Surf Zone Sediment Size Variation, Morphodynamics, and Hydrodynamics During Sea/Land Breeze and El-Norte Storm in Sisal, Yucatan, Mexico

NASA Astrophysics Data System (ADS)

Alrushaid, T.; Figlus, J.; Torres-Freyermuth, A.; Puleo, J. A.; Dellapenna, T. M.

2016-02-01

Coastlines around the world are under ever-increasing pressure due to population trends, commerce, and geophysical processes like tropical storms and erosion. This multi-institutional field campaign was conducted to improve our understanding of complex nearshore processes under varying forcing conditions on a microtidal, sandy beach located in Sisal, Yucatan from 3/27 to 4/12/2014. Hydrodynamics, morphodynamics, and textural variability were investigated during: (1) a cold front event (referred to as El-Norte); (2) land breeze (LB); and (3) sea breeze (SB). The instrumentation layout included three surf/swash zone cross-shore transects where water elevation, suspended sediment concentration, bed load, and current velocities were measured, as well as several offshore ADCP for hydrodynamic measurements. TKE, τb, ɛ and were estimated using the data obtained from surf zone ADV. In addition, Hs and Tsin the surf zone were computed using measurements from ADV pressure sensors, while a separate pressure transducer was used to obtain water free-surface elevation within the swash zone. During SB cycles the study area experienced wind velocities reaching up to 12ms-1, and 15ms-1 during El-Norte. Elevated wind stress during El-Norte resulted in Hs of 1.5m and 0.6m in water depths of 10m and 0.4m, respectively. Surface sediment grab samples during SB/LB cycles showed that the swash zone had a moderately well sorted distribution with a mean grain size of 0.5mm, while poor sorting and a mean grain size of 0.7mm were found during El-Norte. Additionally, measured bathymetry data showed evidence for offshore sandbar migration during strong offshore currents (0.4ms-1) during El-Norte, while onshore sandbar migration was evident during SB/LB periods (0.3ms-1 and 0.1ms-1, respectively). This study highlights how different weather forcing conditions affect hydrodynamics, morphodynamics, and textural variability on a sandy beach. Aside from furthering our knowledge on these complex processes, the findings may lead to improved coastal management strategies for sandy coastlines.

Setting conservation targets for sandy beach ecosystems

NASA Astrophysics Data System (ADS)

Harris, Linda; Nel, Ronel; Holness, Stephen; Sink, Kerry; Schoeman, David

2014-10-01

Representative and adequate reserve networks are key to conserving biodiversity. This begs the question, how much of which features need to be placed in protected areas? Setting specifically-derived conservation targets for most ecosystems is common practice; however, this has never been done for sandy beaches. The aims of this paper, therefore, are to propose a methodology for setting conservation targets for sandy beach ecosystems; and to pilot the proposed method using data describing biodiversity patterns and processes from microtidal beaches in South Africa. First, a classification scheme of valued features of beaches is constructed, including: biodiversity features; unique features; and important processes. Second, methodologies for setting targets for each feature under different data-availability scenarios are described. From this framework, targets are set for features characteristic of microtidal beaches in South Africa, as follows. 1) Targets for dune vegetation types were adopted from a previous assessment, and ranged 19-100%. 2) Targets for beach morphodynamic types (habitats) were set using species-area relationships (SARs). These SARs were derived from species richness data from 142 sampling events around the South African coast (extrapolated to total theoretical species richness estimates using previously-established species-accumulation curve relationships), plotted against the area of the beach (calculated from Google Earth imagery). The species-accumulation factor (z) was 0.22, suggesting a baseline habitat target of 27% is required to protect 75% of the species. This baseline target was modified by heuristic principles, based on habitat rarity and threat status, with final values ranging 27-40%. 3) Species targets were fixed at 20%, modified using heuristic principles based on endemism, threat status, and whether or not beaches play an important role in the species' life history, with targets ranging 20-100%. 4) Targets for processes and 5) important assemblages were set at 50%, following other studies. 6) Finally, a target for an outstanding feature (the Alexandria dunefield) was set at 80% because of its national, international and ecological importance. The greatest shortfall in the current target-setting process is in the lack of empirical models describing the key beach processes, from which robust ecological thresholds can be derived. As for many other studies, our results illustrate that the conservation target of 10% for coastal and marine systems proposed by the Convention on Biological Diversity is too low to conserve sandy beaches and their biota.

Morphodynamic rotation of an embayed sandy beach in a mud-dominated setting

NASA Astrophysics Data System (ADS)

Brunier, Guillaume; Anthony, Edward; Gardel, Antoine; Millet, Bertrand; Fleury, Jules; Dussouillez, Philippe

2016-04-01

The morphodynamics of beaches between bedrock headlands along the muddy French Guiana coast in South America are controlled by rotation induced by the alongshore migration of mud banks from the mouths of the Amazon River. As they migrate alongshore, these mud banks generate changes in shore-incident wave angles, resulting in reversals in longshore drift. A poor appreciation of the problems caused by this process has resulted in the past in damages to the highly urbanized sea-fronts on these beaches, including erosion and flooding. This work enhances our understanding of this rather unusual type of mud-induced rotation based on surveys of the 4 km-long Montjoly beach near Cayenne, in French Guiana, in the course of an approaching mud bank between October 2013 and October 2014. Our method was based on innovative high-resolution topographic surveys from airborne Structure-from-Motion (SfM) photogrammetry over the beach in October 2013, March 2014 and October 2014. We produced digital surface models (DSM) with a resolution of 10 cm/pixel and an accuracy less than 10 cm from RTK-GPS measurements. We further measured incident wave heights from pressure sensors and conducted a bathymetric survey of the nearshore zone in October 2014. We also modelled high-tide wave propagation over the bathymetry using the REF/DIF v2.5 model. The results show the transfer of sand from the northern part of beach to the south between October 2013 and March 2014. The October 2013 DSM shows a reflective beach in the north indicative of erosion, with a narrow 50 m-wide upper beach. The southern sector was smoother and up to 90 m-wide. Between October 2013 and March 2014, the beach rotated under the influence of a mud bank, with a 30-m retreat of the berm in the north and an advance of 40 m in the south. We quantified a loss of ≈66,000 m³ of sand in the north and a gain of ≈22,000 m³ in the south over this six-month period. The October 2014 DSM shows minor morphological changes, thus indicating the end of the rotation around March 2014 and the beginning of a phase of nearshore mud-bounding of the beach as the mud bank migrated westward. The bathymetric survey showed a 2 m-high and 100 m-wide mud bar in the nearshore zone that dissipated wave energy. Hydrodynamic monitoring between March and October 2014 confirmed this low wave-energy regime (Hs < 0.5 m) compared to a more energetic regime in the neighbouring Montabo Bay beach (Hs up to 1.5 m) located downdrift of the mud bank. The REF/DIF model confirmed the strong wave energy dissipation over the mud bar. Our study highlights the rapidity and intensity of the morphodynamic changes these beaches can undergo in a muddy context, and the need for continuous and accurate monitoring in order to assess the erosion hazard caused by rotation. Keywords: Beach rotation; Mud banks; aerial SFM photogrammetry; bathymetric monitoring; hydrodynamic modelling; REF/DIF model.

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.

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.

Issues to Be Considered in Counting Burrows as a Measure of Atlantic Ghost Crab Populations, an Important Bioindicator of Sandy Beaches

PubMed Central

Pombo, Maíra; Turra, Alexander

2013-01-01

The use of indirect estimates of ghost-crab populations to assess beach disturbance has several advantages, including non-destructiveness, ease and low cost, although this strategy may add some degree of noise to estimates of population parameters. Resolution of these shortcomings may allow wider use of these populations as an indicator of differences in quality among beaches. This study analyzed to what extent the number of crab burrows may diverge from the number of animals, considering beach morphology, burrow depth and signs of occupation as contributing factors or indicators of a higher or lower occupation rate. We estimated the occupation rate of crabs in burrows on nine low-use beaches, which were previously categorized as dissipative, intermediate or reflexive. Three random 2-m-wide transects were laid perpendicular to the shoreline, where burrows were counted and excavated to search for crabs. The depth and signs of recent activity around the burrows were also recorded. The occupation rate differed on the different beaches, but morphodynamics was not identified as a grouping factor. A considerable number of burrows that lacked signs of recent activity proved to be occupied, and the proportions of these burrows also differed among beaches. Virtually all burrows less than 10 cm deep were unoccupied; the occupation rate tended to increase gradually to a burrow depth of 20–35 cm. Other methods (water, smoke, and traps) were applied to measure the effectiveness of excavating as a method for burrow counts. Traps and excavation proved to be the best methods. These observations illustrate the possible degree of unreliability of comparisons of beaches based on indirect measures. Combining burrow depth assessment with surrounding signs of occupation proved to be a useful tool to minimize biases. PMID:24376748

Mixed sand and gravel beaches: accurate measurement of active layer depth and sediment transport volumes using PIT tagged tracer pebbles

NASA Astrophysics Data System (ADS)

Holland, A.; Moses, C.; Sear, D. A.; Cope, S.

2016-12-01

As sediments containing significant gravel portions are increasingly used for beach replenishment projects globally, the total number of beaches classified as `mixed sand and gravel' (MSG) increases. Calculations for required replenishment sediment volumes usually assume a uniform layer of sediment transport across and along the beach, but research into active layer (AL) depth has shown variations both across shore and according to sediment size distribution. This study addresses the need for more accurate calculations of sediment transport volumes on MSG beaches by using more precise measurements of AL depth and width, and virtual velocity of tracer pebbles. Variations in AL depth were measured along three main profile lines (from MHWS to MLWN) at Eastoke, Hayling Island (Hampshire, UK). Passive Integrated Transponder (PIT) tagged pebbles were deployed in columns, and their new locations repeatedly surveyed with RFID technology. These data were combined with daily dGPS beach profiles and sediment sampling for detailed analysis of the influence of beach morphodynamics on sediment transport volumes. Data were collected over two consecutive winter seasons: 2014-15 (relatively calm, average wave height <1 m) and 2015-16 (prolonged periods of moderate storminess, wave heights of 1-2 m). The active layer was, on average, 22% of wave height where beach slope (tanβ) is 0.1, with variations noted according to slope angle, sediment distribution, and beach groundwater level. High groundwater levels and a change in sediment proportions in the sandy lower foreshore reduced the AL to 10% of wave height in this area. The disparity in AL depth across the beach profile indicates that traditional models are not accurately representing bulk sediment transport on MSG beaches. It is anticipated that by improving model inputs, beach managers will be better able to predict necessary volumes and sediment grain size proportions of replenishment material for effective management of MSG beaches.

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.

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.

Response to storm conditions of two different beaches at the Mediterranean coast of Morocco

NASA Astrophysics Data System (ADS)

El Mrini, Aldelmounim; Anfuso, Giorgio; Nachite, Driss; Taaouati, Mohamed

2010-05-01

In recent decades the increased demand for the recreational use of beaches has resulted in the uptake of studies on the morphodynamic processes which are acting on beaches. This knowledge is fundamental for appropriate coastal erosion management, suitable tourist use of littoral and for the design and shape of human construction. The Mediterranean sectors of Moroccan littoral investigated in this study, Ksar Rimal and Cabo Negro beaches, are respectively located north and south of Cabo Negro promontory and, over recent years, have been subject to increasing tourist activity. This has consisted mainly of the construction of two tourist ports (Marina Smir and Kabila), residential developments, hotels and a motorway which runs parallel to the coast, affecting the dune ridges and two lagoons which are of great ecological interest. In detail, the dunes located in the backshore at Ksar Rimal beach, are nowadays occupied by summer houses threaten by coastal retreat. A wide, partially urbanized, backshore is observed at Cabo Negro beach. With the intention of characterize the morphodynamic and seasonal behavior and the response of the studied beaches to storm impact, a beach monitoring program was carried out in the period 2006-2008, with special attention to the February-March 2008 stormy period. On analyzing the information obtained, it was possible to characterize the morphology and sedimentology of the studied beaches, and to calculate beach volumetric variations. Ksar Rimal is an open, exposed beach characterized by an intermediate slope (tan β = 0.10) with medium-coarse sands. The beach showed a reflective beach state characterized by plunging breakers. Small morphological seasonal changes were observed, most important morphological and volumetric variations (about 20 m3/m) taking place after winter storms which usually gave rise to a more dissipative beach profile (tan β = 0.05) characterized by spilling breakers. Beach recovery was quite rapid, usually lasting 2-3 weeks. Cabo Negro beach is a partially sheltered area (because of Cabo Negro promontory) and shows a smooth, dissipative slope (tan β = 0.02) characterized by spilling breakers. Small seasonal morphological changes took place and erosion processes associated with storm events did not produce changes in beach slope and morphodynamic state.

Chenier plain genesis explained by feedbacks between waves, mud, and sand

NASA Astrophysics Data System (ADS)

Nardin, William; Fagherazzi, Sergio

2017-04-01

Cheniers are sandy ridges parallel to the coast established by high energy waves. Here we discuss ontogeny of chenier plains through dimensional analysis and numerical results from the morphodynamic model Delft3D-SWAN. Our results show that wave energy and inner-shelf slope play an important role in the formation of chenier plains. In our numerical experiments, waves affect chenier plain development in three ways: by winnowing coarse sediment from the mudflat, by eroding mud and accumulating sand over the beach during extreme wave events. We further show that different sediment characteristics and wave climates can lead to three alternative coastal landscapes: strand plains, mudflats, or the more complex chenier plains. Low inner-shelf slopes are the most favorable for strand plain and chenier plain formation, while high slopes decrease the likelihood of mudflat development and preservation.

Chenier plain development: feedbacks between waves, mud and sand

NASA Astrophysics Data System (ADS)

Nardin, W.; Fagherazzi, S.

2015-12-01

Cheniers are sandy ridges parallel to the coast established by high energy waves. Here we discuss Chenier plains ontogeny through dimensional analysis and numerical results from the morphodynamic model Delft3D-SWAN. Our results show that wave energy and shelf slope play an important role in the formation of Chenier plains. In our numerical experiments waves affect Chenier plain development in three ways: by winnowing sediment from the mudflat, by eroding mud and accumulating sand over the beach during extreme wave events. We further show that different sediment characteristics and wave climates can lead to three alternative coastal landscapes: strand plains, mudflats, or the more complex Chenier plains. Low inner-shelf slopes are the most favorable for strand plain and Chenier plain formation, while high slopes decrease the likelihood of mudflat development and preservation.

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.

[Fish community structure and its seasonal change in subtidal sandy beach habitat off southern Gouqi Island].

PubMed

Wang, Zhen-Hua; Wang, Kai; Zhao, Jing; Zhang, Shou-Yu

2011-05-01

To understand the characteristics of fish community structure in sandy beach habitats of island reef water areas, and to evaluate the potential capacity of these habitats in local fish stock maintenance, fishes were monthly collected with multi-mesh trammel nets in 2009 from the subtidal sandy beach habitat off southern Gouqi Island, taking the adjacent rocky reef habitat as the control. alpha and beta species diversity indices, index of relative importance (IRI), relative catch rate, and dominance curve for abundance and biomass (ABC curve) were adopted to compare the fish species composition, diversity, and community pattern between the two habitats, and multivariate statistical analyses such as non-metric multidimensional scaling (nMDS) and cluster were conducted to discuss the fish assemblage patterns. A total of 63 fish species belonging to 11 orders, 38 families, and 56 genera were collected, of which, 46 fish species were appeared in the two habitats. Due to the appearance of more warm water species in sandy bottom, the fishes in subtidal sandy beach habitat showed much higher richness, and the abundance catch rate (ACR) from May to July was higher than that in rocky reef habitat. In most rest months, the ACR in subtidal sandy beach habitat also showed the similar trend. However, the species richness and diversity in spring and summer were significantly lower in subtidal sandy beach habitat than in rocky reef habitat, because of the high species dominance and low evenness in the sandy beach habitat. Japanese tonguefish (Paraplagusia japonica) was the indicator species in the sandy beach habitat, and dominated in early spring, later summer, autumn, and winter when the fishing pressure was not strong. In sandy bottom, a unique community structure was formed and kept in dynamic, due to the nursery use of sandy beach by Japanese anchovy (Engraulis japonicus) from May to July, the gathering of gray mullet (Mugil cephalus) in most months for feeding, and the large quantity appearance of plotosid catfish (Plotosus anguillaris) in early Autumn, which was quite different from the community structure pattern dominated by reef fishes in rocky-algae habitat. The subtidal sandy bottom off Gouqi Island was serving as both nursery and feeding grounds for many fish species, being a suitable habitat for flatfishes. It was concluded that the sandy beaches around Gouqi Island could be a very important habitat for economic fish species, especially as a nursery ground for juvenile fishes, contributing to the fish stock maintenance in specific area.

Improving understanding of near-term barrier island evolution through multi-decadal assessment of morphologic change

USGS Publications Warehouse

Lentz, Erika E.; Hapke, Cheryl J.; Stockdon, Hilary F.; Hehre, Rachel E.

2013-01-01

Observed morphodynamic changes over multiple decades were coupled with storm-driven run-up characteristics at Fire Island, New York, to explore the influence of wave processes relative to the impacts of other coastal change drivers on the near-term evolution of the barrier island. Historical topography was generated from digital stereo-photogrammetry and compared with more recent lidar surveys to quantify near-term (decadal) morphodynamic changes to the beach and primary dune system between the years 1969, 1999, and 2009. Notably increased profile volumes were observed along the entirety of the island in 1999, and likely provide the eolian source for the steady dune crest progradation observed over the relatively quiescent decade that followed. Persistent patterns of erosion and accretion over 10-, 30-, and 40-year intervals are attributable to variations in island morphology, human activity, and variations in offshore bathymetry and island orientation that influence the wave energy reaching the coast. Areas of documented long-term historical inlet formation and extensive bayside marsh development show substantial landward translation of the dune–beach profile over the near-term period of this study. Correlations among areas predicted to overwash, observed elevation changes of the dune crestline, and observed instances of overwash in undeveloped segments of the barrier island verify that overwash locations can be accurately predicted in undeveloped segments of coast. In fact, an assessment of 2012 aerial imagery collected after Hurricane Sandy confirms that overwash occurred at the majority of near-term locations persistently predicted to overwash. In addition to the storm wave climate, factors related to variations within the geologic framework which in turn influence island orientation, offshore slope, and sediment supply impact island behavior on near-term timescales.

Geomorphometry in coastal morphodynamics

NASA Astrophysics Data System (ADS)

Guisado-Pintado, Emilia; Jackson, Derek

2017-04-01

Geomorphometry is a cross-cutting discipline that has interwoven itself into multiple research themes due to its ability to encompass topographic quantification on many fronts. Its operational focus is largely defined as the extraction of land-surface parameters and earth surface characterisation. In particular, the coastal sciences have been enriched by the use of digital terrain production techniques both on land and in the nearshore/marine area. Numerous examples exist in which the utilisation of field instrumentation (e.g. LIDAR, GPS, Terrestrial Laser Scanning, multi-beam echo-sounders) are used for surface sampling and development of Digital Terrain Models, monitoring topographic change and creation of nearshore bathymetry, and have become central elements in modern investigations of coastal morphodynamics. The coastal zone is a highly dynamic system that embraces variable and at times, inter-related environments (sand dunes, sandy beaches, shoreline and nearshore) all of which require accurate and integrated monitoring. Although coastal studies can be widely diverse (with interconnected links to other related disciplines such as geology or biology), the characterisation of the landforms (coastal geomorphology) and associated processes (morphodynamics, hydrodynamics, aeolian processes) is perhaps where geomorphometry (topo-bathymetry quantification) is best highlighted. In this respect, many tools have been developed (or improved upon) for the acquisition of topographic data that now commands a high degree of accuracy, simplicity, and ultimately acquisition cost reduction. We present a series of field data acquisitions examples that have produced land surface characterisation using a range of techniques including traditional GPS surveys to more recent Terrestrial Laser Scanning and airborne LIDAR. These have been conducted within beach and dune environments and have helped describe erosion and depositional processes driven by wind and wave energy (high-energy events). Other examples include long-term monitoring of beach dynamics and evolution, examining the impact of natural hazards (surges, storms, sea-level rise) on coastal areas using GPS-linked drones to acquire repeat topographic (point clouds) surveys over inter-tidal and dune edge/back beach zones. Nearshore 3D bathymetric information generated from navigation charts, echo-sonar instruments or more recently from Satellite (LANDSAT) imagery is also highlighted as a key dataset in geomorphometry. The recent technological developments in 3D data acquisition within the coastal and marine environment now offers exciting opportunities in which to reveal how these systems function across multiple time and space scales. Whilst this can offer new insights, it also presents significant analytical challenges due to the sheer volume of data generated, the necessity of specialist personnel and software to process the data. Geomorphometry can help play a key role in this progression and take analysis within coastal science to new levels.

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

Effects of Freshwater Discharge in Sandy Beach Populations: The Mole Crab Emerita brasiliensis in Uruguay

NASA Astrophysics Data System (ADS)

Lercari, D.; Defeo, O.

1999-10-01

Sandy beaches are ecosystems which are heavily affected by human activities. An example of this is freshwater discharges, which are known to change salinity, temperature and nutrient regimes and degrade nearshore environments. However, the effects of this kind of disturbance on sandy beach fauna have been little studied. This paper reports the spatial effects of a man-made freshwater canal discharge on the population structure, abundance and reproductive characteristics of the sandy beach mole crab Emerita brasiliensis. Along the 22 km of sandy beach sampled, the mole crab showed a marked longshore variability in population structure and abundance. Abundance of different population components (juveniles, males, females and ovigerous females) significantly decreased towards the canal. Population structure by sex and size, individual weight, fecundity and female maturity patterns at size also displayed a non-linear response to the distance from the freshwater discharge. Only the size structure of males did not follow this pattern. For males, spatial heterogeneity enhanced the detection of density-dependence at less disturbed sites. The authors conclude that artificial freshwater discharges could significantly influence the distribution, abundance and life-history traits of the biota of sandy beaches, and that further study of these ecosystems should include human activities as important factors affecting spatial and temporal trends. The need to consider different spatial and temporal scales in order to detect the effect of anthropogenically-driven impacts in sandy beach populations is stressed.

Morphodynamic implications for shoreline management of the western-Mediterranean sector of Egypt

NASA Astrophysics Data System (ADS)

Frihy, Omran E.

2009-09-01

Although the western-Mediterranean coast of Egypt between Sallum and Alexandria, ~550 km long, has maintained a considerable equilibrium throughout history, developers have built traditional protective structures in an effort to form sheltered recreational beaches without taking into consideration its geomorphologic characteristics, coastal processes and their harmful impact on the coastal environment and human safety. The improper practices in this environmentally valuable region have induced us to undertake an initiative to carry out a morphodynamic analysis to provide a framework for understanding the relationship between coastal morphology and the prevailing dynamic forces. Based on the degree of natural protection or wave sheltering, the study shoreline can be categorized into four distinct morphotypical stretches: (1) high-energy wave-exposed shores and the outer margins of the rocky headlands, (2) moderate to high wave-energy beaches along semi-exposed embayments and bays mostly downdrift of the rocky headlands, (3) low-wave energy at semi-exposed headland lee-sided and pocket beaches, and (4) calm wave-sheltered enclosing water basins for safe anchorages, moorings and recreation beaches. The results deducted will have practical applications for shoreline management initiatives regarding sustained sites suitable for future beachfront development such as safe swimming conditions, sport facilities, water intakes and sheltered areas for vessels. In addition, benefits realized by the understanding of the morphodynamic processes would enhance our awareness of the significance of the role of western coast morphodynamics in supporting sustainable development via shoreline management. As far as sustainability is concerned, the selection of appropriate sites would help avoiding or minimizing the formation of the hard structures needed for creating safe recreation beaches. On a national scale, results reached could provide reliable database for information that can be used in establishing a sustainable shoreline management plan, which is, in turn, an essential part when implementing an Integrated Coastal Zone Management Plan for this region of attraction.

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.

Resource utilization and trophic niche width in sandy beach macrobenthos from an oligotrophic coast

NASA Astrophysics Data System (ADS)

Ortega-Cisneros, Kelly; de Lecea, Ander M.; Smit, Albertus J.; Schoeman, David S.

2017-01-01

One of the paradigms underlying sandy beach ecology is the overriding control by physical processes; thus, biological interactions (i.e. food availability, competition and predation) are believed to play a role structuring macrofaunal communities only in benign habitats such as dissipative beaches. Moreover, sandy beaches are characterized by low in-situ productivity, so their food webs rely heavily on marine inputs. Studies have shown that estuarine organic matter plays a key role in influencing the dynamics of marine ecosystems. However, very few studies have tested the role of estuarine input on sandy beaches. Here, we aim to determine the impact of estuarine input on the food web of a sandy beach macrobenthic community. To this end, particulate organic matter (POM) samples from the marine environment and the estuary, as well as macrobenthic samples from the beach, were analysed for their stable isotope (SI) signature. Our results indicated that the POM SI signatures were not different along the beach, but differences were recorded between marine and estuarine sources. Bayesian mixing models indicated that the organisms did not make use of the estuarine POM at the beginning of the wet season, but relied more heavily on this resource towards the end of the wet season. This leads to the conclusion that changes in estuarine flow throughout the wet season can impact the trophic structure of macrobenthos communities, confirming a link between lotic and marine communities. Moreover, SI signatures suggest that the species collected here exhibit overlapping trophic niches, indicating high level of inter-specific competition. This highlights that species in low-productivity areas, such as the one studied here, can experience high levels of competition even in physically controlled environments such as sandy beaches.

Sensible Heat Flux Related to Variations in Atmospheric Turbulence Kinetic Energy on a Sandy Beach

DTIC Science & Technology

2017-06-01

FLUX RELATED TO VARIATIONS IN ATMOSPHERIC TURBULENCE KINETIC ENERGY ON A SANDY BEACH by Jessica S. Koscinski June 2017 Thesis Advisor...KINETIC ENERGY ON A SANDY BEACH 5. FUNDING NUMBERS 6. AUTHOR(S) Jessica S. Koscinski 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Naval...Sensible heat flux, turbulence kinetic energy , surf zone 15. NUMBER OF PAGES 57 16. PRICE CODE 17. SECURITY CLASSIFICATION OF REPORT

Climate-change impacts on sandy-beach biota: crossing a line in the sand.

PubMed

Schoeman, David S; Schlacher, Thomas A; Defeo, Omar

2014-08-01

Sandy ocean beaches are iconic assets that provide irreplaceable ecosystem services to society. Despite their great socioeconomic importance, beaches as ecosystems are severely under-represented in the literature on climate-change ecology. Here, we redress this imbalance by examining whether beach biota have been observed to respond to recent climate change in ways that are consistent with expectations under climate change. We base our assessments on evidence coming from case studies on beach invertebrates in South America and on sea turtles globally. Surprisingly, we find that observational evidence for climate-change responses in beach biota is more convincing for invertebrates than for highly charismatic turtles. This asymmetry is paradoxical given the better theoretical understanding of the mechanisms by which turtles are likely to respond to changes in climate. Regardless of this disparity, knowledge of the unique attributes of beach systems can complement our detection of climate-change impacts on sandy-shore invertebrates to add rigor to studies of climate-change ecology for sandy beaches. To this end, we combine theory from beach ecology and climate-change ecology to put forward a suite of predictive hypotheses regarding climate impacts on beaches and to suggest ways that these can be tested. Addressing these hypotheses could significantly advance both beach and climate-change ecology, thereby progressing understanding of how future climate change will impact coastal ecosystems more generally.

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.

Microfungi diversity isolation from sandy soil of Acapulco touristic beaches

USDA-ARS?s Scientific Manuscript database

Microscopic fungi diversity in marine sandy soil habitats is associated with key functions of beach ecosystems. There are few reports on their presence in Mexican beaches. Although standard methods to obtain the fungi from soil samples are established, the aim of this pilot study was to test the pla...

The status of sandy beach science: Past trends, progress, and possible futures

NASA Astrophysics Data System (ADS)

Nel, Ronel; Campbell, Eileen E.; Harris, Linda; Hauser, Lorenz; Schoeman, David S.; McLachlan, Anton; du Preez, Derek R.; Bezuidenhout, Karien; Schlacher, Thomas A.

2014-10-01

Open-ocean sandy beaches are coastal ecosystems with growing relevance in the face of global change. They provide key ecosystem services, such as storm buffering, nutrient cycling, water purification, nursery habitats for resource species, and feeding-breeding habitats for focal species (e.g. endangered sea turtles and shorebirds), and have also become nodes for economic development and cultural use. As a result, beaches face a range of threats, primarily from extractive use, habitat modification and development, sea-level rise and coastal squeeze. Consequently, balancing conservation of the ecosystem and sustainable use of the goods and services is particularly important for sandy shores. Thus, the only way to ensure their protection and continued provision of their valuable services, especially in a period of rapid global change, will be to apply knowledge generated from sound science in beach conservation and management. Here we aim to (1) identify and outline the broad ecological paradigms in sandy beach science; (2) report on a citation analysis of the published literature of the past 63 years (1950-2013) to provide context regarding the topics and location of research, the size and institutional composition of the research teams; and (3) investigate whether beach ecology can and has been incorporated into integrated coastal zone management practices. Past research was framed by specific paradigms (chiefly the Swash Exclusion Hypothesis and derivatives), which can be identified with distinct principles and concepts unique to beaches. Most of the sandy beach literature comes from only a few countries (dominated by USA, South Africa, Brazil and Italy), published by small research teams (<4 authors), mostly from single institutes. The field has yet to establish large multi-disciplinary teams to undertake rigorous experimental science in order to contribute to general ecological theory. Despite the constraints, beach science is responding to new challenges, with increasing use of the latest techniques. However, research in conservation and management specifically remains limited, with stronger focus on anthropogenic impacts, in turn leading to management of people on beaches rather than conservation of the ecosystem itself. We conclude with a look to the future for sandy beach science, and a summary of the contributions to this Special Issue.

Diversity of Sarcosaprophagous Calyptratae (Diptera) on Sandy Beaches Exposed to Increasing Levels of Urbanization in Brazil.

PubMed

Barbosa, Taciano Moura; Carmo, Rodrigo Felipe Rodrigues; Silva, Leonardo Pereira; Sales, Raissa Guerra; Vasconcelos, Simao Dias

2017-06-01

Sandy beaches are among the most impacted ecosystems worldwide, and the effects of urbanization on the biodiversity of these habitats are largely unknown, particularly in Brazil. We investigated the composition and structure of assemblages of sarcosaprophagous insects (Diptera: Calliphoridae, Sarcophagidae, and Muscidae) on six sandy beaches exposed to differential levels of human impact in Pernambuco State, Brazil. In total, 20,672 adults of 40 species were collected, of which 70% were Calliphoridae. Sarcophagidae had the highest diversity with 26 species of nine genera. A strong overlap in the composition of the assemblages across the six beaches was observed, with only a few species being restricted to one type of beach. The flesh flies Dexosarcophaga carvalhoi (Lopes), Peckia intermutans (Walker), and Titanogrypa larvicida (Lopes) occurred exclusively in beaches under low anthropogenic impact. Species with strong medical and veterinary importance such as Synthesiomyia nudiseta (Wulp) occurred even in beaches under low human presence. The invasive species Chrysomya albiceps (Wiedemann) and Chrysomya megacephala (F.) (Calliphoridae) were dominant in all beaches, which exposes the vulnerability of sandy beaches to exotic species. Our data imply that sarcosaprophagous flies can be used as early biological indicators to suggest urbanization in coastal environments. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A Study of Sandy Beach Zonation.

ERIC Educational Resources Information Center

Alexander, Steve K.

1991-01-01

Describes the study of sandy beach zonations as a seashore activity for either high school or lower-level college courses in biology, ecology, or marine biology. Students first draw a profile of a beach scene and then collect specimens from the zones of the shore. In a laboratory, students identify their specimens and relate them to the beach…

Hurricane Sandy beach response and recovery at Fire Island, New York: Shoreline and beach profile data, October 2012 to October 2014

USGS Publications Warehouse

Hehre Henderson, Rachel E.; Hapke, Cheryl J.; Brenner, Owen T.; Reynolds, Billy J.

2015-04-30

In response to the forecasted impact of Hurricane Sandy, which made landfall on October 29, 2012, the U.S. Geological Survey (USGS) began a substantial data-collection effort to assess the morphological impacts to the beach and dune system at Fire Island, New York. Global positioning system (GPS) field surveys of the beach and dunes were conducted just prior to and after landfall and these data were used to quantify change in several focus areas. In order to quantify morphologic change along the entire length of the island, pre-storm (May 2012) and post-storm (November 2012) lidar and aerial photography were used to assess changes to the shoreline and beach.As part of the USGS Hurricane Sandy Supplemental Fire Island Study, the beach is monitored periodically to enable better understanding of post-Sandy recovery. The alongshore state of the beach is recorded using a differential global positioning system (DGPS) to collect data around the mean high water (MHW; 0.46 meter North American Vertical Datum of 1988) to derive a shoreline, and the cross-shore response and recovery are measured along a series of 10 profiles.Overall, Hurricane Sandy substantially altered the morphology of Fire Island. However, the coastal system rapidly began to recover after the 2012­–13 winter storm season and continues to recover in the form of volume gains and shoreline adjustment.

Food habits of fishes on an exposed sandy beach at Fukiagehama, South-West Kyushu Island, Japan

NASA Astrophysics Data System (ADS)

Nakane, Yukinori; Suda, Yusuke; Sano, Mitsuhiko

2011-06-01

To clarify the feeding habits and major food sources of sandy beach fishes, the gut contents of 55 fish species collected on a sandy beach at Fukiagehama, South-West Kyushu Island, Japan, were examined. Ontogenetic changes in food preference were recognized in nine species ( Hypoatherina valenciennei, Lateolabrax japonicus, Trachurus japonicus, Sillago japonica, Sphyraena japonica, Paralichthys olivaceus, Heteromycteris japonica, Paraplagusia japonica, and Takifugu niphobles). A cluster analysis based on dietary overlaps showed that the sandy beach fish assemblage comprised six trophic groups (mysid, amphipod, zooplankton, juvenile fish, terrestrial insect, and mollusk feeders). Of these, the first three groups were the most abundantly represented, whereas the last two were represented by only a single species. These results indicated that epibenthic macrofauna, such as mysids and gammaridean amphipods, and zooplankton, were important food resources for the fish assemblage at the study site, but infaunal macrobenthos, such as polychaetes and bivalves, being relatively unimportant.

Utilization of geotextile tube for sandy and muddy coastal management: a review.

PubMed

Lee, Siew Cheng; Hashim, Roslan; Motamedi, Shervin; Song, Ki-Il

2014-01-01

Threats to beaches have accelerated the coastal destruction. In recent decades, geotextile tubes were used around the world to prevent coastal erosion, to encourage beach nourishment, and to assist mangrove rehabilitation. However, the applications of geotextile tube in sandy and muddy coasts have different concerns as the geological settings are different. Applications of geotextile tubes in sandy beaches were mainly to prevent coastline from further erosion and to nourish the beach. However, for the muddy coasts, mangrove rehabilitation and conservation were additional concerns in coastal management schemes. The mangrove forests are natural barriers which can be found on the muddy coasts of many tropical countries. In this paper, the viability of geotextile tubes in sandy and muddy beaches was analysed. The advantages and disadvantages of the utilization of geotextile tubes in coastal management were discussed based on the experiences from the tropical countries such as Mexico, Malaysia, and Thailand. From the case studies, impressive improvements in coastal restoration after installation of geotextile tubes were shown. Based on the discussion, several recommendations to improve the application of geotextile tubes were suggested in this paper.

Utilization of Geotextile Tube for Sandy and Muddy Coastal Management: A Review

PubMed Central

Lee, Siew Cheng; Hashim, Roslan; Motamedi, Shervin; Song, Ki-Il

2014-01-01

Threats to beaches have accelerated the coastal destruction. In recent decades, geotextile tubes were used around the world to prevent coastal erosion, to encourage beach nourishment, and to assist mangrove rehabilitation. However, the applications of geotextile tube in sandy and muddy coasts have different concerns as the geological settings are different. Applications of geotextile tubes in sandy beaches were mainly to prevent coastline from further erosion and to nourish the beach. However, for the muddy coasts, mangrove rehabilitation and conservation were additional concerns in coastal management schemes. The mangrove forests are natural barriers which can be found on the muddy coasts of many tropical countries. In this paper, the viability of geotextile tubes in sandy and muddy beaches was analysed. The advantages and disadvantages of the utilization of geotextile tubes in coastal management were discussed based on the experiences from the tropical countries such as Mexico, Malaysia, and Thailand. From the case studies, impressive improvements in coastal restoration after installation of geotextile tubes were shown. Based on the discussion, several recommendations to improve the application of geotextile tubes were suggested in this paper. PMID:24955408

Development of a new morphometric to assess beach storm response and recovery

NASA Astrophysics Data System (ADS)

Brenner, O.; Hapke, C. J.

2014-12-01

Various morphometrics are used to measure coastal change over a variety of time scales including shoreline, dune elevation and position, and beach profile volume. Each has limitations, many of which became apparent in the aftermath of Hurricane Sandy, including the juxtaposition of levelled dunes and a substantially prograded shoreline. In order to understand sustained beach behavior, including recovery after Hurricane Sandy, we develop a new morphometric - an upper beach change envelope (BCE) specific to Fire Island, NY. The upper beach better captures impacts from more frequent moderate storms during which there may be substantial beach change but less impact to the dune, and is less subject to the variable fluctuations nearer to the shoreline that only marginally influence future vulnerability and overall coastal resilience. The BCE can also be used to quantify the gradual recovery of the beach after storm events and is not reliant on the presence of a morphologic feature such as a dune, which may take many years to recover after a severe storm.The BCE at Fire Island is based on a time series of historical response to storms. The BCE boundaries are elevation contours that capture the portion of the upper beach that experiences erosion during moderate nor'easter events but is above the influence of tides and lesser events. In an application of the BCE concept, we use the BCE boundary elevations to quantify beach response from Hurricane Sandy and document the subsequent recovery, using a time series of post-Sandy elevation contours. The data include 10 profile sites from Fire Island that were surveyed multiple times from October 2012 to June 2014. Utilizing this time series we measure changes in the cross shore position of the BCE elevation boundaries. Initial assessments indicate the BCE successfully captures coastal response through time, including extensive change during Hurricane Sandy as well as subsequent seasonal changes. The recent data indicate there is a temporal trend towards widening of the BCE, due to sustained progradation of the lower boundary. This trend may represent a new "recovery state" of the beach which is wider than the pre-Sandy beach, providing an increase in the fetch that favors the aeolian processes of dune reformation.

Behavioural adaptations of two sympatric sandhoppers living on a mesotidal European Atlantic sandy beach

NASA Astrophysics Data System (ADS)

Bessa, Filipa; Marques, João Carlos; Scapini, Felicita

2014-06-01

Behavioural adaptations of supralittoral species on sandy beaches are expressed as responses to environmental changes and constitute a key factor in their survival and evolution. Two sympatric talitrid amphipods (Talitrus saltator and Britorchestia brito) from a mesotidal exposed sandy beach on the European Atlantic coast (Portugal) were compared as regards orientation and littoral zonation patterns under natural conditions. Orientation experiments were carried out during spring and summer 2011 and 2012 at Quiaios beach, a highly dynamic exposed sandy beach. Multiple regression models were fitted to the angular data and the environmental effects on orientation were investigated for each species. Both talitrids were shown to be well orientated towards the shoreline and finely adapted to the mesotidal environment but a different use of local cues and climatic features between the two species was apparent. T. saltator showed a lower precision in the orientation performance (with a bimodal distribution sea- and land-wards), with less dependence on the sun cues and higher dependence on climatic features. In addition, the zonation of T. saltator was across the land-sea axis during both seasons. For B. brito the landscape vision, sun visibility and the tidal range enhanced the orientation to the shoreline. On this mesotidal Atlantic beach, T. saltator appeared to have a more flexible orientation with respect to B. brito, which appeared to be more dependent on the conditions offered by the intertidal zone, a behaviour confirmed by its restricted zonation below the high tide mark. Consequently, T. saltator showed a more flexible behaviour that may be considered an important evolutionary adaptation to dynamic and mesotidal sandy beaches.

Modeling Hydrodynamics on the Wave Group Scale in Topographically Complex Reef Environments

NASA Astrophysics Data System (ADS)

Reyns, J.; Becker, J. M.; Merrifield, M. A.; Roelvink, J. A.

2016-02-01

The knowledge of the characteristics of waves and the associated wave-driven currents is important for sediment transport and morphodynamics, nutrient dynamics and larval dispersion within coral reef ecosystems. Reef-lined coasts differ from sandy beaches in that they have a steep offshore slope, that the non-sandy bottom topography is very rough, and that the distance between the point of maximum short wave dissipation and the actual coastline is usually large. At this short wave breakpoint, long waves are released, and these infragravity (IG) scale motions account for the bulk of the water level variance on the reef flat, the lagoon and eventually, the sandy beaches fronting the coast through run-up. These IG energy dominated water level motions are reinforced during extreme events such as cyclones or swells through larger incident band wave heights and low frequency wave resonance on the reef. Recently, a number of hydro(-morpho)dynamic models that have the capability to model these IG waves have successfully been applied to morphologically differing reef environments. One of these models is the XBeach model, which is curvilinear in nature. This poses serious problems when trying to model an entire atoll for example, as it is extremely difficult to build curvilinear grids that are optimal for the simulation of hydrodynamic processes, while maintaining the topology in the grid. One solution to remediate this problem of grid connectivity is the use of unstructured grids. We present an implementation of the wave action balance on the wave group scale with feedback to the flow momentum balance, which is the foundation of XBeach, within the framework of the unstructured Delft3D Flexible Mesh model. The model can be run in stationary as well as in instationary mode, and it can be forced by regular waves, time series or wave spectra. We show how the code is capable of modeling the wave generated flow at a number of topographically complex reef sites and for a number of different forcing conditions, by comparison with field data.

Coastal change from Hurricane Sandy and the 2012-13 winter storm season: Fire Island, New York

USGS Publications Warehouse

Hapke, Cheryl J.; Brenner, Owen; Henderson, Rachel E.; Reynolds, B.J.

2013-01-01

The U.S. Geological Survey (USGS) mounted a substantial effort in response to Hurricane Sandy including an assessment of the morphological impacts to the beach and dune system at Fire Island, New York. Field surveys of the beach and dunes collected just prior to and after landfall were used to quantify change in several focus areas. In order to quantify morphologic change along the length of the island, pre-storm (May 2012) and post-storm (November 2012) lidar and aerial photography were used to assess changes to the shoreline and beach, and to measure volumetric changes. The extent and thicknesses of overwash deposits were mapped in the field, and measurements were used to determine volume, distribution, and characteristics of the deposits. The beaches and dunes on Fire Island were severely eroded during Hurricane Sandy, and the island breached in three locations on the eastern segment of the island. Landward shift of the upper portion of the beach averaged 19.7 meters (m) but varied substantially along the coast. Shoreline change was also highly variable, but the shoreline prograded during the storm by an average of 11.4 m, due to the deposition of material eroded from the upper beach and dunes onto the lower portion of the beach. The beaches and dunes lost 54.4 percent of their pre-storm volume, and the dunes experienced overwash along 46.6 percent of the island. The inland overwash deposits account for 14 percent of the volume lost from the beaches and dunes, indicating that the majority of material was moved offshore. In the winter months following Hurricane Sandy, seven storm events with significant wave heights greater than four m were recorded at a wave buoy 30 nautical miles south of Fire Island. Monthly shoreline and profile surveys indicate that the beach continued to erode dramatically. The shoreline, which exhibited a progradational trend immediately after Sandy, eroded an average of 21.4 m between November 2012 and mid-March 2013, with a maximum landward shift of nearly 60 m. By March 2013 the elevation of the beach in the majority of the surveyed profiles was lowered below the mean high water level (0.46 m), and the beach lost an additional 18.9 percent of its remaining volume. In the final time period of the field surveys (March to April 2013), the beach began to show signs of rapid recovery, and in 90 percent of the profiles, the volume of the beach in April 2013 was similar to the volume measured immediately after Hurricane Sandy. Overall, Hurricane Sandy profoundly impacted the morphology of Fire Island and resulted in an extremely low elevation, low relief configuration that has left the barrier island vulnerable to future storms. The coastal system subsequently began to show signs of recovery, and although the beach is likely to experience continued recovery in the form of volume gains, the dunes will take years to rebuild. Events such as Sandy result in a coastal environment that is a more vulnerable to future storm impacts, but they are an important natural process of barrier islands that allow these systems to evolve in response to sea-level rise.

Rip currents, mega-cusps, and eroding dunes

USGS Publications Warehouse

Thornton, E.B.; MacMahan, J.; Sallenger, A.H.

2007-01-01

Dune erosion is shown to occur at the embayment of beach mega-cusps O(200 m alongshore) that are associated with rip currents. The beach is the narrowest at the embayment of the mega-cusps allowing the swash of large storm waves coincident with high tides to reach the toe of the dune, to undercut the dune and to cause dune erosion. Field measurements of dune, beach, and rip current morphology are acquired along an 18 km shoreline in southern Monterey Bay, California. This section of the bay consists of a sandy shoreline backed by extensive dunes, rising to heights exceeding 40 m. There is a large increase in wave height going from small wave heights in the shadow of a headland, to the center of the bay where convergence of waves owing to refraction over the Monterey Bay submarine canyon results in larger wave heights. The large alongshore gradient in wave height results in a concomitant alongshore gradient in morphodynamic scale. The strongly refracted waves and narrow bay aperture result in near normal wave incidence, resulting in well-developed, persistent rip currents along the entire shoreline. The alongshore variations of the cuspate shoreline are found significantly correlated with the alongshore variations in rip spacing at 95% confidence. The alongshore variations of the volume of dune erosion are found significantly correlated with alongshore variations of the cuspate shoreline at 95% confidence. Therefore, it is concluded the mega-cusps are associated with rip currents and that the location of dune erosion is associated with the embayment of the mega-cusp.

Modeling and measuring the relationships between sediment transport processes, alluvial bedforms and channel-scale morphodynamics in sandy braided rivers.

NASA Astrophysics Data System (ADS)

Nicholas, A. P.; Ashworth, P. J.; Best, J.; Lane, S. N.; Parsons, D. R.; Sambrook Smith, G.; Simpson, C.; Strick, R. J. P.; Unsworth, C. A.

2017-12-01

Recent years have seen significant advances in the development and application of morphodynamic models to simulate river evolution. Despite this progress, significant challenges remain to be overcome before such models can provide realistic simulations of river response to environmental change, or be used to determine the controls on alluvial channel patterns and deposits with confidence. This impasse reflects a wide range of factors, not least the fact that many of the processes that control river behaviour operate at spatial scales that cannot be resolved by such models. For example, sand-bed rivers are characterised by multiple scales of topography (e.g., dunes, bars, channels), the finest of which must often by parameterized, rather than represented explicitly in morphodynamic models. We examine these issues using a combination of numerical modeling and field observations. High-resolution aerial imagery and Digital Elevation Models obtained for the sandy braided South Saskatchewan River in Canada are used to quantify dune, bar and channel morphology and their response to changing flow discharge. Numerical simulations are carried out using an existing morphodynamic model based on the 2D shallow water equations, coupled with new parameterisations of the evolution and influence of alluvial bedforms. We quantify the spatial patterns of sediment flux using repeat images of dune migration and bar evolution. These data are used to evaluate model predictions of sediment transport and morphological change, and to assess the degree to which model performance is controlled by the parametrization of roughness and sediment transport phenomena linked to subgrid-scale bedforms (dunes). The capacity of such models to replicate the characteristic multi-scale morphology of bars in sand-bed rivers, and the contrasting morphodynamic signatures of braiding during low and high flow conditions, is also assessed.

Remedial Design-Stage Optimization Review Report: Sandy Beach Ground Water Plume Superfund Site, Tarrant County, Texas, EPA Region 6

EPA Pesticide Factsheets

The Sandy Beach Road Ground Water Plume Superfund Site, CERCLIS ID No. TXN000605649, is located within incorporated areas of Pelican Bay and Azle, Texas and an unincorporated portion of Tarrant County, Texas.

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.

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.

Does human pressure affect the community structure of surf zone fish in sandy beaches?

NASA Astrophysics Data System (ADS)

Costa, Leonardo Lopes; Landmann, Júlia G.; Gaelzer, Luiz R.; Zalmon, Ilana R.

2017-01-01

Intense tourism and human activities have resulted in habitat destruction in sandy beach ecosystems with negative impacts on the associated communities. To investigate whether urbanized beaches affect surf zone fish communities, fish and their benthic macrofaunal prey were collected during periods of low and high human pressure at two beaches on the Southeastern Brazilian coast. A BACI experimental design (Before-After-Control-Impact) was adapted for comparisons of tourism impact on fish community composition and structure in urbanized, intermediate and non-urbanized sectors of each beach. At the end of the summer season, we observed a significant reduction in fish richness, abundance, and diversity in the high tourist pressure areas. The negative association between visitors' abundance and the macrofaunal density suggests that urbanized beaches are avoided by surf zone fish due to higher human pressure and the reduction of food availability. Our results indicate that surf zone fish should be included in environmental impact studies in sandy beaches, including commercial species, e.g., the bluefish Pomatomus saltatrix. The comparative results from the less urbanized areas suggest that environmental zoning and visitation limits should be used as effective management and preservation strategies on beaches with high conservation potential.

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.

Small-scale temporal and spatial variability in the abundance of plastic pellets on sandy beaches: Methodological considerations for estimating the input of microplastics.

PubMed

Moreira, Fabiana Tavares; Prantoni, Alessandro Lívio; Martini, Bruno; de Abreu, Michelle Alves; Stoiev, Sérgio Biato; Turra, Alexander

2016-01-15

Microplastics such as pellets have been reported for many years on sandy beaches around the globe. Nevertheless, high variability is observed in their estimates and distribution patterns across the beach environment are still to be unravelled. Here, we investigate the small-scale temporal and spatial variability in the abundance of pellets in the intertidal zone of a sandy beach and evaluate factors that can increase the variability in data sets. The abundance of pellets was estimated during twelve consecutive tidal cycles, identifying the position of the high tide between cycles and sampling drift-lines across the intertidal zone. We demonstrate that beach dynamic processes such as the overlap of strandlines and artefacts of the methods can increase the small-scale variability. The results obtained are discussed in terms of the methodological considerations needed to understand the distribution of pellets in the beach environment, with special implications for studies focused on patterns of input. Copyright © 2015 Elsevier Ltd. All rights reserved.

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.

Sandy beaches in a coastline vulnerable to erosion in Atlantic Canada: Macrobenthic community structure in relation to backshore and physical features

NASA Astrophysics Data System (ADS)

MacMillan, Mitchell R.; Duarte, Cristian; Quijón, Pedro A.

2017-07-01

Most literature suggests that sandy beach macrobenthic communities are structured by physical factors. However, an aspect that has not been studied in detail is whether those physical factors change with erosion or the association of beaches to backshore features like sand dunes, till bluffs, and sandstone cliffs. We addressed this question by sampling 14 sandy beaches on the north shore of Prince Edward Island, Atlantic Canada. Two null hypotheses were tested: first, there is no relationship between physical factors and community descriptors across sandy beaches, and second, there is no difference among beaches associated with distinct backshore features both in terms of physical factors and community descriptors. In order to test these hypotheses, samples of macrobenthic organisms and measurements of grain size, slope, beach deposit index and erosion rates were obtained. Our surveys collected a total of 14 taxa numerically dominated by the spionid polychaete Scolelepis squamata. With regards to the first hypothesis, regression analyses showed that community descriptors were all positively related to erosion rates while unrelated to the variation in grain size, slope and beach deposit index. As for the second hypothesis, erosion rates were significantly different among beaches associated to till bluffs (highest), dunes and sandstone cliffs (lowest). Meanwhile, the other physical factors did not significantly differ among backshore features. Species richness was highest in beaches associated to till bluffs and lowest in those associated to sandstone cliffs. Abundance values were also lowest in beaches associated to sandstone cliffs, and their community composition was significantly different to those associated to dunes and till bluffs. We suggest that the relationship between erosion rates and community descriptors is complex and may be mediated by the availability of nutrients: higher erosion levels might account for higher concentrations of nutrients for suspension feeders, the numerically dominant organisms in this system. We call for further attention to the relationship between erosion and suspended nutrients.

Morphodynamic evolution of Laida beach (Oka estuary, Urdaibai Biosphere Reserve, southeastern Bay of Biscay) in response to supratidal beach nourishment actions

NASA Astrophysics Data System (ADS)

Monge-Ganuzas, M.; Gainza, J.; Liria, P.; Epelde, I.; Uriarte, A.; Garnier, R.; González, M.; Nuñez, P.; Jaramillo, C.; Medina, R.

2017-12-01

Laida beach, located at the Oka estuary mouth (Urdaibai Biosphere Reserve) in the southeastern region of the Bay of Biscay, suffered the impact of a severe succession of storms during the first months of 2014. As a result of the erosion induced by these events, the beach lost its supratidal zone almost completely. The absence of a supratidal beach generated an impact on the recreational use of the beach during the summer 2014, and represented a potential impact for the coming summer 2015. Furthermore, it resulted in an overexposure and damage of adjacent infrastructures due to impinging strong waves. Therefore, the competent authorities, in coordination, decided to take action in order to nourish the supratidal zone of this beach. The solution adopted combined two different actions. The first one accomplished in spring of 2015, consisted in the mobilization of 44,800 m3 of sand from an area of 35,200 m2 equal to the 7% of the intertidal zone of Laida beach interpreted as the existing surface between the average low and high tidal limits, to the zone next to the eastern rocky beach contour. This action successfully resulted in an increase of the supratidal beach for the entire summer 2015 without negatively perturbing the morphological system. The second action was somewhat experimental and consisted in the mechanical plough of the previously existing intertidal low-amplitude ridges with the aim of increasing the sand transport toward the supratidal beach. Although this action did not lead to the increase of the supratidal beach, it seems to have resulted in an acceleration of the natural onshore migration of the bars. The objective of this contribution is to describe the morphodynamical response of the estuarine mouth after the performed actions with special emphasis on the evolution of extracted sites and the supratidal Laida beach area. The information here presented represents an innovative step in the understanding of the complex mechanisms driving the supratidal beach formation at the mouth of Oka estuary and by extension of the majority of the estuaries of the southeastern Bay of Biscay.

XBeach and CSHORE Numerical Model Assessment of the Beach and Foredune Morphodynamic Response of a Barrier Island during Hurricane Storm Surge Inundation - Folletts Island Case Study

NASA Astrophysics Data System (ADS)

Figlus, J.

