) helps understanding wave forcing across shoreface area and is ran under a number of iterative time intervals. Here, we investigate the role of infrequent and sometimes extreme events in the system to understand the importance of clustering of storminess and the occurrence of single high-magnitude storm events that perturb the inlet-beach system and thus induce key morphodynamic changes. Preliminary results show that ultimately the configuration of the ebb-tide channel influences the geomorphic response of the system. In the short term, a storm induced erosion of the shoreface is observed, which also appears to lead to changes in the ebb-tide channel, and ultimately the welding of a nearshore bar system at the northern part of the site over the medium to long term. We also observe that modal conditions favour intertidal beach recovery in the short and medium term, with a resulting southerly drift of sediment with an offshore return of sediment via the ebb-channel (multi-year response). This work demonstrates that coastal hazard analysis, approached at an appropriate site-specific scale and with suitable numerical modelling and field techniques, must include capturing data on nearshore forcing parameters that are driving shoreline response over various timescales. Understanding of these nearshore and intertidal morphodynamics is an important prelude to examining how a sandy shoreline behaves in response to high energy forcing. We advocate that morphodynamic self-adjustment of the beach system to a set of varying climatic conditions associated with increases in storminess, will have important implications for future coastline response.