2016-02-01

More than 400 barrier islands line the United States coasts providing a first line of defense against surge and wave attack during extreme storm events. While some pre- and post-storm topography and bathymetry data of barrier islands inundated during a storm exist, very little information is available to help understand the complex hydrodynamic and morphodynamic processes during storm impact. These processes are crucial to understanding sediment budgets, potential threats to infrastructure and best coastal management practices for specific locations. Follett's Island (FI) is a low-lying sediment-starved barrier island located on the Upper Texas Coast, a stretch of coastline along the Gulf of Mexico experiencing on average four hurricanes and four tropical cyclones per decade. During Hurricane Ike, water levels and wave heights at FI exceeded the 100-year and 40-year return values, respectively. This caused the island to undergo a sequence of four distinct interaction regimes, including impact, overtopping, inundation, and storm surge ebb. Each regime caused unique morphology changes to the island. The physical processes governing the real-time morphodynamic response of the beach and dune system during 96 hours of hurricane impact were modeled using XBeach (2D) and CSHORE (1D). Hydrodynamic boundary conditions were obtained from ADCIRC/SWAN model runs validated with measured buoy and wave gauge data while LiDAR surveys provided pre- and post-storm measured topography. XBeach displayed a decent model skill and was very useful in qualitatively visualizing erosion and deposition patterns during each regime. CSHORE also displayed a decent model skill and was able to accurately predict the post-storm beach slope and shoreline, but was less effective at simulating the foredune morphology. Modeling results show that the complete morphodynamic response of FI to Hurricane Ike was far more complex than suggested by only before and after storm topography surveys.

A Study of Variations in Atmospheric Turbulence Kinetic Energy on a Sandy Beach

NASA Astrophysics Data System (ADS)

Koscinski, J. S.; MacMahan, J. H.; Wang, Q.; Thornton, E. B.

2016-12-01

A 6-m high, meteorological tower consisting six evenly spaced ultrasonic anemometers and temperature-relative humidity sensors was deployed at the high tide line on sandy, wave-dissipative, meso-tidal beach in southern Monterey Bay, CA in October 2015. The micro-meteorology study focus is to explore the momentum fluxes and turbulent kinetic energy influenced by the interaction between an intensive wave-breaking surf zone and a sandy beach associated with onshore & cross-shore winds, diurnal heating, and differences in ocean-air temperatures. The tower was deployed for approximately 1-month and experienced diurnal wind variations and synoptic storm events with winds measuring up to 10 m/s and an air temperature range of 5-28 oC. This beach environment was found to be primarily unstable in thermal stratification indicating that the air temperature is colder than underlying surface, either the ocean or the sandy beach. The drag coefficient was found to be dependent upon the atmospheric stability. Direct-estimates of atmospheric stability were obtained with the sonic anemometer. The direct estimates are a ratio of w*/u*, where the w*, vertically scaled buoyancy velocity, is greater than u*, horizontally scaled friction velocity. Hypotheses for the enhanced buoyancy are 1) diurnal heating of the sandy beach, 2) warmer ocean temperatures relative to air temperatures, and 3) the wave breaking within the surf zone. Further exploration into these hypotheses is conducted by using vertical tower sensor pairs for estimating the temporal variability of the mechanical shear production and buoyancy production terms in turbulent kinetic energy budget. These results are part of the Coastal Land Air Sea Interaction (CLASI) experiment.

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.

Morphodynamic changes as an impact of human intervention at the Ras El-Bar-Damietta Harbor coast, NW Damietta Promontory, Nile Delta, Egypt

NASA Astrophysics Data System (ADS)

El-Asmar, Hesham M.; Taha, Maysa M. N.; El-Sorogy, Abdelbaset S.

2016-12-01

Due to the absence of a national strategic plan for coastal management, the Nile Delta coast is no longer described as a fully dissipative, divergent, low-gradient beach face composed of fine to very fine sand. Instead, new patterns have emerged depending on rock type, geomorphology of the coast, direction of the shoreline in relation to waves and current, and the implemented defense measures. This study attempts to record the morphodynamic changes which occurred due to human intervention. Landsat satellite images acquired for the periods of time of 1973, 1984, 1989, 2003, and 2015 are used together with geomorphologic observations in order to monitor the changes along the coastal strip between Ras El-Bar and Damietta Harbor. This study reveals two beach segments; one of which lies to the east, it is protected with detached breakwater system, and shows average shoreline accretions of +4.73 myr-1, +5.0 myr-1, and +0.89myr-1 during the periods of 1984-1998, 1998-2003, and 2003-2015 respectively. This segment still has the geomorphologic imprints of the dissipative beach, wave divergence, low-gradient beach face, fine grained sand and spilling breakers. The second is to the west, between the detached breakwaters and the eastern jetty of the Damietta Harbor. It is an erosional segment with shoreline retreat of -7.43 myr-1, -10.90 myr-1, and -3.11myr-1 for the same periods. This segment shows intermediate "d" beach or intermediate-reflective, wave convergence, rip currents, with the characteristic steep sloped and cuspate beach face, cliffy, reworked sediments of coarse grained sands, mud clasts, discoidal gravels, shelly beach, and plunging breakings. The presence of convergent waves along this segment confirms the concept of an emergence of a new wave pattern of reversed eddy which enhances the steepness of the beach face, accelerates erosion, and increases the possibility of drowning of swimmers at Ras El-Bar resort. Under such circumstances the plunge step approaches the shore and its shell content forced by wave to accumulate forming the shelly beach. To secure the coastal strip against erosion and sea level changes the detached breakwaters should be extended to reach the eastern jetty of the Damietta Harbor. The protection of this segment is a matter of interest for investment projects related to industries and trading along the Damietta Harbor as well as the touristic investments at Ras El-Bar, as one of the important tourist destinations in Egypt. Millions of pounds spent by beach visitors and investment annually provide significant input to local and regional economy. Hazards associated with the morphodynamic effects on recreational beaches can influence the suitably of any given stretch of coast as a recreational resource, and thus impact tourist money spent in addition to the safety and well-being of beach visitors.

Morphodynamics of intertidal bars near a seawall on a macrotidal beach, Wissant Bay, northern France

NASA Astrophysics Data System (ADS)

Sedrati, M.; Anthony, E.

2009-04-01

Several studies on beaches with intertidal bar-trough (ridge-and-runnel) systems in settings with relatively large tidal ranges (> 3 m) have focused on cross-shore bar mobility; however a few recent studies have drawn attention to the potential role of longshore transport induced by a mix of wave-tide and wind-forced longshore currents in the morphodynamics of the bars and troughs. The aim of this paper is to briefly highlight the relationship between wind-forced currents on the shallow intertidal zone and rapid intertidal bar-trough morphological response on a macrotidal beach. Fieldwork was conduced on Wissant beach, Wissant Bay, northern France, from 7 to 23 March, 2006. During the experiment, the beach (oriented NE-SW) exhibited three intertidal bar-trough systems and the upper bar was directly attached to a seawall. Seven digital elevation models (DEMs) were generated from high-resolution topographic surveys. Hydrodynamic measurements were obtained from five currentmeters (2 S4 and 3 ADCP) deployed on the bars crests and on the upper beach trough. Wave characteristics were obtained from the measured time series by spectral analysis using Fast Fourier Transforms. Wind speed and direction on the beach were measured using a portable weather station. The mean wind speed and directions averaged every three hours highlight closely-spaced high-energy events during the experiment, with long phases of significant lateral wind stress (NE to ENE). The measured waves and currents showed rapid and strong response to both the changes in wind speed and direction. Longshore currents measured during the experiment on the upper intertidal bar-trough system showed a clear SW flow pattern in response to NE to ENE wind approach directions while the currents in the lower intertidal zone flowed northeastward during the flood, following the coastline, and southwestward during the ebb in response to the tidal current modulation. Strong longshore migration of the upper intertidal bar to the SW was observed during the course of this fieldwork. This longshore migration was attended by erosion of the upper beach in the northeast and accretion in the southwest. Bars in the lower intertidal zone were relatively stable. The SW migration process of the upper intertidal bar during the experiment occurred at rates that fluctuated with the intensity of the longshore current. The net beach volume over the experiment was quite stable, thus showing that morphological change, notably bar migration, simply reflected adjustments to hydrodynamic forcing without new sand inputs into the system. The findings of the present study suggest that cross-shore currents are subordinate to, and may even be mitigated by, wind-forced longshore flows on this beach. The importance of longshore transport on the upper beach is due to hydrodynamic forcing over the shallow depth, with the seawall playing a probable additional longshore canalization effect. Longshore transport should be considered as an essential element of the morphodynamics of bar-trough beaches subject to large tidal ranges and significant lateral wind stress.

Low level off-road vehicle (ORV) traffic negatively impacts macroinvertebrate assemblages at sandy beaches in south-western Australia

NASA Astrophysics Data System (ADS)

Davies, Rebecca; Speldewinde, Peter C.; Stewart, Barbara A.

2016-04-01

Off-road vehicle use is arguably one of the most environmentally damaging human activities undertaken on sandy beaches worldwide. Existing studies focused on areas of high traffic volumes have demonstrated significantly lower abundance, diversity and species richness of fauna in zones where traffic is concentrated. The impact of lower traffic volumes is unknown. This study aimed to investigate the impacts of relatively low-level vehicle traffic on sandy beach fauna by sampling invertebrate communities at eight beaches located in south-western Australia. We found that even low-level vehicle traffic negatively impacts the physical beach environment, and consequently, the ability of many species to survive in this habitat in the face of this disturbance. Compaction, rutting and displacement of the sand matrix were observed over a large area, resulting in significant decreases in species diversity and density, and measurable shifts in community structure on beaches that experienced off-road vehicle traffic. Communities at impact sites did not display seasonal recovery as traffic was not significantly different between seasons. Given a choice between either reducing traffic volumes, or excluding ORV traffic from beaches, our results suggest that the latter would be more appropriate when the retention of ecological integrity is the objective.

Response of intertidal sandy-beach macrofauna to human trampling: An urban vs. natural beach system approach.

PubMed

Reyes-Martínez, Ma José; Ruíz-Delgado, Ma Carmen; Sánchez-Moyano, Juan Emilio; García-García, Francisco José

2015-02-01

Sandy beaches are subjected to intense stressors, which are mainly derived from the increasing pattern of beach urbanization. These ecosystems are also a magnet for tourists, who prefer these locations as leisure and holiday destinations, and such activity further increases the factors that have an adverse effect on beaches. In the study reported here the effect of human trampling on macrofauna assemblages that inhabit intertidal areas of sandy beaches was assessed using a BACI design. For this purpose, three contrasting sectors of the same beach were investigated: an urban area with a high level of visitors, a protected sector with a low density of users, and a transitional area with a high level of human occupancy. The physical variables were constant over time in each sector, whereas differences were found in the intensity of human use between sectors. Density variations and changes in the taxonomic structure of the macrofauna with time were shown by PERMANOVA analysis in the urban and transitional locations whereas the protected sector remained constant throughout the study period. The amphipod Bathyporeia pelagica appears sensitive to human trampling pressure and the use of this species as a bioindicator for these types of impact is recommended. Copyright © 2014 Elsevier Ltd. All rights reserved.

Threats to sandy beach ecosystems: A review

NASA Astrophysics Data System (ADS)

Defeo, Omar; McLachlan, Anton; Schoeman, David S.; Schlacher, Thomas A.; Dugan, Jenifer; Jones, Alan; Lastra, Mariano; Scapini, Felicita

2009-01-01

We provide a brief synopsis of the unique physical and ecological attributes of sandy beach ecosystems and review the main anthropogenic pressures acting on the world's single largest type of open shoreline. Threats to beaches arise from a range of stressors which span a spectrum of impact scales from localised effects (e.g. trampling) to a truly global reach (e.g. sea-level rise). These pressures act at multiple temporal and spatial scales, translating into ecological impacts that are manifested across several dimensions in time and space so that today almost every beach on every coastline is threatened by human activities. Press disturbances (whatever the impact source involved) are becoming increasingly common, operating on time scales of years to decades. However, long-term data sets that describe either the natural dynamics of beach systems or the human impacts on beaches are scarce and fragmentary. A top priority is to implement long-term field experiments and monitoring programmes that quantify the dynamics of key ecological attributes on sandy beaches. Because of the inertia associated with global climate change and human population growth, no realistic management scenario will alleviate these threats in the short term. The immediate priority is to avoid further development of coastal areas likely to be directly impacted by retreating shorelines. There is also scope for improvement in experimental design to better distinguish natural variability from anthropogenic impacts. Sea-level rise and other effects of global warming are expected to intensify other anthropogenic pressures, and could cause unprecedented ecological impacts. The definition of the relevant scales of analysis, which will vary according to the magnitude of the impact and the organisational level under analysis, and the recognition of a physical-biological coupling at different scales, should be included in approaches to quantify impacts. Zoning strategies and marine reserves, which have not been widely implemented in sandy beaches, could be a key tool for biodiversity conservation and should also facilitate spillover effects into adjacent beach habitats. Setback and zoning strategies need to be enforced through legislation, and all relevant stakeholders should be included in the design, implementation and institutionalisation of these initiatives. New perspectives for rational management of sandy beaches require paradigm shifts, by including not only basic ecosystem principles, but also incentives for effective governance and sharing of management roles between government and local stakeholders.

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.

Investigating the Geomorphic Behavior of the Cape Canaveral Coast Through High-Resolution Beach Monitoring, Sediment Analysis, Oceanographic Observations, and Numerical Modeling

NASA Astrophysics Data System (ADS)

Adams, P. N.; Jaeger, J. M.; MacKenzie, R. A.; Kline, S. W.; Maibauer, B. J.; Plant, N. G.; Gravens, M. B.; Pierro, T. P.; Shaffer, J.

2011-12-01

The salient of Cape Canaveral interrupts a relatively straight, sandy, passive margin coastline that extends nearly 400 km from the St. Johns River mouth to the St. Lucie Inlet along the Florida Atlantic coast. OSL dating indicates that the modern cape has been prograding rapidly since the LGM and subtle topographic features, inland from the modern cape, suggest that this salient has persisted over several sea level cycles since the early Pleistocene. Dynamic shoreline change over the past decade at the Kennedy Space Center (KSC) is threatening critical NASA infrastructure and has prompted officials to develop a mitigation strategy through a partnership among researchers from the U.S. Geological Survey, the U.S. Army Corps of Engineers, private coastal engineering firms, and the University of Florida. Since May 2009, the research team has assembled data on decadal to event-scale shoreline change (dGPS), beach and nearshore morphodynamics (dGPS and Argus), beach sedimentary character (grain size analysis), wave climate and transformation (ADCP), and inner shelf bathymetry (Echo Sounding) in an effort to assess dune vulnerability and flooding risk. In addition, SWAN numerical modeling simulations offer insight into the influence of irregular bathymetry (cape-associated shoals) on the alteration of spatial patterns of wave energy flux during a decadal shift in deep-water wave climate. Beach-fx, modeling of cross-shore profile evolution is being applied to evaluate the performance of alternative protective measures, estimate project costs, and examine ecological influences of the proposed alternative protective measures. By combining contemporaneous data of coastal geomorphic and sedimentary response to wave forcing with numerical model results that explore a range of climate scenarios, we aim to develop a useful understanding of the coastal geomorphic behavior at KSC that can be used to make a mitigation recommendation.

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.

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.

THE EFFECT OF AMOUNT OF CRUDE OIL ON EXTENT OF ITS BIODEGRADATION IN OPEN WATER- AND SANDY BEACH- LABORATORY SIMULATIONS

EPA Science Inventory

Lepo, J.E., C. R. Cripe, J.L. Kavanaugh, S. Zhang and G.P. Norton. 2003. Effect of Amount of Crude Oil on Extent of Its Biodegradation in Open Water- and Sandy Beach-Laboratory Simulations. Environ. Technol. 24(10):1291-1302. (ERL,GB 1109).

We examined the biodegradation ...

Human recreation alters behaviour profiles of non-breeding birds on open-coast sandy shores

NASA Astrophysics Data System (ADS)

Schlacher, Thomas A.; Nielsen, Tara; Weston, Michael A.

2013-02-01

Sandy beaches are primarily valued for their amenity and property values rather than for their ecological functions and properties. Some human usage of beaches potentially conflicts with the conservation and management of wildlife, such as beach-dwelling birds, on sandy shorelines. Because responses by birds to environmental change, including disturbance by humans, often involve behaviours that carry fitness costs, we quantify behaviour profiles of birds in relation to human occurrence along 200 km of sandy shoreline in Eastern Australia, including the large conservation area of Fraser Island. Disturbance to birds on these shores was considerable: 1) birds encountered motorized vehicles (cars, trucks, buses etc.) during 80% of focal bird observation bouts, 2) birds were flushed in over half (up to 86% in individual species) of all bouts, and 3) individuals spent, on average, one-third of their time on disturbance-related behaviours; this was particularly prevalent for Crested Terns (Thalasseus bergii) which were alert 42% of the time and spent 12% of their time escaping from human stimuli. Overall, this study demonstrated that motorized traffic is the prime agent of disturbance to birds on these beaches, resulting in frequent and time-consuming escape behaviours. These findings also emphasize that management of vehicle-based recreation on beaches needs to be re-aligned to meet conservation requirements in addition to providing leisure opportunities in National Parks and beyond; we identify some salient issue for this development: a) encouragement of social norms that promote environmentally benign beach use not involving motor vehicles, b) creation of spatial refuges for beach wildlife from traffic and other non-compatible uses, and c) investment in developing complementary management actions such as effective set-back distances.

Ground-based lidar beach topography of Fire Island, New York, April 2013

USGS Publications Warehouse

Brenner, Owen T.; Hapke, Cheryl J.; Spore, Nicholas J.; Brodie, Katherine L.; McNinch, Jesse E.

2015-01-01

The U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center in Florida and the U.S. Army Corps of Engineers Field Research Facility in Duck, North Carolina, collaborated to gather alongshore ground-based lidar beach elevation data at Fire Island, New York. This high-resolution elevation dataset was collected on April 10, 2013, to characterize beach topography following substantial erosion that occurred during Hurricane Sandy, which made landfall on October 29, 2012, and multiple, strong winter storms. The ongoing beach monitoring is part of the Hurricane Sandy Supplemental Project GS2-2B. This USGS data series includes the resulting processed elevation point data (xyz) and an interpolated digital elevation model (DEM).

Mapping coastal morphodynamics with geospatial techniques, Cape Henry, Virginia, USA

NASA Astrophysics Data System (ADS)

Allen, Thomas R.; Oertel, George F.; Gares, Paul A.

2012-01-01

The advent and proliferation of digital terrain technologies have spawned concomitant advances in coastal geomorphology. Airborne topographic Light Detection and Ranging (LiDAR) has stimulated a renaissance in coastal mapping, and field-based mapping techniques have benefitted from improvements in real-time kinematic (RTK) Global Positioning System (GPS). Varied methodologies for mapping suggest a need to match geospatial products to geomorphic forms and processes, a task that should consider product and process ontologies from each perspective. Towards such synthesis, coastal morphodynamics on a cuspate foreland are reconstructed using spatial analysis. Sequential beach ridge and swale topography are mapped using photogrammetric spot heights and airborne LiDAR data and integrated with digital bathymetry and large-scale vector shoreline data. Isobaths from bathymetric charts were digitized to determine slope and toe depth of the modern shoreface and a reconstructed three-dimensional antecedent shoreface. Triangulated irregular networks were created for the subaerial cape and subaqueous shoreface models of the cape beach ridges and sets for volumetric analyses. Results provide estimates of relative age and progradation rate and corroborate other paleogeologic sea-level rise data from the region. Swale height elevations and other measurements quantifiable in these data provide several parameters suitable for studying coastal geomorphic evolution. Mapped paleoshorelines and volumes suggest the Virginia Beach coastal compartment is related to embryonic spit development from a late Holocene shoreline located some 5 km east of the current beach.

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.

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.

Factors influencing fish and macrocrustacean communities in the surf zone of sandy beaches in Belgium: temporal variation

NASA Astrophysics Data System (ADS)

Beyst, Bregje; Hostens, Kris; Mees, Jan

2001-12-01

Monthly samples were taken in the surf zone of sandy beaches along the Belgian coast from May 1996 until July 1997 at four selected stations. Temporal patterns of the macrocrustacean and fish species residing the surf zone were investigated, as well as the abiotic variables structuring the community. In total 34 species were recorded belonging to caridean shrimps (3), anomuran and brachyuran crabs (5), cephalopods (2) and fish (24). The brown shrimp Crangon crangon dominated almost all samples (>80%). Total densities often exceeded 400 ind per 100 m2, and if C. crangon was excluded 10 ind per 100 m2. Notwithstanding the harsh hydrodynamic conditions, the surf zone of Belgian sandy beaches is used intensively by a number of epibenthic macro-crustaceans and demersal fish species. Seven resident and ten migrant species were identified. As mainly juvenile fishes were present, the surf zone of the Belgian sandy beaches may act as a nursery for longer (e.g. plaice Pleuronectes platessa) or shorter (e.g. brill Scophthalmus rhombus) periods. However, its nursery function should be studied in more detail, since the highly dynamic circumstances and more specifically wave height and wind speed may be important structuring factors for the epibenthic communities. The surf zone of Belgian sandy beaches also seems to function as a transient area to other nurseries (e.g. bass Dicentrarchus labrax) or between a nursery and the true marine environment (e.g. dab Limanda limanda). Temporal variation in community structure was greatly masked by spatial differences between sites. Although variables such as salinity and hydrodynamic factors may have influenced the data, clear temperature-related, seasonal patterns occur. Most likely, extreme winter conditions and subsequent migration of organisms to deeper waters caused a decline in winter in both density and diversity.

A global analysis of erosion of sandy beaches and sea-level rise: An application of DIVA

NASA Astrophysics Data System (ADS)

Hinkel, Jochen; Nicholls, Robert J.; Tol, Richard S. J.; Wang, Zheng B.; Hamilton, Jacqueline M.; Boot, Gerben; Vafeidis, Athanasios T.; McFadden, Loraine; Ganopolski, Andrey; Klein, Richard J. T.

2013-12-01

This paper presents a first assessment of the global effects of climate-induced sea-level rise on the erosion of sandy beaches, and its consequent impacts in the form of land loss and forced migration of people. We consider direct erosion on open sandy coasts and indirect erosion near selected tidal inlets and estuaries, using six global mean sea-level scenarios (in the range of 0.2-0.8 m) and six SRES socio-economic development scenarios for the 21st century. Impacts are assessed both without and with adaptation in the form of shore and beach nourishment, based on cost-benefit analysis that includes the benefits of maintaining sandy beaches for tourism. Without nourishment, global land loss would amount to about 6000-17,000 km2 during the 21st century, leading to 1.6-5.3 million people being forced to migrate and migration costs of US 300-1000 billion (not discounted). Optimal beach and shore nourishment would cost about US 65-220 billion (not discounted) during the 21st century and would reduce land loss by 8-14%, forced migration by 56-68% and the cost of forced migration by 77-84% (not discounted). The global share of erodible coast that is nourished increases from about 4% in 2000 to 18-33% in 2100, with beach nourishment being 3-4 times more frequent than shore nourishment, reflecting the importance of tourism benefits. In absolute terms, with or without nourishment, large countries with long shorelines appear to have the largest costs, but in relative terms, small island states appear most impacted by erosion. Considerable uncertainty remains due to the limited availability of basic coastal geomorphological data and models on a global scale. Future work should also further explore the effects of beach tourism, including considering sub-national distributions of beach tourists.

Microplastics on sandy beaches of the Baja California Peninsula, Mexico.

PubMed

Piñon-Colin, Teresita de Jesus; Rodriguez-Jimenez, Ruben; Pastrana-Corral, Miguel Angel; Rogel-Hernandez, Eduardo; Wakida, Fernando Toyohiko

2018-06-01

Microplastics have become a concern in recent years because of their negative impact on marine and freshwater environments. Twenty-one sandy beach sites were sampled to investigate the occurrence and distribution of microplastics on the sandy beaches of the Baja California Peninsula, Mexico, as well as their spectroscopic characterization and morphology. Microplastics were separated using the density method and identified using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR). The mean abundance of microplastics in the samples was 135 ± 92 particles kg−1, and fiber was the most abundant microplastic found in the samples, comprising 91% of the total microplastics identified. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis of the microplastics showed that the main polymers found in microplastics were polyacrylic, polyacrylamide, polyethylene terephthalate, polyesters, and nylon.

Impact of Off-road Vehicles (ORVs) on Ghost Crabs of Sandy Beaches with Traffic Restrictions: A Case Study of Sodwana Bay, South Africa

NASA Astrophysics Data System (ADS)

Lucrezi, Serena; Saayman, Melville; van der Merwe, Peet

2014-03-01

Off-road vehicles (ORVs) are popular in coastal recreation, although they have negative impacts on sandy shores. In South Africa, ORVs are banned from most coastal areas, while some areas are designated for restricted ORV use, providing an opportunity to assess whether ORV traffic restrictions translate into biological returns. In Sodwana Bay, the impact of ORVs on ghost crab populations was investigated. During Easter 2012, ghost crab burrows were counted on beach sections open and closed to traffic. Burrow density in the Impact section was less than a third that of the Reference section, and by the end of the study burrow size in the Impact section was half that of the Reference section. ORV traffic caused a shift in burrow distribution to the Lower beach. However, differences in burrow densities between sections were 14 times smaller than differences obtained at a time when ORV use in Sodwana Bay was not controlled. While confirming the well-established detrimental effects of ORV use on sandy beach ecosystems, results demonstrated that traffic restrictions on beaches measurably minimize impacts to the fauna, thus translating into clear-cut biological returns.

Role of macrofauna on benthic oxygen consumption in sandy sediments of a high-energy tidal beach

NASA Astrophysics Data System (ADS)

Charbonnier, Céline; Lavesque, Nicolas; Anschutz, Pierre; Bachelet, Guy; Lecroart, Pascal

2016-06-01

Sandy beaches exposed to tide and waves are characterized by low abundance and diversity of benthic macrofauna, because of high-energy conditions. This is the reason why there are few studies on benthic communities living in such highly dynamic environments. It has been shown recently that tidal sandy beaches may act as biogeochemical reactors. Marine organic matter that is supplied in the sand during each flood tide is efficiently mineralized through aerobic respiration. In order to quantify the role of macrofauna in the whole beach benthic respiration, we studied the macrofauna and the pore water oxygen content of an exposed sandy beach (Truc Vert, SW of France) during four seasons in 2011. The results showed that macrofauna was characterised by a low number of species of specialized organisms such as the crustaceans Eurydice naylori and Gastrosaccus spp. and the polychaetes Ophelia bicornis and Scolelepis squamata. The distribution and abundance of macrofauna were clearly affected by exposure degree and emersion time. The combined monitoring of benthic macrofauna and pore waters chemistry allowed us to estimate (1) the macrofauna oxygen uptake, calculated with a standard allometric relationship using biomass data, and (2) the total benthic oxygen uptake, calculated from the oxygen deficit measured in pore waters. This revealed that benthic macrofauna respiration represented a variable but low (<10%) contribution to the total benthic oxygen consumption. This suggests that oxygen was mainly consumed by microbial respiration.

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.

Long-term responses of sandy beach crustaceans to the effects of coastal armouring after the 2010 Maule earthquake in South Central Chile

NASA Astrophysics Data System (ADS)

Rodil, Iván F.; Jaramillo, Eduardo; Acuña, Emilio; Manzano, Mario; Velasquez, Carlos

2016-02-01

Earthquakes and tsunamis are large physical disturbances frequently striking the coast of Chile with dramatic effects on intertidal habitats. Armouring structures built as societal responses to beach erosion and shoreline retreat are also responsible of coastal squeeze and habitat loss. The ecological implications of interactions between coastal armouring and earthquakes have recently started to be studied for beach ecosystems. How long interactive impacts persist is still unclear because monitoring after disturbance generally extends for a few months. During five years after the Maule earthquake (South Central Chile, February 27th 2010) we monitored the variability in population abundances of the most common crustacean inhabitants of different beach zones (i.e. upper, medium, and lower intertidal) at two armoured (one concrete seawall and one rocky revetment) and one unarmoured sites along the sandy beach of Llico. Beach morphology changed after the earthquake-mediated uplift, restoring upper- and mid-shore armoured levels that were rapidly colonized by typical crustacean species. However, post-earthquake increasing human activities affected the colonization process of sandy beach crustaceans in front of the seawall. Lower-shore crab Emerita analoga was the less affected by armouring structures, and it was the only crustacean species present at the three sites before and after the earthquake. This study shows that field sampling carried out promptly after major disturbances, and monitoring of the affected sites long after the disturbance is gone are effective approaches to increase the knowledge on the interactive effects of large-scale natural phenomena and artificial defences on beach ecology.

Prediction of supratidal Zones as turtle nesting sites using remote sensing and geographic information system, a case study in Pacitan, Southern Java Sea

NASA Astrophysics Data System (ADS)

Darmawan, A.; Saputra, D. K.; Wiadnya, D. G. R.; Gusmida, A. M.

2018-04-01

Turtles, the most threatened coastal-marine fauna, are protected through both national and global regulations. However, many of their nesting sites have been degraded in the past years. Completing natal homing, adult females emerged at night to lay-down eggs in the upper intertidal and supra-tidal zone of sandy beach from where they hatched. This study explained coastal topology of beaches usually used for nesting sites, covering 117 km coastline at Pacitan Regency, Southern Java Sea. The shift in beach morphology through times was figured out based on Landsat 8 and Sentinel 2a satellite imagery and remote sensing (GIS methods). This was combined with in-situ data on current coastline features, slope, and tide variations. Results showed a typical sandy beach, called Taman Ria Beach, a long time identified as nesting site for Lepidochelys olivacea, locally named as Penyu Lekang. Also, there was approximatelly 3.49 ha of supratidal area predicted in Taman Ria Beach according this study

INFLUENCE OF TIDE AND WAVES ON WASHOUT OF DISSOLVED NUTRIENTS FROM THE BIOREMEDIATION ZONE OF A COARSE-SAND BEACH: APPLICATION IN OIL-SPILL BIOREMEDIATION

EPA Science Inventory

Successful bioremediation of oil-contaminated beaches requires maintenance of a sufficient quantity of growth-limiting nutrients in contact with the oiled beach materials. A conservative tracer study was conducted on a moderate-energy, sandy beach on Delaware Bay to estimate the...

A system for beach video-monitoring: Beachkeeper plus

NASA Astrophysics Data System (ADS)

Brignone, Massimo; Schiaffino, Chiara F.; Isla, Federico I.; Ferrari, Marco

2012-12-01

A suitable knowledge of coastal systems, of their morphodynamic characteristics and their response to storm events and man-made structures is essential for littoral conservation and management. Nowadays webcams represent a useful device to obtain information from beaches. Video-monitoring techniques are generally site specific and softwares working with any image acquisition system are rare. Therefore, this work aims at submitting theory and applications of an experimental video monitoring software: Beachkeeper plus, a freeware non-profit software, can be employed and redistributed without modifications. A license file is provided inside software package and in the user guide. Beachkeeper plus is based on Matlab® and it can be used for the analysis of images and photos coming from any kind of acquisition system (webcams, digital cameras or images downloaded from internet), without any a-priori information or laboratory study of the acquisition system itself. Therefore, it could become a useful tool for beach planning. Through a simple guided interface, images can be analyzed by performing georeferentiation, rectification, averaging and variance. This software was initially operated in Pietra Ligure (Italy), using images from a tourist webcam, and in Mar del Plata (Argentina) using images from a digital camera. In both cases the reliability in different geomorphologic and morphodynamic conditions was confirmed by the good quality of obtained images after georeferentiation, rectification and averaging.

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.

Warming intensify CO2 flux and nutrient release from algal wrack subsidies on sandy beaches.

PubMed

Lastra, Mariano; López, Jesús; Rodil, Iván F

2018-04-18

Algal wrack subsidies underpin most of the food web structure of exposed sandy beaches and are responsible of important biogeochemical processes that link marine and terrestrial ecosystems. The response in decomposition of algal wrack deposits to global warming has not been studied in ocean-exposed sandy beaches to date. With this aim, passive open top chambers (OTCs) were used to increase soil temperature within the range predicted by the IPCC for western Europe (between 0.5 and 1.5°C), following the hypothesis that the biogeochemical processing of macroalgal wrack subsidies would accelerate in response to temperature increase. The effect of temperature manipulation on three target substrates: fresh and aged macroalgae, and bare sand, was tested. Results indicated that a small warming (<0.5°C) affected the wrack decomposition process through traceable increases in soil respiration through CO 2 flux, inorganic nutrients within the interstitial environment (N and P), sediment organic contents measured through the amount of proteins and microbial pool through the total soil DNA. The different responses of soil variables in the studied substrates indicated that the decomposition stage of stranded macroalgae influences the biogeochemical processing of organic matter in sandy beaches. Thus, CO 2 fluxes, releases of organic and inorganic nutrients and microbial activity intensify in aged wrack deposits. Our results predict that expected global warming will increase the release of inorganic nutrients to the coastal ocean by 30% for the N (21 Gg/year) and 5.9% for P (14 Gg/year); that increase for the flow of C to the atmosphere as CO 2 was estimated in 8.2% (523 Gg/year). This study confirms the key role of sandy beaches in recycling ocean-derived organic matter, highlighting their sensitivity to a changing scenario of global warming that predicts significant increases in temperature over the next few decades. © 2018 John Wiley & Sons Ltd.

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.

Beach impacts of shore-parallel breakwaters backing offshore submerged ridges, Western Mediterranean Coast of Egypt.

PubMed

Iskander, Moheb M; Frihy, Omran E; El Ansary, Ahmed E; El Mooty, Mohamed M Abd; Nagy, Hossam M

2007-12-01

Seven breakwaters were constructed behind offshore submerged ridges to create a safe area for swimming and recreational activities west of Alexandria on the Mediterranean coast of Egypt. Morphodynamic evaluation was based on the modified Perlin and Dean numerical model (ImSedTran-2D) combined with successive shoreline and beach profile surveys conducted periodically between April 2001 and May 2005. Results reveal insignificant morphologic changes behind the detached breakwaters with slight coastline changes at the down and up-drift beaches of the examined breakwaters (+/-10 m). These changes are associated with salient accretion (20-7 0m) in the low-energy leeside of such structures. Concurrent with this sand accretion is the accumulation of a large amount of benthic algae (Sargassum) in the coastal water of the shadow area of these structures, which in turn have adverse effects on swimmers. Practical measures proposed in this study have successfully helped in mitigating such accumulation of algae in the recreation leeside of the breakwaters. The accumulation of Sargassum, together with the virtual insignificant changes in the up-drift and down-drifts of these structures, is a direct response to both coastal processes and the submerged carbonate ridges. Coastal processes encompass reversal of the directions of long-shore sand transport versus shoreline orientation, the small littoral drift rate and sand deficiency of the littoral zone. The beach response to the breakwaters together with the submerged ridges has also been confirmed by applying the ImSedTran-2D model. Results indicate that submerged ridges play a principal role in the evolution of beach morphology along the west coast of Alexandria. Although the study area is exposed to more than 70% wave exposures, the morphodynamic behavior of the beaches indicates that the submerged ridges act in a similar way as an additional natural barrier together with the artificial detached structures.

Marine debris in beaches of the Southwestern Atlantic: An assessment of their abundance and mass at different spatial scales in northern coastal Argentina.

PubMed

Becherucci, Maria Eugenia; Rosenthal, Alan Federico; Seco Pon, Juan Pablo

2017-06-15

Argentina is currently undergoing an intensive development of coastal-oriented tourism due to the temperate climate and coastal sceneries of the Southwestern Atlantic and particularly its wide ocean-open sandy beaches, which may turn into an important contributor of marine debris to the beaches. This study was designed to assess at four spatial scales (i) the variation of the abundance and mass of marine debris and (ii) the composition and sources of these items in sandy-tourist beaches of coastal zones of the province of Buenos Aires, in northern Argentina. The abundance and mass of marine debris shifted between sampling localities (separated by ~1.5×10 5 m) and beaches (~3×10 4 m). Debris was primarily from recreational and fishing activities and over 20mm in size. Tackling the complications associated with marine debris in northern Argentina may include intensive educational and advertising campaigns oriented chiefly to beach users and fisherman. Copyright © 2017. Published by Elsevier Ltd.

Spatial variability of macrobenthic zonation on exposed sandy beaches

NASA Astrophysics Data System (ADS)

Veiga, Puri; Rubal, Marcos; Cacabelos, Eva; Maldonado, Cristina; Sousa-Pinto, Isabel

2014-07-01

We analysed the consistence of vertical patterns of distribution (i.e. zonation) for macrofauna at different spatial scales on four intermediate exposed beaches in the North of Portugal. We tested the hypothesis that biological zonation on exposed sandy beaches would vary at the studied spatial scales. For this aim, abundance, diversity and structure of macrobenthic assemblages were examined at the scales of transect and beach. Moreover, the main environmental factors that could potentially drive zonation patterns were investigated. Univariate and multivariate analyses revealed that the number of biological zones ranged from two to three depending on the beach and from indistinct zonation to three zones at the scale of transect. Therefore, results support our working hypothesis because zonation patterns were not consistent at the studied spatial scales. The median particle size, sorting coefficient and water content were significantly correlated with zonation patterns of macrobenthic assemblages. However, a high degree of correlation was not reached when the total structure of the assemblage was considered.

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. 

Impact of coastal forcing and groundwater recharge on the growth of a fresh groundwater lens in a mega-scale beach nourishment

NASA Astrophysics Data System (ADS)

Huizer, Sebastian; Radermacher, Max; de Vries, Sierd; Oude Essink, Gualbert H. P.; Bierkens, Marc F. P.

2018-02-01

For a large beach nourishment called the Sand Engine - constructed in 2011 at the Dutch coast - we have examined the impact of coastal forcing (i.e. natural processes that drive coastal hydro- and morphodynamics) and groundwater recharge on the growth of a fresh groundwater lens between 2011 and 2016. Measurements of the morphological change and the tidal dynamics at the study site were incorporated in a calibrated three-dimensional and variable-density groundwater model of the study area. Simulations with this model showed that the detailed incorporation of both the local hydro- and morphodynamics and the actual recharge rate can result in a reliable reconstruction of the growth in fresh groundwater resources. In contrast, the neglect of tidal dynamics, land-surface inundations, and morphological changes in model simulations can result in considerable overestimations of the volume of fresh groundwater. In particular, wave runup and coinciding coastal erosion during storm surges limit the growth in fresh groundwater resources in dynamic coastal environments, and should be considered at potential nourishment sites to delineate the area that is vulnerable to salinization.

Meiofauna as descriptor of tourism-induced changes at sandy beaches.

PubMed

Gheskiere, Tom; Vincx, Magda; Weslawski, Jan Marcin; Scapini, Felicita; Degraer, Steven

2005-08-01

Tourism has long been considered as a 'clean industry' with almost no negative effects on the environment. This study demonstrated, in two different coastal systems (Mediterranean and Baltic), that tourism related activities are particularly affecting the sandy beach meio- and nematofauna in the upper beach zone, the specific ecotone in which many meiofauna species from both the marine and the terrestrial environment congregate. Tourist upper beaches are characterized by a lower % total organic matter (%TOM), lower densities, lower diversities (absence of Insecta, Harpacticoida, Oligochaeta, terrestrial nematodes and marine Ironidae nematodes) and higher community stress compared to nearby non-tourist locations. The %TOM was found to be the single most important factor for the observed differences in meiofauna assemblage structure at tourist versus non-tourist beaches in both the Mediterranean and the Baltic region. The free-living nematode assemblages from tourist upper zones depart significantly from expectations based on random selections from the regional nematode species pool. Furthermore upper zone assemblages are characterised by a low species diversity consisting of taxonomically closely related nematode species with r-strategist features. Generally, faunal differences between tourist and non-tourist beaches are decreasing towards the lower beach zones.

Coastal topography–Northeast Atlantic coast, post-hurricane Sandy, 2012

USGS Publications Warehouse

Stockdon, Hilary F.; Doran, Kara S.; Sopkin, Kristin L.; Smith, Kathryn E.L.; Fredericks, Xan

2013-01-01

This Data Series contains lidar-derived bare-earth (BE) topography, dune elevations, and mean-high-water shoreline position datasets for most sandy beaches for Fire Island, New York, and from Cape Henlopen, Delaware to Cape Lookout, North Carolina. The data were acquired post-Hurricane Sandy, which made landfall as an extratropical cyclone on October 29, 2012.

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.

Temporal shift of sea turtle nest sites in an eroding barrier island beach

USGS Publications Warehouse

Fujisaki, Ikuko; Lamont, Margaret M.; Carthy, Raymond R.

2018-01-01

Shoreline changes affect functionality of a sandy beach as a wildlife habitat and coastal erosion is among the primary causes of the changes. We examined temporal shifts in locations where loggerheads placed nests in relation to coastal erosion along a barrier island beach in the northern Gulf of Mexico. We first confirmed consistency in long-term (1855–2001), short-term (1976–2001), and more recent (2002–2012) shoreline change rates in two adjacent beach sections, one historically eroding (west beach) and the other accreting (east beach). The mean annual shoreline change rate in the two sections was significantly different in all time periods. The recent (1998–2012) mean change rate was −10.9 ± 9.9 m/year in the west beach and −2.8 ± 4.9 m/year in the east beach, which resulted in the loss of about 70% and 30% of area in the west and east beaches, respectively. Loggerheads nested significantly closer to the vegetation line in 2012 than in 2002 in the west beach but the difference between the two time periods was not significant in the east beach. However, the distance from nests to the vegetation line from 2002 to 2014 was significantly reduced annually in both beaches; on average, loggerheads nested closer to the vegetation line by 9 m/year in the west beach and 5.8 m/year in the east beach. The observed shoreline change rate and corresponding shift of nest placement sites, combined with the forecasted future beach loss, highlighted the importance of addressing the issue of beach erosion to conserve sandy beach habitats.

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.

Quantifying spatial and temporal trends in beach-dune volumetric changes using spatial statistics

NASA Astrophysics Data System (ADS)

Eamer, Jordan B. R.; Walker, Ian J.

2013-06-01

Spatial statistics are generally underutilized in coastal geomorphology, despite offering great potential for identifying and quantifying spatial-temporal trends in landscape morphodynamics. In particular, local Moran's Ii provides a statistical framework for detecting clusters of significant change in an attribute (e.g., surface erosion or deposition) and quantifying how this changes over space and time. This study analyzes and interprets spatial-temporal patterns in sediment volume changes in a beach-foredune-transgressive dune complex following removal of invasive marram grass (Ammophila spp.). Results are derived by detecting significant changes in post-removal repeat DEMs derived from topographic surveys and airborne LiDAR. The study site was separated into discrete, linked geomorphic units (beach, foredune, transgressive dune complex) to facilitate sub-landscape scale analysis of volumetric change and sediment budget responses. Difference surfaces derived from a pixel-subtraction algorithm between interval DEMs and the LiDAR baseline DEM were filtered using the local Moran's Ii method and two different spatial weights (1.5 and 5 m) to detect statistically significant change. Moran's Ii results were compared with those derived from a more spatially uniform statistical method that uses a simpler student's t distribution threshold for change detection. Morphodynamic patterns and volumetric estimates were similar between the uniform geostatistical method and Moran's Ii at a spatial weight of 5 m while the smaller spatial weight (1.5 m) consistently indicated volumetric changes of less magnitude. The larger 5 m spatial weight was most representative of broader site morphodynamics and spatial patterns while the smaller spatial weight provided volumetric changes consistent with field observations. All methods showed foredune deflation immediately following removal with increased sediment volumes into the spring via deposition at the crest and on lobes in the lee, despite erosion on the stoss slope and dune toe. Generally, the foredune became wider by landward extension and the seaward slope recovered from erosion to a similar height and form to that of pre-restoration despite remaining essentially free of vegetation.

Hydro morphodynamic modelling in Mediterranean storms: errors and uncertainties under sharp gradients

NASA Astrophysics Data System (ADS)

Sánchez-Arcilla, A.; Gracia, V.; García, M.

2014-02-01

This paper deals with the limits in hydrodynamic and morphodynamic predictions for semi-enclosed coastal domains subject to sharp gradients (in bathymetry, topography, sediment transport and coastal damages). It starts with an overview of wave prediction limits (based on satellite images) in a restricted domain such as is the Mediterranean basin, followed by an in-depth analysis of the Catalan coast, one of the land boundaries of such a domain. The morphodynamic modeling for such gradient regions is next illustrated with the simulation of the largest recorded storm in the Catalan coast, whose morphological impact is a key element of the storm impact. The driving wave and surge conditions produce a morphodynamic response that is validated against the pre and post storm beach state, recovered from two LIDAR images. The quality of the fit is discussed in terms of the physical processes and the suitability of the employed modeling equations. Some remarks about the role of the numerical discretization and boundary conditions are also included in the analysis. From here an assessment of errors and uncertainties is presented, with the aim of establishing the prediction limits for coastal engineering flooding and erosion analyses.

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.

Localised Effects of a Mega-Disturbance: Spatiotemporal Responses of Intertidal Sandy Shore Communities to the 2010 Chilean Earthquake.

PubMed

Sepúlveda, Roger D; Valdivia, Nelson

2016-01-01

Determining the effects of unpredictable disturbances on dynamic ecological systems is challenged by the paucity of appropriate temporal and spatial coverage of data. On 27 February 2010, an 8.8 Mw mega-earthquake and tsunami struck central Chile and caused coastal land-level changes, massive damage to coastal infrastructure, and widespread mortality of coastal organisms. Wave-exposed sandy beaches showed significant changes of species abundances from before to after the earthquake, but the highly dynamic biotic and abiotic conditions of these habitats make difficult to draw clear-cut conclusions from these patterns. Here, we analysed a beyond-BACI (Before-After Control-Impact) sampling design to test whether the effects of the Maule earthquake on sandy-shore species diversity, abundance, and structure were heterogeneous along the shore. Invertebrate species abundances were quantified before (i.e. February 2010) and after (i.e. March 2010, September 2010, and March 2011) the earthquake at three sandy shores randomly located within the earthquake rupture area and three sites within a "control" area located >400 km southward from epicentre. Immediately after the earthquake took place, the three sites located in the rupture area showed anomalous beach-profile uplifts that did not comply with the erosion (i.e. "negative" uplifts) that regularly occurs during late summer in the region. Species richness, abundance, and community structure significantly varied from before to after the strike, but these patterns of change varied among sites within both areas. Only the site with the strongest and persistent beach-profile uplift within the rupture area showed significant concomitant changes in species richness and community structure; after 13 months, this community showed a similar multivariate structure to the before-disturbance state. This site, in particular, was located in the section of the rupture area that received most of the impact of the after-earthquake tsunami. Therefore, our results suggest that the effects of the Maule mega-earthquake on the ecological communities were spatially heterogeneous and highly localised. We suggest that high mobility and other species' adaptations to the dynamic environmental conditions of sandy beaches might explain the comparatively high resilience of these assemblages. With this work we hope to motivate further experimental research on the role of individual- and population-level properties in the response of sandy-beach communities to interacting sources of disturbances.

Localised Effects of a Mega-Disturbance: Spatiotemporal Responses of Intertidal Sandy Shore Communities to the 2010 Chilean Earthquake

PubMed Central

Sepúlveda, Roger D.; Valdivia, Nelson

2016-01-01

Determining the effects of unpredictable disturbances on dynamic ecological systems is challenged by the paucity of appropriate temporal and spatial coverage of data. On 27 February 2010, an 8.8 Mw mega-earthquake and tsunami struck central Chile and caused coastal land-level changes, massive damage to coastal infrastructure, and widespread mortality of coastal organisms. Wave-exposed sandy beaches showed significant changes of species abundances from before to after the earthquake, but the highly dynamic biotic and abiotic conditions of these habitats make difficult to draw clear-cut conclusions from these patterns. Here, we analysed a beyond-BACI (Before-After Control-Impact) sampling design to test whether the effects of the Maule earthquake on sandy-shore species diversity, abundance, and structure were heterogeneous along the shore. Invertebrate species abundances were quantified before (i.e. February 2010) and after (i.e. March 2010, September 2010, and March 2011) the earthquake at three sandy shores randomly located within the earthquake rupture area and three sites within a “control” area located >400 km southward from epicentre. Immediately after the earthquake took place, the three sites located in the rupture area showed anomalous beach-profile uplifts that did not comply with the erosion (i.e. “negative” uplifts) that regularly occurs during late summer in the region. Species richness, abundance, and community structure significantly varied from before to after the strike, but these patterns of change varied among sites within both areas. Only the site with the strongest and persistent beach-profile uplift within the rupture area showed significant concomitant changes in species richness and community structure; after 13 months, this community showed a similar multivariate structure to the before-disturbance state. This site, in particular, was located in the section of the rupture area that received most of the impact of the after-earthquake tsunami. Therefore, our results suggest that the effects of the Maule mega-earthquake on the ecological communities were spatially heterogeneous and highly localised. We suggest that high mobility and other species’ adaptations to the dynamic environmental conditions of sandy beaches might explain the comparatively high resilience of these assemblages. With this work we hope to motivate further experimental research on the role of individual- and population-level properties in the response of sandy-beach communities to interacting sources of disturbances. PMID:27383744

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).

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

Plastic litter accumulation on high-water strandline of urban beaches in Mumbai, India.

PubMed

Jayasiri, H B; Purushothaman, C S; Vennila, A

2013-09-01

Today, almost every beach on every coastline is threatened by human activities. The inadequate recycling and poor management of waste in developing countries has resulted in considerable quantities of plastic contaminating beaches. Though India has long coastline of 5,420 km along the mainland with 43 % of sandy beaches, data on litter accumulation, particularly the plastics, which are one of the most common and persistent pollutants in marine environment, are scanty. The abundance and distribution of plastic litter was quantitatively assessed in four sandy beaches in Mumbai, India, bimonthly from May 2011 to March 2012. Triplicates of 2 × 2 m (4 m(2)) quadrats were sampled in each beach with a total of 72 quadrats. Overall, average abundance of 11.6 items m(-2) (0.25-282.5 items m(-2)) and 3.24 g m(-2) (0.27-15.53 g m(-2)) plastic litter was recorded in Mumbai beaches. Plastic litter accumulation significantly varied temporally and spatially at p = 0.05. Significantly higher plastic litter accumulation was recorded in Juhu beach. Furthermore, the highest abundance by weight was recorded in November and May numerically. More than 80 % of plastic particles were within the size range of 5-100 mm both by number and weight. Moreover, coloured plastics were predominant with 67 % by number of items and 51 % by weight. Probably, the intense use of beaches for recreation, tourism, and religious activities has increased the potential for plastic contamination in urban beaches in Mumbai.

Exploring the social dimension of sandy beaches through predictive modelling.

PubMed

Domínguez-Tejo, Elianny; Metternicht, Graciela; Johnston, Emma L; Hedge, Luke

2018-05-15

Sandy beaches are unique ecosystems increasingly exposed to human-induced pressures. Consistent with emerging frameworks promoting this holistic approach towards beach management, is the need to improve the integration of social data into management practices. This paper aims to increase understanding of links between demographics and community values and preferred beach activities, as key components of the social dimension of the beach environment. A mixed method approach was adopted to elucidate users' opinions on beach preferences and community values through a survey carried out in Manly Local Government Area in Sydney Harbour, Australia. A proposed conceptual model was used to frame demographic models (using age, education, employment, household income and residence status) as predictors of these two community responses. All possible regression-model combinations were compared using Akaike's information criterion. Best models were then used to calculate quantitative likelihoods of the responses, presented as heat maps. Findings concur with international research indicating the relevance of social and restful activities as important social links between the community and the beach environment. Participant's age was a significant variable in the four predictive models. The use of predictive models informed by demographics could potentially increase our understanding of interactions between the social and ecological systems of the beach environment, as a prelude to integrated beach management approaches. The research represents a practical demonstration of how demographic predictive models could support proactive approaches to beach management. Copyright © 2018 Elsevier Ltd. All rights reserved.

BIODEGRADATION OF POLYCYCLIC AROMATIC HYDROCARBONS (PAH) FROM CRUDE OIL IN SANDY-BEACH MICROCOSMS.

EPA Science Inventory

Though the lower n-alkanes are considered the most degradable components of crude oil, our experiments with microcosms simulating oiled beaches showed substantial depletion of fluorene, phenanthrene, dibenzothiophene, and other PAH in control treatments consisting of raw seawater...

Effects of beach replenishment on intertidal invertebrates: A 15-month, eight beach study.

NASA Astrophysics Data System (ADS)

Wooldridge, Tyler; Henter, Heather J.; Kohn, Joshua R.

2016-06-01

Beach replenishment is an increasingly popular means to remediate coastal erosion, but no consensus exists regarding how long replenishment affects sandy beach intertidal invertebrates, key components of beach ecosystems. We monitored the intertidal invertebrate community for fifteen months following a replenishment project at eight beaches, each with replenished and control sections, across San Diego County. Nearly all taxa showed major declines in abundance immediately following replenishment. Populations of talitrid amphipods and the bean clam Donax gouldii recovered within one year, sooner than in previous studies. On some beaches, populations of the mole crab Emerita analoga bloomed four months after replenishment and were more numerous on replenished portions of beaches at that time. Mole crab populations subsequently declined and no longer differed by treatment. The polychaete community, composed of Scolelepis sp. and several other numerically important taxa, showed a strong replenishment-induced reduction in abundance that persisted through the end of the study. The large negative effect of replenishment on polychaetes, coupled with their overall importance to the invertebrate community, resulted in a more than twofold reduction in overall invertebrate abundance on replenished beaches at 15 months. Such reductions may have far reaching consequences for sandy beach ecosystems, as community declines can reduce prey availability for shorebirds and fish. As this and other recent studies have revealed longer times for the recovery of intertidal invertebrates than previously observed, longer study periods and more cautious estimates regarding the magnitude, variability, and duration of impacts of beach replenishment for management decision-making are warranted.

Installation Restoration Program. Phase I. Records Search, Hazardous Materials Disposal Sites. Myrtle Beach Air Force Base, South Carolina.

DTIC Science & Technology

1981-10-01

Geography 3-1 Topography 3-. Drainage 3-1 ii Page Surface Geology 3-3 Barrier Sediments 3-3 Myrtle Beach Backbarrier Sediments 3-3 soils 3-5 Subsurface...Beach AFB Surface Drainage and Surface Water Sampling Points 3-2 3.2 Myrtle Beach AFB Surface Soils 3-4 3.3 Myrtle Beach AFB Location of Geologic Cross...has created a potential contamination problem. This situation is compounded by the site’s sandy soil and shallow ground water table. b.) Weathering Pit

Set-up and validation of a Delft-FEWS based coastal hazard forecasting system

NASA Astrophysics Data System (ADS)

Valchev, Nikolay; Eftimova, Petya; Andreeva, Nataliya

2017-04-01

European coasts are increasingly threatened by hazards related to low-probability and high-impact hydro-meteorological events. Uncertainties in hazard prediction and capabilities to cope with their impact lie in both future storm pattern and increasing coastal development. Therefore, adaptation to future conditions requires a re-evaluation of coastal disaster risk reduction (DRR) strategies and introduction of a more efficient mix of prevention, mitigation and preparedness measures. The latter presumes that development of tools, which can manage the complex process of merging data and models and generate products on the current and expected hydro-and morpho-dynamic states of the coasts, such as forecasting system of flooding and erosion hazards at vulnerable coastal locations (hotspots), is of vital importance. Output of such system can be of an utmost value for coastal stakeholders and the entire coastal community. In response to these challenges, Delft-FEWS provides a state-of-the-art framework for implementation of such system with vast capabilities to trigger the early warning process. In addition, this framework is highly customizable to the specific requirements of any individual coastal hotspot. Since its release many Delft-FEWS based forecasting system related to inland flooding have been developed. However, limited number of coastal applications was implemented. In this paper, a set-up of Delft-FEWS based forecasting system for Varna Bay (Bulgaria) and a coastal hotspot, which includes a sandy beach and port infrastructure, is presented. It is implemented in the frame of RISC-KIT project (Resilience-Increasing Strategies for Coasts - toolKIT). The system output generated in hindcast mode is validated with available observations of surge levels, wave and morphodynamic parameters for a sequence of three short-duration and relatively weak storm events occurred during February 4-12, 2015. Generally, the models' performance is considered as very good and results obtained - quite promising for reliable prediction of both boundary conditions and coastal hazard and gives a good basis for estimation of onshore impact.

Applying a two-dimensional morphodynamic model to assess impacts to Chinook salmon spawning habitat from dam removal

NASA Astrophysics Data System (ADS)

Lee, A. A.; Crosato, A.; Omer, A. Y. A.; Bregoli, F.

2017-12-01

The need for accurate and robust predictive methods of assessing fluvial ecosystems is highlighted by the accelerating practice of dam removal. Dam removal can be a restorative measure, but the sudden release of impounded sediment and change in flow regime may negatively impact aquatic biota and their habitat. This study assesses the performance of a quasi-three-dimensional morphodynamic numerical model, coupled with habitat suitability indices, to predict short-term impacts to Chinook salmon (Oncorhynchus tshawytscha) spawning habitat from dam removal. The 2007 removal of Marmot Dam on the Sandy River (Oregon, U.S.A.) is used as a case study. Delft3D-FLOW is employed to simulate changes in river channel topography, sediment composition and hydrodynamic conditions for a 20-kilometer reach of the Sandy River. The transport of non-uniform sediment and three-dimensional flow effects are included in the model. Output parameters such as flow depth, velocity and substrate are processed to evaluate habitat quality in the year following the Marmot Dam removal. Impacts are evaluated across four life-stages of Chinook salmon. As a hindcast analysis, the morphodynamic model sufficiently reproduces the evolution of river morphology at the reach-scale while requiring only a low level of calibration. The model performs well in predicting impacts to fish passage, but carries more uncertainty for developing life stages. By coupling flow-sediment-biota interactions, this method shows strong potential for habitat assessment in unsteady and non-uniform environments. Computation time is a primary constraint, as it limits grid-cell resolution, modelling of suspended sediment and capacity to characterize the sediment grain size distribution. Research on the effects of suspended sediment on habitat quality is ongoing, and further research is recommended for modelling reservoir erosion processes numerically.

Plastic in surface waters of the Inside Passage and beaches of the Salish Sea in Washington State.

PubMed

Davis, Wallace; Murphy, Anne G

2015-08-15

We summarize results of two independent studies on plastic pollution in the marine environment that overlap in time and space. One study evaluated the abundance of anthropogenic debris on 37 sandy beaches bordering the Salish Sea in Washington State while the other characterized plastic debris in surface waters of the Salish Sea and the Inside Passage to Skagway, Alaska. Both studies concluded that foam, primarily expanded polystyrene was the dominant pollutant. Plastic was found in surface waters the full length of the Inside Passage but was concentrated near harbors. At the wrack line, an average square meter of Washington's 1180km of sandy beaches in the Salish Sea had 61 pieces of anthropogenic debris weighing approximately 5g. The total loading for the entire 1m wide band is estimated to be 72,000,000 pieces and 5.8metric tons. Most anthropogenic debris on beaches is generated within the region. Copyright © 2015 Elsevier Ltd. All rights reserved.

TOXICITY TRENDS DURING AN OIL SPILL BIOREMEDIATION EXPERIMENT ON A SANDY SHORELINE IN DELAWARE, USA

EPA Science Inventory

A 13-week, refereed, inter-agency toxicity testing program involving five bioassay methods was used to document the effectiveness of shoreline bioremediation to accelerate toxicity reduction of an oiled sandy shoreline at Fowler Beach, Delaware, USA. The study was part of an inte...

Testing the role of bedforms as controls on the morphodynamics of sandy braided rivers with CFD

NASA Astrophysics Data System (ADS)

Unsworth, C. A.; Nicholas, A. P.; Ashworth, P. J.; Best, J.; Lane, S. N.; Parsons, D. R.; Sambrook Smith, G.; Simpson, C.; Strick, R. J. P.

2017-12-01

Sand-bed rivers are characterised by multiple scales of topography (e.g., channels, bars and bedforms). Small scale topographic features (e.g., dunes) exert a significant influence on coherent flow structures and sediment transport processes, over distances that scale with channel depth. However, the extent to which such dune-scale effects control larger, channel and bar-scale morphology and morphodynamics remains unknown. Moreover, such bedform effects are typically neglected in two-dimensional (depth-averaged) morphodynamic models that are used to simulate river evolution. To evaluate the significance of these issues, we report results from a combined numerical modelling and field monitoring study, undertaken in the South Saskatchewan River, Canada. Numerical simulations were carried out, using the OpenFOAM CFD code, to quantify the mean three-dimensional flow structure within a 90 x 350 m section of channel. To isolate the role of bedforms as a control on flow and sediment transport, two simulations were undertaken. The first used a high-resolution ( 3 cm) bedform-resolving DEM. The second used a filtered DEM in which dunes were removed and only large scale topographic features (e.g., bars, scour pools etc) were resolved. The results of these simulations are compared here, in order to quantify the degree to which topographic steering by bedforms influences flow and sediment transport directions at bar and channel scales. Analysis of the CFD simulation results within a 2D morphodynamic modelling framework demonstrates that dunes exert a significant influence on sediment transport, and hence morphodynamics, and highlights important shortcomings in existing 2D model parameterisations of topographic steering.

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.

National assessment of hurricane-induced coastal erosion hazards--Gulf of Mexico

USGS Publications Warehouse

Stockdon, Hilary F.; Doran, Kara S.; Thompson, David M.; Sopkin, Kristin L.; Plant, Nathaniel G.; Sallenger, Asbury H.

2012-01-01

Sandy beaches provide a natural barrier between the ocean and inland communities, ecosystems, and resources. However, these dynamic environments move and change in response to winds, waves, and currents. During a hurricane, these changes can be large and sometimes catastrophic. High waves and storm surge act together to erode beaches and inundate low-lying lands, putting inland communities at risk. A decade of USGS research on storm-driven coastal change hazards has provided the data and modeling capabilities to identify areas of our coastline that are likely to experience extreme and potentially hazardous erosion during a hurricane. This report defines hurricane-induced coastal erosion hazards for sandy beaches along the U.S. Gulf of Mexico coastline. The analysis is based on a storm-impact scaling model that uses observations of beach morphology combined with sophisticated hydrodynamic models to predict how the coast will respond to the direct landfall of category 1-5 hurricanes. Hurricane-induced water levels, due to both surge and waves, are compared to beach and dune elevations to determine the probabilities of three types of coastal change: collision (dune erosion), overwash, and inundation. As new beach morphology observations and storm predictions become available, this analysis will be updated to describe how coastal vulnerability to storms will vary in the future.

Natural versus Urban dunes along the Emilia-Romagna coast, Northern Adriatic (Italy)

NASA Astrophysics Data System (ADS)

Corbau, Corinne; Simeoni, Umberto

2014-05-01

Beach-dune interaction models can be precious tools for land managers and policymakers. However, if the models are inaccurate, land use policies may be designed based on false pretences or assumptions leading to poor land management, long-term erosion and sustainability issues, and increased difficulties in maintaining the dynamic coastal systems. From the literature, it appears that even the most reliable beach-dunes interactions models are not applicable to all coastal systems (Short and Hesp, 1982; Psuty, 1988; Sherman and Bauer, 1993). The study aims to identify the morphological evolution of the Emilia-Romagna coastal dunes according to its natural and "human" characteristics and to classify groups of dunes with similar evolutionary patterns. The coastal area consists essentially of 130 km of low sandy coast, interrupted by vast lagoon areas, harbor jetties and numerous hard coastal defense structures that were built during the first half of the 20th century to protect the Emilia-Romagna coast against erosion. Today about 57% of the littoral is protected by hard defenses, which have modified the morphodynamic characteristics of the beach without inverting the negative coastal evolution's trend. From recent aerial photographs (2011), 62 coastal dunes have been identified and mapped. Furthermore, the dune analysis shows a variability of the "physical characteristics" of coastal-dune systems along the Emilia-Romagna coast. The dune height varies from 1 to 7 meters, the width of the beach and of the active dunes range respectively from 10 to 150 m and from 10 to 65 m. Three main factors may explain the variability of the "physical characteristics": 1- Firstly the frontal dunes may be of different states according to the classification of Hesp (2002) since they correspond to incipient foredunes, well-developed foredunes, blowouts, residual foredunes as well as reactivated relict foredunes, 2- This could also be related to a different orientation of the coastline and foredune's line to the dominant onshore winds and, 3- Human impacts may also explain this variability since most of the dune-beach systems of Emilia-Romagna are characterized by important anthropogenic features that do not adequately describe beach-foredune interactions. A factor analysis of the coastal dunes has allowed formulating hypotheses about their evolutionary trends according to the importance and interference of factors, both natural and anthropic, acting on the beach-dune system. Four groups of dunes have been identified corresponding to natural dunes, semi-anthropic dunes with major natural features, semi-anthropic dunes with major anthropic feature and "urban" dunes. Furthermore, while human activities impede the formation and development of new incipient dunes, other human activities favor the conservation and development of the human-altered foredunes. Hesp, P., 2002: Foredunes and blowouts: initiation, geomorphology and dynamics, Geomorphology, 245-268. Psuty, N. P. 1988. Sediment budget and dune/beach interaction. Journal of Coastal Research Special Issue 3: 1-4. Sherman, D. J., and B. O. Bauer. 1993. Dynamics of beach-dune systems. Progress in Physical Geography 17 (4): 413-447 Short, A. D., and P. A. Hesp. 1982. Wave, beach and dune interactions in South Eastern Australia. Marine Geology 48: 259-284.

A shoreline sand wave formation event at Dungeness, UK.

NASA Astrophysics Data System (ADS)

Falqués, A.; Arriaga, J.; Francesca, R.; Eddie, C.

2016-12-01

Alongshore rhythmic morphological patterns at different length scales are quite common along sandy beaches. Well known examples are megacusps and crescentic bars/rip channel systems with alongshore wavelengths ˜ 100-1000 m. At larger scales (˜ 1-10 km or more) there are the km-scale shoreline sand waves. During the last two decades there has been much research to unravel the origin of such intriguing patterns and to get insight into their dynamics. The hypothesis that they emerge out of positive feedbacks between hydrodynamics and morphology has been amply confirmed by mathematical modelling. In particular, the potential role of high-angle waves (large incidence angles with respect to shore) in driving km-scale shoreline sand waves has been investigated (Ashton et al., 2001, van den Berg et al., 2012). However, direct tests with nature are very difficult and are inexistent to our knowledge. This is so because these tests would require detailed measurements of the bathymetry and the wave conditions at the moment of their formation from a featureless morphology. Dungeness beach is located at the English shore of the Dover straight facing northeast part of a cuspate foreland. It is a gravel beach (D50=6-10 mm) quite steep until 1 m depth (β≈0.13) and gentle until 3 m depth (β≈0.005) without shore-parallel bars. Bathymetric maps of this beach are available since 2007 and the wave conditions are also known from a wave buoy in 43 m depth. The shorelines from 2007 until 2013 show some subtle and evolving undulations. But remarkably, in 2014 a series of two undulations develop with a wavelength of about 0.5 km. They persist until 2016 and migrate to the N. This is a clear formation event that provides a unique opportunity to compare observations with the outputs of morphodynamic models for the initial formation of such features. Therefore, the objectives are: 1) Characterize the bathymetric evolution and the wave conditions prior/during the formation event, 2) run the linear stability model 1Dmorfo (Falqués and Calvete, 2005) and the non-linear morphodyncmic model Q2D-morfo (van den Berg et al., 2012) for the Dungeness conditions, 3) compare model results with observations and 4) discuss whether the shoreline instability mechanism associated to high angle waves could be the main driver of the observed sand waves.

Behaviour of mobile macrofauna is a key factor in beach ecology as response to rapid environmental changes

NASA Astrophysics Data System (ADS)

Scapini, Felicita

2014-10-01

Sandy beach animals show behavioural adaptations that are expressed as contingencies during the life history of individuals to face periodic and episodic environmental changes. Such adaptations include activity rhythms, orientation, zonation, burrowing, escape responses and feeding strategies, the first two being common adaptations to all mobile animals. The complex conditions of a particular beach environment may be integrated in a learning process enhancing the adaptation and survival of individuals and eventually of populations. Evidence exists of genetic determination of some behavioural features that are adaptive in the long term (throughout generations) by increasing individual survival and reproductive potential. The environmental features integrated with the life history of beach animals shape the individual behaviour through ontogenetic processes, as well as population behaviour through evolutionary processes. Thus, behavioural differences among individuals may reflect environmental variation at the local and small/medium temporal scales of beach processes, whereas within-population behavioural coherence and differences among populations may reflect variation at the geographic scale. The different foci stressed by different authors and the variety of evidence dependent upon local geographical and ecological conditions have often resulted in compartmentalised explanations, making generalizations and the repeatability of behavioural studies of beach ecology challenging. There was a need to developing a more synthetic paradigm for beach animal behaviour. This paper gives a brief overview of the theoretical background and keystone studies, which have contributed to our understanding of animal behaviour in sandy beach ecology, and proposes testable hypotheses to be integrated in the beach ecology paradigm.

Post-Sandy, Schools Claw Back

ERIC Educational Resources Information Center

Maxwell, Lesli A.

2012-01-01

David Weiss, the superintendent in Long Beach, N.Y., wrestled with a slew of considerations last week as he weighed when to restart school, nine days after Hurricane Sandy wrecked his community. Just one of seven buildings had most of the essentials: electricity, heat, working fire alarms, sewage, and food. And, with many students and staff…

Regional beach/cliff system dynamics along the california coast

USGS Publications Warehouse

Hapke, C.J.; Reid, Don

2007-01-01

The coast of California is comprised of both sandy shorelines and cliffed coastline, and in many areas these features spatially coincide. In order to better understand the regional trends of change along the California coast, the U.S. Geological Survey is quantifying both sandy shoreline change and coastal cliff retreat for the state. The resulting database was used to examine the dynamics of the beach/cliff system. We found inconsistent evidence of a relationship between rates of cliff retreat and shoreline change on the spatial scale of 100-km cells. However, when the data are correlated within individual regions, a strong relationship exists between the geomorphology of the coast and the behavior of the beach/cliff system. Areas of high-relief coast show negative correlations, indicating that higher rates of cliff retreat correlate with lower rates of shoreline erosion. In contrast, low- to moderate-relief coasts show strong positive correlations.

Multiple scavengers respond rapidly to pulsed carrion resources at the land-ocean interface

NASA Astrophysics Data System (ADS)

Schlacher, Thomas A.; Strydom, Simone; Connolly, Rod M.

2013-04-01

Sandy beaches are the globe's longest interface region between the oceans and the continents, forming highly permeable boundaries across which matter flows readily. Stranded marine carrion supplies a high-quality food source to scavengers, but the role of animal carcasses is generally under-reported in sandy-beach food webs. We examined the response of scavengers to pulsed subsidies in the form of experimental additions of fish carcasses to the dune-beach interface in eastern Australia. Ghost crabs (Ocypode spp.) are the dominant invertebrate scavengers in these habitats and they responded strongly and consistently to changed resource availability: densities increased significantly within days of carrion augmentations. Carcasses added experimentally also formed local nuclei for a diversity of vertebrate scavengers that aggregated at food falls; these included large lizards, several species of birds (including raptors), and foxes. Consumption of fish carrion by the vertebrate scavengers was rapid and often complete. There is also evidence for higher-order interactions, where responses of invertebrate scavengers became depressed in plots where vertebrate scavenger activity was intense. Our findings emphasize that carrion can be a pivotal component of beach food webs.

Complexity of the prey spectrum of Agaronia propatula (Caenogastropoda: Olividae), a dominant predator in sandy beach ecosystems of Pacific Central America

PubMed Central

Robinson, Nathan J.

2018-01-01

Olivid gastropods of the genus Agaronia are dominant predators within invertebrate communities on sandy beaches throughout Pacific Central America. At Playa Grande, on the Pacific Coast of Costa Rica, we observed 327 natural predation events by Agaronia propatula. For each predation event, we documented prey taxa and body size of both predator and prey. The relationship between predator and prey size differed for each of the four main prey taxa: bivalves, crustaceans, heterospecific gastropods, and conspecific gastropods (representing cannibalism). For bivalve prey, there was increased variance in prey size with increasing predator size. Crustaceans were likely subdued only if injured or otherwise incapacitated. Heterospecific gastropods (mostly Olivella semistriata) constituted half of all prey items, but were only captured by small and intermediately sized A. propatula. Large O. semistriata appeared capable of avoiding predation by A. propatula. Cannibalism was more prevalent among large A. propatula than previously estimated. Our findings suggested ontogenetic niche shifts in A. propatula and a significant role of cannibalism in its population dynamics. Also indicated were size-dependent defensive behavior in some prey taxa and a dynamic, fine-scale zonation of the beach. The unexpected complexity of the trophic relations of A. propatula was only revealed though analysis of individual predation events. This highlights the need for detailed investigations into the trophic ecology of marine invertebrates to understand the factors driving ecosystem structuring in sandy beaches. PMID:29736346

Terrestrial-based lidar beach topography of Fire Island, New York, June 2014

USGS Publications Warehouse

Brenner, Owen T.; Hapke, Cheryl J.; Lee, Kathryn G.; Kimbrow, Dustin R.

2016-02-19

The U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center (SPCMSC) in Florida and the USGS Lower Mississippi-Gulf Water Science Center (LMG WSC) in Montgomery, Alabama, collaborated to gather alongshore terrestrial-based lidar beach elevation data at Fire Island, New York. This high-resolution elevation dataset was collected on June 11, 2014, to characterize beach topography and document ongoing beach evolution and recovery, and is part of the ongoing beach monitoring within the Hurricane Sandy Supplemental Project GS2-2B. This USGS data series includes the resulting processed elevation point data (xyz) and an interpolated digital elevation model (DEM).

Human threats to sandy beaches: A meta-analysis of ghost crabs illustrates global anthropogenic impacts.

NASA Astrophysics Data System (ADS)

Schlacher, Thomas A.; Lucrezi, Serena; Connolly, Rod M.; Peterson, Charles H.; Gilby, Ben L.; Maslo, Brooke; Olds, Andrew D.; Walker, Simon J.; Leon, Javier X.; Huijbers, Chantal M.; Weston, Michael A.; Turra, Alexander; Hyndes, Glenn A.; Holt, Rebecca A.; Schoeman, David S.

2016-02-01

Beach and coastal dune systems are increasingly subjected to a broad range of anthropogenic pressures that on many shorelines require significant conservation and mitigation interventions. But these interventions require reliable data on the severity and frequency of adverse ecological impacts. Such evidence is often obtained by measuring the response of 'indicator species'. Ghost crabs are the largest invertebrates inhabiting tropical and subtropical sandy shores and are frequently used to assess human impacts on ocean beaches. Here we present the first global meta-analysis of these impacts, and analyse the design properties and metrics of studies using ghost-crabs in their assessment. This was complemented by a gap analysis to identify thematic areas of anthropogenic pressures on sandy beach ecosystems that are under-represented in the published literature. Our meta-analysis demonstrates a broad geographic reach, encompassing studies on shores of the Pacific, Indian, and Atlantic Oceans, as well as the South China Sea. It also reveals what are, arguably, two major limitations: i) the near-universal use of proxies (i.e. burrow counts to estimate abundance) at the cost of directly measuring biological traits and bio-markers in the organism itself; and ii) descriptive or correlative study designs that rarely extend beyond a simple 'compare and contrast approach', and hence fail to identify the mechanistic cause(s) of observed contrasts. Evidence for a historically narrow range of assessed pressures (i.e., chiefly urbanisation, vehicles, beach nourishment, and recreation) is juxtaposed with rich opportunities for the broader integration of ghost crabs as a model taxon in studies of disturbance and impact assessments on ocean beaches. Tangible advances will most likely occur where ghost crabs provide foci for experiments that test specific hypotheses associated with effects of chemical, light and acoustic pollution, as well as the consequences of climate change (e.g. species range shifts).

Effects of tide cycles on habitat selection and habitat partitioning by migrating shorebirds

USGS Publications Warehouse

Burger, J.; Howe, M.A.; Hahn, D.C.; Chase, J.

1977-01-01

We studied assemblages of feeding shorebirds in three intertidal habitats on the coast of New Jersey during August to document how species segregate spatially both among and within habitats and to determine the effects of tidal cycles on these patterns. The habitats were a sandy beach facing the ocean proper (outer beach), a sandy beach on the mainland side of a barrier island (inner beach), and a small mudflat adjacent to a Spartina alterniflora salt marsh. We were able to identify several microhabitats on the outer beach and mudflat. Most species fed in more than one habitat, but only two, Charadrius semipalmatus and Calidris canutus, used all three habitats regularly. Within habitats, most species exhibited strong preferences for the wettest areas, but we found differences among species in degrees of preference. The least amount of partitioning occurred on the inner beach, where birds crowded into a small zone near the water's edge and had frequent agonistic encounters suggesting intense competition. Shorebird feeding activity was partly a function of tide time: each habitat had a characteristic temporal pattern of use by shorebirds related to tide time rather than diel time; within habitats, we found species-characteristic feeding activity rhythms that were also a function of tide time. Feeding by most species peaked during the first 2 hours after low tide on the outer beach and mudflat. The results are discussed in terms of feeding strategies and interspecific competition.

Photocopy of plan (in U.S. Army office of Army Engineers ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Photocopy of plan (in U.S. Army office of Army Engineers plans and drawings, Fort Hancock and Sandy hook proving ground, record group 7, drawer 44, Cartographic and Architectural branc, The National Archives, Washington, DC) Gillespie, G.L., map of a portion of Sandy Hook, NJ showing condition of beach in vicinity of dynamite gun emplacements, 1894 Engineer's wharf - U.S. Coast Guard Sandy Hook Station, Western Docking Structure, West of intersection of Canfield Road & Hartshorne Drive, Highlands, Monmouth County, NJ

Seabed ripple morphology and surficial sediment size at the SAX04 experiments near Fort Walton Beach, Florida, fall 2004

USGS Publications Warehouse

Hanes, Daniel M.; Erikson, Li H.; Lescinski, Jamie M.R.; Harney, Jodi N.; Carter, Carissa L.; Hatcher, Gerry A.; Lacy, Jessica R.; Rubin, David M.

2007-01-01

Data presented in this report originates from measurements obtained off the Florida coast (fig. 1) as part of the Sediment Acoustics Experiment (SAX04) and Ripples Department Research Initiative (DRI) (Office of Naval Research (ONR), Critical Benthic Environmental Processes and Modeling, Long Range BAA 04-001, Sept. 10, 2003). The aim of this document is to present methods employed to extract data and the resulting measured ripple characteristics (ripple height, wavelength, and orientation) and seabed grain sizes. Application and analysis of the data with respect to hydro- and morphodynamics will be addressed in subsequent reports. Sediment transport in the coastal region is a complex process involving interactions between flow dynamics, sediments, and bedforms. Sediment type and bed geometry directly influence entrainment of sediments into suspension, and at sites where ripples occur (sand formations on the order of several cm high and less than two meter long wavelengths), the understanding of ripple dynamics is an essential component in improving sediment transport models. To gain a better understanding and ability to predict sediment transport, a field study was undertaken to investigate morphology, orientation, and dynamics of ripples on the seafloor. The data obtained from the field campaign also supports an on-going effort to study the effects of ripples on low grazing acoustic penetration into sandy marine sediments for the detection of objects, such as mines (Jackson and others, 2002).

Analysis of beach morphodynamics on the Bragantinian mangrove peninsula (Pará, North Brazil) as prerequisite for coastal zone management recommendations

NASA Astrophysics Data System (ADS)

Krause, Gesche; Soares, Cidiane

2004-05-01

A beach profile monitoring programme was initiated in 1997 as a contribution to the development of recommendations for an integrated coastal zone management scheme of the mangrove peninsula of Bragança, State of Pará (North Brazil). It was the first scientific investigation on the coastal morphodynamics in a mangrove environment, which was opened for human use only since the mid-1970s. The observations were carried out on five sections for 4 years, on a fortnightly basis whenever possible. Temporal evolution of the beach morphology was assessed using time series of beach height, changes in profile shape, sediment transport calculations, and photographs. This unique data set for new settlement areas in this mangrove-dominated coastal zone illuminates the role of the interaction between human activities and natural coastal dynamics. Four coastal cells were identified as coastal management units, each with specific dynamic behaviour and utilisation by humans. The cells are rather small with dimensions in the order of 1-3 km. Only one of the units (cell 1) had a stable coastline during the 4 years of observation, while all others are eroding. Clearing of vegetation is the principal reason for the enhancement of the natural chronic erosion at these sites. In the wake of increasing tourism, housing was erected on the first dune ridge (cell 2) with much damage to the natural vegetation. In this unit, erosion is predominantly targeted on the dunes. In cell 3, the most important reason for the increased erosion is clearing of the adjacent fringing mangroves. This is also true for cell 4, but additionally the construction of large fishing traps, which artificially entrap sand and create sandbanks and thereby increase velocities in the tidal channel tend to enhance erosion at the shoreline. Only for cell 1 can protection measures for the still available vegetation be recommended while a planned retreat of many tourism facilities and fishermen's housings should be included in management recommendations.

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.

Physical factors influencing immature-fish communities in the surf zones of sandy beaches in northwestern Kyushu Island, Japan

NASA Astrophysics Data System (ADS)

Inui, Ryutei; Nishida, Takashi; Onikura, Norio; Eguchi, Katsuhisa; Kawagishi, Motoyoshi; Nakatani, Masaya; Oikawa, Shin

2010-02-01

We aim to understand the relationships between physical conditions and characteristics of the immature-fish community in surf zones of sandy beaches. Therefore, we obtained fish samples between March 2007 and February 2008 and analyzed certain physical conditions in the surf zones of 21 sandy beaches on the coastline of the northwestern Kyushu Island, Japan. We collected a total of 83 species and 6458 immature individuals. In a BIO-ENV analysis, the highest correlation was observed between fish assemblage and S20 (i.e., the slope from the shoreline to the sites where the depth was 20 m) and current velocity (CV) values. Stepwise multiple linear regression analyses revealed that the number of species and individuals decrease with an increase in the S20 and CV values. These results show that species richness and the abundance of immature-fish increase under shelving and calm conditions. Thus, immature-fish assemblages are strongly influenced by the prevailing physical conditions. Moreover, in six of the 10 dominant species, a negative correlation was observed between CV and abundance. On the other hand, S20 was found to be the explanatory variable only in the case of the most dominant species, i.e., Gymnogobius breunigii. Furthermore, a positive correlation was observed between S1 (i.e., the slope from the shoreline to the sites where the depth was 1.0 m at the mean tidal level) and median particle size (i.e., MPS of the sediments) and the abundances of Sillago japonica and Favonigobius gymnauchen, respectively, and a negative correlation with salinity, in the case of Acanthogobius lactipes. We conclude that the characteristics of the fish community in surf zones on sandy beaches are determined by not only the shelving and calm conditions, which influence fish assemblages and abundances, but also the habitat diversity, which influences the diversity of fish species.

Hurricane Sandy's Fingerprint: Ripple Bedforms at an Inner Continental Shelf Sorted Bedform Field Site

NASA Astrophysics Data System (ADS)

DuVal, C.; Trembanis, A. C.; Beaudoin, J. D.; Schmidt, V. E.; Mayer, L. A.

2013-12-01

The hydrodynamics and seabed morphodynamics on the inner continental shelf and near shore environments have increasing relevance with continued development of near shore structures, offshore energy technologies and artificial reef construction. Characterizing the stresses on and response of the seabed near and around seabed objects will inform best practices for structural design, seabed mine and unexploded ordnance detection, and archaeological and benthic habitat studies. As part of an ONR funded project, Delaware's Redbird Reef is being studied for object scour and sorted bedform morphodynamics (Trembanis et al., in press). Central to this study are the effects of large storm events, such as Hurricane Sandy, which have had significant impact on the seafloor. Previous studies of inner shelf bedform dynamics have typically focused on near bed currents and bed stressors (e.g. Trembanis et al., 2004), sorted bedforms (e.g. Green et al., 2004) and object scour (e.g. Quinn, 2006; Trembanis et al., 2007; Mayer et al., 2007), but our understanding of the direct effects of objects and object scour on bedform morphodynamics is still incomplete. With prominent sorted bedform ripple fields, the Delaware Redbird artificial reef site, composed of 997 former New York City subway cars, as well as various military vehicles, tugboats, barges and ballasted tires, has made an ideal study location (Raineault et al., 2013 and 2011). Acoustic mapping of the Redbird reef three days prior to Sandy and two days after the following nor'easter, captured the extensive effects of the storms to the site, while acoustic Doppler current profilers characterized both the waves and bottom currents generated by the storm events. Results of the post-Sandy survey support the theory of sorted bedform evolution proposed by Murray and Thieler (2004). Acoustic imagery analysis indicates a highly energized and mobile bed during the storms, leading to self-organization of bedforms and creation of large orbital ripples. Using the Fingerprint Algorithm technique developed by Skarke and Trembanis (2011), sonar images have been analyzed to quantify ripple orientation, wavelength and defects (e.g. bifurcation and terminations). Correlation to time-series current and wave data shows strong agreement between peak-storm ripple wavelength scaling predictions and Fingerprint Algorithm wavelength measurements of relict ripples, indicating a non-equilibrated response of ripple bedforms to near bed orbital currents. Preliminary results further indicate an increase of ripple bedform defects near seabed objects, and deviations in ripple orientation and wavelength possibly related to current steering and vortices shed from nearby objects. Subsequent surveys and instrument deployments at the site have recorded the burial of these ripple bedforms during low-energy conditions, typical with the cyclical evolution of sorted bedform sites.

Hurricane Sandy: observations and analysis of coastal change

USGS Publications Warehouse

Sopkin, Kristin L.; Stockdon, Hilary F.; Doran, Kara S.; Plant, Nathaniel G.; Morgan, Karen L.M.; Guy, Kristy K.; Smith, Kathryn E.L.

2014-01-01

Hurricane Sandy, the largest Atlantic hurricane on record, made landfall on October 29, 2012, and impacted a long swath of the U.S. Atlantic coastline. The barrier islands were breached in a number of places and beach and dune erosion occurred along most of the Mid-Atlantic coast. As a part of the National Assessment of Coastal Change Hazards project, the U.S. Geological Survey collected post-Hurricane Sandy oblique aerial photography and lidar topographic surveys to document the changes that occurred as a result of the storm. Comparisons of post-storm photographs to those collected prior to Sandy’s landfall were used to characterize the nature, magnitude, and spatial variability of hurricane-induced coastal changes. Analysis of pre- and post-storm lidar elevations was used to quantify magnitudes of change in shoreline position, dune elevation, and beach width. Erosion was observed along the coast from North Carolina to New York; however, as would be expected over such a large region, extensive spatial variability in storm response was observed.

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.

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.

Geophysical features influence the accumulation of beach debris on Caribbean islands.

PubMed

Schmuck, Alexandra M; Lavers, Jennifer L; Stuckenbrock, Silke; Sharp, Paul B; Bond, Alexander L

2017-08-15

Anthropogenic beach debris was recorded during beach surveys of 24 Caribbean islands during April 2014-April 2016. Beach debris was classified according to material type (e.g., polystyrene) and item use (e.g., fishing). Geophysical features (substrate type, beach direction, and human accessibility) of sample sites were recorded in order to investigate their relationship with debris density. Results suggest the density of macro debris (items >5mm) is highest on uninhabited, sandy beaches facing a leeward direction. Higher debris quantities on inaccessible beaches may be due to less frequent beach clean ups. Frequently accessed beaches exhibited lower macro, but higher micro debris (items 1-5mm) densities, possibly due to removal of macro debris during frequent beach clean ups. This suggests that while geophysical features have some influence on anthropogenic debris densities, high debris densities are occurring on all islands within the Caribbean region regardless of substrate, beach direction, or human accessibility. 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.

Shoreface response and recovery to Hurricane Sandy: Fire Island, NY

USGS Publications Warehouse

Nelson, Timothy R.; Hapke, Cheryl J.; Wang, Ping; Rosati, Julie D.; Cheng, Jun

2015-01-01

The shoreface of Fire Island was extensively modified by Hurricane Sandy and subsequent storms in the following winter months. The changes were evaluated using various morphometrics of the shoreface from four bathymetric surveys, one prior to Hurricane Sandy, and three over the course of twenty months following Sandy. The datasets show that the nearshore bar system moved offshore to deeper water depths following Hurricane Sandy with volume lost from the subaerial beach and surfzone. Following the offshore shift, the nearshore bar system increased in size, the trough deepened, and there has been gradual landward movement of the nearshore bar. The steepening of the upper shoreface, landward translation of the profile, and loss of sediment is indicative of barrier island transgression.

The role of wrack deposits for supralittoral arthropods: An example using Atlantic sandy beaches of Brazil and Spain

NASA Astrophysics Data System (ADS)

Ruiz-Delgado, Mª Carmen; Vieira, Jenyffer Vierheller; Veloso, Valéria Gomes; Reyes-Martínez, Mª José; Sallorenzo, Ilana Azevedo; Borzone, Carlos Alberto; Sánchez-Moyano, Juan Emilio; García García, Francisco José

2014-01-01

Wrack deposits, as accumulated detritus, are a common feature on beaches worldwide and significantly contribute to the shaping of supralittoral arthropod communities. The composition and relative age of upper-shore deposits influence the structure and taxonomic composition of invertebrate assemblages. Moreover, these influences may vary geographically, depending on the locally prevailing climatic and hydrodynamic conditions. The amount and composition of wrack deposits as well as community attributes (total density, species richness and diversity) were determined on sandy beaches in three distinct geographical regions: South (Paraná) and Southeast (Rio de Janeiro) of Brazil and SW Spain. These parameters were compared between upper and lower wrack bands on each beach and between beaches in each region. Wrack deposits were composed of mangrove propagules in the Paraná region, by macrophytes, dead invertebrates and macroalgae in Rio de Janeiro region and by seagrass and macroalgae in the SW Spain region. In all regions, the total amount of stranded wrack differed between beaches, but the amount accumulated between bands (i.e upper and lower band) was similar between beaches. Wrack bands shaped the density of common taxa (Talitridae, Tenebrionidae, and Staphylinidae), with consequences for community structures. This result could be due to their preference for specific microhabitats and food sources, which might differ according to the relative age of the wrack deposits. The results suggest that, independent of wrack composition, the distribution of wrack deposits in bands and their relative ages seems to play a role on the structure of supralittoral arthropod assemblages.

The trophic significance of the invasive seaweed Sargassum muticum in sandy beaches

NASA Astrophysics Data System (ADS)

Rossi, Francesca; Olabarria, Celia; Incera, Mónica; Garrido, Josefina

2010-01-01

Native and exotic seaweeds frequently lie on the beach and sustain part of the benthic food web. However, the role of exotic seaweeds as food sources for beach consumers has been poorly studied. We studied the temporal and spatial variability in the trophic significance of the invasive brown seaweed Sargassum muticum on sandy beaches. We measured the stable isotopes ( δ13C and δ15N) in the tissues of S. muticum and of invertebrate consumers and estimated the dietary biomass proportion of S. muticum during four sampling dates at two beaches and heights on the shore. Samples were collected from eight pitfall traps placed at a distance of 2 m from each other. Detrital macroalgae and seagrasses were also collected by hand within an area of 30 cm around each pitfall trap. We measured the spatial and temporal variability in the isotope composition of the beach consumers and of S. muticum using different models of analyses of variance. We then calculated the biomass proportion of S. muticum to the animal diet with a two-isotopic mixing model. The invasive alga S. muticum seemed to be one of the main food sources for the amphipod Talitrus saltator and, to a less extent, for the isopod Tylos europaeus. The importance of S. muticum was however temporally variable and decreased during spring (in March and May), probably due to the availability of native macrophytes. The supply of invasive wrack to beach food webs thus deserves more attention if we want to understand their role in influencing food web dynamics.

Evidence of marine debris usage by the ghost crab Ocypode quadrata (Fabricius, 1787).

PubMed

Costa, Leonardo Lopes; Rangel, Danilo Freitas; Zalmon, Ilana Rosental

2018-03-01

Sandy beaches are sites of marine debris stranding, but the interaction of beach biota with waste is poorly studied. The objective of this study was to investigate whether the ghost crab Ocypode quadrata selects marine debris by types using a non-destructive method on sandy beaches of Southeastern Brazil. We found marine debris in 7% of 1696 surveyed burrows, and the ghost crabs selectivity was mainly by soft plastic (30%), straw (11%), rope (6%) and foam (4%). Burrows with marine debris showed higher occupation rate (~68%) compared to burrows without debris (~28%), indicating that these materials may increase the capacity of ghost crabs to memorize their burrows placement (homing). The percentage of marine debris was not always related to their amount in the drift line, but ghost crabs used more debris near urbanized areas. Future studies should test whether ghost crabs are using marine debris for feeding, homing or other mechanisms. Copyright © 2018 Elsevier Ltd. All rights reserved.

Seafloor off Natural Bridges State Beach, Santa Cruz, California

USGS Publications Warehouse

Storlazzi, Curt D.; Golden, Nadine E.; Gibbons, Helen

2013-01-01

The seafloor off Natural Bridges State Beach, Santa Cruz, California, is extremely varied, with sandy flats, boulder fields, faults, and complex bedrock ridges. These ridges support rich marine ecosystems; some of them form the "reefs" that produce world-class surf breaks. Colors indicate seafloor depth, from red-orange (about 2 meters or 7 feet) to magenta (25 meters or 82 feet).

Use of multiple regression models in the study of sandhopper orientation under natural conditions

NASA Astrophysics Data System (ADS)

Marchetti, Giovanni M.; Scapini, Felicita

2003-10-01

In sandhoppers (Amphipoda; Talitridae), typical dwellers of the supralittoral zone of sandy beaches, orientation with respect to the sun and landscape vision is adapted to the local direction of the shoreline. Variation of this behavioural adaptation can be related to the characteristics of the beach. Measures of orientation with respect to the shoreline direction can thus be made as a tool to assess beach stability versus changeability, once the sources of variation are correctly interpreted. Orientation of animals can be studied by statistical analysis of directions taken after release in nature. In this paper some new tools for exploring directional data are reviewed, with special emphasis on non-parametric smoothers and regression models. Results from a large study concerning one species of sandhoppers, Talitrus saltator (Montagu), from an exposed sandy beach in northeastern Tunisia are presented. Seasonal differences in orientation behaviour were shown with a higher scatter in autumn with respect to spring. The higher scatter shown in autumn depended both on intrinsic (sex) and external (climatic conditions and landscape visibility) factors and was related to the tendency of this species to migrate towards the dune anticipating winter conditions.

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.

Sediment Transport at River Lima Estuary: Developing a Sound Methodology to Assess Sediment River Basin Input to an Erosion Prone Coast (NW Iberian Peninsula)

NASA Astrophysics Data System (ADS)

Pinho, J.; Costa, N.; Venâncio, S.; Martins, M.; Vieira, J.; Granja, H.

2016-12-01

The NW coast of Iberian Peninsula is mainly formed by rocky cliffs northern of the river Minho mouth and by narrow sandy beaches south of this river. These beaches are mainly in a sedimentary deficit status resulting from the north-south longitudinal drift driven by the dominant wave climate that acts from the NW direction. In this scenario understand and quantify river sediment inputs to the coast is crucial in order to follow a sustainable management policy to mitigate erosion impacts both in the natural and social environments. This work will present results from research conducted at rive Lima Estuary, one of the rivers flowing to the NW Iberian coast, based on both numerical modeling and field data acquisition. A hydrological model of the river basin and a detailed morphodynamic model of the estuary were implemented. Instrumentation of the estuary that is being conducted comprises traditional sensor pressures and new ones that are being designed and assembled to be installed at different measurement stations within the estuary. Modelling results for flood events showed that the river is capable of remove all the sediments that are deposited in the narrow estuarine canal located near the river mouth. Some of these sediments are immediately deposited downstream, within the interior of the harbor. Here, there is a strong possibility of silting of the river mouth and the central area of the harbor. Since the river flows during extreme events are controlled by an upstream reservoir, the capacity of the river to transport sediments to the coast was lowered during the last decades, which, moreover, requires dredging works over the years to maintain navigation depth requirements. Dredging sediments should be correctly deposited at the coast in order to properly feed the longitudinal drift, otherwise they will be out of the system, which aggravate the installed erosion tendency.

The Influence of Shoreline Curvature on Rates of Shoreline Change on Sandy Coasts

NASA Astrophysics Data System (ADS)

Murray, A. B.; Lauzon, R.; Cheng, S.; Liu, J.; Lazarus, E.

2017-12-01

The sandy, low-lying barrier islands which characterize much of the US East and Gulf coasts are popular spots to live and vacation, and are often heavily developed. However, sandy shorelines and barriers are also naturally mobile landforms, which are vulnerable to sea level rise and storms and can experience high rates of shoreline change. Many previous studies have attempted to understand and quantify the factors that contribute to those rates of shoreline change, such as grain size, underlying geology, sea level rise, and anthropogenic modification. Shoreline curvature has not been considered in such analyses, but previous research has demonstrated that subtle coastline curvature (and therefore alongshore variation in relative offshore wave angle) can result in gradients in net alongshore transport that cause significant shoreline erosion or accretion. Here we present the results of a spatially extensive analysis of the correlation between shoreline curvature and shoreline change rates for the sandy shorelines of the US East and Gulf coasts. We find that, for wave-dominated sandy coasts where nourishment and shoreline stabilization do not dominate the shoreline change signal (such as parts of Texas, North Carolina, and Florida), there is a significant negative correlation between shoreline curvature and shoreline change rates over 1 - 5 km and decadal to centurial space and time scales. This correlation indicates that a portion of the coastal erosion (and accretion) observed in these areas can be explained by the smoothing of subtle coastline curvature by gradients in alongshore transport, and suggests that shoreline curvature should be included in future attempts to understand historical and future rates of shoreline change. Shoreline stabilization, especially through beach nourishment, complicates the relationship between curvature and shoreline change. Beach construction during nourishment creates a seaward convex curvature in the part of the shoreline moves seaward. These activities tend to produce correlations between observed curvature and shoreline change that would correspond to shoreline roughening rather than smoothing on an unstabilized coastline—even though coastline smoothing occurs between episodes of beach construction.

Light pollution reduces activity, food consumption and growth rates in a sandy beach invertebrate.

PubMed

Luarte, T; Bonta, C C; Silva-Rodriguez, E A; Quijón, P A; Miranda, C; Farias, A A; Duarte, C

2016-11-01

The continued growth of human activity and infrastructure has translated into a widespread increase in light pollution. Natural daylight and moonlight cycles play a fundamental role for many organisms and ecological processes, so an increase in light pollution may have profound effects on communities and ecosystem services. Studies assessing ecological light pollution (ELP) effects on sandy beach organisms have lagged behind the study of other sources of disturbance. Hence, we assessed the influence of this stressor on locomotor activity, foraging behavior, absorption efficiency and growth rate of adults of the talitrid amphipod Orchestoidea tuberculata. In the field, an artificial light system was assembled to assess the local influence of artificial light conditions on the amphipod's locomotor activity and use of food patches in comparison to natural (ambient) conditions. Meanwhile in the laboratory, two experimental chambers were set to assess amphipod locomotor activity, consumption rates, absorption efficiency and growth under artificial light in comparison to natural light-dark cycles. Our results indicate that artificial light have significantly adverse effects on the activity patterns and foraging behavior of the amphipods, resulting on reduced consumption and growth rates. Given the steady increase in artificial light pollution here and elsewhere, sandy beach communities could be negatively affected, with unexpected consequences for the whole ecosystem. Copyright © 2016 Elsevier Ltd. All rights reserved.

Identifying Preserved Storm Events on Beaches from Trenches and Cores

NASA Astrophysics Data System (ADS)

Wadman, H. M.; Gallagher, E. L.; McNinch, J.; Reniers, A.; Koktas, M.

2014-12-01

Recent research suggests that even small scale variations in grain size in the shallow stratigraphy of sandy beaches can significantly influence large-scale morphology change. However, few quantitative studies of variations in shallow stratigraphic layers, as differentiated by variations in mean grain size, have been conducted, in no small part due to the difficulty of collecting undisturbed sediment cores in the energetic lower beach and swash zone. Due to this lack of quantitative stratigraphic grain size data, most coastal morphology models assume that uniform grain sizes dominate sandy beaches, allowing for little to no temporal or spatial variations in grain size heterogeneity. In a first-order attempt to quantify small-scale, temporal and spatial variations in beach stratigraphy, thirty-five vibracores were collected at the USACE Field Research Facility (FRF), Duck, NC, in March-April of 2014 using the FRF's Coastal Research and Amphibious Buggy (CRAB). Vibracores were collected at set locations along a cross-shore profile from the toe of the dune to a water depth of ~1m in the surf zone. Vibracores were repeatedly collected from the same locations throughout a tidal cycle, as well as pre- and post a nor'easter event. In addition, two ~1.5m deep trenches were dug in the cross-shore and along-shore directions (each ~14m in length) after coring was completed to allow better interpretation of the stratigraphic sequences observed in the vibracores. The elevations of coherent stratigraphic layers, as revealed in vibracore-based fence diagrams and trench data, are used to relate specific observed stratigraphic sequences to individual storm events observed at the FRF. These data provide a first-order, quantitative examination of the small-scale temporal and spatial variability of shallow grain size along an open, sandy coastline. The data will be used to refine morphological model predictions to include variations in grain size and associated shallow stratigraphy.

Metrics to assess ecological condition, change, and impacts in sandy beach ecosystems.

PubMed

Schlacher, Thomas A; Schoeman, David S; Jones, Alan R; Dugan, Jenifer E; Hubbard, David M; Defeo, Omar; Peterson, Charles H; Weston, Michael A; Maslo, Brooke; Olds, Andrew D; Scapini, Felicita; Nel, Ronel; Harris, Linda R; Lucrezi, Serena; Lastra, Mariano; Huijbers, Chantal M; Connolly, Rod M

2014-11-01

Complexity is increasingly the hallmark in environmental management practices of sandy shorelines. This arises primarily from meeting growing public demands (e.g., real estate, recreation) whilst reconciling economic demands with expectations of coastal users who have modern conservation ethics. Ideally, shoreline management is underpinned by empirical data, but selecting ecologically-meaningful metrics to accurately measure the condition of systems, and the ecological effects of human activities, is a complex task. Here we construct a framework for metric selection, considering six categories of issues that authorities commonly address: erosion; habitat loss; recreation; fishing; pollution (litter and chemical contaminants); and wildlife conservation. Possible metrics were scored in terms of their ability to reflect environmental change, and against criteria that are widely used for judging the performance of ecological indicators (i.e., sensitivity, practicability, costs, and public appeal). From this analysis, four types of broadly applicable metrics that also performed very well against the indicator criteria emerged: 1.) traits of bird populations and assemblages (e.g., abundance, diversity, distributions, habitat use); 2.) breeding/reproductive performance sensu lato (especially relevant for birds and turtles nesting on beaches and in dunes, but equally applicable to invertebrates and plants); 3.) population parameters and distributions of vertebrates associated primarily with dunes and the supralittoral beach zone (traditionally focused on birds and turtles, but expandable to mammals); 4.) compound measurements of the abundance/cover/biomass of biota (plants, invertebrates, vertebrates) at both the population and assemblage level. Local constraints (i.e., the absence of birds in highly degraded urban settings or lack of dunes on bluff-backed beaches) and particular issues may require alternatives. Metrics - if selected and applied correctly - provide empirical evidence of environmental condition and change, but often do not reflect deeper environmental values per se. Yet, values remain poorly articulated for many beach systems; this calls for a comprehensive identification of environmental values and the development of targeted programs to conserve these values on sandy shorelines globally. Copyright © 2014 Elsevier Ltd. All rights reserved.

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.

Ground-Penetrating Radar Study of Fort Morgan Peninsula Holocene Beach Ridges as Sea-level Indicators

NASA Astrophysics Data System (ADS)

Philbin, A.; Frederick, B.; Blum, M. D.; Tsoflias, G. P.

2017-12-01

Holocene sea-level change along the northern Gulf of Mexico (GoM) coast is controversial. One view interprets basal peats from the Mississippi Delta to indicate continual sea-level (SL) rise for the GoM as a whole. An alternate view proposes that data from the subsiding delta is primarily a subsidence signal, and that sandy non-deltaic shorelines indicate that regional SL reached present elevations by the middle Holocene, with minor oscillations since then. In fact, new regional long-term subsidence records from biostratigraphic indicators display significant subsidence in deltaic areas where basal-peat data were collected, and negligible rates along the GoM shoreline to the east. However, the use of sandy progradational shorelines, commonly known as "beach ridge systems", has been criticized for a lack of precise sea-level indicators, and therefore discounted. This research focuses on developing Holocene progradational sandy shorelines along the Alabama coast in the eastern GoM as SL indicators. Sandy shorelines in this area are ideal to examine SL change because they are well preserved, sufficiently distant from the subsiding delta, well mapped, and ages are known from previous work. Two-dimensional ground-penetrating radar imaging of well-dated beach-ridge successions is used here to examine and identify changes through time in the elevation of the shoreface clinoform topset-foreset break, which represents the transition between flat-lying foreshore and seaward-dipping shoreface facies, and forms in the intertidal zone. Beach-ridge successions with optical luminescence ages of ca. 5500-4800 yrs BP display topset-foreset breaks at current mean sea-level elevation, whereas beach-ridge successions from ca. 3500-2400 yrs BP display topset-foreset breaks that are 1 m above present mean SL and the elevation of modern topset-foreset breaks. These data support the view that current sea-level was reached by the middle Holocene, and was higher than present for at least one protracted period in the late Holocene. In addition to contributing to our understanding of Holocene SL change for the eastern GoM, results of this research provide context for sea-level conditions during which the Mississippi delta was constructed, and may provide insight into future shoreline response to rising sea levels.

Coastline evolution of Portuguese low-lying sandy coast in the last 50 years: an integrated approach

NASA Astrophysics Data System (ADS)

Ponte Lira, Cristina; Nobre Silva, Ana; Taborda, Rui; Freire de Andrade, Cesar

2016-06-01

Regional/national-scale information on coastline rates of change and trends is extremely valuable, but these studies are scarce. A widely accepted standardized methodology for analysing long-term coastline change has been difficult to achieve, but it is essential to conduct an integrated and holistic approach to coastline evolution and hence support coastal management actions. Additionally, databases providing knowledge on coastline evolution are of key importance to support both coastal management experts and users.The main objective of this work is to present the first systematic, national-scale and consistent long-term coastline evolution data of Portuguese mainland low-lying sandy coasts.The methodology used quantifies coastline evolution using a unique and robust coastline indicator (the foredune toe), which is independent of short-term changes.The dataset presented comprises (1) two polyline sets, mapping the 1958 and 2010 sandy beach-dune system coastline, both optimized for working at 1 : 50 000 scale or smaller; (2) one polyline set representing long-term change rates between 1958 and 2010, each estimated at 250 m; and (3) a table with minimum, maximum and mean of evolution rates for sandy beach-dune system coastline. All science data produced here are openly accessible at https://doi.pangaea.de/10.1594/PANGAEA.859136 and can be used in other studies.Results show beach erosion as the dominant trend, with a mean change rate of -0.24 ± 0.01 m year-1 for all mainland Portuguese beach-dune systems. Although erosion is dominant, this evolution is variable in signal and magnitude in different coastal sediment cells and also within each cell. The most relevant beach erosion issues were found in the coastal stretches of Espinho-Torreira and Costa Nova-Praia de Mira, Cova da Gala-Leirosa, and Cova do Vapor-Costa da Caparica. The coastal segments Minho River-Nazaré and Costa da Caparica adjacent to the coast exhibit a history of major human interventions interfering with the coastal system, many of which originated and maintained a sediment deficit. In contrast, the coastal segments Troia-Sines and Sines-Cape S. Vicente have experienced less intervention and show stable or moderate accretion behaviour.

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.

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.

A data driven model for dune morphodynamics

NASA Astrophysics Data System (ADS)

Palmsten, M.; Brodie, K.; Spore, N.

2016-12-01

Dune morphology results from a number of competing feedbacks between wave, Aeolian, and biologic processes. Only now are conceptual and numerical models for dunes beginning to incorporate all aspects of the processes driving morphodynamics. Drawing on a 35-year record of observations of dune morphology and forcing conditions at the Army Corps of Engineers Field Research Facility (FRF) at Duck, NC, USA, we hypothesize that local dune morphology results from the competition between dune growth during dry windy periods and erosion during storms. We test our hypothesis by developing a data driven model using a Bayesian network to hindcast dune-crest elevation change, dune position change, and shoreline position change. Model inputs include a description of dune morphology from dune-crest elevation, dune-base elevation, dune width, and beach width. Wave forcing and the effect of moisture is parameterized in terms of the maximum total water level and period that waves impact the dunes, along with precipitation. Aeolian forcing is parameterized in terms of maximum wind speed, direction and period that wind exceeds a critical value for sediment transport. We test the sensitivity of our model to forcing parameters and hindcast the 35-year record of dune morphodynamics at the FRF. We also discuss the role of vegetation on dune morphologic differences observed at the FRF.

Testing model parameters for wave-induced dune erosion using observations from Hurricane Sandy

NASA Astrophysics Data System (ADS)

Overbeck, J. R.; Long, J. W.; Stockdon, H. F.

2017-01-01

Models of dune erosion depend on a set of assumptions that dictate the predicted evolution of dunes throughout the duration of a storm. Lidar observations made before and after Hurricane Sandy at over 800 profiles with diverse dune elevations, widths, and volumes are used to quantify specific dune erosion model parameters including the dune face slope, which controls dune avalanching, and the trajectory of the dune toe, which controls dune migration. Wave-impact models of dune erosion assume a vertical dune face and erosion of the dune toe along the foreshore beach slope. Observations presented here show that these assumptions are not always valid and require additional testing if these models are to be used to predict coastal vulnerability for decision-making purposes. Observed dune face slopes steepened by 43% yet did not become vertical faces, and only 50% of the dunes evolved along a trajectory similar to the foreshore beach slope. Observations also indicate that dune crests were lowered during dune erosion. Moreover, analysis showed a correspondence between dune lowering and narrower beaches, smaller dune volumes, and/or longer wave impact.

Testing model parameters for wave‐induced dune erosion using observations from Hurricane Sandy

USGS Publications Warehouse

Overbeck, Jacquelyn R.; Long, Joseph W.; Stockdon, Hilary F.

2017-01-01

Models of dune erosion depend on a set of assumptions that dictate the predicted evolution of dunes throughout the duration of a storm. Lidar observations made before and after Hurricane Sandy at over 800 profiles with diverse dune elevations, widths, and volumes are used to quantify specific dune erosion model parameters including the dune face slope, which controls dune avalanching, and the trajectory of the dune toe, which controls dune migration. Wave‐impact models of dune erosion assume a vertical dune face and erosion of the dune toe along the foreshore beach slope. Observations presented here show that these assumptions are not always valid and require additional testing if these models are to be used to predict coastal vulnerability for decision‐making purposes. Observed dune face slopes steepened by 43% yet did not become vertical faces, and only 50% of the dunes evolved along a trajectory similar to the foreshore beach slope. Observations also indicate that dune crests were lowered during dune erosion. Moreover, analysis showed a correspondence between dune lowering and narrower beaches, smaller dune volumes, and/or longer wave impact.

Airflow reversal and alternating corkscrew vortices in foredune wake zones during perpendicular and oblique offshore winds

NASA Astrophysics Data System (ADS)

Jackson, Derek W. T.; Beyers, Meiring; Delgado-Fernandez, Irene; Baas, Andreas C. W.; Cooper, Andrew J.; Lynch, Kevin

2013-04-01

On all sandy coastlines fringed by dunes, understanding localised air flow allows us to examine the potential sand transfer between the beach and dunes by wind-blown (Aeolian) action. Traditional thinking into this phenomenon had previously included only onshore winds as effective drivers of this transfer. Recent research by the authors, however, has shown that offshore air-flow too can contribute significantly, through lee-side back eddies, to the overall windblown sediment budget to coastal dunes. Under rising sea levels and increased erosion scenarios, this is an important process in any post-storm recovery of sandy beaches. Until now though, full visualisation in 3D of this newly recognised mechanism in offshore flows has not been achieved. Here, we show for the first time, this return flow eddy system using 3D computational fluid dynamics modelling, and reveal the presence of complex corkscrew vortices and other phenomena. The work highlights the importance of relatively small surface undulations in the dune crest which act to induce the spatial patterns of airflow (and transport) found on the adjacent beach.

Shore litter along sandy beaches of the Gulf of Oman.

PubMed

Claereboudt, Michel R

2004-11-01

Beach debris abundance and weight were estimated from surveys on 11 beaches of the Gulf of Oman along the Omani coast. Debris were collected on two occasions from 100 m transects, sorted and categorized by origin and type. Overall contaminations ranged from 0.43 to 6.01 items m(-1) of beach front on different beaches with a mean value of 1.79+/-1.04 gm(-1) (95% C.I). In terms of weight, contamination levels ranged from 7.8 to 75.44 gm(-1) of beach front with a mean contamination of 27.02+/-14.48 gm(-1) (95% C.I). In terms of numbers of items, plastic debris ranked first on all beaches followed by either wood items or other organic materials such as cigarette butts. Industrial debris remained few on all beaches (<10%). Most debris had a local origin and, in terms of numbers, were associated with beach recreational activities whereas fishing debris represented the largest proportion of the debris in terms of weight. There were notable differences between beaches in the relative abundance of recreation-related and fishing-related debris.

Looking Back to the Future: Insight on Anthropocene beaches from Holocene and Pleistocene barriers

NASA Astrophysics Data System (ADS)

Dougherty, A. J.; Choi, J. H.; Turney, C. S.; Dosseto, A.

2017-12-01

`Super' storms and accelerated rates of sea-level rise are forecast in the Anthropocene, but how coasts will respond (or even if they have started to be impacted) remain uncertain. The onset of this new anthropogenic age is considered mid-1900s when multiple indices including sea level exceed previous Holocene measurements. Centuries of sea surface elevation data, used to project an increase of up to 2m by 2100, show that the current rise started 200 years ago. Similar records of storms or shoreline evolution over these centennial time-scales do not exist. With empirical studies of coastal morphodynamics concentrated during decades of accelerated sea-level rise, present-day beaches can be considered Anthropocene features. To determine the future of vulnerable sandy shorelines, climate change scenarios of increased sea level and storm intensity have been combined with computer models integrating short-term process data with large-scale coastal evolution. The uncertainty in these models can be reduced with longer sea level and storm records as well as filling the gap between detailed beach profile/wave buoy data and generalized barrier stratigraphy. High-resolution chronostratigraphic models necessary to achieve this can be constructed using Light Detection And Ranging (LiDAR), Ground Penetrating Radar (GPR), and Optically Stimulated Luminescence (OSL). Combined GPR, OSL and LiDAR (GOaL) on prograded barriers enables analysis of shorelines back through time, by comparing behaviour since the onset of anthropogenic global warming to that in the preceding millennia. Extracting a record of coastal evolution prior to and since seas began to rise two centuries ago offers the opportunity to detect any difference indicating if/how shorelines have responded. In double barrier systems with composite Holocene and Pleistocene components GOaL can extend the Anthropocene record back to when seas were known to have been higher than today. To demonstrate the potential of GOaL, data collected over the past twenty years from North America and the South Pacific are presented; including some classic prograded barriers studied initially in the 1960s and extensively the 1980s. The resulting records of sea level, storms and sediment supply provide insight on, and input for modelling of, climate change and coastal evolution.

ELASTOL

EPA Pesticide Factsheets

Technical product bulletin: this moderately volatile oil spill control agent is for use in cleanups on fresh or salt water. Treatment may reduce the emulsification and dispersion of oil, and its penetration into porous soils and sandy beaches.

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.

Quantitative analysis of plastic debris on recreational beaches in Mumbai, India.

PubMed

Jayasiri, H B; Purushothaman, C S; Vennila, A

2013-12-15

Plastic litter was quantified on four sandy beaches in Mumbai. The mean abundance of 7.49 g and 68.83 items per square metre was recorded. The abundance of plastics significantly varied among the beaches showing an increasing trend in the southern part. The abundance of plastics by weight in Dadar was significantly higher than that in Aksa. The size fractionation of plastics proved that small particles (1-20 mm) are predominant with 41.85% microplastics (1-5 mm) which emphasizes the high risk to marine organisms due to possible ingestion. The highest quantity of microplastics was seen in Juhu beach (55.33%) followed by Versova, Aksa and Dadar. The major contributing factors for the abundance are beach usage for different activities such as recreational, religious and fishing which suggest that the land-based sources provide major inputs to plastic pollution in these beaches. Copyright © 2013 Elsevier Ltd. All rights reserved.

The seaweed fly (Coelopidae) can facilitate environmental survival and transmission of E. coli O157 at sandy beaches.

PubMed

Swinscoe, Isobel; Oliver, David M; Gilburn, Andre S; Quilliam, Richard S

2018-06-19

The sustainable management of recreational beaches is essential for minimising risk of human exposure to microbial pathogens whilst simultaneously maintaining valuable ecosystem services. Decaying seaweed on public beaches is gaining recognition as a substrate for microbial contamination, and is a potentially significant reservoir for human pathogens in close proximity to beach users. Closely associated with beds of decaying seaweed are dense populations of the seaweed fly (Coelopidae), which could influence the spatio-temporal fate of seaweed-associated human pathogens within beach environments. Replicated mesocosms containing seaweed inoculated with a bioluminescent strain of the zoonotic pathogen E. coli O157:H7, were used to determine the effects of two seaweed flies, Coelopa frigida and C. pilipes, on E. coli O157:H7 survival dynamics. Multiple generations of seaweed flies and their larvae significantly enhanced persistence of E. coli O157:H7 in simulated wrack habitats, demonstrating that both female and male C. frigida flies are capable of transferring E. coli O157:H7 between individual wrack beds and into the sand. Adult fly faeces can contain significant concentrations of E. coli O157:H7, which suggests they are capable of acting as biological vectors and bridge hosts between wrack habitats and other seaweed fly populations, and facilitate the persistence and dispersal of E. coli O157:H7 in sandy beach environments. This study provides the first evidence that seaweed fly populations inhabiting natural wrack beds contaminated with the human pathogen E. coli O157:H7 have the capacity to amplify the hazard source, and therefore potential transmission risk, to beach users exposed to seaweed and sand in the intertidal zone. The risk to public health from seaweed flies and decaying wrack beds is usually limited by human avoidance behaviour; however, seaweed fly migration and nuisance inland plagues in urban areas could increase human exposure routes beyond the beach environment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Nearshore drift dynamics of natural versus artificial seagrass wrack

NASA Astrophysics Data System (ADS)

Baring, Ryan J.; Fairweather, Peter G.; Lester, Rebecca E.

2018-03-01

Drifting macrophytes such as seagrass and macroalgae are commonly found washed ashore on sandy beaches but few studies have investigated the drift trajectories of macrophytes whilst near to the coast. This is the first study to investigate the surface drifting of small clumps of seagrass released at various distances from shore, across multiple days with contrasting wind and tidal conditions, in a large gulf in southern Australia. Natural and artificial radio-tagged seagrass units generally travelled in the same directions as tides but trajectories were variable across sampling days and when tagged units were released at different distances from shore. Natural and artificial units diverged from each other particularly on days when wind speeds increased but generally drifted in the same direction and ended up within close proximity to each other at the 6-h endpoint. During calm conditions, tagged seagrass units drifted with tides for 0.25-5 km and, during one sampling day when wind speeds increased, drifted for >5 km over the 6-h time period. Only tagged units that were released closest to shore stranded on sandy beaches within the six hours of observation, so it would be difficult to predict the eventual stranding location on shorelines for macrophytes released further offshore. This study provides evidence of the variability of macrophyte drift dynamics near to coastlines. Acknowledging this variability is essential for further understanding of the ecological significance of allochthonous material arriving at shorelines, which should be integrated into future research and management of sandy-beach ecosystems.

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.

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.

Urban cool

NASA Astrophysics Data System (ADS)

Ennos, Roland

2010-08-01

The picture-perfect summer for many involves dipping toes into the water's edge on a sandy beach, strolling through a park licking an ice cream or cracking open a bottle of cold beer as gorgeous smells waft from a barbecue nearby.

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.

Mariana Islands-Hyperspectral Airborne Remote Environmental Sensing Experiment 2010

DTIC Science & Technology

2012-04-09

In some places along the strand, coconut palms (Cocos nucifera) were the dominant plant and the litter which has fallen year after year, posed a...in San Jose, Tinian’s largest village, in order to survey several beaches, the limestone cliffs, and a variety of plant species. The Tinian coastline...thrives on sandy soils and is highly tolerant of salinity. Cordia subcordata niyoron Strand Small (1-7m) tree found along the beach and on

Point Judith, Rhode Island, Breakwater Risk Assessment

DTIC Science & Technology

2015-08-01

output stations. Beach zones considered included the sandy beach to the west side of the HoR, which had significant dune features and was fronting...time dependency for crest height and wave parameters is assumed, hc = total damaged crest height of structure from toe , Lp is the local wave length...computed using linear wave theory and Tp, h is the toe depth, hc’ = total undamaged crest height of structure from toe , At = area of structure enclosed

Recent coastal evolution in a carbonate sandy environments and relation to beach ridge formation: the case of Anegada, British Virgin Islands

NASA Astrophysics Data System (ADS)

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

2014-05-01

In a changing climate context coastal areas will be affected by more frequent extreme events. Understanding the relationship between extreme events and coastal geomorphic response is critical to future adaptation plans. Beach ridge landforms commonly identified as hurricane deposits along tropical coasts in Australia and in the Caribbean Sea. However their formative processes in such environments are still not well understood. In particular, the role of different extreme wave events (storm waves, tsunami waves and extreme swell), in generating beach ridges is critical to their use as palaeotempestology archives. Anegada Island is a carbonate platform situated in the British Virgin Island between the Atlantic Ocean and the Caribbean Sea. Pleistocene in age, Anegada is surrounded by the Horseshoe fringing coral reef. Two Holocene sandy beach ridge plains are present on the western part of the island. The north beach ridge plain is Atlantic facing and has at least 30 ridges; the south beach ridge plain is Caribbean Sea facing and contains 10 ridges. Historical aerial photos enabled the shoreline evolution from 1953 to 2012 to be studied. Three different coastal domains are associate with the beach ridge plains: strong east-west longshore transport affects the north coastline, the south-west coastline from West End to Pomato Point represents an export corridor for these sediments and finally, along the southern coastline, from Pomato Point to Settling Point the area presents a depositional zone with little to no change in the last 70 years. The link between the extreme wave events that have affected Anegada Island in the last 70 years and beach ridge creation is discussed. Hurricane Donna crossed over Anegada Island in 1960: its geomorphological signature is tracked in the shoreline change analysis and its implication in beach ridge formation is discussed. Anegada Island has also been impacted by tsunami waves (Atwater et al., 2012) and a comparative discussion of the effects of hurricane and tsunami on the island will be presented. Atwater, B. et al., 2012. Geomorphic and stratigraphic evidence for an unusual tsunami or storm a few centuries ago at Anegada, British Virgin Islands. Natural Hazards, 63, pp. 51-84.

Surf zone fauna of Ecuadorian sandy beaches: Spatial and temporal patterns

NASA Astrophysics Data System (ADS)

Marin Jarrin, J. R.; Vanaverbeke, J.; Fockedey, N.; de Grunauer, M. del P. Cornejo R.; Dominguez-Granda, L.

2017-02-01

Sandy beaches and their surf zones are the most common open shoreline habitat; however, surf zone fauna in the tropics is one of the least studied communities in the world. In the current study, we tested the hypothesis that Ecuadorian surf zone hyperbenthos (invertebrates and vertebrates 1-5 mm in length) and epibenthos (fish and macrocrustaceans > 5 mm in length) vary among beaches and seasons. Therefore, the fauna was described and related to environmental variables. In addition, indicator taxa were identified. The hyperbenthos was divided into holo- and mero-hyperbenthos depending on whether taxa were present during their entire life or only early life stages, respectively. Samples were collected at eight different beaches during the wet, dry and intermediate or transitional season during the low spring tide, from 1999 to 2000, using a hyperbenthic sledge and epibenthic trawl. A total of 447 hyperbenthic and 30 epibenthic taxa were collected, most of which were crustaceans and fish, respectively (52 and 60% of taxa). The mysid, Metamysidopsis sp., was the most abundant member of the hyperbenthos (average ± SD: 14,425 ± 40,039 ind. 100 m- 2, present in 92% of samples collected), and the swimming blue crab, Areneus mexicanus, was the most encountered species among the epibenthos (1 ± 1 ind. 100 m- 2, 97% of samples collected). All faunal groups varied among beaches, while the holo-hyperbenthos and less strongly the epibenthos varied among seasons. Variability in the three faunas among beaches, distance from the continental slope and the Guayas estuarine system, and beach water physical characteristics were all strongly correlated suggesting adjacent habitats can influence surf zone biological communities and water physical characteristics. Seasonal effects were related to changes in water physical characteristics among seasons potentially reflecting changes in oceanic currents. These results suggest that, similarly to other beaches around the world, Ecuadorian surf zone fauna is abundant, diverse, and vary among beaches and, for some faunal groups, among seasons, potentially due to the influence of adjacent habitats and seasonal changes in oceanic currents.

Spatial and temporal correlation between beach and wave processes: implications for bar-berm sediment transition

NASA Astrophysics Data System (ADS)

Joevivek, V.; Chandrasekar, N.; Saravanan, S.; Anandakumar, H.; Thanushkodi, K.; Suguna, N.; Jaya, J.

2018-06-01

Investigation of a beach and its wave conditions is highly requisite for understanding the physical processes in a coast. This study composes spatial and temporal correlation between beach and nearshore processes along the extensive sandy beach of Nagapattinam coast, southeast peninsular India. The data collection includes beach profile, wave data, and intertidal sediment samples for 2 years from January 2011 to January 2013. The field data revealed significant variability in beach and wave morphology during the northeast (NE) and southwest (SW) monsoon. However, the beach has been stabilized by the reworking of sediment distribution during the calm period. The changes in grain sorting and longshore sediment transport serve as a clear evidence of the sediment migration that persevered between foreshore and nearshore regions. The Empirical Orthogonal Function (EOF) analysis and Canonical Correlation Analysis (CCA) were utilized to investigate the spatial and temporal linkages between beach and nearshore criterions. The outcome of the multivariate analysis unveiled that the seasonal variations in the wave climate tends to influence the bar-berm sediment transition that is discerned in the coast.

Hurricane Sandy science plan: coastal impact assessments

USGS Publications Warehouse

Stronko, Jakob M.

2013-01-01

Hurricane Sandy devastated some of the most heavily populated eastern coastal areas of the Nation. With a storm surge peaking at more than 19 feet, the powerful landscape-altering destruction of Hurricane Sandy is a stark reminder of why the Nation must become more resilient to coastal hazards. In response to this natural disaster, the U.S. Geological Survey (USGS) received a total of $41.2 million in supplemental appropriations from the Department of the Interior (DOI) to support response, recovery, and rebuilding efforts. These funds support a science plan that will provide critical scientific information necessary to inform management decisions for recovery of coastal communities, and aid in preparation for future natural hazards. This science plan is designed to coordinate continuing USGS activities with stakeholders and other agencies to improve data collection and analysis that will guide recovery and restoration efforts. The science plan is split into five distinct themes: coastal topography and bathymetry, impacts to coastal beaches and barriers, impacts of storm surge, including disturbed estuarine and bay hydrology, impacts on environmental quality and persisting contaminant exposures, impacts to coastal ecosystems, habitats, and fish and wildlife. This fact sheet focuses assessing impacts to coastal beaches and barriers.

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

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.

Modelling shoal margin collapses and their morphodynamic effect on channels and shoals in a sandy estuary

NASA Astrophysics Data System (ADS)

van Dijk, W. M.; Mastbergen, D. R.; Van der Werf, J. J.; Leuven, J.; Kleinhans, M. G.

2017-12-01

Channel bank failure and collapses of shoal margins due to flow slides have been recorded in Dutch estuaries for the past 200 years. The effects of these collapses on the morphodynamics of estuaries are unknown, but could potentially increase the dynamics of channel-shoal interactions by causing perturbations of up to a million cubic meters per event, which could impact habitats and navigability. The processes of shoal margin collapses are currently not included in numerical morphodynamic models. The objectives of this study are to investigate where shoal margins collapses typically occur, what their dimensions are, and to model how shoal margin collapses affect the morphodynamics at the channel-shoal scale. We identified 300 shoal margin collapses from bathymetry data of the Western Scheldt estuary for the period 1959-2015, and found that the shape of a shoal margin collapse is well represented by 1/3 of an ellipsoid, and that its volume has a log-normal distribution with an average of 100,000 m3. We implemented a parameterization for shoal margin collapses and tested their effects on morphodynamics in a Delft3D numerical model schematization of the Western Scheldt estuary. Three sets of scenarios were analyzed for near-field morphodynamics and far-field effects on flow pattern and channel-bar morphology: 1) an observed single shoal margin collapse of 2014, 2) collapses on various locations that are susceptible to collapses, and 3) our novel stochastic model producing collapses over a time span of a decade. Results show that single shoal margin collapses only affect the local dynamics in longitudinal direction and dampen out within a year when the collapse is small. When larger disturbances reach the seaward or landward sill at tidal channel junctions over a longer time span, the bed elevation at the sill increases on average and decrease the hydraulic geometry of the channel junctions. The extent of far-field effects is sensitive to the grain-size of the deposit, where finer sediments are transported further away. The location of the deposit across the channel matters for disturbing the region around the collapse, where sediment transport is highest for the strongest residual current. These results imply that disturbances caused by dredging and dumping may likewise affect the dynamics of channel junctions.

Users' perception as a tool to improve urban beach planning and management.

PubMed

Cervantes, Omar; Espejel, Ileana; Arellano, Evarista; Delhumeau, Sheila

2008-08-01

Four beaches that share physiographic characteristics (sandy, wide, and long) but differ in socioeconomic and cultural terms (three are located in northwestern Mexico and one in California, USA) were evaluated by beach users. Surveys (565) composed of 36 questions were handed out to beach users on weekends and holidays in 2005. The 25 questions that revealed the most information were selected by factor analysis and classified by cluster analysis. Beach users' preferences were assigned a value by comparing the present survey results with the characteristics of an "ideal" recreational urban beach. Cluster analysis separated three groups of questions: (a) services and infrastructure, (b) recreational activities, and (c) beach conditions. Cluster linkage distance (r=0.82, r=0.78, r=0.67) was used as a weight and multiplied by the value of beach descriptive factors. Mazatlán and Oceanside obtained the highest values because there are enough infrastructure and services; on the contrary, Ensenada and Rosarito were rated medium and low because infrastructure and services are lacking. The presently proposed method can contribute to improving current beach evaluations because the final score represents the beach users' evaluation of the quality of the beach. The weight considered in the present study marks the beach users' preferences among the studied beaches. Adding this weight to beach evaluation will contribute to more specific beach planning in which users' perception is considered.

Users' Perception as a Tool to Improve Urban Beach Planning and Management

NASA Astrophysics Data System (ADS)

Cervantes, Omar; Espejel, Ileana; Arellano, Evarista; Delhumeau, Sheila

2008-08-01

Four beaches that share physiographic characteristics (sandy, wide, and long) but differ in socioeconomic and cultural terms (three are located in northwestern Mexico and one in California, USA) were evaluated by beach users. Surveys (565) composed of 36 questions were handed out to beach users on weekends and holidays in 2005. The 25 questions that revealed the most information were selected by factor analysis and classified by cluster analysis. Beach users’ preferences were assigned a value by comparing the present survey results with the characteristics of an “ideal” recreational urban beach. Cluster analysis separated three groups of questions: (a) services and infrastructure, (b) recreational activities, and (c) beach conditions. Cluster linkage distance ( r = 0.82, r = 0.78, r = 0.67) was used as a weight and multiplied by the value of beach descriptive factors. Mazatlán and Oceanside obtained the highest values because there are enough infrastructure and services; on the contrary, Ensenada and Rosarito were rated medium and low because infrastructure and services are lacking. The presently proposed method can contribute to improving current beach evaluations because the final score represents the beach users’ evaluation of the quality of the beach. The weight considered in the present study marks the beach users’ preferences among the studied beaches. Adding this weight to beach evaluation will contribute to more specific beach planning in which users’ perception is considered.

Photocopy of plan (in U.S. Army office of Army Engineers ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Photocopy of plan (in U.S. Army office of Army Engineers plans and drawings, Fort Hancock and Sandy hook proving ground, record group 7, drawer 44, Cartographic and Architectural branc, The National Archives, Washington, DC), cartographer unknown, title unknown, March 28, 1892 1890 lifesaving station shown near fort and beach, no boathouse near engineer's wharf - U.S. Coast Guard Sandy Hook Station, Western Docking Structure, West of intersection of Canfield Road & Hartshorne Drive, Highlands, Monmouth County, NJ

Inner shelf morphologic controls on the dynamics of the beach and bar system, Fire Island, New York

USGS Publications Warehouse

Hapke, Cheryl J.; Schwab, William C.; Gayes, Paul T.; McCoy, Clay; Viso, Richard; Lentz, Erika E.; Rosati, Julie D.; Wang, Ping; Roberts, Tiffany M.

2011-01-01

The mechanism of sediment exchange between offshore sand ridges and the beach at Fire Island, New York is largely unknown. However, recent evidence from repeat nearshore bathymetry surveys, coupled with the complex but consistent bar morphology and patterns of shoreline change demonstrate that there is a feedback occurring between the regional geologic framework and modern processes. Analysis of bathymetric survey data provides direct confirmation that the offshore ridges are connected to the shoreface and are spatially persistent. The fixed nature of the nearshore morphology is further supported by time series camera data that indicate persistent bars with breaks that re-form in the same locations. A long-term time series of shoreline change shows distinct zones of erosion and accretion that are pervasive over time scales greater than a half-century, and their length-scales are similar to the spacing of the offshore ridge-trough system. The first-order geologic framework is responsible for the existence and locations of the ridges and troughs, which then influence the morphodynamics of the beach and bar system.

Innovative bio-mediated particulate materials for sustainable maritime transportation infrastructure.

DOT National Transportation Integrated Search

2017-08-15

The mechanical properties of sandy soils in the coastal area and beach sands often do not satisfy construction expectation for maritime transportation infrastructure. The salty, loose sand makes it difficult for quick construction of port, building a...

Pro-environmental beach driving is uncommon and ineffective in reducing disturbance to beach-dwelling birds.

PubMed

Weston, Michael A; Schlacher, Thomas A; Lynn, David

2014-05-01

Vehicles on beaches cause numerous deleterious effects to coastal wildlife. These impacts may, hypothetically, be lessened if drivers act to reduce disturbance. Since it is unknown to what extent such behavior occurs, and whether it can reduce disturbance, we quantified the behavior of drivers who encountered birds on open-coast, sandy beaches in eastern Australia and the consequent bird responses. Drivers of commercial tourist buses never slowed or altered course ("evaded birds") to avoid disturbing birds; conversely, 34 % of drivers of private cars did evade birds. Drivers of vehicles with fishing rod holders tended (P = 0.09) to evade birds more frequently than non-fishing vehicles. Evasion, when it occurred, was modest, and did not significantly decrease the intensity of bird response or the probability of escapes on the wing. Voluntary behavioral adjustments to alleviate impacts on wildlife may be unworkable, suggesting that other solutions (e.g., beach closures) might be the only effective and feasible way to reduce disturbance to birds on ocean beaches.

Seasonal variation in the free-running period in two Talitrus saltator populations from Italian beaches differing in morphodynamics and human disturbance

NASA Astrophysics Data System (ADS)

Nardi, M.; Morgan, E.; Scapini, F.

2003-10-01

The sandhopper Talitrus saltator Montagu (Amphipoda) is a widespread species adapted to different changing environmental conditions and which typically shows a clear circadian rhythm of locomotor activity. The populations from two beaches on the western Italian coast differing in coastline dynamics (eroded versus dynamically stable) and human disturbance (inside a natural park versus freely used and cleaned for leisure) were studied to highlight intrapopulation variation in the endogenous locomotor rhythm. The activity of adult sandhoppers was studied under constant laboratory conditions within individual recording chambers. Variation of the free-running period was analysed at individual level within each population. Greater variability was found than previously reported for the circadian rhythm period of T. saltator, and seasonal variation was shown for the first time. Differences in the level of variation were correlated with coastline dynamics.

A method for determining average beach slope and beach slope variability for U.S. sandy coastlines

USGS Publications Warehouse

Doran, Kara S.; Long, Joseph W.; Overbeck, Jacquelyn R.

2015-01-01

The U.S. Geological Survey (USGS) National Assessment of Hurricane-Induced Coastal Erosion Hazards compares measurements of beach morphology with storm-induced total water levels to produce forecasts of coastal change for storms impacting the Gulf of Mexico and Atlantic coastlines of the United States. The wave-induced water level component (wave setup and swash) is estimated by using modeled offshore wave height and period and measured beach slope (from dune toe to shoreline) through the empirical parameterization of Stockdon and others (2006). Spatial and temporal variability in beach slope leads to corresponding variability in predicted wave setup and swash. For instance, seasonal and storm-induced changes in beach slope can lead to differences on the order of 1 meter (m) in wave-induced water level elevation, making accurate specification of this parameter and its associated uncertainty essential to skillful forecasts of coastal change. A method for calculating spatially and temporally averaged beach slopes is presented here along with a method for determining total uncertainty for each 200-m alongshore section of coastline.

Beach litter occurrence in sandy littorals: The potential role of urban areas, rivers and beach users in central Italy

NASA Astrophysics Data System (ADS)

Poeta, Gianluca; Conti, Luisa; Malavasi, Marco; Battisti, Corrado; Acosta, Alicia Teresa Rosario

2016-11-01

Litter washed ashore on the coastline, also called beach litter, constitutes one of the most obvious signs of marine litter pollution. Surveys of beach litter represent a fundamental tool for monitoring pollution in the marine environment and have been used world-wide to classify and quantify marine litter. Identifying the sources of marine and beach litter is, together with education, the prime weapon in combating this type of pollution. This work investigates the impact of three main potential land sources on litter occurrence: urban areas, rivers and beach users. Three sources were analyzed simultaneously on a broad scale (Lazio region, central Italy) using a random sampling design and fitting a generalized linear mixed-effect model. The results show that urban areas are the main drivers for the occurrence of marine litter along central Italy's coastal ecosystems, suggesting that the presence of such litter on Lazio beaches could be effectively reduced by identifying failings in recycling and waste collection procedures and by improving waste processing systems and sewage treatment in urban areas.

[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.

Intrawave sand suspension in the shoaling and surf zone of a field-scale laboratory beach

NASA Astrophysics Data System (ADS)

Brinkkemper, J. A.; de Bakker, A. T. M.; Ruessink, B. G.

2017-01-01

Short-wave sand transport in morphodynamic models is often based solely on the near-bed wave-orbital motion, thereby neglecting the effect of ripple-induced and surface-induced turbulence on sand transport processes. Here sand stirring was studied using measurements of the wave-orbital motion, turbulence, ripple characteristics, and sand concentration collected on a field-scale laboratory beach under conditions ranging from irregular nonbreaking waves above vortex ripples to plunging waves and bores above subdued bed forms. Turbulence and sand concentration were analyzed as individual events and in a wave phase-averaged sense. The fraction of turbulence events related to suspension events is relatively high (˜50%), especially beneath plunging waves. Beneath nonbreaking waves with vortex ripples, the sand concentration close to the bed peaks right after the maximum positive wave-orbital motion and shows a marked phase lag in the vertical, although the peak in concentration at higher elevations does not shift to beyond the positive to negative flow reversal. Under plunging waves, concentration peaks beneath the wavefront without any notable phase lags in the vertical. In the inner-surf zone (bores), the sand concentration remains phase coupled to positive wave-orbital motion, but the concentration decreases with distance toward the shoreline. On the whole, our observations demonstrate that the wave-driven suspended load transport is onshore and largest beneath plunging waves, while it is small and can also be offshore beneath shoaling waves. To accurately predict wave-driven sand transport in morphodynamic models, the effect of surface-induced turbulence beneath plunging waves should thus be included.

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.

Building of tropical beach ridges, northeastern Queensland, Australia: Cyclone inundation and aeolian decoration

NASA Astrophysics Data System (ADS)

Tamura, Toru; Nicholas, William; Brooke, Brendan; Oliver, Thomas

2016-04-01

Processes associated with tropical cyclones are thought responsible for building coarse sand beach ridges along the northeastern Queensland coast, Australia. While these ridges are expected to be geological records of the past cyclone, they question the general consensus of the aeolian genesis of sandy beach ridges. To explore the ridge-forming process, we carried out the GPR survey, auger drilling, pit excavation, grain-size analysis, and OSL dating for coarse sand beach ridges at the Cowley Beach, northeastern Queensland. The Cowley Beach is a mesotidal beach characterized by a low-tide terrace and steep beach face. Ten beach ridges are recognized along the survey transect that extends 700 m inland from the shore. 37 OSL ages are younger seawards, indicating the seaward accretion of the ridge sequence over the last 2700 years. The highest ridge is +5.1 m high above AHD (Australian Height Datum). Two GPR units are bounded by a groundwater surface at c. +1.5 m AHD. The upper unit is characterized by horizontal to hummocky reflectors punctuated by seaward dipping truncation surfaces. These reflectors in places form dome-like structure that appears to be the nucleus of a beach ridge. The shape and level (+2.5 m AHD) of the dome are similar to those of the present swash berm. The lower unit shows a sequence of reflectors that dip at an angle of present beach face. The sequence is dissected by truncation surfaces, some of which are continuous to those in the upper unit. Coarse sand mainly forms beach ridge deposits below +4.0 m AHD, while a few higher ridges have an upward fining layer composed of medium sand above +4.0 m, which is finer than aeolian ripples found on the backshore during the survey. In addition, pumice gravel horizons underlie the examined ridge crests. The sequence of seaward dipping reflectors indicates that the Cowley Beach, like other many sandy beaches, has prograded during onshore sand accretion by fairweather waves and has been eroded by storms waves. It is evident that increased water level and high waves associated with tropical cyclones are responsible for ridge building between +2.5 and +4.0 m AHD. However, astronomical tide should be critical rather than rare, intense cyclones for frequent coastal inundations up to +4.0 m AHD, just 1.5 m higher than the high-tide swash limit. The medium-grained sand layer on a few beach ridges higher than +4.0 m AHD can be accounted for by aeolian origin, but pumice gravels indicate the contribution of cyclone inundation. The building process of the ridges at Cowley Beach is thus most likely a mixture of fairweather swash and cyclone inundation modulated by tides, and aeolian processes during cyclonic and non-cyclonic conditions. For the reconstruction of the past cyclone based on these ridges, the roles of higher astronomical tides and aeolian processes should be taken into account.

The relative contribution of waves, tides, and nontidal residuals to extreme total water levels on U.S. West Coast sandy beaches

USGS Publications Warehouse

Serafin, Katherine A.; Ruggiero, Peter; Stockdon, Hilary F.

2017-01-01

To better understand how individual processes combine to cause flooding and erosion events, we investigate the relative contribution of tides, waves, and nontidal residuals to extreme total water levels (TWLs) at the shoreline of U.S. West Coast sandy beaches. Extreme TWLs, defined as the observed annual maximum event and the simulated 100 year return level event, peak in Washington, and are on average larger in Washington and Oregon than in California. The relative contribution of wave-induced and still water levels (SWL) to the 100 year TWL event is similar to that of the annual maximum event; however, the contribution of storm surge to the SWL doubles across events. Understanding the regional variability of TWLs will lead to a better understanding of how sea level rise, changes in storminess, and possible changes in the frequency of major El Niños may impact future coastal flooding and erosion along the U.S. West Coast and elsewhere.

Strategy for mitigation of marine debris: analysis of sources and composition of marine debris in northern Taiwan.

PubMed

Kuo, Fan-Jun; Huang, Hsiang-Wen

2014-06-15

Six sites (two sites for each of rocky shores, sandy beaches, and fishing ports) in northern Taiwan were selected to investigate the amount and density of marine debris in each of the four seasons and after spring and neap tides from 2012 to 2013. The results indicate that marine debris was higher on rocky shores than sandy beaches and fishing ports. There is no significant difference between season and tide. The dominant debris was plastic-type, followed by polystyrene. The majority of debris originated from recreational activities, followed from ocean/waterway activities. The results suggest that the following actions are needed: (1) continue and reinforce the plastic-limit policy; (2) increase the cleaning frequency at rocky shores; (3) promote marine environmental education, with a goal of debris-free coasts; (4) recycle fishing gear and to turn that gear into energy; and (5) coordinate between agencies to establish a mechanism to monitor debris. Copyright © 2014 Elsevier Ltd. All rights reserved.

Reversing storm hotspots on sandy beaches: Spatial and temporal characteristics

USGS Publications Warehouse

List, J.H.; Farris, A.S.; Sullivan, C.

2006-01-01

Coastal erosion hotspots are defined as sections of coast that exhibit significantly higher rates of erosion than adjacent areas. This paper describes the spatial and temporal characteristics of a recently identified type of coastal erosion hotspot, which forms in response to storms on uninterrupted sandy coasts largely free from human intervention. These are referred to here as reversing storm hotspots because the erosion is reversed by accretion of a similar magnitude to the storm-induced erosion. The accretion occurs within a few days or weeks of fair weather after the storm. Reversing storm hotspots observed here, on two US east coast beaches, have a longshore length averaging 3.86 km, a cross-shore excursion (magnitude of erosion or accretion) averaging 15.4 m, and a time scale of days to weeks associated with individual storm events. These spatial and temporal scales clearly distinguish reversing storm hotspots from previously described forms of longshore variability in erosion, including those attributed to several types of shoreline undulations and hotspots associated with long-term shoreline change. 

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.

Behavioural adaptations in talitrids from two Atlantic beaches

NASA Astrophysics Data System (ADS)

Rossano, Claudia; Gambineri, Simone; Fanini, Lucia; Durier, Virginie; Rivault, Colette; Scapini, Felicita

2009-12-01

The aim of the present study was to test sun orientation and rhythmic activity of two sandhopper populations from two Atlantic macro-tidal beaches. A population from Le Verger beach (orientated to 346°, Ille et Vilaine, Brittany, France) and a population from Damgan (orientated to 195°, Morbihan, Brittany, France), were tested on the beach under clear sky discriminating for landscape vision. For both populations locomotor activity rhythm was recorded in the laboratory. The two beaches differed for climatic features, tidal range and for human use. Both talitrid populations resulted very well orientated toward the shoreline, and both used solar position and landscape vision to orient. However the multiple regression analysis of orientation with climatic features showed a different use of local cues by the two populations and a slight influence of tidal regime (ebbing and rising tide), in spite of the supralittoral zonation of sandhoppers. In the laboratory they showed a well defined rhythmic behaviour as well as a bimodal rhythmicity, explained as a tidal one. These results are a new brick in the complex picture of orientation and rhythm studies on sandy beach invertebrates.

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.

5. Rear view of lower dam showing crest, masonry pier ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. Rear view of lower dam showing crest, masonry pier and sluice gate. Photograph taken from east bank of the sandy beach. VIEW SOUTH - Loleta Recreation Area, Lower Dam, 6 miles Southeast of interesection of State Route 24041 & State Route 66, Loleta, Elk County, PA

CRUDE OIL BIOREMEDIATION: THE AMERICAN EXPERIENCE (PRESENTATION)

EPA Science Inventory

This is a state-of-the-art extended abstract presentation summary of the outputs from the oil spill program over the last 11 years. It summarizes the results of 3 field studies involving intentional releases of crude oil: the Delaware study in 1994 (sandy beach), the St. Lawrence...

Nearshore sandbar rotation at single-barred embayed beaches

NASA Astrophysics Data System (ADS)

Blossier, B.; Bryan, K. R.; Daly, C. J.; Winter, C.

2016-04-01

The location of a shore-parallel nearshore sandbar derived from 7 years of video imagery data at the single-barred embayed Tairua Beach (NZ) is investigated to assess the contribution of barline rotation to the overall morphodynamics of sandbars in embayed environments and to characterize the process of rotation in relation to external conditions. Rotation induces cross-shore barline variations at the embayment extremities on the order of magnitude of those induced by alongshore uniform cross-shore migration of the bar. Two semiempirical models have been developed to relate the barline cross-shore migration and rotation to external wave forcing conditions. The rotation model is directly derived from the cross-shore migration model. Therefore, its formulation advocates for a primary role of cross-shore processes in the rotation of sandbars at embayed beaches. The orientation evolves toward an equilibrium angle directly related to the alongshore wave energy gradient due to two different mechanisms. Either the bar extremities migrate in opposite directions with no overall cross-shore bar migration (pivotal rotation) or the rotation relates to an overall migration of the barline which is not uniform along the beach (migration-driven rotation). Migration and rotation characteristic response times are similar, ranging from 10 to 30 days for mild and energetic wave conditions and above 200 days during very calm conditions or when the bar is located far offshore.

Responses of dune plant communities to continental uplift from a major earthquake: sudden releases from coastal squeeze.

PubMed

Rodil, Iván F; Jaramillo, Eduardo; Hubbard, David M; Dugan, Jenifer E; Melnick, Daniel; Velasquez, Carlos

2015-01-01

Vegetated dunes are recognized as important natural barriers that shelter inland ecosystems and coastlines suffering daily erosive impacts of the sea and extreme events, such as tsunamis. However, societal responses to erosion and shoreline retreat often result in man-made coastal defence structures that cover part of the intertidal and upper shore zones causing coastal squeeze and habitat loss, especially for upper shore biota, such as dune plants. Coseismic uplift of up to 2.0 m on the Peninsula de Arauco (South central Chile, ca. 37.5º S) caused by the 2010 Maule earthquake drastically modified the coastal landscape, including major increases in the width of uplifted beaches and the immediate conversion of mid to low sandy intertidal habitat to supralittoral sandy habitat above the reach of average tides and waves. To investigate the early stage responses in species richness, cover and across-shore distribution of the hitherto absent dune plants, we surveyed two formerly intertidal armoured sites and a nearby intertidal unarmoured site on a sandy beach located on the uplifted coast of Llico (Peninsula de Arauco) over two years. Almost 2 years after the 2010 earthquake, dune plants began to recruit, then rapidly grew and produced dune hummocks in the new upper beach habitats created by uplift at the three sites. Initial vegetation responses were very similar among sites. However, over the course of the study, the emerging vegetated dunes of the armoured sites suffered a slowdown in the development of the spatial distribution process, and remained impoverished in species richness and cover compared to the unarmoured site. Our results suggest that when released from the effects of coastal squeeze, vegetated dunes can recover without restoration actions. However, subsequent human activities and management of newly created beach and dune habitats can significantly alter the trajectory of vegetated dune development. Management that integrates the effects of natural and human induced disturbances, and promotes the development of dune vegetation as natural barriers can provide societal and conservation benefits in coastal ecosystems.

Responses of Dune Plant Communities to Continental Uplift from a Major Earthquake: Sudden Releases from Coastal Squeeze

PubMed Central

Rodil, Iván F.; Jaramillo, Eduardo; Hubbard, David M.; Dugan, Jenifer E.; Melnick, Daniel; Velasquez, Carlos

2015-01-01

Vegetated dunes are recognized as important natural barriers that shelter inland ecosystems and coastlines suffering daily erosive impacts of the sea and extreme events, such as tsunamis. However, societal responses to erosion and shoreline retreat often result in man-made coastal defence structures that cover part of the intertidal and upper shore zones causing coastal squeeze and habitat loss, especially for upper shore biota, such as dune plants. Coseismic uplift of up to 2.0 m on the Peninsula de Arauco (South central Chile, ca. 37.5º S) caused by the 2010 Maule earthquake drastically modified the coastal landscape, including major increases in the width of uplifted beaches and the immediate conversion of mid to low sandy intertidal habitat to supralittoral sandy habitat above the reach of average tides and waves. To investigate the early stage responses in species richness, cover and across-shore distribution of the hitherto absent dune plants, we surveyed two formerly intertidal armoured sites and a nearby intertidal unarmoured site on a sandy beach located on the uplifted coast of Llico (Peninsula de Arauco) over two years. Almost 2 years after the 2010 earthquake, dune plants began to recruit, then rapidly grew and produced dune hummocks in the new upper beach habitats created by uplift at the three sites. Initial vegetation responses were very similar among sites. However, over the course of the study, the emerging vegetated dunes of the armoured sites suffered a slowdown in the development of the spatial distribution process, and remained impoverished in species richness and cover compared to the unarmoured site. Our results suggest that when released from the effects of coastal squeeze, vegetated dunes can recover without restoration actions. However, subsequent human activities and management of newly created beach and dune habitats can significantly alter the trajectory of vegetated dune development. Management that integrates the effects of natural and human induced disturbances, and promotes the development of dune vegetation as natural barriers can provide societal and conservation benefits in coastal ecosystems. PMID:25946057

Multi-scale Modeling of the Evolution of a Large-Scale Nourishment

NASA Astrophysics Data System (ADS)

Luijendijk, A.; Hoonhout, B.

2016-12-01

Morphological predictions are often computed using a single morphological model commonly forced with schematized boundary conditions representing the time scale of the prediction. Recent model developments are now allowing us to think and act differently. This study presents some recent developments in coastal morphological modeling focusing on flexible meshes, flexible coupling between models operating at different time scales, and a recently developed morphodynamic model for the intertidal and dry beach. This integrated modeling approach is applied to the Sand Engine mega nourishment in The Netherlands to illustrate the added-values of this integrated approach both in accuracy and computational efficiency. The state-of-the-art Delft3D Flexible Mesh (FM) model is applied at the study site under moderate wave conditions. One of the advantages is that the flexibility of the mesh structure allows a better representation of the water exchange with the lagoon and corresponding morphological behavior than with the curvilinear grid used in the previous version of Delft3D. The XBeach model is applied to compute the morphodynamic response to storm events in detail incorporating the long wave effects on bed level changes. The recently developed aeolian transport and bed change model AeoLiS is used to compute the bed changes in the intertidal and dry beach area. In order to enable flexible couplings between the three abovementioned models, a component-based environment has been developed using the BMI method. This allows a serial coupling of Delft3D FM and XBeach steered by a control module that uses a hydrodynamic time series as input (see figure). In addition, a parallel online coupling, with information exchange in each timestep will be made with the AeoLiS model that predicts the bed level changes at the intertidal and dry beach area. This study presents the first years of evolution of the Sand Engine computed with the integrated modelling approach. Detailed comparisons are made between the observed and computed morphological behaviour for the Sand Engine on an aggregated as well as sub-system level.

Coastal Awareness: A Resource Guide for Teachers in Junior High Science.

ERIC Educational Resources Information Center

Rasmussen, Frederick A.

Background information, activity suggestions, and recommended resource materials comprise this guide for designing a week-long ecology unit for junior high school students on Coastal Awareness. Discussed is how various physical processes such as waves, currents, and tides affect rocky shores, marshes, sandy beaches, and estuaries. To encourage…

Translations on USSR Science and Technology, Physical Sciences and Technology, Number 14.

DTIC Science & Technology

1977-07-14

colored filament of the sandy beach , swamps, tiny lakes, and forests are clearly visible. The forest vegetation has its own range of colors. Large... handball , chess, skating, classical wrestling, underwater swimming, sport orientation, and bow and arrow shooting. One team of the institute is

DEVELOPMENT AND APPLICATION OF PROTOCOLS FOR EVALUATION OF OIL SPILL BIOREMEDIATION (RESEARCH BRIEF)

EPA Science Inventory

Protocols were developed and evaluated to assess the efficacy and environmental safety of commercial oil spill bioremediation agents (CBAs). Test systems that simulate oil slicks on open water or oiled sandy beaches were used to test the effectiveness of CBAs. Gravimetric and gas...

EFFECT OF AMOUNT OF CRUDE OIL ON EXTENT OF ITS BIODEGRADATION IN OPEN WATER- AND SANDY BEACH-LABORATORY SIMULATIONS

EPA Science Inventory

Bioremediation of marine oil spills, a technology using hydrocarbon-degrading and emulsifying capabilities of microorganisms, has many unexplored limitations, and among them is degree of environmental oil contamination. We examined the biodegradation of varying amounts of artifi...

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).

Nest placement of the giant Amazon river turtle, Podocnemis expansa, in the Araguaia River, Goiás State, Brazil.

PubMed

Ferreira, Paulo Dias Júnior; Castro, Paulo de Tarso Amorim

2005-05-01

The giant Amazon river turtle (Podocnemis expansa) nests on extensive sand bars on the margins and interior of the channel during the dry season. The high concentration of nests in specific points of certain beaches indicates that the selection of nest placement is not random but is related to some geological aspects, such as bar margin inclination and presence of a high, sandy platform. The presence of access channels to high platform points or ramp morphology are decisive factors in the choice of nesting areas. The eroded and escarped margins of the beaches hinder the Amazon river turtle arriving at the most suitable places for nesting. Through the years, changes in beach morphology can alter nest distribution.

Surf zone fish diet as an indicator of environmental and anthropogenic influences

NASA Astrophysics Data System (ADS)

Costa, Leonardo Lopes; Zalmon, Ilana Rosental

2017-10-01

Changes in species' abundance have been used as indicators of environmental and anthropogenic disturbances. However, sublethal, e.g., diet, changes should be detected before some alterations in the composition and structure of fish assemblages occur as a result of ecological negative impacts. The objective of the present study was to assess possible changes in surf zone fish diet in response to environmental and anthropogenic disturbances. Surf zone fish were sampled and their stomach contents were analyzed on two sandy beaches under different levels of human pressure in Southeastern Brazil. Habitat variables related to seasonality, food availability, anthropogenic disturbance, upwelling and river influence were measured as follows: (1) wave height; (2) water temperature; (3) intertidal macroinvertebrates abundance; (4) solid waste amount; (5) salinity; (6) particulate organic carbon (POC) and (7) chlorophyll a (Chl a). Our results showed the influence of seasonality, prey abundance and hydrodynamics in prey selection, and diet overlap between typical surf zone residents. A literature search was also performed and it shows that insects and Emerita brasiliensis eggs, which were the main food item consumed by some surf zone fish at urbanized Brazilian beaches, are unusual worldwide. Furthermore, solid waste was related to high consumption of insects by pompanos fish in urbanized areas, suggesting that this fish diet could be a sublethal indicator of human impact on sandy beaches.

Coastal Land Air Sea Interaction: "the" beach towers

NASA Astrophysics Data System (ADS)

MacMahan, J. H.; Koscinski, J. S.; Ortiz-Suslow, D. G.; Haus, B. K.; Thornton, E. B.

2016-12-01

As part of the Coastal Land Air Sea Interaction (CLASI) experiment, an alongshore array of 6-m high towers instrumented with ultrasonic 3D anemometers and temperature-relative humidity sensors were deployed at five sandy beaches near the high-tide line in Monterey Bay, CA, in May-June 2016. A cross-shore array of towers was also deployed from within the active surfzone to the toe of the dune at one beach. In addition, waves and ocean temperature were obtained along the 10m isobath for each beach. The dissipative surfzone was O(80m) wide. The wave energy varies among the beaches owing to sheltering and refraction by the Monterey Canyon and headlands. The tides are semi-diurnal mixed, meso-tidal with a maximum tidal range of 2m. This results in a variable beach width from the tower to the tidal line. Footprint analysis for estimating the source region for the turbulent momentum fluxes, suggests that the observations represent three scenarios described as primarily ocean, mixed beach and ocean, and primarily beach. The direct-estimate of the atmospheric stability by the sonic anemometer suggest that all of the beaches are mostly unstable except for a few occurrences in the evening during low wind conditions. The onshore neutral drag coefficient (Cd) estimated at 10m heights is 3-5 times larger than open ocean estimates. Minimal variability was found in Cd based on the footprint analysis. Beach-specific spatial variability in Cd was found related to atmospheric stability and wave energy.

Novel foraging in the swash zone on Pacific sand crabs (Emerita analoga, Hippidae) by mallards

USGS Publications Warehouse

Lafferty, Kevin D.; McLaughlin, John P.; Dugan, Jenifer E.

2013-01-01

Mallards (Anas platyrhynchos) have been observed foraging on intertidal Pacific sand crabs (Hippidae, Emerita analoga) in the swash zone of sandy beaches around Coal Oil Point Reserve, California, and several other beaches on the west coast since at least November 2010. Unlike foraging shorebirds, Mallards do not avoid incoming swashes. Instead, the incoming swash lifts and deposits them down the beach. Shorebirds and diving ducks commonly feed on sand crabs, but sand crabs appear to be a novel behavior and food source for Mallards. Previous surveys of beaches did not report foraging Mallards on regional beaches, whereas foraging Mallards were common in contemporary (recent) surveys and anecdotal reports. Observations of this potentially new behavior were separated by as much as 1,300 km, indicating that this was not a local phenomenon. Mallards foraged singly, in pairs, and in flocks. An expansion of diet to sand crabs carries risks of exposure to surf, human disturbance, high salt intake, and transmission of acanthocephalan and trematode parasites for Mallards but has the benefit of providing a dependable source of animal protein.

Assessment of island beach erosion due to sea level rise: the case of the Aegean archipelago (Eastern Mediterranean)

NASA Astrophysics Data System (ADS)

Monioudi, Isavela N.; Velegrakis, Adonis F.; Chatzipavlis, Antonis E.; Rigos, Anastasios; Karambas, Theophanis; Vousdoukas, Michalis I.; Hasiotis, Thomas; Koukourouvli, Nikoletta; Peduzzi, Pascal; Manoutsoglou, Eva; Poulos, Serafim E.; Collins, Michael B.

2017-03-01

The present contribution constitutes the first comprehensive attempt to (a) record the spatial characteristics of the beaches of the Aegean archipelago (Greece), a critical resource for both the local and national economy, and (b) provide a rapid assessment of the impacts of the long-term and episodic sea level rise (SLR) under different scenarios. Spatial information and other attributes (e.g., presence of coastal protection works and backshore development) of the beaches of the 58 largest islands of the archipelago were obtained on the basis of remote-sensed images available on the web. Ranges of SLR-induced beach retreats under different morphological, sedimentological and hydrodynamic forcing, and SLR scenarios were estimated using suitable ensembles of cross-shore (1-D) morphodynamic models. These ranges, combined with empirically derived estimations of wave run-up induced flooding, were then compared with the recorded maximum beach widths to provide ranges of retreat/erosion and flooding at the archipelago scale. The spatial information shows that the Aegean pocket beaches may be particularly vulnerable to mean sea level rise (MSLR) and episodic SLRs due to (i) their narrow widths (about 59 % of the beaches have maximum widths < 20 m), (ii) their limited terrestrial sediment supply, (iii) the substantial coastal development and (iv) the limited existing coastal protection. Modeling results indeed project severe impacts under mean and episodic SLRs, which by 2100 could be devastating. For example, under MSLR of 0.5 m - representative concentration pathway (RCP) 4.5 of the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate change (IPCC) - a storm-induced sea level rise of 0.6 m is projected to result in a complete erosion of between 31 and 88 % of all beaches (29-87 % of beaches are currently fronting coastal infrastructure and assets), at least temporarily. Our results suggest a very considerable risk which will require significant effort, financial resources and policies/regulation in order to protect/maintain the critical economic resource of the Aegean archipelago.

Optimal index related to the shoreline dynamics during a storm: the case of Jesolo beach

NASA Astrophysics Data System (ADS)

Archetti, Renata; Paci, Agnese; Carniel, Sandro; Bonaldo, Davide

2016-05-01

The paper presents an application of shoreline monitoring aimed at understanding the response of a beach to single storms and at identifying its typical behaviour, in order to be able to predict shoreline changes and to properly plan the defence of the shore zone. On the study area, in Jesolo beach (northern Adriatic Sea, Italy), a video monitoring station and an acoustic wave and current profiler were installed in spring 2013, recording, respectively, images and hydrodynamic data. The site lacks previous detailed hydrodynamic and morphodynamic data. Variations in the shoreline were quantified in combination with available near-shore wave conditions, making it possible to analyse the relationship between the shoreline displacement and the wave features. Results denote characteristic patterns of beach response to storm events, and highlight the importance of improving beach protection in this zone, notwithstanding the many interventions experimented in the last decades. A total of 31 independent storm events were selected during the period October 2013-October 2014, and for each of them synthetic indexes based on storm duration, energy and maximum wave height were developed and estimated. It was found that the net shoreline displacements during a storm are well correlated with the total wave energy associated to the considered storm by an empirical power law equation. A sub-selection of storms in the presence of an artificial dune protecting the beach (in the winter season) was examined in detail, allowing to conclude that the adoption of this coastal defence strategy in the study area can reduce shoreline retreat during a storm. This type of intervention can sometimes contribute to prolonging overall stability not only in the replenished zone but also in downdrift areas. The implemented methodology, which confirms to be economically attractive if compared to more traditional monitoring systems, proves to be a valuable system to monitor beach erosive processes and provide detailed indications on how to better plan beach-maintenance activities. The presented methodology and the proposed results can therefore be used as a basis for improving the collaboration between coastal scientists and managers to solve beach erosion problems, in locations where data are scattered and sporadic.

National assessment of hurricane-induced coastal erosion hazards: Mid-Atlantic Coast

USGS Publications Warehouse

Doran, Kara S.; Stockdon, Hilary F.; Sopkin, Kristin L.; Thompson, David M.; Plant, Nathaniel G.

2013-01-01

Beaches serve as a natural buffer between the ocean and inland communities, ecosystems, and natural resources. However, these dynamic environments move and change in response to winds, waves, and currents. During extreme storms, changes to beaches can be large, and the results are sometimes catastrophic. Lives may be lost, communities destroyed, and millions of dollars spent on rebuilding. During storms, large waves may erode beaches, and high storm surge shifts the erosive force of the waves higher on the beach. In some cases, the combined effects of waves and surge may cause overwash (when waves and surge overtop the dune, transporting sand inland) or flooding. Building and infrastructure on or near a dune can be undermined during wave attack and subsequent erosion. During Hurricane Ivan in 2004, a five-story condominium in Orange Beach, Alabama, collapsed after the sand dune supporting the foundation eroded. Hurricane Sandy, which made landfall as an extra-tropical cyclone on October 29, 2012, caused erosion and undermining that destroyed roads, boardwalks, and foundations in Seaside Heights, New Jersey. Waves overtopping a dune can transport sand inland, covering roads and blocking evacuation routes or emergency relief. If storm surge inundates barrier island dunes, currents flowing across the island can create a breach, or a new inlet, completely severing evacuation routes. Waves and surge during Hurricane Sandy, which made landfall on October 29, 2012, left a breach that cut the road and bridge to Mantoloking, N.J. Extreme coastal changes caused by hurricanes may increase the vulnerability of communities both during a storm and to future storms. For example, when sand dunes on a barrier island are eroded substantially, inland structures are exposed to storm surge and waves. Absent or low dunes also allow water to flow inland across the island, potentially increasing storm surge in the back bay, on the soundside of the barrier, and on the mainland.

Spatial-temporal analysis of marine debris on beaches of Niterói, RJ, Brazil: Itaipu and Itacoatiara.

PubMed

Silva, Melanie Lopes da; Araújo, Fábio Vieira de; Castro, Rebeca Oliveira; Sales, Alessandro Souza

2015-03-15

In many areas of the world, studies of marine debris are conducted with an emphasis on analyzing their composition, quantification and distribution on sandy beaches. However, in Brazil, studies are still restricted to some areas of the coast, and the quantities and the spatial and temporal patterns are unknown. To enhance the marine debris information in these areas, we selected the Itaipu and Itacoatiara beaches in Niterói, RJ, to collect, quantify and qualify the solid residues present in their sands. We collected 12 samples and recorded 118.39 kg of residues in Itaipu and 62.94 kg in Itacoatiara. At both beaches, the largest portion of debris was located on the upper part of the beach. Several debris items were related to food and drink consumption on the beaches, which indicated the contribution of beach users to pollution. Most of the debris was plastic. The greatest amount of debris was found at Itaipu in January and February and at Itacoatiara in January and March, months related to both the holiday season and abundant rainfall. The results demonstrated the necessity to implement an Environmental Education project for these areas to reduce its degradation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Paleochannel and beach-bar palimpsest topography as initial substrate for coralligenous buildups offshore Venice, Italy.

PubMed

Tosi, Luigi; Zecchin, Massimo; Franchi, Fulvio; Bergamasco, Andrea; Da Lio, Cristina; Baradello, Luca; Mazzoli, Claudio; Montagna, Paolo; Taviani, Marco; Tagliapietra, Davide; Carol, Eleonora; Franceschini, Gianluca; Giovanardi, Otello; Donnici, Sandra

2017-05-02

We provide a model for the genesis of Holocene coralligenous buildups occurring in the northwestern Adriatic Sea offshore Venice at 17-24 m depth. High-resolution geophysical surveys and underwater SCUBA diving reconnaissance revealed meandering shaped morphologies underneath bio-concretionned rocky buildups. These morphologies are inferred to have been inherited from Pleistocene fluvial systems reactivated as tidal channels during the post- Last Glacial Maximum transgression, when the study area was a lagoon protected by a sandy barrier. The lithification of the sandy fossil channel-levee systems is estimated to have occurred at ca. 7 cal. ka BP, likely due to the interaction between marine and less saline fluids related to onshore freshwater discharge at sea through a sealed water-table. The carbonate-cemented sandy layers served as nucleus for subsequent coralligenous buildups growth.

77 FR 32573 - Takes of Marine Mammals Incidental to Specified Activities; Construction and Race Event...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-01

... operations, support space, media operations, hospitality services, sponsored commercial space, and...). Intertidal habitats in the Central Bay, or those that lie between low and high tides, include sandy beaches... sediment and hard substrate habitat. Soft bottom substrate ranges between soft mud with high silt and clay...

Noodling for Mollusks

ERIC Educational Resources Information Center

Sukkestad, Kathryn; Curran, Mary Carla

2012-01-01

Mollusks, such as mussels and snails, are a great group to noodle because they are prevalent in banks and bottoms of river basins and in sandy beach habitats. Furthermore, their shells are easy to come by and safe to handle. There are six classes within the phylum Mollusca. In the activities described in this article, the authors focus on the…

USE OF HOPANE AS A CONSERVATIVE BIOMARKER FOR MONITORING THE BIOREMEDIATION EFFECTIVENESS OF CRUDE OIL CONTAMINATING A SANDY BEACH

EPA Science Inventory

Much of the variability inherent in crude oil bioremediation field studies can be eliminated by normalizing analyte concentrations to the concentration of a nonbiodegradable biomarker such as hopane. This was demonstrated with data from a field study in which crude oil was intent...

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.

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

Alloxenic distribution of cystacanths of two Profilicollis species in sympatric crustacean hosts in Chile.

PubMed

Balboa, L; Hinojosa, A; Riquelme, C; Rodríguez, S; Bustos, J; George-Nascimento, M

2009-10-01

The taxonomic status of Profilicollis ( = Falsifilicollis Webster, 1948) species in crustaceans in Chile is examined. Mole crabs, Emerita analoga (Stimpson 1857), living in the splash zone of a sandy beach at Lenga off the coast of central Chile, harbor Polymorphus (Profilicollis) bullocki Mateo, Córdova and Guzmán 1982, while the estuarine crabs, Hemigrapsus crenulatus (Milne-Edwards, 1837), living in an oligohaline inlet at the same site, harbor Profilicollis spp. cystacanths which cannot be distinguished specifically to either Profilicollis antarcticus or P. chasmagnathi Holcman-Spector, Mañé-Garzón and Dei-Cas 1977. We found no morphological data supporting records of P. altmani along the coast of Chile. Therefore, and after examination of both their morphology and the literature, we consider that P. bullocki must be reinstated as a valid species in the genus. There is a widespread distribution of habitats, such as sandy beaches and inlets, as well as a variety of host taxa involved in the life cycle of Profilicollis spp. Consequently, they provide an interesting scenario for testing hypotheses regarding the coevolution and host specificity of these parasites.

Coupled economic-coastline modeling with suckers and free riders

NASA Astrophysics Data System (ADS)

Williams, Zachary C.; McNamara, Dylan E.; Smith, Martin D.; Murray, A. Brad.; Gopalakrishnan, Sathya

2013-06-01

erosion is a natural trend along most sandy coastlines. Humans often respond to shoreline erosion with beach nourishment to maintain coastal property values. Locally extending the shoreline through nourishment alters alongshore sediment transport and changes shoreline dynamics in adjacent coastal regions. If left unmanaged, sandy coastlines can have spatially complex or simple patterns of erosion due to the relationship of large-scale morphology and the local wave climate. Using a numerical model that simulates spatially decentralized and locally optimal nourishment decisions characteristic of much of U.S. East Coast beach management, we find that human erosion intervention does not simply reflect the alongshore erosion pattern. Spatial interactions generate feedbacks in economic and physical variables that lead to widespread emergence of "free riders" and "suckers" with subsequent inequality in the alongshore distribution of property value. Along cuspate coastlines, such as those found along the U.S. Southeast Coast, these long-term property value differences span an order of magnitude. Results imply that spatially decentralized management of nourishment can lead to property values that are divorced from spatial erosion signals; this management approach is unlikely to be optimal.

Assessment of surf zone environmental variables in a southwestern Atlantic sandy beach (Monte Hermoso, Argentina).

PubMed

Menéndez, M Clara; Fernández Severini, Melisa D; Buzzi, Natalia S; Piccolo, M Cintia; Perillo, Gerardo M E

2016-08-01

The aim of this study was to investigate the temporal dynamics (monthly/tidal) of water temperature, salinity, chlorophyll-a (chlo-a), suspended particulate matter (SPM), particulate organic carbon (POC), and dissolved nutrients in the surf zone of Monte Hermoso sandy beach, Argentina. We also aimed to understand the underlying mechanisms responsible for the observed variability. Sampling was carried out approximately monthly (September 2009-November 2010), and all samples were collected in a fixed station during high and low tide. Water temperature showed a clear seasonal variability (July: 9 °C-December: 26.5 °C) and a thermal amplitude of 17.5 °C. Salinity ranged from 33 to 37, without a pronounced seasonality. SPM (10-223 mg L(-1)) and POC concentrations (399-6445 mg C m(-3)) were high in surf zone waters. Chlo-a (0.05-9.16 μg L(-1)) was low and did not evidence the occurrence of surf diatom accumulations. Dissolved nutrient concentration was quite fluctuating. None of the variables seemed to be affected by tidal stage. The results showed how fluctuating the physico-chemical and biological variables can be in this particular system. The observed variability can be related with local beach conditions but also with regional processes. The study area is highly influenced by a neighbor estuary and as a consequence, could be vulnerable to their seasonal and inter-annual dynamics. All of these characteristics must be considered for further studies and planning of the uses of natural resources and should be taken into account in any environmental monitoring program conducted in a similar beach system.

Subsurface Flow and Moisture Dynamics in Response to Swash Motions: Effects of Beach Hydraulic Conductivity and Capillarity

NASA Astrophysics Data System (ADS)

Geng, Xiaolong; Heiss, James W.; Michael, Holly A.; Boufadel, Michel C.

2017-12-01

A combined field and numerical study was conducted to investigate dynamics of subsurface flow and moisture response to waves in the swash zone of a sandy beach located on Cape Henlopen, DE. A density-dependent variably saturated flow model MARUN was used to simulate subsurface flow beneath the swash zone. Values of hydraulic conductivity (K) and characteristic pore size (α, a capillary fringe property) were varied to evaluate their effects on subsurface flow and moisture dynamics in response to swash motions in beach aquifers. The site-specific modeling results were validated against spatiotemporal measurements of moisture and pore pressure in the beach. Sensitivity analyses indicated that the hydraulic conductivity and capillary fringe thickness of the beach greatly influenced groundwater flow pathways and associated transit times in the swash zone. A higher value of K enhanced swash-induced seawater infiltration into the beach, thereby resulting in a faster expansion of a wedge of high moisture content induced by swash cycles, and a flatter water table mound beneath the swash zone. In contrast, a thicker capillary fringe retained higher moisture content near the beach surface, and thus, significantly reduced the available pore space for infiltration of seawater. This attenuated wave effects on pore water flow in the unsaturated zone of the beach. Also, a thicker capillary fringe enhanced horizontal flow driven by the larger-scale hydraulic gradient caused by tides.

Contamination of New Jersey beach sand with magnetite spherules from industrial air pollution

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

Hassinan, W.T.; Puffer, J.H.

1992-01-01

Spherical particles composed of magnetite, typically 120 [mu]m to 2,450 [mu]m in diameter, are accumulating in the beach sands of New Jersey. Most magnetite spherule surfaces are highly polished but some are corroded or abraded. Their interiors are typically vesicular. Magnetite spherules from 213 New Jersey beach sand samples collected during May 1991 are chemically and morphologically the same as those filtered from industrial smokestacks and the air supplied of Newark, New Jersey and Philadelphia. The average concentration of spherules in New Jersey beach sand is 35 per kg throughout the northern 43 km of beach south of Newark (frommore » Sandy Hook to Belmar Beach). They are rare to absent in the central 86 km stretch of beach but average 34 per kg of sand throughout the southern 91 km of beach east of Philadelphia (from Ventnor City to Villas Beach). The distribution of magnetite spherules in New Jersey beach sand is consistent with a transport pathway model that involves: (1) Prevailing wind dispersal from industrial sources, (2) erosion of spherules that have settled out of the air into the surface drainage system that flows toward the New Jersey coast and (3) longshore transport of spherule contaminated sand away from inlets identified as locations where most of the spherules enter the beach system. The spherules, therefore, are useful tracers indicating how industrial airborne fallout is transported to and along shorelines. The distribution pattern is consistent with generally northward longshore currents north of the Manasquan inlet and generally southward longshore currents south of the Abescon inlet.« less

Beach debris in the Azores (NE Atlantic): Faial Island as a first case study.

PubMed

Pieper, Catharina; Ventura, Maria A; Martins, Ana; Cunha, Regina T

2015-12-30

Marine debris is widely recognised as a global environmental problem. This study assesses density, type, and temporal trends of marine debris in two sandy beaches of Faial Island (Azores, NE-Atlantic). During seven months (six days per month) the beaches were surveyed by performing 10 random transects at each site. Recorded items within the range 2-30 cm were organised into seven categories. Densities of total debris varied from 0 to 1.940 items m(-2), with plastics dominating both areas. Both beaches, presented the highest debris abundance in February, most probably related to prevailing winds and swell. Location and/or time of year also seemed to influence the type of debris present. These findings provide new insights into debris accumulation rates in the Azores, where no previous studies were made. It also confirms the global trend of increased plastics accumulation on shorelines, highlighting the need for further research in remote islands. Copyright © 2015 Elsevier Ltd. All rights reserved.

Distribution and quantity of microplastic on sandy beaches along the northern coast of Taiwan.

PubMed

Kunz, Alexander; Walther, Bruno A; Löwemark, Ludvig; Lee, Yao-Chang

2016-10-15

Plastic pollution is now ubiquitous in the world's oceans, and studies have shown macroplastic and microplastic pollution of beaches in several East Asian countries. However, to our knowledge, no study of microplastic pollution has been conducted in Taiwan yet. Therefore, we collected sand samples from four beaches along the northern coast of Taiwan in 2015 and extracted microplastic particles using a saturated NaCl solution. Microplastic particles were identified using synchrotron-based FTIR spectroscopy. We recovered 4 to 532 particles from eight 0.0125m(3) samples, with a total of 1097 particles weighing 0.771g. A negative trend between the size of the particles and their numbers was documented. We thus established that microplastic pollution was ubiquitous along Taiwan's northern coast. Future research should more comprehensively sample beaches around the entirety of Taiwan's coast, and special emphasis should be placed on identifying different sources and movements of microplastic. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

Citizen science datasets reveal drivers of spatial and temporal variation for anthropogenic litter on Great Lakes beaches.

PubMed

Vincent, Anna; Drag, Nate; Lyandres, Olga; Neville, Sarah; Hoellein, Timothy

2017-01-15

Accumulation of anthropogenic litter (AL) on marine beaches and its ecological effects have been a major focus of research. Recent studies suggest AL is also abundant in freshwater environments, but much less research has been conducted in freshwaters relative to oceans. The Adopt-a-BeachTM (AAB) program, administered by the Alliance for the Great Lakes, organizes volunteers to act as citizen scientists by collecting and maintaining data on AL abundance on Great Lakes beaches. Initial assessments of the AAB records quantified sources and abundance of AL on Lake Michigan beaches, and showed that plastic AL was >75% of AL on beaches across all five Great Lakes. However, AAB records have not yet been used to examine patterns of AL density and composition among beaches of all different substrate types (e.g., parks, rocky, sandy), across land-use categories (e.g., rural, suburban, urban), or among seasons (i.e., spring, summer, and fall). We found that most AL on beaches are consumer goods that most likely originate from beach visitors and nearby urban environments, rather than activities such as shipping, fishing, or illegal dumping. We also demonstrated that urban beaches and those with sand rather than rocks had higher AL density relative to other sites. Finally, we found that AL abundance is lowest during the summer, between the US holidays of Memorial Day (last Monday in May) and Labor Day (first Monday in September) at the urban beaches, while other beaches showed no seasonality. This research is a model for utilizing datasets collected by volunteers involved in citizen science programs, and will contribute to AL management by offering priorities for AL types and locations to maximize AL reduction. Copyright © 2016 Elsevier B.V. All rights reserved.

Geologic records of Pleistocene, Holocene and Anthropocene beach profiles?

NASA Astrophysics Data System (ADS)

Dougherty, Amy; Choi, Jeong-Heon; Dosseto, Anthony

2017-04-01

The Anthropocene Working Group recently concluded that we have entered a new Epoch; starting during the last century when carbon dioxide, temperatures, and sea level all exceeding previous Holocene measurements. Climate change models predict a 1m rise in sea-level by 2100 coupled with increased storm intensity. Determining how vulnerable coasts will respond to global warming in the future, requires past records of sea-level and storm impacts to be deciphered. Paying specific attention to any changes prior to, and since, the onset of the Industrial Revolution. Coastal change over centennial time-scales has long fallen within a knowledge gap that exists between our understanding of shoreline behaviour measured over decades and that inferred from the landscape over millennia. Insight on shoreline behaviour across spatial and temporal scales is gained using computers to integrate models of short-term morphodynamics along beaches with longer-term coastal landscape evolution models. However, limitations exist as process-based engineering models depend on wave climate and beach profile data that is restricted to regional/historical records, while large-scale coastal behaviour models are based on general chronostratographic data from topographic profiles, interpolated cores, and isochrons extrapolated from deep radiocarbon ages. Here we demonstrate a unique methodology combining state-of-the-art geophysics, luminescence, and remote sensing techniques on prograded barriers to extract comprehensive chronostratigraphic records. Ground Penetrating Radar (GPR) data document beach and dune stratigraphy at decimetre resolution. Optically Stimulated Luminescence (OSL) directly date the formation of paleo-beachfaces and dunes. Light Detection and Ranging (LiDAR) image the lateral extent of strandplain ridge morphology. The resulting record of paleo-beach profiles spanning from the present-day beach through Holocene and Pleistocene barriers, enables our in-depth understanding of morphodynamics to interpret paleoenvironmental histories. Data from prograded barriers in North America, New Zealand and Australia are used to illustrate the potential of utilizing GPR, OSL, and LiDAR. Exploiting the fundamental link between paleo-beachfaces and past ocean levels, new sea level curves were constructed by mapping their height over time. Examples from far-field sites capture Eemian and mid-Holocene highstands with a subsequent fall indicating a non-linear nature. The geometry of paleo-beachfaces, intrinsically linked to wave-energy, were analyzed in comparison to present-day beach profile data to extract storm records. The results yielded recurrence intervals with differing coastal impacts, which indicated storm intensity increased as frequency decreased. Volumes of the barrier lithesome were quantified to provide insight on sediment supply and accommodation space over time. Findings show sand supply increased drastically starting in the mid-19th century causing a shift in foredune evolution from previous millennia. Do anomalous foredunes define Anthropocene coastal barriers in the geologic record? Global stratigraphic signatures, distinct from Holocene deposits, are needed to formally establish this 'Human' Epoch. Applying this novel methodology to the more than 300 prograded barriers around the world, including 50+ in Europe, can: 1) augment traditional proxy from ice and sediment cores to help delineate the Anthropocene, 2) determine changes in coastlines since the onset of global warming, and 3) provide insight, and input to forecasting models, needed to mitigate and manage future impacts of climate change.

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

Davis, R.J.; Johnson, C.A.; Gilreath, J.A.

Depositional systems in the Medina Group (Lower Silurian) of western New York have been studied using stratigraphic dipmeter data. Results of this study indicate a nearshore-deltaic-interdeltaic depositional environment. Only minor deltaic episodes are preserved in the study area. This fits the generally arid climate with seasonal wet periods suggested by C.D. Laughrey. Facies recognized include: longshore-current sand waves in a shoreface environment, distributary mouth bars, distributary channels, tidal inlets, flood deltas, beaches, sandy tidal flats on which beach ridges were formed, and possible upper delta-plain sediments. Once the depositional sequences are recognized, paleocurrents within key sand units can be interpretedmore » to determine favorable directions for successfully locating offset wells.« less

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.

Coastal Awareness: A Resource Guide for Teachers in Senior High Science. Preprint.

ERIC Educational Resources Information Center

Rasmussen, Frederick A.

The stated purpose of this resource guide is to entice teachers to explore ecological aspects of coastal awareness. Discussions describe different characteristics of the coast such as: (1) waves, currents, and tides; (2) sandy beaches; (3) rocky shores; (4) estuaries; and (5) marshes. These discussions present some of the physical processes that…

Effects of Fishing and Fishing Closures on Beach Clams: Experimental Evaluation across Commercially Fished and Non-Fished Beaches before and during Harvesting

PubMed Central

Gray, Charles A.

2016-01-01

Management responses to reconcile declining fisheries typically include closed areas and times to fishing. This study evaluated this strategy for a beach clam fishery by testing the hypothesis that changes in the densities and size compositions of clams from before to during harvesting would differ between commercially fished and non-fished beaches. Sampling was spatially stratified across the swash and dry sand habitats on each of two commercially fished and two non-fished beaches, and temporally stratified across three six-week blocks: before, early and late harvesting. Small-scale spatio-temporal variability in the densities and sizes of clams was prevalent across both habitats and the components of variation were generally greatest at the lowest levels examined. Despite this, differences in the densities and sizes of clams among individual beaches were evident, but there were few significant differences across the commercially fished versus non-fished beaches from before to during harvesting. There was no evidence of reduced densities or truncated size compositions of clams on fished compared to non-fished beaches, contrasting reports of some other organisms in protected areas. This was probably due to a combination of factors, including the current levels of commercial harvests, the movements and other local-scale responses of clams to ecological processes acting independently across individual beaches. The results identify the difficulties in detecting fishing-related impacts against inherent levels of variability in clam populations. Nevertheless, continued experimental studies that test alternate management arrangements may help refine and determine the most suitable strategies for the sustainable harvesting of beach clams, ultimately enhancing the management of sandy beaches. PMID:26731102

Effects of Fishing and Fishing Closures on Beach Clams: Experimental Evaluation across Commercially Fished and Non-Fished Beaches before and during Harvesting.

PubMed

Gray, Charles A

2016-01-01

Management responses to reconcile declining fisheries typically include closed areas and times to fishing. This study evaluated this strategy for a beach clam fishery by testing the hypothesis that changes in the densities and size compositions of clams from before to during harvesting would differ between commercially fished and non-fished beaches. Sampling was spatially stratified across the swash and dry sand habitats on each of two commercially fished and two non-fished beaches, and temporally stratified across three six-week blocks: before, early and late harvesting. Small-scale spatio-temporal variability in the densities and sizes of clams was prevalent across both habitats and the components of variation were generally greatest at the lowest levels examined. Despite this, differences in the densities and sizes of clams among individual beaches were evident, but there were few significant differences across the commercially fished versus non-fished beaches from before to during harvesting. There was no evidence of reduced densities or truncated size compositions of clams on fished compared to non-fished beaches, contrasting reports of some other organisms in protected areas. This was probably due to a combination of factors, including the current levels of commercial harvests, the movements and other local-scale responses of clams to ecological processes acting independently across individual beaches. The results identify the difficulties in detecting fishing-related impacts against inherent levels of variability in clam populations. Nevertheless, continued experimental studies that test alternate management arrangements may help refine and determine the most suitable strategies for the sustainable harvesting of beach clams, ultimately enhancing the management of sandy beaches.

Temporal and spatial variation in bird and human use of beaches in southern California

USGS Publications Warehouse

Lafferty, Kevin D.; Rodriguez, Donald A.; Chapman, Angela

2013-01-01

Southern California’s beaches can support a remarkable diversity of birds along the Pacific Flyway. We asked whether seasonal, annual, and spatial factors affect bird richness and abundance on public beaches. To do so, we conducted three years of monthly bird surveys on 12 sandy beaches in Ventura California. Across all surveys, we counted 22 shorebird species, 8 gull species, 24 other water bird species, and 24 landbird species. Sanderling, western gull, Heerman’s gull, willet, marbled godwit, and whimbrel were the most abundant members of the bird community. Beach wrack was uncommon, particularly where beaches were groomed, and did not have a large effect on bird abundance, though it was positively associated with overall bird richness. Beaches near estuaries tended to be wide, and such beaches had a higher richness and abundance of birds. Beaches with shallow slopes tended to have more gulls and shorebirds. People and (illegal) unleashed dogs were common, particularly at beaches fronted by houses. The abundance and richness of shorebirds and the richness of other waterbirds was lower where human activity was high. Bird richness and abundance was strongly affected by season, with the highest density of birds being seen during the fall shorebird migration. Gull abundance peaked earlier (August-September) than shorebird abundance (October through December). A brief pulse of shorebirds also occurred in May due to spring migration. Comparing these data with surveys in the 1990’s found no evidence for a decline in shorebirds over time, though black-bellied plover appear to still be recovering from the strong 1997-1998 ENSO. Opportunities to conserve birds on these beaches are limited, but could include enforcing leash laws and setting up human exclosures near estuary mouths.

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.

Environmental drivers defining linkages among life-history traits: mechanistic insights from a semiterrestrial amphipod subjected to macroscale gradients.

PubMed

Gómez, Julio; Barboza, Francisco R; Defeo, Omar

2013-10-01

Determining the existence of interconnected responses among life-history traits and identifying underlying environmental drivers are recognized as key goals for understanding the basis of phenotypic variability. We studied potentially interconnected responses among senescence, fecundity, embryos size, weight of brooding females, size at maturity and sex ratio in a semiterrestrial amphipod affected by macroscale gradients in beach morphodynamics and salinity. To this end, multiple modelling processes based on generalized additive mixed models were used to deal with the spatio-temporal structure of the data obtained at 10 beaches during 22 months. Salinity was the only nexus among life-history traits, suggesting that this physiological stressor influences the energy balance of organisms. Different salinity scenarios determined shifts in the weight of brooding females and size at maturity, having consequences in the number and size of embryos which in turn affected sex determination and sex ratio at the population level. Our work highlights the importance of analysing field data to find the variables and potential mechanisms that define concerted responses among traits, therefore defining life-history strategies.

Field observation of morpho-dynamic processes during storms at a Pacific beach, Japan: role of long-period waves in storm-induced berm erosion.

PubMed

Mizuguchi, Masaru; Seki, Katsumi

2015-01-01

Many ultrasonic wave gages were placed with a small spacing across the swash zone to monitor either sand level or water level. Continuous monitoring conducted for a few years enabled the collection of data on the change in wave properties as well as swash-zone profiles. Data sets including two cases of large-scale berm erosion were analyzed. The results showed that 1) shoreline erosion started when high waves with significant power in long-period (1 to 2 min.) waves reached the top of a well-developed berm with the help of rising tide; 2) the beach in the swash zone was eroded with higher elevation being more depressed, while the bottom elevation just outside the swash zone remained almost unchanged; and 3) erosion stopped in a few hours after the berm was completely eroded or the swash-zone slope became uniformly mild. These findings strongly suggest that long waves play a dominant role in the swash-zone dynamics associated with these erosional events.

76 FR 47133 - Endangered and Threatened Wildlife and Plants; 90-Day Finding and 12-Month Determination on a...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-04

..., the main nesting beaches occur in the Solomon Islands, Papua, Indonesia, and Papua New Guinea (Limpus... presented below. We have organized the petition's claims into four categories relative to 50 CFR 424.14(c)(2... observed females at Sandy Point from 1986 to 2004, the Turtle Expert Working [[Page 47137

Fault history of the Pribilof Island and its relevance to bottom stability in the St. George Basin

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

Hopkins, D.M.

1976-04-01

This study evaluates frequency of faulting and volcanic eruptions on the Pribilof Islands and in nearby waters, examines rates and directions of changes in the island shorelines during the 20th Century, and investigates the nature of the soils and thier susceptibility to erosion after disturbance. Volcanos have been active in the Pribilof Island area throughout the last 8 my, activity during the last 300,000 years and has been confined to the vicinity of St. Paul Island. Eruptions recur at intervals of about 10,000 years. Faulting is also an ongoing process. Fault movements recur at rather long but still unknown intervals.more » Although the recurrence interval of movement on individual faults is long, the fault hazard is significant, because faluts cross any possible path for a pipeline connecting production areas in the St. George Basin with terminal facilities on the Pribilof Islands. The sandy beaches and sandy soils of St. Paul Island are sensitive to human activity. Perturbations related to construction of logistic bases and pipeline and transhipment facilities are likely to result in extensive changes in the beaches and loss of surface soils by wind deflation.« less

An evolving research agenda for human-coastal systems

NASA Astrophysics Data System (ADS)

Lazarus, Eli D.; Ellis, Michael A.; Brad Murray, A.; Hall, Damon M.

2016-03-01

Within the broad discourses of environmental change, sustainability science, and anthropogenic Earth-surface systems, a focused body of work involves the coupled economic and physical dynamics of developed shorelines. Rapid rates of change in coastal environments, from wetlands and deltas to inlets and dune systems, help researchers recognize, observe, and investigate coupling in natural (non-human) morphodynamics and biomorphodynamics. This same intrinsic quality of fast-paced change also makes developed coastal zones exemplars of observable coupling between physical processes and human activities. In many coastal communities, beach erosion is a natural hazard with economic costs that coastal management counters through a variety of mitigation strategies, including beach replenishment, groynes, revetments, and seawalls. As cycles of erosion and mitigation iterate, coastline change and economically driven interventions become mutually linked. Emergent dynamics of two-way economic-physical coupling is a recent research discovery. Having established a strong theoretical basis, research into coupled human-coastal systems has passed its early proof-of-concept phase. This paper frames three major challenges that need resolving in order to advance theoretical and empirical treatments of human-coastal systems: (1) codifying salient individual and social behaviors of decision-making in ways that capture societal actions across a range of scales (thus engaging economics, social science, and policy disciplines); (2) quantifying anthropogenic effects on alongshore and cross-shore sediment pathways and long-term landscape evolution in coastal zones through time, including direct measurement of cumulative changes to sediment cells resulting from coastal development and management practices (e.g., construction of buildings and artificial dunes, bulldozer removal of overwash after major storms); and (3) reciprocal knowledge and data exchange between researchers in coastal morphodynamics and practitioners of coastal management. Future research into human-coastal systems can benefit from decades of interdisciplinary work on the complex dynamics of common-pool resources, from computational efficiency and new techniques in numerical modeling, and from the growing catalog of high-resolution geospatial data for natural and developed coastlines around the world.

Biogeography of Anurans from the Poorly Known and Threatened Coastal Sandplains of Eastern Brazil.

PubMed

Xavier, Ariane Lima; Guedes, Thaís Barreto; Napoli, Marcelo Felgueiras

2015-01-01

The east coast of Brazil comprises an extensive area inserted in the Tropical Atlantic Domain and is represented by sandy plains of beach ridges commonly known as Restingas. The coastal environments are unique and house a rich amphibian fauna, the geographical distribution patterns of which are incipient. Biogeographical studies can explain the current distributional patterns and provide the identification of natural biogeographical units. These areas are important in elucidating the evolutionary history of the taxa and the areas where they occur. The aim of this study was to seek natural biogeographical units in the Brazilian sandy plains of beach ridges by means of distribution data of amphibians and to test the main predictions of the vicariance model to explain the patterns found. We revised and georeferenced data on the geographical distribution of 63 anuran species. We performed a search for latitudinal distribution patterns along the sandy coastal plains of Brazil using the non-metric multidimensional scaling method (NMDS) and the biotic element analysis to identify natural biogeographical units. The results showed a monotonic variation in anuran species composition along the latitudinal gradient with a break in the clinal pattern from 23°S to 25°S latitude (states of Rio de Janeiro to São Paulo). The major predictions of the vicariance model were corroborated by the detection of four biotic elements with significantly clustered distribution and by the presence of congeneric species distributed in distinct biotic elements. The results support the hypothesis that vicariance could be one of the factors responsible for the distribution patterns of the anuran communities along the sandy coastal plains of eastern Brazil. The results of the clusters are also congruent with the predictions of paleoclimatic models made for the Last Glacial Maximum of the Pleistocene, such as the presence of historical forest refugia and biogeographical patterns already detected for amphibians in the Atlantic Rainforest.

Biogeography of Anurans from the Poorly Known and Threatened Coastal Sandplains of Eastern Brazil

PubMed Central

Xavier, Ariane Lima; Guedes, Thaís Barreto; Napoli, Marcelo Felgueiras

2015-01-01

The east coast of Brazil comprises an extensive area inserted in the Tropical Atlantic Domain and is represented by sandy plains of beach ridges commonly known as Restingas. The coastal environments are unique and house a rich amphibian fauna, the geographical distribution patterns of which are incipient. Biogeographical studies can explain the current distributional patterns and provide the identification of natural biogeographical units. These areas are important in elucidating the evolutionary history of the taxa and the areas where they occur. The aim of this study was to seek natural biogeographical units in the Brazilian sandy plains of beach ridges by means of distribution data of amphibians and to test the main predictions of the vicariance model to explain the patterns found. We revised and georeferenced data on the geographical distribution of 63 anuran species. We performed a search for latitudinal distribution patterns along the sandy coastal plains of Brazil using the non-metric multidimensional scaling method (NMDS) and the biotic element analysis to identify natural biogeographical units. The results showed a monotonic variation in anuran species composition along the latitudinal gradient with a break in the clinal pattern from 23°S to 25°S latitude (states of Rio de Janeiro to São Paulo). The major predictions of the vicariance model were corroborated by the detection of four biotic elements with significantly clustered distribution and by the presence of congeneric species distributed in distinct biotic elements. The results support the hypothesis that vicariance could be one of the factors responsible for the distribution patterns of the anuran communities along the sandy coastal plains of eastern Brazil. The results of the clusters are also congruent with the predictions of paleoclimatic models made for the Last Glacial Maximum of the Pleistocene, such as the presence of historical forest refugia and biogeographical patterns already detected for amphibians in the Atlantic Rainforest. PMID:26047484

"Managed Retreat" in Response to Superstorm Sandy: The Oakwood Beach Story

NASA Astrophysics Data System (ADS)

Tirone, J.

2017-12-01

This presentation shares lessons learned from firsthand experience of the home buyout process in New York City after Superstorm Sandy. Many have described Sandy as "the perfect storm" from a meteorological perspective, but it was also the perfect storm from a government-buyout perspective. For a buyout to work in New York City, with its high property values and dense housing and population, many conditions had to be in place before the storm. Before Sandy hit, Oakwood Beach on Staten Island had already had enough. Hurricane Isaac flooded streets and basements in 2010, followed by Hurricane Irene in 2011. Many residents of this multi-generational neighborhood had just finished fixing their homes. A few years before, a brush fire spread through the invasive and highly flammable Phragmites reeds, destroying a protective berm installed by the Army Corps of Engineers in 2000 and threatening to damage many homes. An aerial view would show how these homes incredulously sat in the middle of a marsh, a marsh designated as part of the Bluebelt wetlands storm water management system by New York City's Department of Environmental Protection. Even more incredulously, while New York City was buying up unimproved lots to expand the Bluebelt to improve drainage for inland homes, the City was also issuing building permits to developers - sometimes for lots directly in the Bluebelt's path. Welcome to Staten Island, where the political influence of developers made any effort to retreat from the waterfront especially difficult and contentious. Before the storm, no one knew what a buyout was, never mind how to go about seeking one. For the most part, this included local officials. Managed retreat is typically understood as a top-down directive, but in this case the buyout plan was initiated from the bottom up by eight ordinary citizens who used research, trust, and networking to get their voices heard and, against all odds, to drive a highly successful State-supported buyout program.

Dynamic groundwater flows and geochemistry in a sandy nearshore aquifer over a wave event

NASA Astrophysics Data System (ADS)

Malott, Spencer; O'Carroll, Denis M.; Robinson, Clare E.

2016-07-01

Dynamic coastal forcing influences the transport of pollutants in nearshore aquifers and their ultimate flux to coastal waters. In this study, field data are presented that show, for the first time, the influence of a period of intensified wave conditions (wave event) on nearshore groundwater flows and geochemistry in a sandy beach. Field measurements at a freshwater beach allow wave effects to be quantified without other complex forcing that are present along marine shorelines (e.g., tides). Pressure transducer data obtained over an isolated wave event reveal the development of transient groundwater flow recirculations. The groundwater flows were simulated in FEFLOW using a phase-averaged wave setup approach to represent waves acting on the sediment-water interface. Comparison of measured and simulated data indicates that consideration of wave setup alone is able to adequately capture wave-induced perturbations in groundwater flows. While prior studies have shown sharp pH and redox spatial zonations in nearshore aquifers, this study reveals rapid temporal variations in conductivity, pH, and redox (ORP) in shallow sediments (up to 0.5 m depth) in response to varying wave conditions. Comparison of head gradients with calculated conductivity and pH mixing ratios indicates the controlling effect of the wave-induced water exchange and flows in driving the observed geochemical dynamics. While we are not able to conclusively determine the extent to which temporal variations are caused by conservative mixing versus reactive processes, the pH and ORP variations observed will have significant implications for the fate of reactive pollutants discharging through sandy nearshore aquifers.

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.

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.

Phylogeography of the sandy beach amphipod Haustorioides japonicus along the Sea of Japan: Paleogeographical signatures of cryptic regional divergences

NASA Astrophysics Data System (ADS)

Takada, Yoshitake; Sakuma, Kay; Fujii, Tetsuo; Kojima, Shigeaki

2018-01-01

Recent findings of genetic breaks within apparently continuous marine populations challenge the traditional vicariance paradigm in population genetics. Such "invisible" boundaries are sometimes associated with potential geographic barriers that have forced divergence of an ancestral population, habitat discontinuities, biogeographic disjunctions due to environmental gradients, or a combination of these factors. To explore the factors that influence the genetic population structure of apparently continuous populations along the Sea of Japan, the sandy beach amphipod Haustorioides japonicus was examined. We sampled a total of 300 individuals of H. japonicus from the coast of Japan, and obtained partial sequences of the mitochondrial COI gene. The sequences from 19 local populations were clustered into five groups (Northwestern Pacific, Northern, Central, Southern Sea of Japan, and East China Sea) based on a spatial genetic mixture analysis and a minimum-spanning network. AMOVA and pairwise Fst tests further supported the significant divergence of the five groups. Phylogenetic analysis revealed the relationship among the haplotypes of H. japonicus and outgroups, which inferred the northward range expansion of the species. A relaxed molecular-clock Bayesian analysis inferred the early-to middle-Pleistocene divergence of the populations. Among the five clusters, the Central Sea of Japan showed the highest values for genetic diversity indices indicating the existence of a relatively stable and large population there. The hypothesis is also supported by Bayesian Skyline Plots that showed sudden population expansion for all the clusters except for Central Sea of Japan. The present study shows genetic boundaries between the Sea of Japan and the neighboring seas, probably due to geographic isolation during the Pleistocene glacial periods. We further found divergence between the populations along the apparently continuous coast of the Sea of Japan. Historical changes in the geographic range of H. japonicus in relation to sandy beach habitat availability, account for the genetic breaks among the three populations in the Sea of Japan. The present results infer that the past geographic events influenced the population formation of H. japonicus.

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.

Bathymetry data collected in October 2014 from Fire Island, New York—The wilderness breach, shoreface, and bay

USGS Publications Warehouse

Nelson, Timothy R.; Miselis, Jennifer L.; Hapke, Cheryl J.; Brenner, Owen T.; Henderson, Rachel E.; Reynolds, Billy J.; Wilson, Kathleen E.

2017-03-24

Scientists from the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center in St. Petersburg, Florida, conducted a bathymetric survey of Fire Island, New York, from October 5 to 10, 2014. The U.S. Geological Survey is involved in a post-Hurricane Sandy effort to map and monitor the morphologic evolution of the wilderness breach, which formed in October 2012 during Hurricane Sandy, as part of the Hurricane Sandy Supplemental Project GS2-2B. During this study, bathymetry data were collected, using single-beam echo sounders and global positioning systems mounted to personal watercraft, along the Fire Island shoreface and within the wilderness breach, Fire Island Inlet, Narrow Bay, and Great South Bay east of Nicoll Bay. Additional bathymetry and elevation data were collected using backpack and wheel-mounted global positioning systems along the subaerial beach (foreshore and backshore), flood shoals, and shallow channels within the wilderness breach and adjacent shoreface.

Beach protection by a system of permeable groins

NASA Astrophysics Data System (ADS)

Boczar-Karakiewicz, B.; Romanczyk, W.; Roy, N.

2002-12-01

A new type of permeable groin (called System of Groins Maltec-Savard - SGMS) has been installed at three eroded sites located in the coastal area on the north shore of the St. Lawrence, Quebec, Canada. In this area, the narrow sandy beaches with sandy or sand-silty cliff of variable height (10-15~m) are exposed to obliquely incident waves arriving from both west (summer) and east (autumn), and to tidal currents (maximum tidal rate is 4.3~m). The periods of summer waves equal 3-5~s, with wave heights of about 0.4-0.7~m. In the autumn, major storm waves reach periods of up to 7-10~s, with wave heights of 1.0-1.2~m. The new groins are sediment traps formed by a central double and permeable groin with several smaller lateral, groins installed on one or both sides of the central groin (Boczar-Karakiewicz et al., 2001). The permeable central and lateral groins are structured by inserting double ranges of wooden piles (diameter of about 10 cm). The space between the ranges of piles (some 0.8~m wide) is filled with tree branches (e.g., the top parts of pine trees, a waste product of the local forest industry). A permeable grid covering the top of the groins forms a cage that holds the branches in place. The lateral groins, are identical but much shorter than the central groin. The whole system dissipates the incident energy of wave- and tidally-generated currents and causes accretion of sand transported by these currents. The GSMS also allows the by-pass of some sediment to adjacent zones without groins. Observations and results of measurements from three experiments field show that: (1) a sandy beach in front of a coastal cliff secures its stability and attenuates the erosion caused by waves and tidal currents; (2) permeability and flexibility of the SGMS causes the accretion of sediment in the protected area without erosion in the neighboring zones; (3) the SGMS does not generate wave reflection and any secondary current; (4) the materials of the groins are easily available, and the cost is low (waste material of the local forest industry); (5) the construction is simple and can be carried out by low-skilled labor force. Boczar-Karakiewicz, B., W. Romanczyk, N. Roy, N. Pelletier, L. Maltec and J.-P. Savard. 2001. New method of beach protection adapted to coastal zones of the estuary of the Saint Lawrence river, Quebec, Canada. Proc. Can. Coast. Conf., Quebec, QC, Canada: 201-214 (in French).

Morphologic evolution of the wilderness area breach at Fire Island, New York—2012–15

USGS Publications Warehouse

Hapke, Cheryl J.; Nelson, Timothy R.; Henderson, Rachel E.; Brenner, Owen T.; Miselis, Jennifer L.

2017-09-18

IntroductionHurricane Sandy, which made landfall on October 29, 2012, near Atlantic City, New Jersey, had a significant impact on the coastal system along the south shore of Long Island, New York. A record significant wave height of 9.6 meters (m) was measured at wave buoy 44025, approximately 48 kilometers offshore of Fire Island, New York. Surge and runup during the storm resulted in extensive beach and dune erosion and breaching of the Fire Island barrier island system at two locations, including a breach that formed within the Otis Pike Fire Island High Dune Wilderness area on the eastern side of Fire Island.The U.S. Geological Survey (USGS) has a long history of conducting morphologic change and processes research at Fire Island. One of the primary objectives of the current research effort is to understand the morphologic evolution of the barrier system on a variety of time scales (from storm scale to decade(s) to century). A number of studies that support the project objectives have been published. Prior to Hurricane Sandy, however, little information was available on specific storm-driven change in this region. The USGS received Hurricane Sandy supplemental funding (project GS2–2B: Linking Coastal Processes and Vulnerability, Fire Island, New York, Regional Study) to enhance existing research efforts at Fire Island. The existing research was greatly expanded to include inner continental shelf mapping and investigations of processes of inner shelf sediment transport; beach and dune response and recovery; and observation, analysis, and modeling of the newly formed breach in the Otis Pike High Dune Wilderness area, herein referred to as the wilderness breach. The breach formed at the site of Old Inlet, which was open from 1763 to 1825. The location of the initial island breaching does not directly correspond with topographic lows of the dunes, but instead the breach formed in the location of a cross-island boardwalk that was destroyed during Hurricane Sandy.From 2013 to November 2015, bathymetric data were collected by the USGS St. Petersburg Coastal and Marine Science Center during three surveys of the breach channel and tidal shoals, and shoreline positions on each side of the breach (also collected by the National Park Service). Additionally, pre-storm topography/bathymetry EAARL–B light detection and ranging (lidar) data were collected by the USGS the day prior to Hurricane Sandy’s landfall. These data serve as a baseline for change analyses during four subsequent periods: June 2013, June 2014, October 2014, and May 2015. The June 2013 single-beam bathymetry data were collected in collaboration with the U.S. Army Corps of Engineers (USACE), using the Lighter Amphibious Resupply Cargo (LARC) vessel, and included the ebb shoal and breach channel. The USGS collected and processed the three additional bathymetric datasets using personal watercraft equipped with single-beam echo sounders and backpack Global Positioning System (GPS) over shallow flood shoals.Eastern and western breach shorelines were surveyed weekly to monthly beginning on November 6, 2012 (by the National Park Service [NPS], and USGS St. Petersburg Coastal and Marine Science Center), with measurements made every few weeks for the first year and every few months after October 2013. The NPS and researchers from Stony Brook University monitored the breach by collecting field data of the breach channel bathymetry, conducting aerial photographic overflights, and performing water-quality analyses (see http://po.msrc.sunysb.edu/GSB/). The aerial photography collected and rectified by Stony Brook University is used extensively in our morphologic change description to examine changes to breach shorelines (supplementing shoreline data collected in the field), channel width, and orientation. Due to the uncertainties and the variation in survey methods, a rigorous quantitative analysis was not performed. However, average calculations of various breach metrics allow a qualitative analysis of breach development and evolution.This report presents an overview of the data collected and a summary discussion of the observed changes to the breach system and the seasonal wave climatology associated with the breach morphodynamic response.

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

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.

Simulation of morphodinamic processes in small coastal systems: application to the Aljezur coastal stream (Portugal)

NASA Astrophysics Data System (ADS)

Guerreiro, Martha; Fortunato, André B.; Oliveira, Anabela; Bertin, Xavier; Bruneau, Nicolas; Rodrigues, Marta

2010-05-01

In small and shallow coastal streams, morphological changes may have a dramatic effect on tidal propagation and distortion, on hydrodynamics and, ultimately, on the transport and fate of water-borne material. Hence, the ability to simulate the morphodynamic evolution of these dynamic and complex systems can be required for water quality studies. This work aimed at implementing, validating and exploring the morphodynamic modelling system MORSYS2D (Fortunato and Oliveira, 2004, Bertin et al., 2009) in the Aljezur stream, a small and dynamic coastal system located in south-west Portugal. Four extensive field campaigns were carried out in 2008 and 2009 to measure bathymetry, water levels, waves and currents, in both the estuary and the adjoining beach. Between the two 2009 campaigns, bathymetry was measured on a monthly basis. Data revealed significant morphological changes, including channel migration and the formation of sandbars. The morphodynamic modelling system MORSYS2D consists of a wave model (SWAN - Booij et al., 1999), a circulation model (ELCIRC - Zhang et al., 2004) and a sediment transport and bottom update model (SAND2D, Fortunato and Oliveira, 2004), and is controlled by a script that runs the models, manages the transfer of information between them and performs control checks. The model was shown to reproduce successfully the waves, the water levels and the velocities. Preliminary morphodynamic simulations revealed that the model is highly sensitive to small changes in the initial conditions, the parameterization of friction and the sediment transport formulation. This presentation will describe the calibration and validation of the morphodynamic modelling system and will investigate on the circumstances that can lead to the inlet closure (including wave action and river flow). Acknowledgements This work was sponsored by the Portuguese Science and Technology Foundation (FCT), project MADyCOS (PTDC/ECM/66484/2006). The authors thank the developers of the models ELCIRC and SWAN for making their source codes available and Guillaume Dodet for providing the time-series of wave spectra. The first author is grateful to Prof. João Dias for the orientation provided during this work. This research would not have been be possible without the participants in the field campaigns: R. Taborda, C. Andrade, C. Freitas, A.M. Silva, C. Antunes (Faculdade de Ciências de Lisboa), L. David, P. Freire, R. Capitão, C.J.E.M Fortes, L.S. Pedro, J. Vale, A. Nahon, D. Neves, C. Zózimo, L. Pinheiro (LNEC), A. Cravo, M. Rosa, C. Monteiro, S. Cardeira and C. Loureiro (Universidade do Algarve). The authors are grateful for all the effort and support. References Bertin, X., Oliveira, A. and Fortunato, A.B. 2009. Simulating morphodynamics with unstructured grids: description and validation of a modeling system for coastal applications, Ocean Modelling, 28/1-3: 75-87. Booij, N., Ris, R.C. and Holthuijsen, L.H., 1999. A third generation wave model for coastal regions; Part I: model description and validation. Journal of Geophysical Research, 104: 7649-7666. Dodet, G., Bertin, X. and Taborda, R. 2010. Wave climate variability in the North-East Atlantic Ocean over the last six decades, Ocean Modelling, 31: 120 - 131. Fortunato, A.B. and Oliveira, A. 2004. A modeling system for tidally driven long-term morphodynamics, Journal of Hydraulic Research, 42/4: 426-434. Zhang, Y.-L., Baptista, A.M. and Myers, E. P. 2004. A cross-scale model for 3D baroclinic circulation in estuary-plume-shelf systems: I. Formulation and skill assessment, Continental Shelf Research, 24/18: 2187-2214.

Post-earthquake coastal evolution and recovery of an embayed beach in central-southern Chile

NASA Astrophysics Data System (ADS)

Martínez, Carolina; Rojas, Daniel; Quezada, Matías; Quezada, Jorge; Oliva, Ricardo

2015-12-01

Earthquakes and tsunamis are significant factors for change along active margin shores, and influence coastal evolution. The Chilean coast was affected in 2010 by a subduction earthquake with a magnitude of Mw 8.8 and also by a trans-Pacific tsunami, which generated violent geomorphologic changes and damaged homes. Following these events, the magnitude of the changes which affect Chile's central-southern coast (37°S) and the role of subduction earthquakes in coastal evolution on a historical scale were investigated. At Lebu bay (an embayed beach) data were generated for variations in time and space along the shoreline, topographical and bathymetric changes in the bay, and for morphodynamic littoral processes. Logarithmic and parabolic models were applied to the shoreline along with map overlays in order to determine changes. The shoreline processes were analyzed based on statistics for waves, tides and sediment transport for pre- and post-tsunami conditions. An average accretion rate of 2.80 m/year (1984-2010) was established for the shoreline, with a strong trend towards accretion in the last 30 years. A parabolic function best represented the general form of the shoreline, although the presence of a river in the concave zone affected the fit in this sector. Two factors controlled historical changes on the beach: one of anthropic origin in addition to the earthquake and tsunami on February 27th, 2010. The post-earthquake recovery was fast, and currently the beach is in a stable condition despite the inter-seismic subsidence process previous to the event. This coastal system showed a high resilience in the face of coastal geomorphological changes induced by high-impact natural disturbances. However, the opposite occurred in relation to changes induced by anthropogenic disturbances.

Effects of a groyne field on inner bar dynamics: Anglet, France

NASA Astrophysics Data System (ADS)

de Santiago, Inaki; Morichon, Denis; Arnould, Philippe

2017-04-01

Groynes are usually designed to limit beach erosion by mitigating longshore sediment transport. However, little is known about their side effects on inner-bar morphodynamics in double sandbar systems. While most of the studies are focused on natural systems where the outer-bar morphology drives inner-bar dynamics (offshore to nearshore process), this work focuses on the role of groynes on the inner bar dynamics (nearshore to offshore process). The study is based on 3-years field observations carried out at the beach of Anglet in the south-west of France. This engineered beach is 4 km long, limited by a rocky headland in the south and a 1 km long jetty at the entrance of the Adour river in the North. The study area concerns the south part of the beach and includes a series of four groynes, unevenly spaced and extending about 100 m seaward. Morphology changes observations were derived from images collected with a video system (http://sirena.univ-pau.fr/), and bi-annual topo-Bathymetric surveys. A special attention was paid to study the mechanisms controlling the observed morphology changes using the XBeach numerical model. Data analysis reveals that the study site is dominated by a double sandbar system. Both bars can evolve from reasonably alongshore-uniform to crescentic bars. Surprisingly, the beach may show episodes where the inner bar evolves from alonghsore uniform to non-uniform despite an alongshore uniform outer bar. Numerical results corroborate that the formation of inner bar crescentic features can be formed without the presence of an outer non-uniform bar under certain wave conditions for the study site. This study shows that inner bar evolution in the presence of groynes can be controlled by topographic rip channels and not only by morphological coupling as usually observed on natural double sandbar systems.

A First Survey on the Abundance of Plastics Fragments and Particles on Two Sandy Beaches in Kuching, Sarawak, Malaysia

NASA Astrophysics Data System (ADS)

Noik, V. James; Mohd Tuah, P.

2015-04-01

Plastic fragments and particles as an emerging environmental contaminant and pollutant are gaining scientific attention in the recent decades due to the potential threats on biota. This study aims to elucidate the presence, abundance and temporal change of plastic fragments and particles from two selected beaches, namely Santubong and Trombol in Kuching on two sampling times. Morphological and polymer identification assessment on the recovered plastics was also conducted. Overall comparison statistical analysis revealed that the abundance of plastic fragments/debris on both of sampling stations were insignificantly different (p>0.05). Likewise, statistical analysis on the temporal changes on the abundance yielded no significant difference for most of the sampling sites on each respective station, except STB-S2. Morphological studies revealed physical features of plastic fragments and debris were diverse in shapes, sizes, colors and surface fatigues. FTIR fingerprinting analysis shows that polypropylene and polyethylene were the dominant plastic polymers debris on both beaches.

PTTI Capabilities of the Modernized LORAN System

DTIC Science & Technology

2008-12-01

Cape Elizabeth LCCS Carolina Beach 9960-Y Dana 9960-Z Seneca 9960-M LSU 9960-T Sandy Hook Plumbrook Dunbar Forest LCCS Transmitting Station ...reference clocks at the individual transmitting stations , the intra-chain timing between stations , and the overall system synchronization to UTC. Each... station has three cesium clocks installed, and new Time and Frequency Equipment (TFE) was installed at the stations , beginning in the spring of 2003

Seawater-groundwater exchange and nutrients carried by submarine groundwater discharge in different types of wetlands at Jiaozhou Bay, China

NASA Astrophysics Data System (ADS)

Qu, Wenjing; Li, Hailong; Huang, Hao; Zheng, Chunmiao; Wang, Chaoyue; Wang, Xuejing; Zhang, Yan

2017-12-01

In Jiaozhou Bay, there are four wetland types, including sandy beaches, mud flats, tidal marshes, and estuarine intertidal zones. Four typical transects representing each of the wetland types were selected to investigate the flow dynamics, seawater-groundwater exchange and nutrients carried by submarine groundwater discharge (SGD). Based on field measurements of groundwater heads and salinity along each transect, the SGD averaged over the observation period was estimated using generalized Darcy's law. The SGD along the four transects ranges from 3.6 × 10-3 to 7.6 cm/d with the maximum occurring at the sandy beach. The SGD rate has a good correlation with the hydraulic conductivities of the wetland sediments. There is a positive correlation between the ratio of NO3-N/DIN and SGD rates. The SGD-associated nutrient output rate ranges from 3.3 × 10-2 to 9.5 mmol/m2/d for DIN (dissolved inorganic nitrogen), and from 6.2 × 10-5 to 1.8 × 10-2 mmol/m2/d for DIP (dissolved inorganic phosphorus). Compared to the nutrients delivered by the river, nutrients carried by SGD provide a more important source for the phosphate-limited environment to plankton in Jiaozhou Bay.

Conceptual hydrogeologic framework of the shallow aquifer system at Virginia Beach, Virginia

USGS Publications Warehouse

Smith, Barry S.; Harlow, George E.

2002-01-01

The hydrogeologic framework of the shallow aquifer system at Virginia Beach was revised to provide a better understanding of the distribution of fresh ground water, its potential use, and its susceptibility to contamination. The revised conceptual framework is based primarily on analyses of continuous cores and downhole geophysical logs collected at 7 sites to depths of approximately 200 ft.The shallow aquifer system at Virginia Beach is composed of the Columbia aquifer, the Yorktown confining unit, and the Yorktown-East-over aquifer. The shallow aquifer system is separated from deeper units by the continuous St. Marys confining unit.The Columbia aquifer is defined as the predominantly sandy surficial deposits above the Yorktown confining unit. The Yorktown confining unit is composed of a series of very fine sandy to silty clay units of various colors at or near the top of the Yorktown Formation. The Yorktown confining unit varies in thickness and in composition, but on a regional scale is a leaky confining unit. The Yorktown-Eastover aquifer is defined as the predominantly sandy deposits of the Yorktown Formation and the upper part of the Eastover Formation above the confining clays of the St. Marys Formation. The limited areal extent of highly permeable deposits containing freshwater in the Yorktown-Eastover aquifer precludes the installation of highly productive freshwater wells over most of the city. Some deposits of biofragmental sand or shell hashes in the Yorktown-Eastover aquifer can support high-capacity wells.A water sample was collected from each of 10 wells installed at 5 of the 7 core sites to determine the basic chemistry of the aquifer system. One shallow well and one deep well was installed at each site. Concentrations of chloride were higher in the water from the deeper well at each site. Concentrations of dissolved iron in all of the water samples were higher than the U.S. Environmental Protection Agency Secondary Drinking Water Regulations. Concentrations of manganese and chloride were higher than the Secondary Drinking Water Regulations in samples from some wells.In the humid climate of Virginia Beach, the periodic recharge of freshwater through the sand units of the shallow aquifer system occurs often enough to create a dynamic equilibrium whereby freshwater flows continually down and away from the center of the ridges to mix with and sweep brackish water and saltwater back toward the tidal rivers, bays, salt marshes, and the Atlantic Ocean.The aquifers and confining units of the shallow aquifer system at Virginia Beach are heterogeneous, discontinuous, and without exact marker beds, which makes correlations in the study area difficult. Investigations using well cuttings, spot cores, or split-spoon samples with geophysical logs are not as definitive as continuous cores for determining or correlating hydrogeologic units. Future investigations of the shallow aquifer system would benefit by collecting continuous cores.

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.

A simple and inexpensive method for muddy shore profiling

NASA Astrophysics Data System (ADS)

Chowdhury, Sayedur Rahman; Hossain, M. Shahadat; Sharifuzzaman, S. M.

2014-11-01

There are several well-established methods for obtaining beach profiles, and more accurate and precise high-tech methods are emerging. Traditional low-cost methods requiring minimal user skill or training are still popular among professionals, scientists, and coastal zone management practitioners. Simple methods are being developed with a primary focus on sand and gravel beaches. This paper describes a simple, low-cost, manual field method for measuring profiles of beaches, which is particularly suitable for muddy shores. The equipment is a type of flexible U-tube manometer that uses liquid columns in vertical tubes to measure differences in elevation; the supporting frame is constructed from wooden poles with base disks, which hold measuring scales and a PVC tube. The structure was trialed on a mudflat characterized by a 20-40-cm-thick surface layer of silt and clay, located at the Kutubdia Island, Bangladesh. The study results are discussed with notes on the method's applicability, advantages and limitations, and several optional modifications for different scenarios for routine profiling of muddy shores. The equipment can be used by one person or two people, and the accuracy of the method is comparable to those in other methods. The equipment can also be used on sandy or gravel beaches.

Field_ac: a research project on ocean modelling in coastal areas. The experience in the Catalan Sea.

NASA Astrophysics Data System (ADS)

Grifoll, Manel; Pallarès, Elena; Tolosana-Delgado, Raimon; Fernandez, Juan; Lopez, Jaime; Mosso, Cesar; Hermosilla, Fernando; Espino, Manuel; Sanchez-Arcilla, Agustín

2013-04-01

The EU founded Field_ac project has investigated during the last three years methods and strategies for improving operational services in coastal areas. The objective has been to generate added value for shelf and regional scale predictions from GMES Marine Core Services. In this sense the experience in the Catalan Sea site has allowed to combine high-resolution numerical modeling tools nested into regional GMES services, data from intensive field campaigns or local observational networks and remote sensing products. Multi-scale coupled models have been implemented to evaluate different temporal and spatial scales of the dominant physical processes related with waves, currents, continental/river discharges or sediment transport. In this sense the experience of the Field_ac project in the Catalan Sea has permit to "connect" GMES marine core service results to the coastal (local) anthropogenic forcing (e.g. causes of morphodynamic evolution and ecosystem degradation) and will support a knowledge-based assessment of decisions in the coastal zone. This will contribute to the implementation of EU directives (e.g., the Water Framework Directive for water quality at beaches near harbour entrances or the Risk or Flood Directives for waves and sea-level at beach/river-mouth scales).

Cliff top habitats provide important alternative feeding resources for wading birds of conservation importance wintering on non-estuarine coasts

NASA Astrophysics Data System (ADS)

Furnell, Julie; Hull, Susan L.

2014-02-01

Rocky shores and beaches are important over-wintering areas for non-estuarine waders but have rarely been studied. We examined cliff top habitat use by 6 species of wader over 75 km of coast to assess their potential value as alternative feeding sites to rocky and sandy shores. Both the regional and local survey showed that waders occurred on golf courses and recreational grasslands in higher frequencies than expected but arable and pasture use was lower than expected. We also compared local wader densities on rocky and sandy shores, pastures, golf courses, caravan parks and recreational grasslands over two winters. Sanderling predominantly fed on the beach whereas Oystercatcher, Dunlin, Turnstone and Redshank numbers significantly increased on golf courses and recreational grasslands over the winter period, with pasture being rarely used. General linear models were used to relate environmental factors to the presence and absence of each species on the cliff top habitats. Redshank was the only species that showed a higher probability of occurrence on cliff top habitats at high tide whereas the probability of Turnstone, Oystercatcher and Redshank occurring increased as temperatures declined. Using core sampling, we determined that invertebrate richness and abundance was significantly higher on the recreational grasslands and golf courses than on the pasture or the beach. Our data demonstrated that cliff top habitats are important alternative feeding areas for over-wintering waders in areas where the intertidal is bounded by cliffs. Current management creates short sward, open field habitats with a diverse and abundant invertebrate food supply exploited by waders. Any alterations to the land use of these areas should be carefully considered by planning authorities in light of the fact that they support species that are of conservation concern.

Life-history, substrate choice and Cytochrome Oxidase I variations in sandy beach peracaridans along the Rio de la Plata estuary

NASA Astrophysics Data System (ADS)

Fanini, L.; Zampicinini, G.; Tsigenopoulos, C. S.; Barboza, F. R.; Lozoya, J. P.; Gómez, J.; Celentano, E.; Lercari, D.; Marchetti, G. M.; Defeo, O.

2017-03-01

Life-history, substrate choice and Cytochrome Oxidase I (COI) sequences were analysed in populations of two peracaridans, the supralittoral talitrid Atlantorchestoidea brasiliensis and the intertidal cirolanid Excirolana armata. Three populations of each species, from beaches with similar grain size and located at different points along the natural gradient generated by the Rio de la Plata estuary were analysed. Abundance of E. armata increased with distance from the estuary, while the opposite trend was observed for A. brasiliensis. The proportion of females decreased towards high salinities for both species, significantly for E. armata. A test on substrate salinity preference revealed the absence of patterns due to active choice in E. armata. By contrast, A. brasiliensis showed no preference for the population closer to the estuary, while individuals from the other two sites significantly preferred high salinity substrates. Mitochondrial COI sequences were obtained from A. brasiliensis specimens tested for behaviour. Sequence analysis showed the population from the intermediate site to differ significantly from the other two. No significant genetic differentiation was instead found between populations from the two most distant sites, nor between individuals that expressed different salinity preference. Results showed that diverse sets of traits at the population level enable sandy beach species to cope with local environmental changes: life-history and behavioural traits appear to change in response to different ecological conditions, and, in the case of A brasiliensis, independently of the population structure inferred from COI sequence variation. Information from multiple traits allowed detection of population profiles, highlighting the relevance of multidisciplinary information and the concurrent analysis of field data and laboratory experiments, to detect responses of resident biota to environmental changes.

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.

Decoupling processes and scales of shoreline morphodynamics

USGS Publications Warehouse

Hapke, Cheryl J.; Plant, Nathaniel G.; Henderson, Rachel E.; Schwab, William C.; Nelson, Timothy R.

2016-01-01

Behavior of coastal systems on time scales ranging from single storm events to years and decades is controlled by both small-scale sediment transport processes and large-scale geologic, oceanographic, and morphologic processes. Improved understanding of coastal behavior at multiple time scales is required for refining models that predict potential erosion hazards and for coastal management planning and decision-making. Here we investigate the primary controls on shoreline response along a geologically-variable barrier island on time scales resolving extreme storms and decadal variations over a period of nearly one century. An empirical orthogonal function analysis is applied to a time series of shoreline positions at Fire Island, NY to identify patterns of shoreline variance along the length of the island. We establish that there are separable patterns of shoreline behavior that represent response to oceanographic forcing as well as patterns that are not explained by this forcing. The dominant shoreline behavior occurs over large length scales in the form of alternating episodes of shoreline retreat and advance, presumably in response to storms cycles. Two secondary responses include long-term response that is correlated to known geologic variations of the island and the other reflects geomorphic patterns with medium length scale. Our study also includes the response to Hurricane Sandy and a period of post-storm recovery. It was expected that the impacts from Hurricane Sandy would disrupt long-term trends and spatial patterns. We found that the response to Sandy at Fire Island is not notable or distinguishable from several other large storms of the prior decade.

Depositional environments of some Pleistocene coastal terrace deposits, southwestern Oregon - case history of progradational beach and dune sequence.

USGS Publications Warehouse

Hunter, R.E.

1980-01-01

These deposits comprise a basal gravelly unit and 3 overlying sandy units, each with mud beds, a paleosol, or the modern soil in its uppermost part. The gravelly unit is interpreted as a progradational deposit. The main parts of the sandy units are made up of 1) a crossbedded sand facies, the dominant structure in which is medium-scale crossbedding (interpreted as the product of small eolian dunes), and 2) an irregularly bedded sand facies, which is locally pebbly and is dominated by scour-and-fill structures, interpreted as deposits of interdune ephemeral streams, ephemeral ponds, and wet to dry subaerial flats. The mud beds and paleosols represent times of temporary stabilization of the dune field.- from Author

Modelling changes in the coastal geomorphology of Unst, Shetland and the implications for understanding High to Late Medieval harbour changes in the Norse North Atlantic

NASA Astrophysics Data System (ADS)

Preston, John; Dugmore, Andrew; Newton, Anthony; Mudd, Simon

2016-04-01

The Norse settlement of the North Atlantic islands relied upon a network of harbours that also played a key role in the development of North European economies through the late Middle Ages. However, many of these harbours fell into disuse, their locations are uncertain and the reasons for this are unclear. A crucial geomorphological characteristic of a successful harbour is structural equilibrium. A harbour must have physical stability (or a dynamic equilibrium in the case of a beach) for boats to use it safely season to season, year on year. In the absence of a major civil engineering effort, something that was not possible in the pre-modern Atlantic islands, the geomorphology of a harbour is a key indicator of its physical equilibrium (or otherwise). Should the harbour be located on a changeable coastline (or one that becomes changeable) it may become unviable. Conversely, a harbour may be located on a coastline stable over centennial timescales, where little geomorphological change occurs, infrastructure can endure and many aspects of the physical environment remain predictable. The geomorphological setting of Norse harbours in the Atlantic is variable, with contrasting landform stability over short, medium and long time scales. We assess geomorphological change on the island of Unst, the most northerly of the British Isles, a coastline used by the Norse as well as earlier and later societies. This island offers a complex coastline of deep fjords and arcuate embayments and thus significant differences in forces acting upon the coastline. There is also evidence for instability in the beaches used by the Norse that could have been driven by the changes in climate conditions from the Medieval Climatic Anomaly to the Little Age and the present day. We model coastlines using the sediment dynamics model MIKE21. Model results agree well with the location of extant sandy beaches on Unst, but model runs with modern environmental drivers also build sandy beaches where none currently exist. Blown sand deposits were formed in the 12th-13th century, consistent with High Medieval settlement times and the onset of the Little Ice Age, suggesting that some of the Norse landing sites began to destabilise at this time. This research shows how beach instability can be modelled to determine the likely circumstances under which beaches formed, changed or disappeared and thus the potential geomorphological drivers of coastal change, harbour use and our ability to identify past harbour sites.

Soft Soil Mobility

DTIC Science & Technology

2016-02-11

Wind speed ± 2 knots (kts), 3 km/hr, 1 meter per second (m/s), or ± 5% of reading (whichever is higher) Wind direction ± 7 degrees NOTE: Values...longitudinal sand grades are located in an alluvial plain that lies next to Highway 95. The course material is, soft, loose, dry, wind sorted beach...particles. These soils are easily moved by wind action and tend to build extensive low dunes. The sand dynamometer terrain is described as sandy

Measuring and building resilience after big storms: Lessons learned from Super-Storm Sandy for the Harvey, Irma, Jose, and Maria coasts

NASA Astrophysics Data System (ADS)

Murdoch, P. S.; Penn, K. M.; Taylor, S. M.; Subramanian, B.; Bennett, R.

2017-12-01

As we recover from recent large storms, we need information to support increased environmental and socio-economic resilience of the Nation's coasts. Defining baseline conditions, tracking effects of mitigation actions, and measuring the uncertainty of resilience to future disturbance are essential so that the best management practices can be determined. The US Dept. of the Interior invested over $787 million dollars in 2013 to understand and mitigate coastal storm vulnerabilities and enhance resilience of the Northeast coast following Super-Storm Sandy. Several lessons-learned from that investment have direct application to mitigation and restoration needs following Hurricanes Harvey, Irma, Jose and Maria. New models of inundation, overwash, and erosion, developed during the Sandy projects have already been applied to coastlines before and after these recent storms. Results from wetland, beach, back-bay, estuary, and built-environment projects improved models of inundation and erosion from surge and waves. Tests of nature-based infrastructure for mitigating coastal disturbance yielded new concepts for best-practices. Ecological and socio-economic measurements established for detecting disturbance and tracking recovery provide baseline data critical to early detection of vulnerabilities. The Sandy lessons and preliminary applications on the recent storms could help define best-resilience practices before more costly mitigation or restoration efforts are required.

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.

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.

Evaluation of airborne topographic lidar for quantifying beach changes

USGS Publications Warehouse

2003-01-01

A scanning airborne topographic lidar was evaluated for its ability to quantify beach topography and changes during the Sandy Duck experiment in 1997 along the North Carolina coast. Elevation estimates, acquired with NASA's Airborne Topographic Mapper (ATM), were compared to elevations measured with three types of ground-based mea- surements-1) differential GPS equipped all-terrain vehicle (ATV) that surveyed a 3-km reach of beach from the shoreline to the dune, 2) GPS antenna mounted on a stadia rod used to intensely survey a different 100 m reach of beach, and 3) a second GPS-equipped ATV that surveyed a 70-km-long transect along the coast. Over 40,000 individual intercomparisons between ATM and ground surveys were calculated. RMS vertical differences associated with the ATM when compared to ground measurements ranged from 13 to 19 cm. Considering all of the intercomparisons together, RMS ≃15 cm. This RMS error represents a total error for individual elevation estimates including uncertainties associated with random and mean errors. The latter was the largest source of error and was attributed to drift in differential GPS. The ≃15cm vertical accuracy of the ATM is adequate to resolve beach-change signals typical of the impact of storms. For example, ATM surveys of Assateague Island (spanning the border of MD and VA) prior to and immediately following a severe northeaster showed vertical beach changes in places greater than 2 m, much greater than expected errors associated with the ATM. A major asset of airborne lidar is the high spatial data density. Measurements of elevation are acquired every few m2 over regional scales of hundreds of kilometers. Hence, many scales of beach morphology and change can be resolved, from beach cusps tens of meters in wavelength to entire coastal cells com- prising tens to hundreds of kilometers of coast. Topographic lidars similar to the ATM are becoming increasingly available from commercial vendors and should, in the future, be widely used in beach su

Plastics and microplastics on recreational beaches in Punta del Este (Uruguay): Unseen critical residents?

PubMed

Lozoya, J P; Teixeira de Mello, F; Carrizo, D; Weinstein, F; Olivera, Y; Cedrés, F; Pereira, M; Fossati, M

2016-11-01

Beaches are social-ecological systems that provide several services improving human well-being. However, as one of the major coastal interfaces they are subject to plastic pollution, one of the most significant global environmental threats at present. For the first time for Uruguayan beaches, this study assessed and quantified the accumulation of plastic and microplastic debris on sandy beaches of the major touristic destination Punta del Este during the austral spring of 2013. Aiming to provide valuable information for decision-making, we performed a detailed analysis of plastic debris, their eventual transport pathways to the coast (from land and sea), and the associated persistent pollutants. The results indicated that the smallest size fractions (<20 mm) were the dominant size range, with fragments and resin pellets as types with the highest number of items. PAHs and PCBs were found in plastic debris, and their levels did not differ from baseline values reported for similar locations. The abundance of plastic debris was significantly and positively correlated with both the presence of possible land-based sources (e.g. storm-water drains, beach bars, beach access, car parking, and roads), and dissipative beach conditions. The analysis of coastal currents suggested some potential deposition areas along Punta del Este, and particularly for resin pellets, although modeling was not conclusive. From a local management point of view, the development and use of indices that allow predicting trends in the accumulation of plastic debris would be critically useful. The time dimension (e.g. seasonal) should also be considered for this threat, being crucial for locations such as Uruguay, where the use of beaches increases significantly during the summer. This first diagnosis aims to generate scientific baseline, necessary for improved management of plastic litter on beaches and their watersheds. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluation of airborne topographic lidar for quantifying beach changes

USGS Publications Warehouse

Sallenger, A.H.; Krabill, W.B.; Swift, R.N.; Brock, J.; List, J.; Hansen, M.; Holman, R.A.; Manizade, S.; Sontag, J.; Meredith, A.; Morgan, K.; Yunkel, J.K.; Frederick, E.B.; Stockdon, H.

2003-01-01

A scanning airborne topographic lidar was evaluated for its ability to quantify beach topography and changes during the Sandy Duck experiment in 1997 along the North Carolina coast. Elevation estimates, acquired with NASA's Airborne Topographic Mapper (ATM), were compared to elevations measured with three types of ground-based measurements - 1) differential GPS equipped all-terrain vehicle (ATV) that surveyed a 3-km reach of beach from the shoreline to the dune, 2) GPS antenna mounted on a stadia rod used to intensely survey a different 100 m reach of beach, and 3) a second GPS-equipped ATV that surveyed a 70-km-long transect along the coast. Over 40,000 individual intercomparisons between ATM and ground surveys were calculated. RMS vertical differences associated with the ATM when compared to ground measurements ranged from 13 to 19 cm. Considering all of the intercomparisons together, RMS ??? 15 cm. This RMS error represents a total error for individual elevation estimates including uncertainties associated with random and mean errors. The latter was the largest source of error and was attributed to drift in differential GPS. The ??? 15 cm vertical accuracy of the ATM is adequate to resolve beach-change signals typical of the impact of storms. For example, ATM surveys of Assateague Island (spanning the border of MD and VA) prior to and immediately following a severe northeaster showed vertical beach changes in places greater than 2 m, much greater than expected errors associated with the ATM. A major asset of airborne lidar is the high spatial data density. Measurements of elevation are acquired every few m2 over regional scales of hundreds of kilometers. Hence, many scales of beach morphology and change can be resolved, from beach cusps tens of meters in wavelength to entire coastal cells comprising tens to hundreds of kilometers of coast. Topographic lidars similar to the ATM are becoming increasingly available from commercial vendors and should, in the future, be widely used in beach surveying.

Ecological implications of extreme events: footprints of the 2010 earthquake along the Chilean coast.

PubMed

Jaramillo, Eduardo; Dugan, Jenifer E; Hubbard, David M; Melnick, Daniel; Manzano, Mario; Duarte, Cristian; Campos, Cesar; Sanchez, Roland

2012-01-01

Deciphering ecological effects of major catastrophic events such as earthquakes, tsunamis, volcanic eruptions, storms and fires, requires rapid interdisciplinary efforts often hampered by a lack of pre-event data. Using results of intertidal surveys conducted shortly before and immediately after Chile's 2010 M(w) 8.8 earthquake along the entire rupture zone (ca. 34-38°S), we provide the first quantification of earthquake and tsunami effects on sandy beach ecosystems. Our study incorporated anthropogenic coastal development as a key design factor. Ecological responses of beach ecosystems were strongly affected by the magnitude of land-level change. Subsidence along the northern rupture segment combined with tsunami-associated disturbance and drowned beaches. In contrast, along the co-seismically uplifted southern rupture, beaches widened and flattened increasing habitat availability. Post-event changes in abundance and distribution of mobile intertidal invertebrates were not uniform, varying with land-level change, tsunami height and coastal development. On beaches where subsidence occurred, intertidal zones and their associated species disappeared. On some beaches, uplift of rocky sub-tidal substrate eliminated low intertidal sand beach habitat for ecologically important species. On others, unexpected interactions of uplift with man-made coastal armouring included restoration of upper and mid-intertidal habitat seaward of armouring followed by rapid colonization of mobile crustaceans typical of these zones formerly excluded by constraints imposed by the armouring structures. Responses of coastal ecosystems to major earthquakes appear to vary strongly with land-level change, the mobility of the biota and shore type. Our results show that interactions of extreme events with human-altered shorelines can produce surprising ecological outcomes, and suggest these complex responses to landscape alteration can leave lasting footprints in coastal ecosystems.

Algal subsidies enhance invertebrate prey for threatened shorebirds: A novel conservation tool on ocean beaches?

NASA Astrophysics Data System (ADS)

Schlacher, Thomas A.; Hutton, Briony M.; Gilby, Ben L.; Porch, Nicholaus; Maguire, Grainne S.; Maslo, Brooke; Connolly, Rod M.; Olds, Andrew D.; Weston, Michael A.

2017-05-01

Birds breeding on ocean beaches are threatened globally, often requiring significant investments in species conservation and habitat management. Conservation actions typically encompass spatial and temporal threat reductions and protection of eggs and broods. Still, populations decline or recover only slowly, calling for fresh approaches in beach-bird conservation. Because energetic demands are critically high during the nesting and chick rearing phases, and chick survival is particularly low, supplementing prey to breeding birds and their offspring is theoretically attractive as a means to complement more traditional conservation measures. Prey for plovers and similar species on ocean beaches consists of invertebrates (e.g. small crustaceans, insects) many of which feed on stranded masses of plant material (e.g. kelp and seagrass) and use this 'wrack' as habitat. We added wrack to the upper beach where plovers nest and their chicks forage to test whether algal subsidies promote the abundance and diversity of their invertebrate prey. Adding wrack to the upper beach significantly increased the abundance and diversity of invertebrate prey items. At wrack subsidies greater than 50% of surface cover invertebrate assemblages became highly distinct compared with those that received smaller additions of wrack. Substantial (2-4 fold) increases in the abundance amphipods and isopods that are principal prey items for plovers drove these shifts. This proof-of-concept study demonstrates the feasibility of food provisioning for birds on ocean shores. Whilst novel, it is practicable, inexpensive and does not introduce further restrictions or man-made structures. Thus, it can meaningfully add to the broader arsenal of conservation tools for threatened species that are wholly reliant on sandy beaches as breeding and foraging habitats.

Sandy beach molluscs as possible bio-indicators of metal pollution 2. laboratory studies. [South Africa

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

Watling, H.R.; Watling, R.J.

Donax serra and Bullia rhodostoma have been selected as possible indicators of metal pollution and the results of a survey of the metal concentrations in these two molluscs have been summarized. The present study is concerned with the ability of these molluscs to accumulate metals, without being killed by levels encountered, in such a way that the rates of accumulation can be related to the average metal concentration in the surrounding water.

Environmental Control on Fish and Macrocrustacean Spring Community-Structure, on an Intertidal Sandy Beach

PubMed Central

Benazza, Achwak; Selleslagh, Jonathan; Breton, Elsa; Rabhi, Khalef; Cornille, Vincent; Bacha, Mahmoud; Lecuyer, Eric; Amara, Rachid

2015-01-01

The inter-annual variability of the fish and macrocrustacean spring community on an intertidal sandy beach near the Canche estuary (North of France) was studied from 2000 to 2013 based on weekly spring sampling over an 11-year period. Twenty-eight species representing 21 families were collected during the course of the study. The community was dominated by a few abundant species accounting for > 99% of the total species densities. Most individuals caught were young-of-the-year indicating the importance of this ecosystem for juvenile fishes and macrocrustaceans. Although standard qualitative community ecology metrics (species composition, richness, diversity, evenness and similarity) indicated notable stability over the study period, community structure showed a clear change since 2009. Densities of P. platessa, P. microps and A. tobianus decreased significantly since 2009, whereas over the period 2010-2013, the contribution of S. sprattus to total species density increased 4-fold. Co-inertia and generalised linear model analyses identified winter NAO index, water temperature, salinity and suspended particular matter as the major environmental factors explaining these changes. Although the recurrent and dense spring blooms of the Prymnesiophyte Phaeocystis globosa is one of the main potential threats in shallow waters of the eastern English Channel, no negative impact of its temporal change was detected on the fish and macrocrustacean spring community structure. PMID:25617852

Study of beach cusps via high resolution TLS acquisitions on the pocket beach of Porsmilin (Brittany)

NASA Astrophysics Data System (ADS)

Chabrol, C.; Jaud, M.; Delacourt, C.; Allemand, P.; Augereau, E.; Cuq, V.

2011-12-01

Beach cusps are rhythmic shoreline features made up of series of horns and embayments. Their build-up occurs in specific conditions (steep beachface, low-energy wave conditions...). These features can notably be characterized by the cusp spacing λ and their prominence ɛ (difference in beachface gradient between embayment and horn). At present, two main theories confront to explain the formation of such features on natural beaches : standing edge waves (special class of waves propagating longshore) and self-organisation hypothesis. - Standing edge wave theory proposes that the superimposition of incident waves and standing edge waves generates longshore variations of swash height linked with the position of edge wave nodes and anti-nodes. These variations of swash height result in regular zones of erosion. Depending on the context, different types of edge-waves may occur. The predicted beach cusp spacing is : λ = (g T^2 tanβ) / π for a sub-harmonic edge wave model λ = (g T^2 tanβ) / 2π for a synchronous edge wave model with : λ : beach cusp spacing (m) g : gravitational acceleration (9.81 m/s) T : incident wave period (s) tanβ : beach gradient - Self-organisation theory suggests that a combination of interactions and feedbacks between swash flow and beach topography leads to the growth of morphologic irregularities of a given wavelength (because of flow divergence or convergence), resulting in beach cusp formation and maintaining. The predicted beach cusp spacing is then : λ = f S with : λ : beach cusp spacing (m) S : horizontal extent of the swash flow (m) f : empirical constant (~1.5) Three multitemporal Terrestrial Laser Scan acquisitions have been carried out for three consecutive days on the sandy beach of Porsmilin (Brittany, France) with a spatial resolution varying from few centimetres to few metres. Moreover the hydrodynamic conditions have been obtained thanks to the Previmer project website (http://www.previmer.org/), notably based on WaveWatch3 and MARS-2D models. This study proposes to profit from the high resolution and accuracy of Terrestrial Laser data to measure the geometry and the spacing of beach cusps, to compare the measured parameters to the predicted ones (with both theories) and thus to attempt to identify the hydrodynamic process which sparks off their formation.

Bioecological Aspects and Heavy Metal Contamination of the Mollusk Donax denticulatus in the Colombian Caribbean Coastline.

PubMed

Valdelamar-Villegas, Juan; Olivero-Verbel, Jesus

2018-02-01

Donax denticulatus is a key mollusk for the ecology of sandy beaches, serving as a controller of organic matter, microorganisms, and as bioindicator of heavy metals pollution. The goal of this study was to characterize some ecological aspects of D. denticulatus and its relationship with the content of heavy metals in their tissue, in three beaches of the Caribbean coast of Colombia. The results showed the study populations were different in terms of morphological characteristics and density (Berrugas-Sucre < Cartagena-Bolívar < Riohacha-Guajira), but not in sexual proportion; although density was clearly related to beach occupancy by tourists. Analysis of metals revealed tissue concentrations varied depending on the location (Greater means: Hg = 0.018 ± 0.004 in Riohacha; Pb = 0.110 ± 0.060 in Berrugas and Cd = 0.040 ± 0.010 µg/g in Cartagena). No relationships were found between morphometric variables and heavy metals content. Principal components analysis highlighted Riohacha for presenting differences respecting to Bocagrande and Berrugas in terms of physicochemical water parameters such as pH, temperature, salinity, dissolved oxygen and conductivity. Results suggest tourism rather than environmental pollution could be a sensitive factor for biota survival in Caribbean beaches.

Characteristics, seasonal distribution and surface degradation features of microplastic pellets along the Goa coast, India.

PubMed

Veerasingam, S; Saha, Mahua; Suneel, V; Vethamony, P; Rodrigues, Andrea Carmelita; Bhattacharyya, Sourav; Naik, B G

2016-09-01

Microplastic pellets (MPPs) are ubiquitous contaminants, recognised as a serious threat to the biota in coastal, estuarine and marine environment. The distribution, abundance, weathering and chemical characteristics of MPPs on the beaches of Goa, and their transport to the coast during the southwest (SW) monsoon are discussed in this paper. MPP samples collected from six sandy beaches were categorised based on colour and polymer types using Stereoscope microscope and FTIR-ATR spectroscopy, respectively. White colour MPPs were the most abundant, and Polyethylene (PE) and Polypropylene (PP) were the dominant polymer types of MPPs deposited on all the beaches. Carbonyl index values showed that MPPs collected in June 2015 (representing SW monsoon) were 'new', whereas the MPPs collected in January 2015 were 'aged', showing that MPPs are arriving at Goa coast only during SW monsoon due to conducive hydrodynamic conditions. Characteristics of MPPs suggest that they could be originated primarily from ocean-based sources. The winds and surface currents during SW monsoon are the driving forces for the transportation and deposition of MPPs on the Goa beaches. The results of this study will be useful to the National 'Clean India' program for effective plastic debris removal management. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dynamics of Shengjini beach (Albania)

NASA Astrophysics Data System (ADS)

Gashi, Ferim; Nikolli, Pal

2015-04-01

Dynamics of Shengjini beach (Albania) Pal Nikolli , Ferim GASHI Through archaeological and historical data, presentations of ancient topographic, cartographic materials (topographic maps obtained at different periods from 1870 to 1990), aerial photographs (2007), satellite images (2014) and direct measurements, paper defines and analyzes the position of the coastline of Shengjini beach (Lezha) from century XVI until today. The coastline of the Shengjini city (port) to Drin River estuary is oriented north-south direction and is approximately 10.5 km long. This part of the coast is sandy and sediment comes mainly from the River Drin and distributed by currents along the coast. In this paper are make provision for the position of the coastline in the future and analyzed the possibilities of human intervention in the coastal environment , etc. This work forms the basis for the issuance of necessary data required for various projections at the coastal environment Shëngjini. Results of this study will have a significant impact on state policies for integrated management of the coastal zone in the study and development of tourism. Key words: GIS, Remonte Sennsing, cartography, management of coastal zone, tourism, environment.

Origin and abundance of marine litter along sandy beaches of the Turkish Western Black Sea Coast.

PubMed

Topçu, Eda N; Tonay, Arda M; Dede, Ayhan; Öztürk, Ayaka A; Öztürk, Bayram

2013-04-01

Beach debris abundance was estimated from surveys on 10 beaches of the Turkish Western Black Sea Coast. Debris was collected from 20 m long transects during four different seasons; sorted and categorized by type, usage and origin. Litter density varied from 0.085 to 5.058 items m(-2). Debris was mainly composed of unidentifiable small size (2-7 cm) plastic pieces and beverage-related litter such as bottles and bottle caps. About half of the labeled litter was of foreign origin, including 25 different countries, 23% of which are in the Black Sea region. The south-western Black Sea Coast seems to receive foreign litter from two main sources: land-based debris from the neighboring countries and seaborne debris due to international shipping. Standardized methodology and indicators need to be designated all over the Black Sea basin in order to quantify and qualify coastal litter pollution, monitor compliance with MARPOL and develop regionally effective mitigation measures. Copyright © 2012 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.

Ecological Effects of Rubble Weir Jetty Construction at Murrells Inlet, South Carolina. Volume 2. Changes in Macrobenthic Communities of Sandy Beach and Nearshore ENvironments.

DTIC Science & Technology

1984-06-01

species were not commonly observed, and oligochaetes and nematodes were abundant in the area. Rany of these differences were attributed to normal...1977-78 (Table 3). Subtidally, amphipods and pelecypods were most abundant in 1982, while oligochaetes and nematodes largely dominated the intertidal...generally restricted to that level and the highest intertidal level (Table 10). Nematodes were also abundant in the upper intertidal zone, with greatest

Stability and Decay Properties of Foam in Seawater.

DTIC Science & Technology

1987-04-24

DECAY PROPERTIES OF FOAM IN SEAWATER FMRODUCTION Foam is formed by the entrainment of air in the form of small bubbles at and just beneath the...181 has examined how the size distributions of foam patches formed by wave action on a sandy beach vary with time. It was found that the mean diameter...typical foam patch was 25 seconds. Zheng et al [25] also measured the average lifetime of a foam layer formed at the surface by wave breaking on a

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.

Αutomated 2D shoreline detection from coastal video imagery: an example from the island of Crete

NASA Astrophysics Data System (ADS)

Velegrakis, A. F.; Trygonis, V.; Vousdoukas, M. I.; Ghionis, G.; Chatzipavlis, A.; Andreadis, O.; Psarros, F.; Hasiotis, Th.

2015-06-01

Beaches are both sensitive and critical coastal system components as they: (i) are vulnerable to coastal erosion (due to e.g. wave regime changes and the short- and long-term sea level rise) and (ii) form valuable ecosystems and economic resources. In order to identify/understand the current and future beach morphodynamics, effective monitoring of the beach spatial characteristics (e.g. the shoreline position) at adequate spatio-temporal resolutions is required. In this contribution we present the results of a new, fully-automated detection method of the (2-D) shoreline positions using high resolution video imaging from a Greek island beach (Ammoudara, Crete). A fully-automated feature detection method was developed/used to monitor the shoreline position in geo-rectified coastal imagery obtained through a video system set to collect 10 min videos every daylight hour with a sampling rate of 5 Hz, from which snapshot, time-averaged (TIMEX) and variance images (SIGMA) were generated. The developed coastal feature detector is based on a very fast algorithm using a localised kernel that progressively grows along the SIGMA or TIMEX digital image, following the maximum backscatter intensity along the feature of interest; the detector results were found to compare very well with those obtained from a semi-automated `manual' shoreline detection procedure. The automated procedure was tested on video imagery obtained from the eastern part of Ammoudara beach in two 5-day periods, a low wave energy period (6-10 April 2014) and a high wave energy period (1 -5 November 2014). The results showed that, during the high wave energy event, there have been much higher levels of shoreline variance which, however, appeared to be similarly unevenly distributed along the shoreline as that related to the low wave energy event, Shoreline variance `hot spots' were found to be related to the presence/architecture of an offshore submerged shallow beachrock reef, found at a distance of 50-80 m from the shoreline. Hydrodynamic observations during the high wave energy period showed (a) that there is very significant wave energy attenuation by the offshore reef and (b) the generation of significant longshore and rip flows. The study results suggest that the developed methodology can provide a fast, powerful and efficient beach monitoring tool, particularly if combined with pertinent hydrodynamic observations.

Impact of oil in the tropical marine environment. Technical pub

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

Cintron, G.; Lugo, A.E.; Martinez, R.

1981-11-01

Oil spills have a devastating effect on biologically rich coastal environments. This report investigates this problem, covering damage by oil to biological systems, the use of dispersants (toxicity and considerations for dispersant use), impact of oil and dispersants on coral reefs, impact of oil on seagrass beds and sandy beaches, impact of oil on mangroves (seedling survival and tolerance, regeneration, forest type vulnerability, and cleanup and recovery activities in mangroves), conclusions, and recommendations. The study concludes that coral reefs and seagrass beds may escape significant spill damage if pollution is not chronic and if dispersants are not used. Sandy andmore » rocky shores may be severely impacted but recover quickly. Mangroves are the most vulnerable coastal ecosystem. Recommendations are that oil spill contingency plans must be prepared for all areas, and that the necessary equipment for the plans must be in place.« less

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).

Wave induced coastal cliff top ground motions and infragravity wave dissipation under high energy wave conditions.

NASA Astrophysics Data System (ADS)

Earlie, C. S.; le Dantec, N.; Young, A.

2016-12-01

Coastal cliff erosion is a widespread problem that threatens property and infrastructure globally. The prediction of this risk calls for robust understanding of the processes and mechanisms involved in causing coastal cliff failure. Over the last decade, a number of geomorphological studies have highlighted the importance of the relationship between the offshore wave climate and cliff-toe water levels, and the resultant coastal response in terms of cliff-top ground motion and erosion. Field-based studies of instantaneous cliff response to direct wave impact have shown that wave-induced loading of the foreshore leads to cliff-top ground motions that may have the potential to weaken the integrity of the rocks and prepare them for failure. In order to understand wave-cliff interaction and how beach morphodynamics influences cliff-top ground motion and cliff erosion, two field experiments were carried out simultaneously at two locations in Northern Brittany (France). This three-month long winter field campaign (Jan-Mar 2016) included, for the first time, a comparison of cliff-top ground motion and cliff erosion at sites fronted by different beach morphologies (reflective/dissipative), along with monitoring of hydrodynamic forcing and beach topography. The magnitude of cliff-top displacements at both sites were dependent on tidal stage and free water surface elevation at the cliff toe, with the greatest contributions of cliff-top ground motions found at infragravity frequencies (0.05-0.005 Hz). Vertical displacements at infragravity and incident sea-swell (0.1-0.5 Hz) frequencies were greater at the dissipative site, apart from during spring high tide and energetic wave conditions, where displacements were two times that at the reflective site. Combining these wave-cliff interaction data with beach morphology and nearshore bathymetry will be key to understanding the spatial variability in cliff erosion under a variety of environmental settings and forcing conditions.

Impact of the winter 2013-2014 series of severe Western Europe storms on a double-barred sandy coast: Beach and dune erosion and megacusp embayments

NASA Astrophysics Data System (ADS)

Castelle, Bruno; Marieu, Vincent; Bujan, Stéphane; Splinter, Kristen D.; Robinet, Arhur; Sénéchal, Nadia; Ferreira, Sophie

2015-06-01

The winter of 2013/2014 was characterized by a striking pattern of temporal and spatial extreme storm wave clustering in Western Europe. The 110-km long Gironde coast, SW France, was exposed to the most energetic wave conditions over the last 18 years. The period was outstanding in terms of the available energy to move sediment and cause large-scale erosion with the 2-month average significant wave height (Hs) exceeding 3.6 m, just below the 0.95 quantile, and 4 distinct 10-year return period storms with Hs > 9 m. These storm waves caused unprecedented beach and dune erosion along the Gironde coast, including severely damaged sea defences at the coastal towns. At the end of the winter, dune erosion scarp height was highly variable alongshore and often exceeded 10 m. Megacusp embayments were observed along the Gironde coast with an average alongshore spacing of 1000 m in the south progressively decreasing to 500 m in the north, with an average cross-shore amplitude of 20 m. While beach megacusps were previously observed to systematically couple to the inner bar along the Gironde coast during low- to moderate-energy wave conditions, severe storm-driven megacusp embayments cutting the dune were found to be enforced and coupled to the outer crescentic bar. A detailed inspection of the 1500 m-long bimonthly topographic surveys of Truc Vert beach shows that in early January 2014 the outstanding shore-normal incident storm swell 'Hercules', with Hs and peak wave period Tp peaking at 9.6 m and 22 s, respectively, triggered the formation of a localized megacusp embayment with the erosion scarp height exceeding 6 m in its centre where the dune retreat reached 30 m. The subsequent storms progressively smoothed the megacusp by the end of the winter, mostly through severe erosion of the megacusp horns. Because of the very long period (16 s < Tp < 23 s) storm waves with persistent shore-normal incidence, the well-developed outer crescentic bar observed prior to the winter did not straighten. Instead, the outer-bar three-dimensionality developed further, particularly during 'Hercules'. Our observations indicate that both the antecedent outer sandbar morphology and storm wave characteristics, including period and angle of incidence, govern patterns of beach and dune erosion along open multiple-barred sandy coasts during severe storms.

Disentangling the effects of solar radiation, wrack macroalgae and beach macrofauna on associated bacterial assemblages.

PubMed

Rodil, Iván F; Fernandes, Joana P; Mucha, Ana P

2015-12-01

Wrack detritus plays a significant role in shaping community dynamics and food-webs on sandy beaches. Macroalgae is the most abundant beach wrack, and it is broken down by the combination of environmental processes, macrofauna grazing, and microbial degradation before returning to the sea as nutrients. The role of solar radiation, algal species and beach macrofauna as ecological drivers for bacterial assemblages associated to wrack was investigated by experimental manipulation of Laminaria ochroleuca and Sargassum muticum. We examined the effects of changes in solar radiation on wrack-associated bacterial assemblages by using cut-off filters: PAR + UVA + UVB (280-700 nm; PAB), PAR + UVA (320-700 nm; PA), PAR (400-700 nm; P), and a control with no filter (C). Results showed that moderate changes in UVR are capable to promote substantial differences on bacterial assemblages so that wrack patches exposed to full sunlight treatments (C and PAB) showed more similar assemblages among them than compared to patches exposed to treatments that blocked part of the solar radiation (P and PA). Our findings also suggested that specific algal nutrient quality-related variables (i.e. nitrogen, C:N ratio and phlorotannins) are main determinants of bacterial dynamics on wrack deposits. We showed a positive relationship between beach macrofauna, especially the most abundant and active wrack-users, the amphipod Talitrus saltator and the coleopteran Phaleria cadaverina, and both bacterial abundance and richness. Moderate variations in natural solar radiation and shifts in the algal species entering beach ecosystems can modify the role of wrack in the energy-flow of nearshore environments with unknown ecological implications for coastal ecosystems. Copyright © 2015 Elsevier Ltd. All rights reserved.

Flow and discharge of groundwater from a snowmelt-affected sandy beach

NASA Astrophysics Data System (ADS)

Chaillou, G.; Lemay-Borduas, F.; Larocque, M.; Couturier, M.; Biehler, A.; Tommi-Morin, G.

2018-02-01

The study is based on a complex and unique data set of water stable isotopes (i.e., δ18O and δ2H), radon-222 activities (i.e., 222Rn) and groundwater levels to better understand the interaction of fresh groundwater and recirculated seawater in a snowmelt-affected subterranean estuary (STE) in a boreal region (Îles-de-la-Madeleine, Qc, Canada). By using a combination of hydrogeological and marine geochemical approaches, the objective was to analyze and quantify submarine groundwater discharge processes through a boreal beach after the snow melt period, in early June. The distribution of δ18O and δ2H in beach groundwater showed that inland fresh groundwater contributed between 97 and 30% of water masses presented within the STE. A time series of water table levels during the 16 days of the study indicated that tides propagated as a dynamic wave limiting the mass displacement of seawater within the STE. This up-and-down movement of the water table (∼10-30 cm) induced the vertical infiltration of seawater at the falling tide. At the front of the beach, a radon-based mass balance calculated with high-resolution 222Rn survey estimated total SGD of 3.1 m3/m/d at the discharge zone and a mean flow to 1.5 m3/m/d in the bay. The nearshore discharge agreed relatively well with Darcy fluxes calculated at the beach face. Fresh groundwater makes up more than 50% of the total discharge during the measuring campaign. These results indicate that beaches in boreal and cold regions could be important sources of freshwater originate and groundwater-borne solutes and contaminants to the marine environment after the snowmelt.

Neural network modelling of planform geometry of headland-bay beaches

NASA Astrophysics Data System (ADS)

Iglesias, G.; López, I.; Castro, A.; Carballo, R.

2009-02-01

The shoreline of beaches in the lee of coastal salients or man-made structures, usually known as headland-bay beaches, has a distinctive curvature; wave fronts curve as a result of wave diffraction at the headland and in turn cause the shoreline to bend. The ensuing curved planform is of great interest both as a peculiar landform and in the context of engineering projects in which it is necessary to predict how a coastal structure will affect the sandy shoreline in its lee. A number of empirical models have been put forward, each based on a specific equation. A novel approach, based on the application of artificial neural networks, is presented in this work. Unlike the conventional method, no particular equation of the planform is embedded in the model. Instead, it is the model itself that learns about the problem from a series of examples of headland-bay beaches (the training set) and thereafter applies this self-acquired knowledge to other cases (the test set) for validation. Twenty-three headland-bay beaches from around the world were selected, of which sixteen and seven make up the training and test sets, respectively. As there is no well-developed theory for deciding upon the most convenient neural network architecture to deal with a particular data set, an experimental study was conducted in which ten different architectures with one and two hidden neuron layers and five training algorithms - 50 different options combining network architecture and training algorithm - were compared. Each of these options was implemented, trained and tested in order to find the best-performing approach for modelling the planform of headland-bay beaches. Finally, the selected neural network model was compared with a state-of-the-art planform model and was shown to outperform it.

First account of apochlorotic diatoms from intertidal sand of a south Florida beach

NASA Astrophysics Data System (ADS)

Blackburn, Michele V.; Hannah, Fiona; Rogerson, Andrew

2009-10-01

During the period January to December 2004, monthly intertidal sand samples were collected from John U. Lloyd State Park beach, Florida. This study is the first to report on spatial and temporal distributions of heterotrophic (apochlorotic) diatoms in a sub-tropical beach, or indeed any sandy beach. Two non-pigmented, apochlorotic diatom morphotypes (strains III and IV) were consistently isolated from two intertidal beach sites and neither conformed to the morphologies of described species. Apochlorotic diatoms were found throughout the year and formed significant peaks in April, attaining total diatom counts of 71.1 and 94.9 cells g -1 wet sand, for the upper tidal zone and lower tidal zone, respectively. Valve morphology is described in detail for the two diatom morphotypes isolated from the beach sites (strains III and IV). Growth responses to changes in salinity (reflecting those of the intertidal zone) were examined in the laboratory for these diatoms. Both morphotypes were euryhaline, tolerating salinities between 10 and 50, and maximum growth rates were achieved at salinities between 20 and 40. Diatoms grew equally well whether grown in the light or the dark and showed no evidence of pigments when viewed by epifluorescence microscopy. The ability of diatoms to burrow into agar and carrageenan at different concentrations was tested. Both morphotypes were observed to develop burrows through non-nutrient agar up to twice the standard concentration (30 g agar l -1). The ease with which these heterotrophic diatoms formed burrows suggests that they were digesting these complex carbohydrates (i.e. phycocolloids) as a nutrient source. Strain IV, however, failed to burrow in a different phycocolloid, carrageenan. Similar degradative actions in the field might have implications for the breakdown of recalcitrant materials or allow diatoms to effectively compete with bacteria for carbon and nutrients.

Removal of Fast Flowing Nitrogen from Marshes Restored in Sandy Soils

PubMed Central

Sparks, Eric L.; Cebrian, Just; Smith, Sara M.

2014-01-01

Groundwater flow rates and nitrate removal capacity from an introduced solution were examined for five marsh restoration designs and unvegetated plots shortly after planting and 1 year post-planting. The restoration site was a sandy beach with a wave-dampening fence 10 m offshore. Simulated groundwater flow into the marsh was introduced at a rate to mimic intense rainfall events. Restoration designs varied in initial planting density and corresponded to 25%, 50%, 75% and 100% of the plot area planted. In general, groundwater flow was slower with increasing planting density and decreased from year 0 to year 1 across all treatments. Nevertheless, removal of nitrate from the introduced solution was similar and low for all restoration designs (3–7%) and similar to the unvegetated plots. We suggest that the low NO3 − removal was due to sandy sediments allowing rapid flow of groundwater through the marsh rhizosphere, thereby decreasing the contact time of the NO3 − with the marsh biota. Our findings demonstrate that knowledge of the groundwater flow regime for restoration projects is essential when nutrient filtration is a target goal of the project. PMID:25353607

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.

Morphological Inheritance in Sandy Coastline Morphologies Subject to Long-Term Changes in Wave Climate: Surprising Insights from a Coastline Evolution Model

NASA Astrophysics Data System (ADS)

Murray, A. B.; Thomas, C.; Hurst, M. D.; Barkwith, A.; Ashton, A. D.; Ellis, M. A.

2014-12-01

Recent numerical modelling demonstrates that when sandy coastlines are affected predominantly by waves approaching from "high" angles (> ~45° between the coastline and wave crests at the offshore limit of shore-parallel contours), large-scale (kms to 100 kms) morphodynamic instabilities and finite-amplitude interactions can lead to the emergence of striking coastline features, including sand waves, capes and spits. The type of feature that emerges depends on the wave climate, defined as the angular distribution of wave influences on alongshore sediment transport. Under a constant wave climate, coastline morphology reaches a dynamical steady state; the cross-shore/alongshore aspect ratio and the general appearance of the features remains constant. In previous modelling involving wave-climate change, as well as comparisons between observed coastline morphologies and wave climates, it has been implicitly assumed that the morphology adjusts in a quasi-equilibrium fashion, so that at any time the coastline shape reflects the current forcing. However, here we present new model results showing pronounced path dependence in coastline morphodynamics. In experiments with a period of constant wave climate followed by a period of transition to a new wave climate and then a run-on phase, the features that exist during the run-on phase can be qualitatively and quantitatively different from those that would develop initially under the final wave climate. Although the features inherited from the past wave-climate history may in some case be true alternate stable states, in other cases the inherited features gradually decay toward the morphology that would be expected given the final wave climate. A suite of such experiments allows us to characterize how the e-folding timescale of this decay depends on 1) the initial wave climate, 2) the path through wave-climate space, and 3) the rate of transition. When the initial features are flying spits with cross-shore amplitudes of 6 - 8 km, e-folding times can be on the order of millennia or longer. These results could provide a new perspective when interpreting current and past coastline features. In addition, the complex paleo-coastline structure that develops in the coastal hinterlands in these experiments could be relevant to the structures observed in some coastal environments.

Coastal protection by a small scale river plume against oil spills in the Northern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Kuitenbrouwer, Daan; Reniers, Ad; MacMahan, Jamie; Roth, Mathias K.

2018-07-01

The Deepwater Horizon oil spill damaged some beaches along the Northern Gulf of Mexico (NGoMex) coast more than others, possibly related to the presence of natural protection mechanisms. In order to optimize future mitigation efforts to protect the coast, these mechanisms should be understood. The NGoMex coast is characterized by relatively long stretches of sandy beach interrupted by tidal inlets creating ebb-tidal river plumes featuring frontal zones that may act as transport barriers. This research investigates to what extent these plumes are capable of protecting the adjacent coast. This is done by means of a combination of a 3D Eulerian flow model and a Lagrangian particle model to track oil pathways and visualize Lagrangian Coherent Structures located at the plume front. The models are verified with measurements from a field experiment adjacent to Destin Inlet, Florida. The effects of wind, tidal range and river discharge on the oil fate are discussed. It was found that wind is the dominant parameter. Offshore wind prevents oil from beaching. During onshore winds, oil is pushed to shore, but near the inlet the plume is effective in reducing the amount of oil washing ashore during the ebbing tide. In general, the plume redistributes the oil but is not capable of preventing oil from beaching. For strong winds, the influence of the plume is reduced.

Sex, Status, and Sand: California Academy of Sciences' Teen Interns Examine Trends of the Pacific Mole Crab (Emerita analoga) at Ocean Beach, San Francisco

NASA Astrophysics Data System (ADS)

Chu, J. B.; Conrad-Saydah, A.; Cohen, S.; Tom, R.; Robins-Moloney, M.; Masters, D.; Mason, K.; Alfaro, F.

2003-12-01

Student interns from the California Academy of Sciences' Careers in Sciences program monitored the Pacific mole crab (Emerita analoga), or sand crabs, in collaboration with the Farallones Marine Sanctuary Association. These small crustaceans live in the swash zone of the sandy beach habitat. Sand crabs are important in the food web, and therefore their status can help indicate the health of the larger environment. The interns helped the Gulf of the Farallones National Marine Sanctuary by monitoring the abundance and distribution of sand crabs at Ocean Beach in San Francisco, California. Students set up transects perpendicular to the shoreline, collected 10 samples along the transect, measured the carapace length, determined the sex of each crab, and checked for the presence of eggs. Students monitored June through September, 2003. Trends examined included differences in the gender ratio, size frequency, and distribution along the beach. Students also compared their data to other student data taken from other sites in San Francisco and Marin counties during 2001-2003 from the online database at http://www.sandcrabs.org. Using comparisons, interns were able to better understand the processes and significance of studying marine species. Implementation of the project was invaluable in aiding the interns in their understanding of the natural sciences and the role of monitoring habitats in environmental health.

Two year study of swash zone suprabenthos of two Galician beaches (NW Spain)

NASA Astrophysics Data System (ADS)

Bernardo-Madrid, Rubén; Martínez-Vázquez, Juan M.; Viéitez, José M.; Junoy, Juan

2013-10-01

The suprabenthos is considered a major food resource for some fish and birds. Moreover, it plays a key role in the food chain and in nutrient regeneration in the surf zone. The aim of this study was to determine the factors that regulate this fauna and the differences between the suprabenthic groups, to study the possibility of seasonal variations and to compare these results with those of other studies conducted in Europe. A study and geographical comparison was conducted of the temporal patterns of the suprabenthos in the swash zone at two sandy beaches on the NE Atlantic coast (Altar and Ladeira beaches) in the NW of Spain. The study was carried out from September 2005 to August 2007 (24 months). To study the fauna, 60 m2 was sampled monthly with a suprabenthic sledge, and a total of 101 species belonging to Peracarida and Decapoda were recorded. Total densities ranged from 0.42 ind·m- 2 to 178.75 ind·m- 2. Ladeira beach showed higher densities and species richness than Altar beach, and the biocoenosis showed a different dynamic over the 24 months and between years and locations. These results indicate that there is no clear seasonality in the dynamic of suprabenthic species, although the variance of Peracarida orders was explained in diverse degree by environmental variables. The environmental models implemented explained between 27.7% and 93.8% of the faunal data, and hydrodynamic factors and daily global irradiance were selected as the best factors to explain the temporal variations.

Global styrene oligomers monitoring as new chemical contamination from polystyrene plastic marine pollution.

PubMed

Kwon, Bum Gun; Koizumi, Koshiro; Chung, Seon-Yong; Kodera, Yoichi; Kim, Jong-Oh; Saido, Katsuhiko

2015-12-30

Polystyrene (PS) plastic marine pollution is an environmental concern. However, a reliable and objective assessment of the scope of this problem, which can lead to persistent organic contaminants, has yet to be performed. Here, we show that anthropogenic styrene oligomers (SOs), a possible indicator of PS pollution in the ocean, are found globally at concentrations that are higher than those expected based on the stability of PS. SOs appear to persist to varying degrees in the seawater and sand samples collected from beaches around the world. The most persistent forms are styrene monomer, styrene dimer, and styrene trimer. Sand samples from beaches, which are commonly recreation sites, are particularly polluted with these high SOs concentrations. This finding is of interest from both scientific and public perspectives because SOs may pose potential long-term risks to the environment in combination with other endocrine disrupting chemicals. From SOs monitoring results, this study proposes a flow diagram for SOs leaching from PS cycle. Using this flow diagram, we conclude that SOs are global contaminants in sandy beaches around the world due to their broad spatial distribution. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

The impact of the 2009-10 El Niño Modoki on U.S. West Coast beaches

USGS Publications Warehouse

Barnard, Patrick L.; Allan, Jonathan; Hansen, Jeff E.; Kaminsky, George M.; Ruggiero, Peter; Doria, André

2011-01-01

High-resolution beach morphology data collected along much of the U.S. West Coast are synthesized to evaluate the coastal impacts of the 2009-10 El Nio. Coastal change observations were collected as part of five beach monitoring programs that span between 5 and 13 years in duration. In California, regional wave and water level data show that the environmental forcing during the 2009-10 winter was similar to the last significant El Nio of 1997-98, producing the largest seasonal shoreline retreat and/or most landward shoreline position since monitoring began. In contrast, the 2009-10 El Nio did not produce anomalously high mean winter-wave energy in the Pacific Northwest (Oregon and Washington), although the highest 5% of the winter wave-energy measurements were comparable to 1997-98 and two significant non-El Nio winters. The increase in extreme waves in the 2009-10 winter was coupled with elevated water levels and a more southerly wave approach than the long-term mean, resulting in greater shoreline retreat than during 1997-98, including anomalously high shoreline retreat immediately north of jetties, tidal inlets, and rocky headlands. The morphodynamic response observed throughout the U.S. West Coast during the 2009-10 El Nio is principally linked to the El Nio Modoki phenomena, where the warm sea surface temperature (SST) anomaly is focused in the central equatorial Pacific (as opposed to the eastern Pacific during a classic El Nio), featuring a more temporally persistent SST anomaly that results in longer periods of elevated wave energy but lower coastal water levels. ?? 2011 by the American Geophysical Union.

The impact of the 2009-10 El Niño Modoki on U.S. West Coast beaches

USGS Publications Warehouse

Barnard, Patrick L.; Allan, Jonathan; Hansen, Jeff E.; Kaminsky, George M.; Ruggiero, Peter; Doria, André

2011-01-01

High-resolution beach morphology data collected along much of the U.S. West Coast are synthesized to evaluate the coastal impacts of the 2009–10 El Niño. Coastal change observations were collected as part of five beach monitoring programs that span between 5 and 13 years in duration. In California, regional wave and water level data show that the environmental forcing during the 2009–10 winter was similar to the last significant El Niño of 1997–98, producing the largest seasonal shoreline retreat and/or most landward shoreline position since monitoring began. In contrast, the 2009–10 El Niño did not produce anomalously high mean winter-wave energy in the Pacific Northwest (Oregon and Washington), although the highest 5% of the winter wave-energy measurements were comparable to 1997–98 and two significant non-El Niño winters. The increase in extreme waves in the 2009–10 winter was coupled with elevated water levels and a more southerly wave approach than the long-term mean, resulting in greater shoreline retreat than during 1997–98, including anomalously high shoreline retreat immediately north of jetties, tidal inlets, and rocky headlands. The morphodynamic response observed throughout the U.S. West Coast during the 2009–10 El Niño is principally linked to the El Niño Modoki phenomena, where the warm sea surface temperature (SST) anomaly is focused in the central equatorial Pacific (as opposed to the eastern Pacific during a classic El Niño), featuring a more temporally persistent SST anomaly that results in longer periods of elevated wave energy but lower coastal water levels.

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.

Modeling and simulation of storm surge on Staten Island to understand inundation mitigation strategies

USGS Publications Warehouse

Kress, Michael E.; Benimoff, Alan I.; Fritz, William J.; Thatcher, Cindy A.; Blanton, Brian O.; Dzedzits, Eugene

2016-01-01

Hurricane Sandy made landfall on October 29, 2012, near Brigantine, New Jersey, and had a transformative impact on Staten Island and the New York Metropolitan area. Of the 43 New York City fatalities, 23 occurred on Staten Island. The borough, with a population of approximately 500,000, experienced some of the most devastating impacts of the storm. Since Hurricane Sandy, protective dunes have been constructed on the southeast shore of Staten Island. ADCIRC+SWAN model simulations run on The City University of New York's Cray XE6M, housed at the College of Staten Island, using updated topographic data show that the coast of Staten Island is still susceptible to tidal surge similar to those generated by Hurricane Sandy. Sandy hindcast simulations of storm surges focusing on Staten Island are in good agreement with observed storm tide measurements. Model results calculated from fine-scaled and coarse-scaled computational grids demonstrate that finer grids better resolve small differences in the topography of critical hydraulic control structures, which affect storm surge inundation levels. The storm surge simulations, based on post-storm topography obtained from high-resolution lidar, provide much-needed information to understand Staten Island's changing vulnerability to storm surge inundation. The results of fine-scale storm surge simulations can be used to inform efforts to improve resiliency to future storms. For example, protective barriers contain planned gaps in the dunes to provide for beach access that may inadvertently increase the vulnerability of the area.

The first record of the slender sunfish Ranzania laevis from the Red Sea.

PubMed

Abu El-Regal, M A; El-Moselhy, K

2013-11-01

A female specimen of the slender sunfish Ranzania laevis of 600 mm total length was recorded for the first time from the Red Sea after being stranded on a shallow sandy bay at Hurghada beach (27° 06' 16″ N; 33° 50' 01″ E) on 13 May 2012. Ranzania laevis is believed to have migrated from the Indian Ocean as the nearest area where it was found is coastal waters of Oman. © 2013 The Fisheries Society of the British Isles.

Earth Observation taken by the STS-129 Crew

NASA Image and Video Library

2009-11-21

S129-E-007324 (21 Nov. 2009) --- One of the crew members onboard the space shuttle Atlantis recorded this still image of the Bahamas' lengthy narrow Eleuthra Island. Like most of the Bahama Islands, Eleuthra is composed mainly of limestone and coral, and rises from a vast submarine plateau. The island, 80 miles (133 kilometers) long, about two miles (three kilometers) wide and covering an area of 164 square miles (425 square kilometers), is generally low and flat, has many mangrove swamps, brackish lakes, coral reefs and shoals, and many miles of sandy beaches.

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.

Barrier-island and estuarine-wetland physical-change assessment after Hurricane Sandy

USGS Publications Warehouse

Plant, Nathaniel G.; Smith, Kathryn E.L.; Passeri, Davina L.; Smith, Christopher G.; Bernier, Julie C.

2018-04-03

IntroductionThe Nation’s eastern coast is fringed by beaches, dunes, barrier islands, wetlands, and bluffs. These natural coastal barriers provide critical benefits and services, and can mitigate the impact of storms, erosion, and sea-level rise on our coastal communities. Waves and storm surge resulting from Hurricane Sandy, which made landfall along the New Jersey coast on October 29, 2012, impacted the U.S. coastline from North Carolina to Massachusetts, including Assateague Island, Maryland and Virginia, and the Delmarva coastal system. The storm impacts included changes in topography, coastal morphology, geology, hydrology, environmental quality, and ecosystems.In the immediate aftermath of the storm, light detection and ranging (lidar) surveys from North Carolina to New York documented storm impacts to coastal barriers, providing a baseline to assess vulnerability of the reconfigured coast. The focus of much of the existing coastal change assessment is along the ocean-facing coastline; however, much of the coastline affected by Hurricane Sandy includes the estuarine-facing coastlines of barrier-island systems. Specifically, the wetland and back-barrier shorelines experienced substantial change as a result of wave action and storm surge that occurred during Hurricane Sandy (see also USGS photograph, http://coastal.er.usgs.gov/hurricanes/sandy/photo-comparisons/virginia.php). Assessing physical shoreline and wetland change (land loss as well as land gains) can help to determine the resiliency of wetland systems that protect adjacent habitat, shorelines, and communities.To address storm impacts to wetlands, a vulnerability assessment should describe both long-term (for example, several decades) and short-term (for example, Sandy’s landfall) extent and character of the interior wetlands and the back-barrier-shoreline changes. The objective of this report is to describe several new wetland vulnerability assessments based on the detailed physical changes estimated from observations. The scope includes understanding changes caused by both short- and long-term processes using both remotely sensed and in situ observations to characterize changes to the wetland in terms of accretion/expansion and erosion/contraction. Accretion may be due to net vertical and (or) horizontal deposition, including estuarine-shoreline change due to overwash. Wetland erosion may be due to elevated waves and water levels in the estuary itself. We included additional information based on wave runup and storm-surge elevations based on models and elevation data. We then developed a predictive assessment for wetland vulnerability that describes the likelihood of changes of the estuarine shoreline and the landward extent of sand overwash driven by processes occurring on the ocean-facing shoreline. This assessment is intended to be linked to the beach and dune vulnerability assessments that have been developed previously.

Impact of Hurricane Sandy on the Shoreface and Inner Shelf, Offshore Long Island: Evidence for Ravinement?

NASA Astrophysics Data System (ADS)

Goff, J. A.; Austin, J. A.; Flood, R. D.; Schwab, W. C.; Denny, J. F.; Christensen, B. A.; Browne, C. M.; Saustrup, S.

2013-12-01

In January 2013, approximately two months after Hurricane Sandy made landfall in the Mid-Atlantic Bight, a scientific team from the University of Texas Institute for Geophysics, partnering with colleagues at Adelphi and Stony Brook universities and the USGS, conducted marine geophysical and surficial sampling surveys both offshore and in the inshore bays of Long Island, NY. The primary scientific goal was to assess the impact of the storm on the shoreface and inner shelf. Sandy made landfall as a post-tropical cyclone near Brigantine, NJ, with 70-kt maximum sustained winds. However, its unusual trajectory and massive size created record storm surges along the heavily-populated NJ and NY coastlines. As a result, infrastructure in the NY metropolitan area was damaged, and the Long Island barrier island system was both breached in places and elsewhere seriously eroded. The surveys included ten days of operations aboard Stony Brook's R/V Seawolf, offshore of Long Beach and Fire Island, barrier islands south of Long Island, complementing ongoing land-based studies of Sandy's impact on the NY-NJ barrier island system. Data collection involved multibeam bathymetric swath mapping, CHIRP very high resolution acoustic subbottom profiling, and surface sediment (grab) sampling to provide ground truth for the geophysical data. We surveyed regions that had been previously surveyed, both by Stony Brook in 2001 and 2005 to support reef management, and by the USGS for coastal sedimentary research, most recently in 2011 offshore Fire Island. These areas include shoreface-attached sand ridges that may be exchanging sand with the barrier island shoreface. We focus on before-and-after data comparisons on the shoreface and inner shelf, searching in particular for evidence that the storm contributed significantly to ravinement, either by wave- or current-forced erosion along the shoreface or via migration of shoreface-attached or detached sand ridges on the inner shelf. The interpreted (Holocene) transgressive ravinement surface, which may have been modified in part by Sandy, is frequently well-imaged in CHIRP data on the inner- to outer shelf; it represents the physical contrast between Holocene sands above and either Holocene estuarine (often residing in buried river channels) or older (Pleistocene) material below, typically with coarser-grained lag material at the interface. However, the process of ravinement in response to shelf-wide base-level changes is not well understood, and is also difficult to observe because it presumably happens during the most inclement of conditions. Our study provides an opportunity to investigate the ravinement process directly in response to a specific event, to link that process to the stratigraphic record, and therefore to gauge one large storm's contribution to this important part of the sediment budget for inner shelf/beach barrier systems.

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.

National Assessment of Shoreline Change; historical shoreline change along the New England and Mid-Atlantic coasts

USGS Publications Warehouse

Hapke, Cheryl J.; Himmelstoss, Emily A.; Kratzmann, Meredith G.; List, Jeffrey H.; Thieler, E. Robert

2011-01-01

Beach erosion is a chronic problem along many open-ocean shores of the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information regarding past and present trends and rates of shoreline movement. There is also a need for a comprehensive analysis of shoreline movement that is consistent from one coastal region to another. To meet these national needs, the U.S. Geological Survey (USGS) is conducting an analysis of historical shoreline changes along open-ocean sandy shores of the conterminous United States and parts of Hawaii, Alaska, and the Great Lakes. One purpose of this work is to develop standard, repeatable methods for mapping and analyzing shoreline movement so that periodic, systematic, internally consistent updates regarding coastal erosion and land loss can be made nationally. In the case of this study, the shoreline is the interpreted boundary between the ocean water surface and the sandy beach. This report on the New England and Mid-Atlantic coasts is the fifth in a series of reports on historical shoreline change. Previous investigations include analyses and descriptive reports of the Gulf of Mexico, the Southeast Atlantic, and, for California, the sandy shoreline and the coastal cliffs. The rates of change presented in this report represent conditions up to the date of the most recent shoreline data and therefore are not intended for predicting future shoreline positions or rates of change. Because of the geomorphology of the New England and Mid-Atlantic (rocky coastlines, large embayments and beaches) as well as data gaps in some areas, this report presents beach erosion rates for 78 percent of the 1,360 kilometers of the New England and Mid-Atlantic coasts. The New England and Mid-Atlantic shores were subdivided into a total of 10 analysis regions for the purpose of reporting regional trends in shoreline change rates. The average rate of long-term shoreline change for the New England and Mid-Atlantic coasts was -0.5 meters per year with an uncertainty in the long-term trend of plus or minus 0.09 meters per year. The rate is based on shoreline change rates averaged from 21,184 individual transects, of which 68 percent were eroding. In both the long and short term, the average rates of shoreline change for New England and the Mid-Atlantic were erosional. Long-term erosion rates were generally lower in New England than in the Mid-Atlantic. This is a function of the dominant coastal geomorphology; New England has a greater percentage of shore types that tend to erode more slowly (rocky coasts, pocket beaches, and mainland beaches), whereas the Mid-Atlantic is dominated by more vulnerable barrier islands and dynamic spit/inlet environments. However, the percentage of coastline eroding was higher in New England than in the Mid-Atlantic, highlighting that although rates of shoreline erosion may not be extreme, coastal erosion is still widespread along this region of the U.S. coastline. The average rate of short-term shoreline change for the New England and Mid-Atlantic coasts was also erosional but the rate of erosion decreased in comparison to long-term rates. The net short-term rate as averaged along 17,045 transects was -0.3 meters per year. Uncertainties for these rates range from 0.06 to 0.1 meters per year depending on the data sources used in the rate calculations. Of transects used to measure short-term change, 60 percent were erosional, as compared to 65 percent of coast eroding in the long term. The slight decrease (5 percent) in the amount of coastline eroding may be related to an increase in the frequency and extent of nourishment programs and (or) the effects of hardened structures during the more recent time period. The most stable (lower rates of erosion) beaches were more commonly found in New England. Despite an overall lowering of the average rates of erosion from long-term to short-term, the amount

Hurricane Sandy science plan: coastal topographic and bathymetric data to support hurricane impact assessment and response

USGS Publications Warehouse

Stronko, Jakob M.

2013-01-01

Hurricane Sandy devastated some of the most heavily populated eastern coastal areas of the Nation. With a storm surge peaking at more than 19 feet, the powerful landscape-altering destruction of Hurricane Sandy is a stark reminder of why the Nation must become more resilient to coastal hazards. In response to this natural disaster, the U.S. Geological Survey (USGS) received a total of $41.2 million in supplemental appropriations from the Department of the Interior (DOI) to support response, recovery, and rebuilding efforts. These funds support a science plan that will provide critical scientific information necessary to inform management decisions for recovery of coastal communities, and aid in preparation for future natural hazards. This science plan is designed to coordinate continuing USGS activities with stakeholders and other agencies to improve data collection and analysis that will guide recovery and restoration efforts. The science plan is split into five distinct themes: • Coastal topography and bathymetry • Impacts to coastal beaches and barriers • Impacts of storm surge, including disturbed estuarine and bay hydrology • Impacts on environmental quality and persisting contaminant exposures • Impacts to coastal ecosystems, habitats, and fish and wildlife This fact sheet focuses on coastal topography and bathymetry. This fact sheet focuses on coastal topography and bathymetry.

Chemical contamination of soils in the New York City area following Hurricane Sandy.

PubMed

Mandigo, Amy C; DiScenza, Dana J; Keimowitz, Alison R; Fitzgerald, Neil

2016-10-01

This paper presents a unique data set of lead, arsenic, polychlorinated biphenyl (PCB), and polycyclic aromatic hydrocarbon (PAH) concentrations in soil samples collected from the metropolitan New York City area in the aftermath of Hurricane Sandy. Initial samples were collected by citizen scientists recruited via social media, a relatively unusual approach for a sample collection project. Participants in the affected areas collected 63 usable samples from basements, gardens, roads, and beaches. Results indicate high levels of arsenic, lead, PCBs, and PAHs in an area approximately 800 feet south of the United States Environmental Protection Agency (US EPA) Superfund site at Newtown Creek. A location adjacent to the Gowanus Canal, another Superfund site, was found to have high PCB concentrations. Areas of high PAH contamination tended to be near high traffic areas or next to sites of known contamination. While contamination as a direct result of Hurricane Sandy cannot be demonstrated conclusively, the presence of high levels of contamination close to known contamination sites, evidence for co-contamination, and decrease in number of samples containing measureable amounts of semi-volatile compounds from samples collected at similar locations 9 months after the storm suggest that contaminated particles may have migrated to residential areas as a result of flooding.

National Assessment of Shoreline Change Part 3: Historical Shoreline Change and Associated Coastal Land Loss Along Sandy Shorelines of the California Coast

USGS Publications Warehouse

Hapke, Cheryl J.; Reid, David; Richmond, Bruce M.; Ruggiero, Peter; List, Jeff

2006-01-01

Beach erosion is a chronic problem along many open-ocean shores of the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information regarding past and present trends and rates of shoreline movement. There is also a need for a comprehensive analysis of shoreline movement that is consistent from one coastal region to another. To meet these national needs, the U.S. Geological Survey is conducting an analysis of historical shoreline changes along open-ocean sandy shores of the conterminous United States and parts of Hawaii and Alaska. One purpose of this work is to develop standard repeatable methods for mapping and analyzing shoreline movement so that periodic updates regarding coastal erosion and land loss can be made nationally that are systematic and internally consistent. In the case of this study, the shoreline being measured is the boundary between the ocean water surface and the sandy beach. This report on the California Coast represents the first of two reports on long-term sandy shoreline change for the western U.S., the second of which will include the coast of the Pacific NW, including Oregon and Washington. A report for the Gulf of Mexico shoreline was completed in 2004 and is available at: http://pubs.usgs.gov/of/2004/1043/. This report summarizes the methods of analysis, interprets the results, provides explanations regarding long-term and short-term trends and rates of change, and describes how different coastal communities are responding to coastal erosion. Shoreline change evaluations are based on comparing three historical shorelines digitized from maps, with a recent shoreline derived from lidar (Light Detection and Ranging) topographic surveys. The historical shorelines generally represent the following periods: 1800s, 1920s-1930s, and 1950s-1970s, whereas the lidar shoreline is from 1998-2002. Long-term rates of change are calculated using all four shorelines (1800s to lidar shoreline), whereas short-term rates of change are calculated for only the most recent period (1950s-1970s to lidar shoreline). The rates of change presented in this report represent past conditions and therefore are not intended for predicting future shoreline positions or rates of change. Due to the geomorphology of the California Coast (rocky coastline instead of beach) as well as to data gaps in some areas, this report presents beach erosion rates for 45% of California's 1100 km of coast. The average rate of long-term shoreline change for the State of California was 0.2?0.1 m/yr, an accretional trend. This is based on shoreline change rates averaged from 14,562 individual transects, of which 40% were eroding. Of the transects on which the shoreline was eroding, the long-term erosion rates were generally lowest in Southern California where coastal engineering projects have greatly altered the natural shoreline movement. On a regional scale, long-term accretion rates were either equal to (Central California) or greater than (Northern and Southern California) the long-term erosion rates, yielding the net accretional trend for the entire state. This accretional trend is most likely due to changes in the large volumes of sediment that are added to the system from large rivers and to the impact from coastal engineering and beach nourishment projects. The average rate of short-term shoreline change for the state was erosional. The net short-term rate as averaged along 16,142 transects was -0.2?0.4 m/yr. Of the transects used to measure short-term change, 66% had erosional trends. In addition erosion rates were higher in the short-term period, possibly related to the localized artificial nourishment that occurred over much of the 20th century but that has recently slowed or stopped (Flick, 1993; Wiegel, 1994). Short-term accretion rates were highest in Northern California where the overall magnitudes of shoreline change are systematically higher than in Central and Southern California. The most stable (low erosion and accretion rates) California beaches were most commonly found in Central California. Seawalls and/or riprap revetments have been constructed in all three sections of California, although many of these structures were built to protect houses and infrastructures from the erosion of coastal cliffs and bluffs rather than to protect against long-term beach erosion. California permits shoreline stabilization structures where homes, buildings or other community infrastructure are imminently threatened by erosion. A second California report that is following this publication will include analyses and reports on long-term coastal cliff erosion, as this hazard is of equal or greater concern to coastal communities in many areas along the California Coast.

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.

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.

Historical shoreline changes along the US Gulf of Mexico: A summary of recent shoreline comparisons and analyses

USGS Publications Warehouse

Morton, R.A.; Miller, T.; Moore, L.

2005-01-01

The US Geological Survey is systematically analyzing historical shoreline changes along open-ocean sandy shores of the United States. This National Assessment of Shoreline Change Project is developing standard repeatable methods for mapping and analyzing shoreline movement so that internally consistent updates can periodically be made to record coastal erosion and land loss along US shores. Recently, shoreline change maps and a report were published for states bordering the Gulf of Mexico. Long-term and short-term average rates of change were calculated by comparing three historical shorelines (1800s, 1930s, 1970s) with an operational mean high water shoreline derived from lidar (light detection and ranging) surveys (post-1998). The rates of change, statistical uncertainties, original shorelines, and complementary geographic information system layers, such as areas of beach nourishment, are available on an Internet Map Server (IMS). For the Gulf of Mexico region, rates of erosion are generally highest in Louisiana along barrier island and headland shores associated with the Mississippi delta. Erosion also is rapid along some barrier islands and headlands in Texas, whereas barrier islands in Mississippi are migrating laterally. Highest rates of erosion in Florida are generally localized around tidal inlets. The most stable Gulf beaches generally are along the west coast of Florida, where low wave energy and frequent beach nourishment minimize erosion. Some long beach segments in Texas have accreted as a result of net longshore drift convergence and around tidal inlets that have been stabilized by long jetties. Individuals and some communities have attempted to mitigate the effects of erosion by emplacement of coastal structures, but those efforts largely have been abandoned in favor of periodic beach nourishment.

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.

The Role of Bed Roughness in Wave Transformation Across Sloping Rock Shore Platforms

NASA Astrophysics Data System (ADS)

Poate, Tim; Masselink, Gerd; Austin, Martin J.; Dickson, Mark; McCall, Robert

2018-01-01

We present for the first time observations and model simulations of wave transformation across sloping (Type A) rock shore platforms. Pressure measurements of the water surface elevation using up to 15 sensors across five rock platforms with contrasting roughness, gradient, and wave climate represent the most extensive collected, both in terms of the range of environmental conditions, and the temporal and spatial resolution. Platforms are shown to dissipate both incident and infragravity wave energy as skewness and asymmetry develop and, in line with previous studies, surf zone wave heights are saturated and strongly tidally modulated. Overall, the observed properties of the waves and formulations derived from sandy beaches do not highlight any systematic interplatform variation, in spite of significant differences in platform roughness, suggesting that friction can be neglected when studying short wave transformation. Optimization of a numerical wave transformation model shows that the wave breaker criterion falls between the range of values reported for flat sandy beaches and those of steep coral fore reefs. However, the optimized drag coefficient shows significant scatter for the roughest sites and an alternative empirical drag model, based on the platform roughness, does not improve model performance. Thus, model results indicate that the parameterization of frictional drag using the bottom roughness length-scale may be inappropriate for the roughest platforms. Based on these results, we examine the balance of wave breaking to frictional dissipation for rock platforms and find that friction is only significant for very rough, flat platforms during small wave conditions outside the surf zone.

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.

Pollutant impacts to Cape Hatteras National Seashore from urban runoff and septic leachate.

PubMed

Mallin, Michael A; McIver, Matthew R

2012-07-01

The sandy barrier islands of Cape Hatteras National Seashore, USA, attract large seasonal influxes of tourists, and are host to numerous motels, rentals and second homes. To investigate the impacts of nearby urbanization on public trust waters, sampling was conducted in nine brackish water bodies within this coastal national park. A large tidal urban ditch delivered runoff-driven fecal-contaminated water directly into public beach waters. At all sites except the control, ammonium, phosphorus and fecal bacteria concentrations were high, strongly seasonal and significantly correlated with community water usage, indicating that increased septic tank usage led to increased pollutant concentrations in area waterways. Nutrients from septic systems caused ecosystem-level problems from algal blooms, BOD, and hypoxia while fecal microbes created potential human health problems. Septic system usage is widespread in sensitive coastal areas with high water tables and sandy soils and alternatives to standard septic systems must be required to protect human health and the environment. Copyright © 2012 Elsevier Ltd. All rights reserved.

Monitoring Coastal Processes at Local and Regional Geographic Scales with UAS

NASA Astrophysics Data System (ADS)

Starek, M. J.; Bridges, D.; Prouty, D.; Berryhill, J.; Williams, D.; Jeffress, G.

2014-12-01

Unmanned Aerial Systems (UAS) provide a powerful tool for coastal mapping due to attractive features such as low cost data acquisition, flexibility in data capture and resolution, rapid response, and autonomous flight. We investigate two different scales of UAS platforms for monitoring coastal processes along the central Texas Gulf coast. Firstly, the eBee is a small-scale UAS weighing ~0.7 kg designed for localized mapping. The imaging payload consists of a hand held RGB digital camera and NIR digital camera, both with 16.1 megapixel resolutions. The system can map up to 10 square kilometers on a single flight and is capable of acquiring imagery down to 1.5 cm ground sample distance. The eBee is configured with a GPS receiver, altitude sensor, gyroscope and a radio transmitter enabling autonomous flight. The system has a certificate of authorization (COA) from the FAA to fly over the Ward Island campus of Texas A&M University-Corpus Christi (TAMUCC). The campus has an engineered beach, called University Beach, located along Corpus Christi Bay. A set of groins and detached breakwaters were built in an effort to protect the beach from erosive wave action. The eBee is being applied to periodically survey the beach (Figure 1A). Through Structure from Motion (SfM) techniques, eBee-derived image sequences are post-processed to extract 3D topography and measure volumetric change. Additionally, when water clarity suffices, this approach enables the extraction of shallow-water bathymetry. Results on the utilization of the eBee to monitor beach morphodynamics will be presented including a comparison of derived estimates to RTK GPS and airborne lidar. Secondly, the RS-16 UAS has a 4 m wingspan and 11 kg sensor payload. The system is remotely piloted and has a flight endurance of 12 to 16 hours making it suitable for regional scale coastal mapping. The imaging payload consists of a multispectral sensor suite measuring in the visible, thermal IR, and ultraviolet ranges of the spectrum. The RS-16 is being used to conduct surveys along the shoreline of North Padre Island, which is a high wind energy and wave-dominated barrier island system (Figure 1B). Results on the utilization of the RS-16 to study alongshore variability in shoreline dynamics and surf zone processes, such as wave runup, will be presented.

Observations of Morphodynamics During a Winter Storm at the Mouth of the Misa River

NASA Astrophysics Data System (ADS)

Calantoni, J.; Sheremet, A.; Brocchini, M.; Postacchini, M.

2016-02-01

The shallow mouth of the Misa River, Senigallia, Italy is exposed to wind and waves from the Adriatic Sea and is vulnerable to morphodynamic activity during even moderate storm events. Sediment loads and transport patterns may be strongly influenced by the confluence of fine cohesive suspended sediment contained in the discharge from the river mixing with coarser sandy material stirred up by waves impinging on the river mouth. Observations of rapid changes in bed elevation along a transect extending offshore of the river mouth were made using a combination of instruments deployed from 23-27 January 2014 at two locations in roughly 5 m water depth and 6 m water depth. Additionally, an up looking ADCP was located farther offshore in approximately 7 m water depth. The deposited sediment quickly consolidated into a hardened mixture of sand, mud, and venerids over the base of our instrument frames. At the 5 m water depth location over 0.4 m of deposition was observed roughly during a 6-hour period. Similarly, at the 6 m water depth location nearly 0.2 m of deposition was observed roughly over a 6-hour period with approximately a two-hour time lag. The onset of deposition was concurrent with a change in direction of the mean currents at both locations and a change in direction of wave skewness observed at the 5 m water depth location. We hypothesize that sandbar migration was responsible for the observed changes in bed elevation at both locations. Our analysis will focus on sediment transport modeling to explain rates of deposition and time lag of the observed changes in bed elevation at the 5 m and 6 m water depth locations.

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)

Morphodynamic Impacts of Hurricane Sandy on the Inner-shelf (Invited)

NASA Astrophysics Data System (ADS)

Trembanis, A. C.; Beaudoin, J. D.; DuVal, C.; Schmidt, V. E.; Mayer, L. A.

2013-12-01

Through the careful execution of precision high-resolution acoustic sonar surveys over the period of October 2012 through July 2013, we have obtained a unique set of high-resolution before and after storm measurements of seabed morphology and in situ hydrodynamic conditions (waves and currents) capturing the impact of the storm at an inner continental shelf field site known as the 'Redbird reef' (Raineault et al., 2013). Understanding the signature of this storm event is important for identifying the impacts of such events and for understanding the role that such events have in the transport of sediment and marine debris on the inner continental shelf. In order to understand and characterize the ripple dynamics and scour processes in an energetic, heterogeneous inner-shelf setting, a series of high-resolution geoacoustic surveys were conducted before and after Hurricane Sandy. Our overall goal is to improve our understanding of bedform dynamics and spatio-temporal length scales and defect densities through the application of a recently developed fingerprint algorithm technique (Skarke and Trembanis, 2011). Utilizing high-resolution swath sonar collected by an AUV and from surface vessel multibeam sonar, our study focuses both on bedforms in the vicinity of manmade seabed objects (e.g. shipwrecks and subway cars) and dynamic natural ripples on the inner-shelf in energetic coastal settings with application to critical military operations such as mine countermeasures. Seafloor mapping surveys were conducted both with a ship-mounted multibeam echosounder (200 kHz and 400 kHz) and an Autonomous Underwater Vehicle (AUV) configured with high-resolution side-scan sonar (900 and 1800 kHz) and a phase measuring bathymetric sonar (500 kHz). These geoacoustic surveys were further augmented with data collected by in situ instruments placed on the seabed that recorded measurements of waves and currents at the site before, during, and after the storm. Multibeam echosounder map of the Redbird reef site after Hurricane Sandy. Image resolution is 25 cm/pixel.

Shoreline Position Dynamics: Measurement and Analysis

NASA Astrophysics Data System (ADS)

Barton, C. C.; Rigling, B.; Hunter, N.; Tebbens, S. F.

2012-12-01

The dynamics of sandy shoreline position is a fundamental property of complex beach face processes and is characterized by the power scaling exponent. Spectral analysis was performed on the temporal position of four sandy shorelines extracted from four shore perpendicular profiles each resurveyed approximately seven times per year over twenty-seven years at the Field Research Facility (FRF) by the U.S. Army Corps of Engineers, located at Kitty Hawk, NC. The four shorelines we studied are mean-higher-high-water (MHHW), mean-high-water (MHW), and mean-low-water (MLW) and mean-lower-low-water (MLLW) with elevations of 0.75m, 0.65m, -0.33m, and -0.37m respectively, relative to the NGVD29 geodetic datum. Spectral analysis used to quantify scaling exponents requires data evenly spaced in time. Our previous studies of shoreline dynamics used the Lomb Periodogram method for spectral analysis, which we now show does not return the correct scaling exponent for unevenly spaced data. New to this study is the use of slotted resampling and a linear predictor to construct an evenly spaced data set from an unevenly spaced data set which has been shown with synthetic data to return correct values of the scaling exponents. A periodogram linear regression (PLR) estimate is used to determine the scaling exponent β of the constructed evenly spaced time series. This study shows that sandy shoreline position exhibits nonlinear self-affine dynamics through time. The times series of each of the four shorelines has scaling exponents ranging as follows: MHHW, β = 1.3-2.2; MHW, β = 1.3-2.1; MLW, β = 1.2-1.6; and MLLW, β = 1.2-1.6. Time series with β greater than 1 are non-stationary (mean and standard deviation are not constant through time) and are increasingly internally correlated with increasing β. The range of scaling exponents of the MLW and MLLW shorelines, near β = 1.5, is indicative of a diffusion process. The range of scaling exponents for the MHW and MHHW shorelines indicates spatially variable dynamics higher on the beach face.

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.

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.

A Tale of Two Recent Spills—Comparison of 2014 Galveston Bay and 2010 Deepwater Horizon Oil Spill Residues

PubMed Central

Yin, Fang; Hayworth, Joel S.; Clement, T. Prabhakar

2015-01-01

Managing oil spill residues washing onto sandy beaches is a common worldwide environmental problem. In this study, we have analyzed the first-arrival oil spill residues collected from two Gulf of Mexico (GOM) beach systems following two recent oil spills: the 2014 Galveston Bay (GB) oil spill, and the 2010 Deepwater Horizon (DWH) oil spill. This is the first study to provide field observations and chemical characterization data for the 2014 GB oil spill. Here we compare the physical and chemical characteristics of GB oil spill samples with DWH oil spill samples and present their similarities and differences. Our field observations indicate that both oil spills had similar shoreline deposition patterns; however, their physical and chemical characteristics differed considerably. We highlight these differences, discuss their implications, and interpret GB data in light of lessons learned from previously published DWH oil spill studies. These analyses are further used to assess the long-term fate of GB oil spill residues and their potential environmental impacts. PMID:25714100

Elemental concentrations and bioaccessibilities in beached plastic foam litter, with particular reference to lead in polyurethane.

PubMed

Turner, Andrew; Lau, Kwan S

2016-11-15

Seventy samples of foamed plastic collected from a high-energy, sandy beach in SW England have been characterised by FTIR and XRF. Most samples were polyurethane (PU; n=39) or polystyrene (PS; n=27) that were associated with variable concentrations of Br-Cl, Fe and Zn, indicative of the presence of halogenated flame retardants, iron oxides and Zn-based additives, respectively. Many samples of rigid PU contained Pb, historically used as a catalyst, at concentrations of up to 16,000μgg -1 . A physiological extraction test that simulates the conditions in the gizzard of plastic-ingesting seabirds was applied to selected samples and results revealed that while Br and Zn were not measurably bioaccessible, Pb mobilisation progressed logarithmically over a period of time with maximum accessibilities after 220h of ~10% of total metal. Foamed PU is a source of bioaccessible Pb in the marine environment that has not previously been documented. Copyright © 2016 Elsevier Ltd. All rights reserved.

A tale of two recent spills--comparison of 2014 Galveston Bay and 2010 Deepwater Horizon oil spill residues.

PubMed

Yin, Fang; Hayworth, Joel S; Clement, T Prabhakar

2015-01-01

Managing oil spill residues washing onto sandy beaches is a common worldwide environmental problem. In this study, we have analyzed the first-arrival oil spill residues collected from two Gulf of Mexico (GOM) beach systems following two recent oil spills: the 2014 Galveston Bay (GB) oil spill, and the 2010 Deepwater Horizon (DWH) oil spill. This is the first study to provide field observations and chemical characterization data for the 2014 GB oil spill. Here we compare the physical and chemical characteristics of GB oil spill samples with DWH oil spill samples and present their similarities and differences. Our field observations indicate that both oil spills had similar shoreline deposition patterns; however, their physical and chemical characteristics differed considerably. We highlight these differences, discuss their implications, and interpret GB data in light of lessons learned from previously published DWH oil spill studies. These analyses are further used to assess the long-term fate of GB oil spill residues and their potential environmental impacts.

Donor-Control of Scavenging Food Webs at the Land-Ocean Interface.

PubMed

Schlacher, Thomas A; Strydom, Simone; Connolly, Rod M; Schoeman, David

2013-01-01

Food webs near the interface of adjacent ecosystems are potentially subsidised by the flux of organic matter across system boundaries. Such subsidies, including carrion of marine provenance, are predicted to be instrumental on open-coast sandy shores where in situ productivity is low and boundaries are long and highly permeable to imports from the sea. We tested the effect of carrion supply on the structure of consumer dynamics in a beach-dune system using broad-scale, repeated additions of carcasses at the strandline of an exposed beach in eastern Australia. Carrion inputs increased the abundance of large invertebrate scavengers (ghost crabs, Ocypode spp.), a numerical response most strongly expressed by the largest size-class in the population, and likely due to aggregative behaviour in the short term. Consumption of carrion at the beach-dune interface was rapid and efficient, driven overwhelmingly by facultative avian scavengers. This guild of vertebrate scavengers comprises several species of birds of prey (sea eagles, kites), crows and gulls, which reacted strongly to concentrations of fish carrion, creating hotspots of intense scavenging activity along the shoreline. Detection of carrion effects at several trophic levels suggests that feeding links arising from carcasses shape the architecture and dynamics of food webs at the land-ocean interface.

Donor-Control of Scavenging Food Webs at the Land-Ocean Interface

PubMed Central

Schlacher, Thomas A.; Strydom, Simone; Connolly, Rod M.; Schoeman, David

2013-01-01

Food webs near the interface of adjacent ecosystems are potentially subsidised by the flux of organic matter across system boundaries. Such subsidies, including carrion of marine provenance, are predicted to be instrumental on open-coast sandy shores where in situ productivity is low and boundaries are long and highly permeable to imports from the sea. We tested the effect of carrion supply on the structure of consumer dynamics in a beach-dune system using broad-scale, repeated additions of carcasses at the strandline of an exposed beach in eastern Australia. Carrion inputs increased the abundance of large invertebrate scavengers (ghost crabs, Ocypode spp.), a numerical response most strongly expressed by the largest size-class in the population, and likely due to aggregative behaviour in the short term. Consumption of carrion at the beach-dune interface was rapid and efficient, driven overwhelmingly by facultative avian scavengers. This guild of vertebrate scavengers comprises several species of birds of prey (sea eagles, kites), crows and gulls, which reacted strongly to concentrations of fish carrion, creating hotspots of intense scavenging activity along the shoreline. Detection of carrion effects at several trophic levels suggests that feeding links arising from carcasses shape the architecture and dynamics of food webs at the land-ocean interface. PMID:23826379

Setback Distances as a Conservation Tool in Wildlife-Human Interactions: Testing Their Efficacy for Birds Affected by Vehicles on Open-Coast Sandy Beaches

PubMed Central

Schlacher, Thomas A.; Weston, Michael A.; Lynn, David; Connolly, Rod M.

2013-01-01

In some wilderness areas, wildlife encounter vehicles disrupt their behaviour and habitat use. Changing driver behaviour has been proposed where bans on vehicle use are politically unpalatable, but the efficacy of vehicle setbacks and reduced speeds remains largely untested. We characterised bird-vehicle encounters in terms of driver behaviour and the disturbance caused to birds, and tested whether spatial buffers or lower speeds reduced bird escape responses on open beaches. Focal observations showed that: i) most drivers did not create sizeable buffers between their vehicles and birds; ii) bird disturbance was frequent; and iii) predictors of probability of flushing (escape) were setback distance and vehicle type (buses flushed birds at higher rates than cars). Experiments demonstrated that substantial reductions in bird escape responses required buffers to be wide (> 25 m) and vehicle speeds to be slow (< 30 km h-1). Setback distances can reduce impacts on wildlife, provided that they are carefully designed and derived from empirical evidence. No speed or distance combination we tested, however, eliminated bird responses. Thus, while buffers reduce response rates, they are likely to be much less effective than vehicle-free zones (i.e. beach closures), and rely on changes to current driver behaviour. PMID:24039711

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.

The behavioural ecology of two sympatric talitrid species, Talitrus saltator (Montagu) and Orchestia gammarellus (Pallas) on a Tyrrhenian sandy beach dune system

NASA Astrophysics Data System (ADS)

Colombini, Isabella; Fallaci, Mario; Gagnarli, Elena; Rossano, Claudia; Scapini, Felicita; Chelazzi, Lorenzo

2013-01-01

The behavioural ecology of a sub-population of Talitrus saltator living on the sandy shore of the Maremma Regional Park (Italy) was compared with that of Orchestia gammarellus inhabiting the retrodunal dune slack area. Monthly monitoring over a year determined the mean distribution patterns, their changes and whether these overlapped. Standard pitfall traps were placed along transects across the beach-dune-dune slack area. Experiments analysed the diel activity rhythms during spring and the activity patterns of the different age classes and the two sexes were compared within and between species. Local environmental conditions were registered with a microclimatic station. During May and September, plant hummocks were monitored to see whether surface movements of O. gammarellus could be restricted to certain periods of the year and to estimate densities within the vegetation. The plant biomass and moisture conditions within the hummocks were also recorded and substratum samples were collected at the base of the shrubs for laboratory analysis. To test for visual cues, orientation experiments with and without landscape view were carried out on the beach during morning and afternoon hours and contemporaneously for each species. Experiments to test the diel variation of scototaxis to a black shape were also performed over a 24 h period of time under controlled conditions. There was a spatial partitioning of the two species, with T. saltator moving along a sea-land axis according to diel and seasonal changes and with some individuals reaching the back of the dune in particular environmental conditions. No spatial overlap with the zonation patterns of O. gammarellus was observed, which was restricted to the dune slack area. Nocturnal surface activity was observed for both species with juveniles peaking at dawn and with O. gammarellus being strictly more nocturnal than T. saltator. Orientation experiments showed a higher ability of T. saltator to orient towards the shoreline using solar and local cues, whereas O. gammarellus seemed to have a stronger scototaxis. Differences in the behavioural responses are discussed in terms of the species ecological adaptations to their particular habitats.

Process-based model predictions of hurricane induced morphodynamic change on low-lying barrier islands

USGS Publications Warehouse

Plant, Nathaniel G.; Thompson, David M.; Elias, Edwin; Wang, Ping; Rosati, Julie D.; Roberts, Tiffany M.

2011-01-01

Using Delft3D, a Chandeleur Island model was constructed to examine the sediment-transport patterns and morphodynamic change caused by Hurricane Katrina and similar storm events. The model setup included a coarse Gulf of Mexico domain and a nested finer-resolution Chandeleur Island domain. The finer-resolution domain resolved morphodynamic processes driven by storms and tides. A sensitivity analysis of the simulated morphodynamic response was performed to investigate the effects of variations in surge levels. The Chandeleur morphodynamic model reproduced several important features that matched observed morphodynamic changes. A simulation of bathymetric change driven by storm surge alone (no waves) along the central portion of the Chandeleur Islands showed (1) a general landward retreat and lowering of the island chain and (2) multiple breaches that increased the degree of island dissection. The locations of many of the breaches correspond with the low-lying or narrow sections of the initial bathymetry. The major part of the morphological change occurred prior to the peak of the surge when overtopping of the islands produced a strong water-level gradient and induced significant flow velocities.

Spatial Patterns of Groundwater Biogeochemical Reactivity in an Intertidal Beach Aquifer

NASA Astrophysics Data System (ADS)

Kim, Kyra H.; Heiss, James W.; Michael, Holly A.; Cai, Wei-Jun; Laattoe, Tariq; Post, Vincent E. A.; Ullman, William J.

2017-10-01

Beach aquifers host a dynamic and reactive mixing zone between fresh and saline groundwater of contrasting origin and composition. Seawater, driven up the beachface by waves and tides, infiltrates into the aquifer and meets the seaward-discharging fresh groundwater, creating and maintaining a reactive intertidal circulation cell. Within the cell, land-derived nutrients delivered by fresh groundwater are transformed or attenuated. We investigated this process by collecting pore water samples from multilevel wells along a shore-perpendicular transect on a beach near Cape Henlopen, Delaware, and analyzing solute and particulate concentrations. Pore water incubation experiments were conducted to determine rates of oxygen consumption and nitrogen gas production. A numerical model was employed to support field and laboratory interpretations. Results showed that chemically sensitive parameters such as pH and ORP diverged from salinity distribution patterns, indicating biogeochemical reactivity within the circulation cell. The highest respiration rates were found in the landward freshwater-saltwater mixing zone, supported by high dissolved inorganic carbon. Chlorophyll a, a proxy for phytoplankton, and particulate carbon did not co-occur with the highest respiration rates but were heterogeneously distributed in deeper and hypoxic areas of the cell. The highest rates of N2 production were also found in the mixing zone coinciding with elevated O2 consumption rates but closer to the lower discharge point. Model results were consistent with these observations, showing heightened denitrification in the mixing zone. The results of this work emphasize the relationship between the physical flow processes of the circulation cell and its biogeochemical reactivity and highlight the environmental significance of sandy beaches.

Challenges in estimating the health impact of Hurricane Sandy using macro-level flood data.

NASA Astrophysics Data System (ADS)

Lieberman-Cribbin, W.; Liu, B.; Schneider, S.; Schwartz, R.; Taioli, E.

2016-12-01

Background: Hurricane Sandy caused extensive physical and economic damage but the long-term health impacts are unknown. Flooding is a central component of hurricane exposure, influencing health through multiple pathways that unfold over months after flooding recedes. This study assesses concordance in Federal Emergency Management (FEMA) and self-reported flood exposure after Hurricane Sandy to elucidate discrepancies in flood exposure assessments. Methods: Three meter resolution New York State flood data was obtained from the FEMA Modeling Task Force Hurricane Sandy Impact Analysis. FEMA data was compared to self-reported flood data obtained through validated questionnaires from New York City and Long Island residents following Sandy. Flooding was defined as both dichotomous and continuous variables and analyses were performed in SAS v9.4 and ArcGIS 10.3.1. Results: There was a moderate agreement between FEMA and self-reported flooding (Kappa statistic 0.46) and continuous (Spearman's correlation coefficient 0.50) measures of flood exposure. Flooding was self-reported and recorded by FEMA in 23.6% of cases, while agreement between the two measures on no flooding was 51.1%. Flooding was self-reported but not recorded by FEMA in 8.5% of cases, while flooding was not self-reported but indicated by FEMA in 16.8% of cases. In this last instance, 84% of people (173/207; 83.6%) resided in an apartment (no flooding reported). Spatially, the most concordance resided in the interior of New York City / Long Island, while the greatest areas of discordance were concentrated in the Rockaway Peninsula and Long Beach, especially among those living in apartments. Conclusions: There were significant discrepancies between FEMA and self-reported flood data. While macro-level FEMA flood data is a relatively less expensive and faster way to provide exposure estimates spanning larger geographic areas affected by Hurricane Sandy than micro-level estimates from cohort studies, macro-level exposure estimates may underestimate the full flooding and health impacts of the hurricane. Future disaster preparedness efforts must integrate micro and macro-level flood exposures to produce the most accurate evaluation of health impacts in affected populations.

Morphodynamic signature of the 1985 hurricane impacts on the northern Gulf of Mexico

USGS Publications Warehouse

Penland, Shea; Suter, John R.; Sallenger, Ashbury H.; Williams, S. Jeffress; McBride, Randolph A.; Westphal, Karen E.; Reimer, P. Douglas; Jaffe, Bruce E.

1989-01-01

Three hurricanes hit Lousiana (LA), Mississippi (MS), Alabama (AL), and the Florida (FL) panhandle in 1985, producing dramatic geomorphic changes in a wide variety of coastal environments. The impact zone for hurricanes Danny, Elena, and Juan stretched 1000 km between the Sabine River in LA to the Apalachicola River in FL. Barrier shorelines experienced repeated intense overwash events, producing beach and dune erosion exceeding 30 m, as well as producing classic examples of storm surge deposits. Pre- and post-storm airborne videotape surveys, sequential vertical mapping photography, and field surveys provide the data base for this regional hurricane impact assessment on the northern Gulf of Mexico. Hurricane impacts on the low-profile and high-profile barrier shorelines, as well as on the marine terrace cliffs were systematic and predictable. Controlling the direction of overwash flow and the impact distribution pattern is the relationship among shoreline orientation, hurricane storm track, and regional wind field. The relationship between shore-zone geomorphology and storm surge overwash controls the impact response.

Foraging ecology of sanderlings Calidris alba wintering in estuarine and non-estuarine intertidal areas

NASA Astrophysics Data System (ADS)

Lourenço, Pedro M.; Alves, José A.; Catry, Teresa; Granadeiro, José P.

2015-10-01

Outside the breeding season, most shorebirds use either estuarine or non-estuarine intertidal areas as foraging grounds. The sanderling Calidris alba is mostly associated with coastal sandy beaches, a habitat which is currently at risk worldwide due to increasing coastal erosion, but may also use estuarine sites as alternative foraging areas. We aimed to compare the trophic conditions for sanderlings wintering in estuarine and non-estuarine sites within and around the Tejo estuary, Portugal, where these two alternative wintering options are available within a relatively small spatial scale. To achieve this, we analysed sanderling diet, prey availability, foraging behaviour, and time and energy budgets in the different substrates available in estuarine and non-estuarine sites. In terms of biomass, the most important sanderling prey in the estuarine sites were siphons of the bivalve Scrobicularia plana, polychaetes, staphylinids and the gastropod Hydrobia ulvae. In non-estuarine sites the main prey were polychaetes, the bivalve Donax trunculus and chironomid larvae. Both food availability and energetic intake rates were higher on estuarine sites, and sanderlings spent a higher proportion of time foraging on non-estuarine sites. In the estuary, sanderlings foraged in muddy-sand substrate whenever it was available, achieving higher intake rates than in sandy substrates. In the non-estuarine sites they used both sandy and rocky substrates throughout the tidal cycle but had higher intakes rates in sandy substrate. Estuarine sites seem to offer better foraging conditions for wintering sanderlings than non-estuarine sites. However, sanderlings only use muddy-sand and sandy substrates, which represent a small proportion of the intertidal area of the estuary. The extent of these substrates and the current sanderling density in the estuary suggest it is unlikely that the estuary could provide alternative wintering habitat for sanderlings if they face habitat loss and degradation in coastal sites.

Investigating historical changes in morphodynamic processes associated with channelization of a large Alpine river: the Etsch/Adige River, NE Italy

NASA Astrophysics Data System (ADS)

Zen, Simone; Scorpio, Vittoria; Mastronunzio, Marco; Proto, Matteo; Zolezzi, Guido; Bertoldi, Walter; Comiti, Francesco; Surian, Nicola; Prà, Elena Dai

2016-04-01

River channel management within the last centuries has largely modified fluvial processes and morphodynamic evolution of most large European rivers. Several river systems experienced extensive channelization early in the 19th century, thus strongly challenging our present ability to detect their morphodynamic functioning with contemporary photogrammetry or cartographical sources. This consequently leaves open questions about their potential future response, especially to management strategies that "give more room" to the river, aiming at partially rehabilitating their natural functioning. The Adige River (Etsch in German), the second longest Italian river, is an exemplary case where channelization occurred more than 150 years ago, and is the focus of the present work. This work aims (i) to explore changes in fundamental morphodynamic processes associated with massive channelization of the Adige River and (ii) to quantify the alteration in river bars characteristics, by using morphodynamic models of bars and meandering. To fulfil our aims we combine the analysis of historical data with morphodynamic mathematical modelling. Historical sources (recovered in a number of European archives), such as hydrotopographical maps, airborne photogrammetry and hydrological datasets were collected to investigate channel morphology before and after the channelization. Information extracted from this analysis was combined with morphodynamic linear models of free migrating and forced steady bars, to investigate river bars and bend stability properties under different hydromorphological scenarios. Moreover, a morphodynamic model for meandering channel was applied to investigate the influence of river channel planform on the evolution of the fluvial bars. Results from the application of morphodynamic models allowed to predict the type, position and geometry of bars characterizing the channelized configuration of the river, and to explain the presently observed relative paucity of bars if compared to the previous, less confined, river planform. The application of a meander model allows insight into the properties of bars that were observed in the old historical maps. A threshold range of the imposed channel width can be predicted above which the river may partially restore conditions for bar instability to occur and for their further development, with direct management implications. Overall the conducted analysis confirms the potential of integrating morphodynamic models with geomorphological and time-series analysis of historical large-scale maps and airborne photogrammetry to increase our understanding and predictive ability of the evolution of rivers with a long-lasting record of morphological regulation.

Movement Patterns and Residency of the Critically Endangered Horseshoe Crab Tachypleus tridentatus in a Semi-Enclosed Bay Determined Using Acoustic Telemetry.

PubMed

Wada, Toshifumi; Mitsushio, Takahiro; Inoue, Shinya; Koike, Hiroko; Kawabe, Ryo

2016-01-01

The horseshoe crab Tachypleus tridentatus is critically endangered in Japan due to rapidly decreasing numbers resulting from the loss of tidal flats and sandy beaches, and the deterioration of coastal environments. We monitored the year-round migratory patterns and residency of this species in a coastal embayment at Tsuyazaki, Japan, using acoustic telemetry. Total 20 adult crabs (15 males and 5 females) were tagged with ultrasonic transmitters and tracked during two periods (2006-2008; n = 10 and 2007-2009; n = 10). Adult crabs were more active during periods of higher water temperatures and their activity peaked in July, during the spawning period. Water temperature appeared to be one of the key factors influencing the movement patterns for the species. Moreover, the crabs tended to be more active at night than in the day. The nocturnal activity pattern was clearly evident before and during the reproductive period (May-August). Tracking data also showed that one pair-bond was maintained for a maximum of 17 days after the pair-bonded female had spawned. Overall, 11 males (73% of 15 individuals) remained in the bay area over winter, whereas three females (60% of 5 individuals) overwintered outside of the bay. Telemetry data showed that over 60% (13 of 20) of tagged crabs overwintered within the bay where there are sandy beaches, mudflats, and scattered seagrass beds. This year-round residence by adult T. tridentatus in the bay area identifies it as a critical habitat for the management of this species, regardless of life-stage. Not only is it a comprehensive management strategy that effectively reflects this species' habitat use patterns but also its implementation, such as the establishment of a protected area, would contribute to its conservation.

Local extirpations and regional declines of endemic upper beach invertebrates in southern California

NASA Astrophysics Data System (ADS)

Hubbard, D. M.; Dugan, J. E.; Schooler, N. K.; Viola, S. M.

2014-10-01

Along the world's highly valued and populous coastlines, the upper intertidal zones of sandy beach ecosystems and the biodiversity that these zones support are increasingly threatened by impacts of human activities, coastal development, erosion, and climate change. The upper zones of beaches typically support invertebrates with restricted distributions and dispersal, making them particularly vulnerable to habitat loss and fragmentation. We hypothesized that disproportionate loss or degradation of these zones in the last century has resulted in declines of upper shore macroinvertebrates in southern California. We identified a suite of potentially vulnerable endemic upper beach invertebrates with direct development, low dispersal and late reproduction. Based on the availability of printed sources and museum specimens, we investigated historical changes in distribution and abundance of two intertidal isopod species (Tylos punctatus, Alloniscus perconvexus) in southern California. Populations of these isopods have been extirpated at numerous historically occupied sites: T. punctatus from 16 sites (57% decrease), and A. perconvexus from 14 sites (64% decrease). During the same period, we found evidence of only five colonization events. In addition, the northern range limit of the southern species, T. punctatus, moved south by 31 km (8% of range on California mainland) since 1971. Abundances of T. punctatus have declined on the mainland coast; only three recently sampled populations had abundances >7000 individuals m-1. For A. perconvexus populations, abundances >100 individuals m-1 now appear to be limited to the northern part of the study area. Our results show that numerous local extirpations of isopod populations have resulted in regional declines and in greatly reduced population connectivity in several major littoral cells of southern California. Two of the six major littoral cells (Santa Barbara and Zuma) in the area currently support 74% of the remaining isopod populations. These isopods persist primarily on relatively remote, ungroomed, unarmored beaches with restricted vehicle access and minimal management activity. These predominantly narrow, bluff-backed beaches also support species-rich upper beach assemblages, suggesting these isopods can be useful indicators of biodiversity. The high extirpation rates of isopod populations on the southern California mainland over the last century provide a compelling example of the vulnerability of upper beach invertebrates to coastal urbanization. Climate change and sea level rise will exert further pressures on upper beach zones and biota in southern California and globally. In the absence of rapid implementation of effective conservation strategies, our results suggest many upper intertidal invertebrate species are at risk.

Impact of Hurricanes and Nor'easters on a Migrating Inlet System

NASA Astrophysics Data System (ADS)

Hopkins, J.; Elgar, S.; Raubenheimer, B.

2016-12-01

After breaching in 2007, Katama Inlet, connecting Katama Bay to the Atlantic Ocean on the south shore of Martha's Vineyard, MA, migrated 2 km until it closed in 2015. Bathymetric surveys before and after Hurricanes Irene (2011) and Sandy (2012) indicate the strong waves and currents associated with these storms caused 2 m of erosion and deposition around the inlet mouth. The waves, currents, and bathymetric change observed during the hurricanes were used to validate the hydrodynamic and morphodynamic components of a Delft3D numerical model of the Martha's Vineyard coastline for storm (> 3 m wave heights) conditions. When driven with observed bathymetry and offshore waves, as well as simulated (WaveWatch3) winds and barometric pressures, the model reproduces the pattern and range of bathymetric change observed around the inlet. Model simulations of realistic (i.e., Irene and Sandy) and idealized storm conditions with a range of durations and wave conditions are used to test the relative importance of short-duration, high-intensity storms (hurricanes) and longer-duration, lower-intensity storms (nor'easters) on inlet migration. The simulations suggest that longer-duration, lower-intensity storms cause a higher range and variance in bathymetric change around the inlet than shorter-duration, higher-intensity storms. However, the simulations also suggest that the storm-induced migration of the inlet depends more on the wave direction at the peak of the storm than on the duration of the storm peak. The effect of storms on inlet migration over yearly time scales will be discussed. Funded by NSF, NOAA, ONR, and ASD(R&E).

Environmental forcing metrics to quantify short-term foredune morphodynamics

NASA Astrophysics Data System (ADS)

Spore, N.; Conery, I.; Brodie, K. L.; Palmsten, M.

2016-12-01

Coastal foredunes evolve continuously due to competing aeolian and hydrodynamic processes. Onshore to shore-parallel winds transport sand to the dune while storm-driven surge and wave runup remove sand from the dune. Dune-growth requires periods of time when the wind exceeds a threshold velocity to initiate transport and the relative geometry of the dry beach to the wind direction to create large fetches. This study aims to derive an aeolian transport potential (ATP) metric from the precipitation, available fetch (a function of wind angle and dry-beach width), and a threshold wind speed to initiate transport. ATP is then combined with a hydrodynamic transport potential (HTP) metric, defined as the number of hours of wave impact to the foredune or upper beach, to assess the time-dependent magnitude of the forcing factors affecting morphological evolution of the foredune between monthly terrestrial lidar surveys.This study focuses on two distinctly different dune fields and their frontal or incipient dune ridges in Duck, NC at the USACE Field Research Facility (FRF): (1) an undisturbed, tall and narrow recently impacted dune with a near vertical face; and (2) an undisturbed, shorter and wider dune with gentler and more hummocky slopes. The two sites are separated by < 1km alongshore and experience similar environmental forcings due to their close proximity. We used hourly precipitation, wind, wave, and imagery-derived runup data from the FRF and surrounding weather stations as inputs to ATP and HTP for each site. We scanned each site at monthly intervals for 18 months with high-resolution terrestrial lidar and generated 10 cm digital elevation models (DEM) for each scan. Incremental and cumulative changes in elevation, volume, and dune toe position were extracted from the DEMs and compared to the ATP and HTP values between the surveys to evaluate the dominant factors affecting sediment flux to the system.

Environmental analyses of the parasitic profile found in the sandy soil from the Santos municipality beaches, SP, Brazil.

PubMed

Rocha, Silvana; Pinto, Rosa Maria Ferreiro; Floriano, Aline Petrollini; Teixeira, Lais Helena; Bassili, Bianca; Martinez, Araceles; Costa, Sergio Olavo Pinto da; Caseiro, Marcos Montani

2011-01-01

The environmental contamination by geohelminths represents a world public health problem and has been well documented by several authors. However, few papers describe the presence of such contamination in saline soils of coastal beaches. A study was performed on the beaches of the municipality of Santos in the period between May 2004 to April 2005 with the aim of determining the degree of contamination, and the correlation between contamination level and seasonal conditions and characteristics of the environment. Of the 2,520 samples analyzed, 18.2% (458) were contaminated, 32.3% (148) of which were localized in children's recreational areas (playgrounds). The parasite profile found in the analyzed samples indicated the presence of several zoonotic parasites: Ancylostoma larvae (82.5%), Toxocara sp. eggs (59.4%), Ancylostomidae-like eggs (37.1%), coccid oocysts (13.5%), Trichostrongylus sp. eggs and larvae, Ascaris lumbricoides eggs, (11.6%), Entamoeba sp. cysts (10.0%), Strongyloides sp. (4.8%), several free nematoids and some non-identified parasitic structures (3.3%). It was established that the highest frequency of parasitic structures occurred in the months between May and October 2004, and from February to March 2005. An increase in the diversity of parasitic forms was documented in the months between February to December 2004 and from January to April 2005, these periods having the highest rainfall.

Local v. microhabitat influences on the fish fauna of tidal pools in north-east Brazil.

PubMed

Godinho, W O; Lotufo, T M C

2010-02-01

This study explored the influence of microhabitat characteristics, such as sandy, rocky and algal bottom, holes, area and depth, on tide-pool fish descriptors (evenness, total number of fish, diversity and species richness). Even when the rockpool microhabitats differed amongst beaches, the tidal fish assemblages were closely grouped by site rather than by characteristics of the tide pools. Fish assemblages were mostly represented by juvenile fishes from 29 species, of which 14 were observed in only one of the three sites. This indicates that sites, rather than microhabitat association, might play a major role for the rockpool ichthyofauna in north-east Brazil.

KSC Wildlife

NASA Image and Video Library

2007-02-09

A pair of brown pelicans rest on a wall near the turn basin at NASA's Kennedy Space Center. The turn basin was carved out of the Banana River when KSC was built. The birds' habitat is sandy coastal beaches and lagoons, ranging along the Atlantic Coast from North Carolina south to Venezuela. It nests in colonies. KSC shares a boundary with the Merritt Island Wildlife Nature Refuge. The refuge is a habitat for more than 310 species of birds, 25 mammals, 117 fishes and 65 amphibians and reptiles. In addition, the Refuge supports 19 endangered or threatened wildlife species on Federal or State lists, more than any other single refuge in the U.S.

Enhanced ex situ bioremediation of crude oil contaminated beach sand by supplementation with nutrients and rhamnolipids.

PubMed

Nikolopoulou, M; Pasadakis, N; Norf, H; Kalogerakis, N

2013-12-15

Mediterranean coastal regions are particularly exposed to oil pollution due to extensive industrialization, urbanization and transport of crude and refined oil to and from refineries. Bioremediation of contaminated beach sand through landfarming is both simple and cost-effective to implement compared to other treatment technologies. The purpose of the present study was to investigate the effect of alternative nutrients on biodegradation of crude oil contaminated beach sand in an effort to reduce the time required for bioremediation employing only indigenous hydrocarbon degraders. A natural sandy soil was collected from Agios Onoufrios beach (Chania, Greece) and was contaminated with weathered crude oil. The indigenous microbial population in the contaminated sand was tested alone (control treatment) or in combination with inorganic nutrients (KNO3 and K2HPO4) to investigate their effects on oil biodegradation rates. In addition, the ability of biosurfactants (rhamnolipids), in the presence of organic nutrients (uric acid and lecithin), to further stimulate biodegradation was investigated in laboratory microcosms over a 45-day period. Biodegradation was tracked by GC/MS analysis of aliphatic and polycyclic aromatic hydrocarbons components and the measured concentrations were corrected for abiotic removal by hopane normalizations. It was found that the saturated fraction of the residual oil is degraded more extensively than the aromatic fraction and the bacterial growth after an incubation period of approximately 3 weeks was much greater from the bacterial growth in the control. The results show that the treatments with inorganic or organic nutrients are equally effective over almost 30 days where C12-C35n-alkanes were degraded more than 97% and polyaromatic hydrocarbons with two or three rings were degraded more than 95% within 45 days. The results clearly show that the addition of nutrients to contaminated beach sand significantly enhanced the activity of indigenous microorganisms, as well as the removal of total recoverable petroleum hydrocarbons (TRPH) over a 45-day study period. Copyright © 2013 Elsevier Ltd. All rights reserved.

Long-term monitoring data to describe the fate of polycyclic aromatic hydrocarbons in Deepwater Horizon oil submerged off Alabama's beaches.

PubMed

Yin, Fang; John, Gerald F; Hayworth, Joel S; Clement, T Prabhakar

2015-03-01

The 2010 Deepwater Horizon (DWH) catastrophe had considerable impact on the ∼ 50 km long sandy beach system located along the Alabama shoreline. We present a four-year dataset to characterize the temporal evolution of various polycyclic aromatic hydrocarbons (PAHs) and their alkylated homologs trapped in the residual oil buried along the shoreline. Field samples analyzed include the first arrival oil collected from Perdido Bay, Alabama in June 2010, and multiple oil spill samples collected until August 2014. Our field data show that, as of August 2014, DWH oil is still trapped along Alabama's beaches as submerged oil, predominately in the form of surface residual oil balls (SRBs). Chemical characterization data show that various PAHs present in the spilled oil (MC252 crude) weathered by about 45% to 100% when the oil was floating over the open ocean system in the Gulf of Mexico. Light PAHs, such as naphthalenes, were fully depleted, whereas heavy PAHs, such as chrysenes, were only partially depleted by about 45%. However, the rate of PAH weathering appears to have decreased significantly once the oil was buried within the partially-closed SRB environment. Concentration levels of several heavy PAHs have almost remained constant over the past 4 years. Our data also show that evaporation was most likely the primary weathering mechanism for PAH removal when the oil was floating over the ocean, although photo-degradation and other physico-chemical processes could have contributed to some additional weathering. Chemical data presented in this study indicate that submerged oil containing various heavy PAHs (for example, parent and alkylated chrysenes) is likely to remain in the beach system for several years. It is also likely that the organisms living in these beach environments would have an increased risk of exposure to heavy PAHs trapped in the non-recoverable form of buried DWH oil spill residues. Copyright © 2014 Elsevier B.V. All rights reserved.

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.

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.

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

Rivera, S.; Lugo, T.; Hazen, T.C.

Water and shellfish samples collected from estuaries, mangroves, and beaches along the coast of Puerto Rico were examined for Vibrio vulnificus and Vibrio parahaemolyticus. An array of water quality parameters were also measured simultaneous with bacteria sampling. Both species of vibrio were associated with estuary and mangrove locations, and neither was isolated from sandy beaches. Densities of V. vulnificus were negatively correlated with salinity, 10--15 ppt being optimal. V. parahaemolyticus was isolated from sites with salinities between 20 and 35 ppt, the highest densities occurring at 20 ppt. Densities of Vibrio spp. and V. parahaemolyticus for a tropical estuary surpassedmore » those reported for temperate estuaries by several orders of magnitude. Both densities of total Vibrio spp. and V. parahaemolyticus in the water were directly related to densities of fecal coliforms, unlike V. vulnificus. The incidence of ONPG(+) strains among sucrose({minus}) Vibrio spp. served as an indicator of the frequency of V. vulnificus in this group. More than 63% of the V. vulnificus isolated were pathogenic. V. vulnificus and V. parahaemolyticus occupy clearly separate niches within the tropical estuarine-marine ecosystem.« less

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

Sather, NK; Johnson, GE; Storch, AJ

The tidal freshwater monitoring (TFM) project reported herein is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, the U.S. Army Corps of Engineers [USACE], and the U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act (ESA) as a result of operation of the Federal Columbia River Power System. The project is being performed under the auspices of the Northwest Power and Conservation Council's Columbia Basin Fish and Wildlife Program (Project No. 2005-001-00). The research is a collaborative effort among the Pacific Northwest National Laboratory, the Oregon Departmentmore » of Fish and Wildlife, the National Marine Fisheries Service, and the University of Washington. The overarching goal of the TFM project is to bridge the gap in knowledge between tidal freshwater habitats and the early life history attributes of migrating salmon. The research questions include: In what types of habitats within the tidal freshwater area of the Columbia River are juvenile salmon found, when are they present, and under what environmental conditions? What is the ecological contribution of shallow (0-5 m) tidal freshwater habitats to the recovery of ESA-listed salmon in the Columbia River basin? Field data collection for the TFM project commenced in June 2007 and since then has continued monthly at six to nine sites in the vicinity of the Sandy River delta (river kilometer 192-208). While this report includes summary data spanning the 19-month period of study from June 2007 through December 2008, it highlights sampling conducted during calendar year 2008. Detailed data for calendar year 2007 were reported previously. The 2008 research objectives were as follows: (1) Characterize the vegetation composition and percent cover, conventional water quality, water surface elevation, substrate composition, bathymetry, and beach slope at the study sites within the vicinity of the Sandy River delta. (2) Characterize the fish community and juvenile salmon migration, including species composition, length-frequency distribution, density (number/m{sup 2}), and temporal and spatial distributions in the vicinity of the Sandy River delta in the lower Columbia River and estuary (LCRE). (3) Determine the stock of origin for juvenile Chinook salmon (Oncorhynchus tshawytscha) captured at sampling sites through genetic identification. (4) Characterize the diets of juvenile Chinook and coho (O. kisutch) salmon captured within the study area. (5) Estimate run timing, residence times, and migration pathways for acoustic-tagged fish in the study area. (6) Conduct a baseline evaluation of the potential restoration to reconnect the old Sandy River channel with the delta. (7) Apply fish density data to initiate a design for a juvenile salmon monitoring program for beach habitats within the tidal freshwater segment of the LCRE (river kilometer 56-234).« less

A 3D unstructured grid nearshore hydrodynamic model based on the vortex force formalism

NASA Astrophysics Data System (ADS)

Zheng, Peng; Li, Ming; van der A, Dominic A.; van der Zanden, Joep; Wolf, Judith; Chen, Xueen; Wang, Caixia

2017-08-01

A new three-dimensional nearshore hydrodynamic model system is developed based on the unstructured-grid version of the third generation spectral wave model SWAN (Un-SWAN) coupled with the three-dimensional ocean circulation model FVCOM to enable the full representation of the wave-current interaction in the nearshore region. A new wave-current coupling scheme is developed by adopting the vortex-force (VF) scheme to represent the wave-current interaction. The GLS turbulence model is also modified to better reproduce wave-breaking enhanced turbulence, together with a roller transport model to account for the effect of surface wave roller. This new model system is validated first against a theoretical case of obliquely incident waves on a planar beach, and then applied to three test cases: a laboratory scale experiment of normal waves on a beach with a fixed breaker bar, a field experiment of oblique incident waves on a natural, sandy barred beach (Duck'94 experiment), and a laboratory study of normal-incident waves propagating around a shore-parallel breakwater. Overall, the model predictions agree well with the available measurements in these tests, illustrating the robustness and efficiency of the present model for very different spatial scales and hydrodynamic conditions. Sensitivity tests indicate the importance of roller effects and wave energy dissipation on the mean flow (undertow) profile over the depth. These tests further suggest to adopt a spatially varying value for roller effects across the beach. In addition, the parameter values in the GLS turbulence model should be spatially inhomogeneous, which leads to better prediction of the turbulent kinetic energy and an improved prediction of the undertow velocity profile.

Wind-Powered Wheel Locomotion, Initiated by Leaping Somersaults, in Larvae of the Southeastern Beach Tiger Beetle (Cicindela dorsalis media)

PubMed Central

Harvey, Alan; Zukoff, Sarah

2011-01-01

Rapid movement is challenging for elongate, soft-bodied animals with short or no legs. Leaping is known for only a few animals with this “worm-like” morphology. Wheel locomotion, in which the animal's entire body rolls forward along a central axis, has been reported for only a handful of animals worldwide. Here we present the first documented case of wind-powered wheel locomotion, in larvae of the coastal tiger beetle Cicindela dorsalis media. When removed from their shallow burrows, larvae easily can be induced to enter a behavioral sequence that starts with leaping; while airborne, larvae loop their body into a rotating wheel and usually either “hit the ground rolling” or leap again. The direction larvae wheel is closely related to the direction in which winds are blowing; thus, all our larvae wheeled up-slope, as winds at our study site consistently blew from sea to land. Stronger winds increased both the proportion of larvae wheeling, and the distance traveled, exceeding 60 m in some cases. In addition, the proportion of larvae that wheel and the distance traveled by wheeling larvae are significantly greater on smooth sandy beaches than on beach surfaces made rough and irregular by pedestrian, equestrian, and vehicular traffic. Like other coastal species of tiger beetles, C. dorsalis media has suffered major declines in recent years that are clearly correlated with increased human impacts. The present study suggests that the negative effects of beach traffic may be indirect, preventing larvae from escaping from predators using wheel locomotion by disrupting the flat, hard surface necessary for efficient wheeling. PMID:21448275

Do mud deposition events on sandy beaches affect surf zone ichthyofauna? A southern Brazilian case study

NASA Astrophysics Data System (ADS)

Mont'Alverne, Renata; Moraes, Leonardo E.; Rodrigues, Fábio L.; Vieira, João P.

2012-05-01

Using fluid mud deposition events which occur regularly at Cassino Beach in south Brazil, we evaluated the influence of such events on the structure of the ichthyofauna inhabiting its shallow surf zone. Wave action was the dominant factor in differentiating between sampling sites, being lower or even absent at the mud-influenced sectors compared to beach area without mud. Samples were collected using a beach seine net at two control locations (A1 and A2), and at three locations influenced by mud deposition (B1, B2, and B3). During the study period (21 April-04 August 2009), 15,245 fishes were captured and separated into 26 taxonomic groups, from species to family. Individuals of a total length (TL) up to 50 mm accounted for 65% of the catch, while individuals of TL < 30 mm were the most numerous and more responsible for the total abundance spatial pattern. The area with higher wave action (A2) had the lowest relative species abundance and greatest diversity, whereas the areas with mud-forced lowest wave action (B2 and B3) had the highest species abundance values. Three hypotheses were proposed to explain the higher concentration and capture of juvenile fishes at mud locations. First, longshore currents may be responsible for the displacement of juvenile aggregations toward areas of lower energy. Second, individuals may select habitats with turbid waters, which may provide greater protection from predators and increased food availability. Third, areas under the influence of fluid mud deposition show higher values of viscosity, which may reduce swimming activity and hinder the escape of juvenile fishes from nets, resulting in an increased capture of individuals compared to areas without mud.

Hydrogeologic framework of the shallow ground-water system in the Cox Hall Creek basin, Cape May County, New Jersey

USGS Publications Warehouse

Lacombe, Pierre J.; Zapecza, Otto S.

2006-01-01

Cape May County is investigating the feasibility of restoring the lowermost reach of Cox Hall Creek to its former state as a tidal saltwater wetland; however, the potential for contamination of the shallow ground-water system, which provides water to hundreds of nearby privately owned domestic wells, with saltwater from the restored wetland is of particular concern. To evaluate the potential effectiveness and risks of restoring the saltwater wetlands, the County needs information about the hydrogeologic framework in the area, and about the potential vulnerability of the domestic wells to contamination. The shallow ground-water system in the Cox Hall Creek area consists of unconsolidated Holocene and Pleistocene deposits. The Holly Beach water-bearing zone, the unconfined (water-table) aquifer, is about 35 feet thick and contains a 2- to 4-foot-thick clay lens about 10 feet below land surface; a lower, more discontinuous clay lens about 30 to 35 feet below land surface ranges up to 5 feet in thickness. A 75-foot-thick confining unit separates the Holly Beach water-bearing zone from the underlying estuarine sand aquifer. The clay lenses in the Holly Beach water-bearing zone likely retard the movement of contaminants from septic tanks, lawns, and other surficial sources, protecting wells that tap the lower, sandy part of the aquifer. The clay lenses also may protect these wells from salty surface water if withdrawals from the Holly Beach water-bearing zone are not increased substantially. Deeper wells that tap the estuarine sand aquifer are more effectively protected from saltwater from surface sources because of the presence of the overlying confining unit.

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.

Mapping Shoreline Change Using Digital Orthophotogrammetry on Maui, Hawaii

USGS Publications Warehouse

Fletcher, C.; Rooney, J.; Barbee, M.; Lim, S.-C.; Richmond, B.

2003-01-01

Digital, aerial orthophotomosaics with 0.5-3.0 m horizontal accuracy, used with NOAA topographic maps (T-sheets), document past shoreline positions on Maui Island, Hawaii. Outliers in the shoreline position database are determined using a least median of squares regression. Least squares linear regression of the reweighted data (outliers excluded) is used to determine a shoreline trend termed the reweighted linear squares (RLS). To determine the annual erosion hazard rate (AEHR) for use by shoreline managers the RLS data is smoothed in the longshore direction using a weighted moving average five transects wide with the smoothed rate applied to the center transect. Weightings within each five transect group are 1,3,5,3,1. AEHR's (smoothed RLS values) are plotted on a 1:3000 map series for use by shoreline managers and planners. These maps are displayed on the web for public reference at http://www.co.maui.hi.us/ departments/Planning/erosion.htm. An end-point rate of change is also calculated using the earliest T-sheet and the latest collected shoreline (1997 or 2002). The resulting database consists of 3565 separate erosion rates spaced every 20 m along 90 km of sandy shoreline. Three regions are analyzed: Kihei, West Maui, and North Shore coasts. The Kihei Coast has an average AEHR of about 0.3 m/yr, an end point rate (EPR) of 0.2 m/yr, 2.8 km of beach loss and 19 percent beach narrowing in the period 1949-1997. Over the same period the West Maui coast has an average AEHR of about 0.2 m/yr, an average EPR of about 0.2 m/yr, about 4.5 km of beach loss and 25 percent beach narrowing. The North Shore has an average AEHR of about 0.4 m/yr, an average EPR of about 0.3 m/yr, 0.8 km of beach loss and 15 percent beach narrowing. The mean, island-wide EPR of eroding shorelines is 0.24 m/yr and the average AEHR of eroding shorelines is about 0.3 m/yr. The overall shoreline change rate, erosion and accretion included, as measured using the unsmoothed RLS technique is 0.21 m/yr. Island wide changes in beach width show a 19 percent decrease over the period 1949/ 1950 to 1997/2002. Island-wide, about 8 km of dry beach has been lost since 1949 (i.e., high water against hard engineering structures and natural rock substrate).

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.

Analysis of Time-Motion and Heart Rate in Elite Male and Female Beach Handball

PubMed Central

Pueo, Basilio; Jimenez-Olmedo, Jose M.; Penichet-Tomas, Alfonso; Ortega Becerra, Manuel; Espina Agullo, Jose J.

2017-01-01

Beach handball is a spectacular new team sport; however, scientific knowledge about the demands in beach handball is very low. Consequently, the aim of this study was to analyze the physical demands of elite beach handball players by means of time-motion analysis with GPS technology and physiological response with Heart Rate (HR). Both male (n = 12) and female (n = 12) players from the Spanish Beach Handball National Team were recruited for this study. The sample consisted in four matches of two 10-min periods each. Time-motion analysis was performed through GPS devices (SPI Pro X, 15 Hz, GPSports) with synchronized HR monitoring (Polar Electro, Finland). All parameters were recorded for matches and halves to express overall and time-dependent physical and physiological responses. Total match distance covered by male and female players were 1234.7 ± 192 m and 1118.2 ± 221.8 m, respectively. Female players covered more total distance (p = 0.049, ES = 0.79) and distance walking (p < 0.001, ES = 2.04) in the first half, whereas they covered more distance standing (p = 0.008, ES = 1.05) in the second half at a higher average speed (p < 0.001, ES = 2.28). The number of accelerations distributed over low-, moderate- and high-intensity categories were 43.2 ± 11.6, 9.4 ± 4.9; 0.8 ± 0.9 m/s2 for male players, and 40.3 ± 12.7, 4.3 ± 3.0; 0.1 ± 0.3 m/s2 for female players; equivalent to one body acceleration every 23 s and 27 s, respectively. Finally, male and female players obtained a maximum/mean HR of 173 ± 13 / 137 ± 12 bpm, and 177 ± 13 / 138 ± 18 bpm, with 20.3% and 29.2% of the total time in the anaerobic zone (81 – 90% HRmax), respectively. These results demonstrated that beach handball is a demanding sport, with numerous moderate-to-high intensity displacements, distributed intermittently throughout the game: long periods of low intensity activity interspersed by short bursts of high intensity. Key points Beach handball is a demanding sport, with numerous moderate-to-high intensity displacements, distributed intermittently throughout the match. Despite the sandy surface, the distance covered per minute in beach handball is similar to team handball. On average, every 23 s and 27 s, a body acceleration was produced by male and female players, respectively. Female players covered substantially more distance in the first half but at the expense of lower speed. PMID:29238243

Building Ecological and Community Resilience and Measuring Success of the Department of Interior Hurricane Sandy Resilience Projects

NASA Astrophysics Data System (ADS)

Taylor, S. M.; Worman, S. L.; Bennett, R.; Bassow, A.

2017-12-01

The Department of the Interior (DOI) partnered with the National Fish and Wildlife Foundation (NFWF) to administer an external funding competition to support coastal resilience projects in the region affected by Hurricane Sandy. The projects complement the DOI Bureau-led projects, but are led by state and local governments, universities, non-profits, community groups, tribes, and other non-Federal entities. In total, the Hurricane Sandy Resilience Program invested over $750 million in approximately 180 projects to repair damage and improve the resilience of habitats, communities and infrastructure to future storms and sea level rise. Project activities include waterway connection and opening, living shoreline, marsh restoration, community resilience planning, data/mapping/modeling, and beach and dune restoration. DOI and NFWF initiated a resilience assessment in 2015 to evaluate the impact of this investment. The assessment began by clarifying the program's resilience goals and the development of ecological and socio-economic metrics across the project activities. Using these metrics, the evaluation is assessing the ecological and community outcomes, cost effectiveness of activities, improved scientific understanding, and temporal and spatial scaling of benefits across resilience activities. Recognizing the unique opportunity afforded by the scale and distribution of projects, NFWF and DOI have invested in monitoring through 2024 to better understand how these projects perform over time. This presentation will describe the evaluation questions, approach, long-term monitoring, online metrics portal, and findings to date.

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.

Coupling alongshore variations in wave energy to beach morphologic change using the SWAN wave model at Ocean Beach, San Francisco, CA

USGS Publications Warehouse

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

2007-01-01

Coastal managers have faced increasing pressure to manage their resources wisely over the last century as a result of heightened development and changing environmental forcing. It is crucial to understand seasonal changes in beach volume and shape in order to identify areas vulnerable to accelerated erosion. Shepard (1950) was among the first to quantify seasonal beach cycles. Sonu and Van Beek (1971) and Wright et al. (1985) described commonly occurring beach states. Most studies utilize widest spaced 2-D cross shore profiles or shorelines extracted from aerial photographs (e.g. Winant et al. 1975; Aubrey, 1979, Aubrey and Ross, 1985; Larson and Kraus, 1994; Jimenez et al., 1977; Lacey and Peck, 1998; Guillen et al., 1999; Norcorss et al., 2002) to analyzed systematic changes in beach evolution. But with the exception of established field stations, such as Duck, NC (Birkemeier and Mason, 1984), ans Hazaki Oceanographical Research Station (HORS) in Japan (Katoh, 1997), there are very few beach change data sets with high temporal and spatial resolutions (e.g. Dail et al., 2000; Ruggiero et al., 2005; Yates et al., in press). Comprehensive sets of nearshore morphological data and local in situ measurements outside of these field stations are very rare and virtually non-existent high-energy coasts. Studied that have attempted to relate wave statistics to beach morphology change require some knowledge of the nearshore wave climate, and have had limited success using offshore measurement (Sonu and Van Beek, 1971; Dail et al., 2000). The primary objective of this study is to qualitatively compare spatially variable nearshore wave predictions to beach change measurements in order to understand the processes responsible for a persistent erosion 'hotspot' at Ocean Beach, San Francisco, CA. Local wave measurements are used to calibrate and validate a wave model that provides nearshore wave prediction along the beach. The model is run for thousands of binned offshore wave conditions to help isolate the effects of offshore wave direction and period on nearshore wave predictions. Alongshore varying average beach change statistics are computed at specific profile locations from topographic beach surveys and lidar data. The study area is located in the San Francisco Bight in central California. Ocean Beach is a seven kilometer long north-south trending sandy coastline located just south of the entrance to the San Francisco Bay Estuary (Figure 1). It contains an erosion hotspot in the southern part of the beach which has resulted in damage to local infrastructure and is the cause of continued concern. A wide range of field data collection and numerical modeling efforts have been focused here as part of the United States Geological Survey's (USGS) San Francisco Bight Coastal Processes Study, which began in October 2003 and represents the first comprehensive study of coastal processes at the mouth of San Francisco Bay. Ocean Beach is exposed to very strong tidal flows, with measured currents often in excess of 1 m/s at the north end of the beach. Current profiler measurements indicate that current magnitudes are greater in the northern portion of the beach, while wave energy is greater in the southern portion where erosion problems are greatest (Barnard et al., 2007). The sub-aerial beach volume fluctuates seasonally over a maximum envelope of 400,000 m3 for the seven kilometer stretch (Barnard et al, 2007). The wave climate in the region is dominated by an abundance of low frequency energy (greater than 20 s period) and prevailing northwest incident wave angles. The application of a wave model to the region is further complicated by the presence of the Farallon Islands 40 kilometers west, and a massive ebb tidal delta at the mouth of San Francisco Bay (~150 km2), which creates complicated refraction patterns as wave energy moves from offshore Ocean Beach; however the cost and threat of the energetic nearshore environment have limited the temporal and spatial resolution of these measurements. Applying numerical models to predict wave and current patterns along the beach can help supplement the filed data that exists and provide opportunities to make prediction about the impacts of changing environmental forcing.

KSC-07pd0357

NASA Image and Video Library

2007-02-12

KENNEDY SPACE CENTER, FLA. -- A pair of brown pelicans rest on a wall near the turn basin at NASA's Kennedy Space Center. The turn basin was carved out of the Banana River when KSC was built. The birds' habitat is sandy coastal beaches and lagoons, ranging along the Atlantic Coast from North Carolina south to Venezuela. It nests in colonies. KSC shares a boundary with the Merritt Island Wildlife Nature Refuge. The refuge is a habitat for more than 310 species of birds, 25 mammals, 117 fishes and 65 amphibians and reptiles. In addition, the Refuge supports 19 endangered or threatened wildlife species on Federal or State lists, more than any other single refuge in the U.S. Photo credit: NASA/George Shelton

Climate Adaptation and Policy-Induced Inflation of Coastal Property Value

PubMed Central

McNamara, Dylan E.; Gopalakrishnan, Sathya; Smith, Martin D.; Murray, A. Brad

2015-01-01

Human population density in the coastal zone and potential impacts of climate change underscore a growing conflict between coastal development and an encroaching shoreline. Rising sea-levels and increased storminess threaten to accelerate coastal erosion, while growing demand for coastal real estate encourages more spending to hold back the sea in spite of the shrinking federal budget for beach nourishment. As climatic drivers and federal policies for beach nourishment change, the evolution of coastline mitigation and property values is uncertain. We develop an empirically grounded, stochastic dynamic model coupling coastal property markets and shoreline evolution, including beach nourishment, and show that a large share of coastal property value reflects capitalized erosion control. The model is parameterized for coastal properties and physical forcing in North Carolina, U.S.A. and we conduct sensitivity analyses using property values spanning a wide range of sandy coastlines along the U.S. East Coast. The model shows that a sudden removal of federal nourishment subsidies, as has been proposed, could trigger a dramatic downward adjustment in coastal real estate, analogous to the bursting of a bubble. We find that the policy-induced inflation of property value grows with increased erosion from sea level rise or increased storminess, but the effect of background erosion is larger due to human behavioral feedbacks. Our results suggest that if nourishment is not a long-run strategy to manage eroding coastlines, a gradual removal is more likely to smooth the transition to more climate-resilient coastal communities. PMID:25806944

Climate adaptation and policy-induced inflation of coastal property value.

PubMed

McNamara, Dylan E; Gopalakrishnan, Sathya; Smith, Martin D; Murray, A Brad

2015-01-01

Human population density in the coastal zone and potential impacts of climate change underscore a growing conflict between coastal development and an encroaching shoreline. Rising sea-levels and increased storminess threaten to accelerate coastal erosion, while growing demand for coastal real estate encourages more spending to hold back the sea in spite of the shrinking federal budget for beach nourishment. As climatic drivers and federal policies for beach nourishment change, the evolution of coastline mitigation and property values is uncertain. We develop an empirically grounded, stochastic dynamic model coupling coastal property markets and shoreline evolution, including beach nourishment, and show that a large share of coastal property value reflects capitalized erosion control. The model is parameterized for coastal properties and physical forcing in North Carolina, U.S.A. and we conduct sensitivity analyses using property values spanning a wide range of sandy coastlines along the U.S. East Coast. The model shows that a sudden removal of federal nourishment subsidies, as has been proposed, could trigger a dramatic downward adjustment in coastal real estate, analogous to the bursting of a bubble. We find that the policy-induced inflation of property value grows with increased erosion from sea level rise or increased storminess, but the effect of background erosion is larger due to human behavioral feedbacks. Our results suggest that if nourishment is not a long-run strategy to manage eroding coastlines, a gradual removal is more likely to smooth the transition to more climate-resilient coastal communities.

Measuring spatial and temporal variation in surface moisture on a coastal beach with a near-infrared terrestrial laser scanner

NASA Astrophysics Data System (ADS)

Smit, Yvonne; Ruessink, Gerben; Brakenhoff, Laura B.; Donker, Jasper J. A.

2018-04-01

Wind-alone predictions of aeolian sand deposition on the most seaward coastal dune ridge often exceed measured deposition substantially. Surface moisture is a major factor limiting aeolian transport on sandy beaches, but existing measurement techniques cannot adequately characterize the spatial and temporal distribution of surface moisture content. Here, we present a new method for detecting surface moisture at high temporal and spatial resolution using a near-infrared terrestrial laser scanner (TLS), the RIEGL VZ-400. Because this TLS operates at a wavelength (1550 nm) near a water absorption band, TLS reflectance is an accurate parameter to measure surface moisture over its full range. Five days of intensive laser scanning were performed on a Dutch beach to illustrate the applicability of the TLS. Gravimetric surface moisture samples were used to calibrate the relation between reflectance and surface moisture. Results reveal a robust negative relation for the full range of possible surface moisture contents (0%-25%), with a correlation-coefficient squared of 0.85 and a root-mean-square error of 2.7%. This relation holds between 20 and 60 m from the TLS. Within this distance the TLS typically produces O (106-107) data points, which we averaged into surface moisture maps with a 1 × 1 m resolution. This grid size largely removes small reflectance disturbances induced by, for example, footprints or tire tracks, while retaining larger scale moisture trends.

National assessment of shoreline change: historical shoreline change along the Pacific Northwest coast

USGS Publications Warehouse

Ruggerio, Peter; Kratzmann, Meredith G.; Himmelstoss, Emily A.; Reid, David; Allan, Jonathan; Kaminsky, George

2013-01-01

Beach erosion is a chronic problem along most open ocean shores of the United States. As coastal populations continue to increase and infrastructure is threatened by erosion, there is increased demand for accurate information regarding past and present trends and rates of shoreline movement. There is also a need for a comprehensive analysis of shoreline movement that is consistent from one coastal region to another. To meet these national needs, the U.S. Geological Survey (USGS) is conducting an analysis of historical shoreline changes along the open-ocean sandy shores of the conterminous United States and parts of Hawaii, Alaska, and the Great Lakes. One purpose of this work is to develop standard, repeatable methods for mapping and analyzing shoreline movement so that periodic, systematic, and internally consistent updates regarding coastal erosion and land loss can be made nationally. In the case of the analysis of shoreline change in the Pacific Northwest (PNW), the shoreline is the interpreted boundary between the ocean water surface and the sandy beach. This report on the PNW coasts of Oregon and Washington is the seventh in a series of regionally focused reports on historical shoreline change. Previous investigations include analyses and descriptive reports of the U.S. Gulf of Mexico (Morton and others, 2004), the southeastern Atlantic (Morton and Miller, 2005), the sandy shorelines (Hapke and others, 2006) and coastal cliffs (Hapke and Reid, 2007) of California, the New England and mid-Atlantic coasts (Hapke and others, 2011), and parts of the Hawaii coast (Fletcher and others, 2012). Like the earlier reports in this series, this report summarizes the methods of analysis, interprets the results of the analysis, provides explanations regarding long- and short-term trends and rates of shoreline change, and describes how different coastal communities are responding to coastal erosion. This report differs from the early USGS reports in the series in that those shoreline change analyses incorporated only four total shorelines to represent specific time periods. This assessment of the PNW incorporates all available shorelines that meet minimum quality standards for resolution and positional accuracy. Shoreline change evaluations are based on a comparison of historical shoreline positions digitized from maps or aerial photographic data sources with recent shorelines, at least one of which is derived from lidar surveys. The historical shorelines cover a variety of time periods ranging from the 1800s through the 1980s, whereas the lidar shoreline is from 2002. Long-term rates of change are calculated using all available shoreline data and short-term rates of change are calculated using the lidar shoreline and the historical shoreline that will produce an assessment for a 15- to 35-year period. The rates of change presented in this report represent conditions up to the date of only the most recent shoreline data and therefore are not intended for predicting future shoreline positions or rates of change. The PNW coast was subdivided into eight analysis regions for the purpose of graphically reporting regional trends in shoreline change rates. The average rate of long-term shoreline change for the entire PNW coast was 0.9 meter per year (m/yr) of progradation with an uncertainty of 0.07 m/yr. This rate is based on 8,823 individual transects, of which 36 percent was determined to be eroding. Long-term shoreline change was generally more progradational in Washington than in Oregon. This is primarily due to the influence of the Columbia River and human perturbations to the natural system, particularly the construction of jetties at both the mouth of the Columbia River and at Grays Harbor, Washington. The majority of the beaches in southwestern Washington have responded to these large-scale engineered structures by experiencing dramatic beach progradation during the past century. Although these beaches are still responding to the human effects, in several locations beaches that had been rapidly prograding are now either prograding at a slower rate or eroding. The average rate of short-term shoreline change in the PNW was also progradational at a rate of 0.9 m/yr with an uncertainty of 0.03 m/yr. This rate is based on 9,087 individual transects, of which 44 percent was determined to be eroding. Similar to the results of the long-term shoreline change analysis, the shorelines in Washington were typically more progradational than those in Oregon in the short term. However, many stretches of coast in Oregon are either less accretional, changed from accretional to erosional, or more erosional when comparing the long- and short-term rate calculations. In the long and short term, there are significantly different historical shoreline change trends for beaches deriving their modern sediments from the Columbia River in southwestern Washington and northwestern Oregon, and beaches elsewhere in the PNW. The majority of shorelines in Oregon and in Washington’s Olympic Peninsula are not influenced by the human effects to the Columbia River littoral cell and typically have not experienced the human-induced century-scale trends apparent in southwestern Washington and northwestern Oregon. An increase in erosion hazards in much of Oregon may be related to the effects of sea-level rise and increasing storm wave heights. Of importance, particularly in the short term, is the alongshore variability in land uplift rates due to tectonics, which results in an alongshore varying rate of relative sea level rise that appears to at least partially control the regional variability in short-term shoreline change rates. Other climate related processes, such as the occurrence of major El Niño events, also significantly affect the shoreline changes in the region. Major El Niño events elevate monthly mean sea levels by tens of centimeters throughout the winter and produce a shift in the storm tracks, resulting in alongshore redistributions in sand volumes on the beaches, leading to hotspot beach erosion and property losses north of headlands and tidal inlets to bays and estuaries. There are limited modern-day sources of sand to Oregon’s beaches, with much of the sand being relict in having arrived thousands of years ago at a time of lowered sea levels when headlands did not prevent the alongshore movement of the beach sediments, the result being that many beaches today are deficient in sand volumes and therefore do not provide sufficient buffer protection to backshore properties during winter storms.

Global Climate Change Consequences Changing the Middle Sea Level in the Brazilian Coast: Impacts on Ceará State

NASA Astrophysics Data System (ADS)

Lacerda, E. G.; Pires, L. B. M.; Pinto, V. K. E.

2015-12-01

Since the Industrial Revolution, man started to generate increasing amounts of waste and pollutants, which on a large scale in the long term is causing a series of climate change consequences, both globally as well as locally. One of the many effects of these changes has been reflected in the ocean levels, depending on various factors. Thus, the population living in coastal areas suffers from the negative effects of the advancement of ocean waters. The coast of northeastern Brazil is an example of this, especially the state of Ceará coast. The state of Ceará has 573 km of coastline, a region that has suffered extensive erosion, in which the Middle Sea Level (MSL) changes exert a significant influence. The coastal plain is a strip of land of small extent, with an average width of 2.5 km, formed depending on the availability of high sediment stocks provided through the action of wind, marine, or river processes, individually in combination with each other. In many beaches it is observed that the strip of beach is narrow due to the presence of topographic elevations carved into sharp cliffs. Between periods of high tide and low tide, often rocky beach features are observed that have recently formed. The waves control the stretches of beach which are mostly sandy. This paper presents a survey about the evidence already apparent on the rise in the MSL and correlates it with the advance of the sea on the coast of Ceará, as well as assesses the possible consequences of this process. Therefore, a literature search was conducted in relevant scientific publications. The data used are from the station "Global Sea Level Observing System - GLOSS" which maintains a tide gauge installed in Ceará in Fortaleza. The analyses show that the phenomenon has caused a lot of inconvenience to the people, streets have disappeared, as well as several buildings located along the coast. The sea advances destroyed beaches and have promoted an accelerated level of erosion, changing the landscape of the region significantly. Data collected between 1996 and 2006 show that the sea height demonstrated a significant increase, especially from 2000. Keywords: Climate Change, Middle Sea Level, Ceará Coastline.Since the Industrial Revolution, man started to generate increasing amounts of waste and pollutants, which on a large scale in the long term is causing a series of climate change consequences, both globally as well as locally. One of the many effects of these changes has been reflected in the ocean levels, depending on various factors. Thus, the population living in coastal areas suffers from the negative effects of the advancement of ocean waters. The coast of northeastern Brazil is an example of this, especially the state of Ceará coast. The state of Ceará has 573 km of coastline, a region that has suffered extensive erosion, in which the Middle Sea Level (MSL) changes exert a significant influence. The coastal plain is a strip of land of small extent, with an average width of 2.5 km, formed depending on the availability of high sediment stocks provided through the action of wind, marine, or river processes, individually in combination with each other. In many beaches it is observed that the strip of beach is narrow due to the presence of topographic elevations carved into sharp cliffs. Between periods of high tide and low tide, often rocky beach features are observed that have recently formed. The waves control the stretches of beach which are mostly sandy. This paper presents a survey about the evidence already apparent on the rise in the MSL and correlates it with the advance of the sea on the coast of Ceará, as well as assesses the possible consequences of this process. Therefore, a literature search was conducted in relevant scientific publications. The data used are from the station "Global Sea Level Observing System - GLOSS" which maintains a tide gauge installed in Ceará in Fortaleza. The analyses show that the phenomenon has caused a lot of inconvenience to the people, streets have disappeared, as well as several buildings located along the coast. The sea advances destroyed beaches and have promoted an accelerated level of erosion, changing the landscape of the region significantly. Data collected between 1996 and 2006 show that the sea height demonstrated a significant increase, especially from 2000. Keywords: Climate Change, Middle Sea Level, Ceará Coastline.

Numerical modelling of river morphodynamics: Latest developments and remaining challenges

NASA Astrophysics Data System (ADS)

Siviglia, Annunziato; Crosato, Alessandra

2016-07-01

Numerical morphodynamic models provide scientific frameworks for advancing our understanding of river systems. The research on involved topics is an important and socially relevant undertaking regarding our environment. Nowadays numerical models are used for different purposes, from answering questions about basic morphodynamic research to managing complex river engineering problems. Due to increasing computer power and the development of advanced numerical techniques, morphodynamic models are now more and more used to predict the bed patterns evolution to a broad spectrum of spatial and temporal scales. The development and the success of application of such models are based upon a wide range of disciplines from applied mathematics for the numerical solution of the equations to geomorphology for the physical interpretation of the results. In this light we organized this special issue (SI) soliciting multidisciplinary contributions which encompass any aspect needed for the development and applications of such models. Most of the papers in the SI stem from contributions to session HS9.5/GM7.11 on numerical modelling and experiments in river morphodynamics at the European Geosciences Union (EGU) General Assembly held in Vienna, April 27th to May 2nd 2014.

An idealised study for the long term evolution of crescentic bars

NASA Astrophysics Data System (ADS)

Chen, W. L.; Dodd, N.; Tiessen, M. C. H.; Calvete, D.

2018-01-01

An idealised study that identifies the mechanisms in the long term evolution of crescentic bar systems in nature is presented. Growth to finite amplitude (i.e., equilibration, sometimes referred to as saturation) and higher harmonic interaction are hypothesised to be the leading nonlinear effects in long-term evolution of these systems. These nonlinear effects are added to a linear stability model and used to predict crescentic bar development along a beach in Duck, North Carolina (USA) over a 2-month period. The equilibration prolongs the development of bed patterns, thus allowing the long term evolution. Higher harmonic interaction enables the amplitude to be transferred from longer to shorter lengthscales, which leads to the dominance of shorter lengthscales in latter post-storm stages, as observed at Duck. The comparison with observations indicates the importance of higher harmonic interaction in the development of nearshore crescentic bar systems in nature. Additionally, it is concluded that these nonlinear effects should be included in models simulating the development of different bed patterns, and that this points a way forward for long-term morphodynamical modelling in general.

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.

Bed composition generation for morphodynamic modeling: Case study of San Pablo Bay in California, USA

USGS Publications Warehouse

van der Wegen, M.; Dastgheib, A.; Jaffe, B.E.; Roelvink, D.

2011-01-01

Applications of process-based morphodynamic models are often constrained by limited availability of data on bed composition, which may have a considerable impact on the modeled morphodynamic development. One may even distinguish a period of "morphodynamic spin-up" in which the model generates the bed level according to some ill-defined initial bed composition rather than describing the realistic behavior of the system. The present paper proposes a methodology to generate bed composition of multiple sand and/or mud fractions that can act as the initial condition for the process-based numerical model Delft3D. The bed composition generation (BCG) run does not include bed level changes, but does permit the redistribution of multiple sediment fractions over the modeled domain. The model applies the concept of an active layer that may differ in sediment composition above an underlayer with fixed composition. In the case of a BCG run, the bed level is kept constant, whereas the bed composition can change. The approach is applied to San Pablo Bay in California, USA. Model results show that the BCG run reallocates sand and mud fractions over the model domain. Initially, a major sediment reallocation takes place, but development rates decrease in the longer term. Runs that take the outcome of a BCG run as a starting point lead to more gradual morphodynamic development. Sensitivity analysis shows the impact of variations in the morphological factor, the active layer thickness, and wind waves. An important but difficult to characterize criterion for a successful application of a BCG run is that it should not lead to a bed composition that fixes the bed so that it dominates the "natural" morphodynamic development of the system. Future research will focus on a decadal morphodynamic hindcast and comparison with measured bathymetries in San Pablo Bay so that the proposed methodology can be tested and optimized. ?? 2010 The Author(s).

Last century seabed morphodynamics of the Magra River estuary (Western Mediterranean Sea)

NASA Astrophysics Data System (ADS)

Pratellesi, Marta; Ivaldi, Roberta; Ciavola, Paolo; Sinapi, Luigi

2016-04-01

The estimation of morphological and volumetric changes of the delta system at the mouth of the Magra River is presented in this paper using bathymetric and sedimentological data. The data series were collected during several hydro-oceanographic surveys carried out from 1882 to 2014, processed following the hydrographic international standards and stored in the Italian Navy Hydrographic Institute database. In particular, bathymetric data characterized by the same standard and accuracy were collected using different devices such as sounding lines, single-beam and multi-beam acoustic system. This research compares Digital Terrain Models (DTMs), derived from highly accurate bathymetric data and covering different time scales (secular, half-century and decade) in order to assess and quantify the seabed morphodynamics in relation with the river sedimentary budget. The methodology and data exploitation consist mainly in the production of DTMs to study the elevation change, two-dimensional and three dimensional maps, cross-sections of the seabed, difference surfaces and computation of net volumes as well as an historical sedimentological map. These products are also an useful contribution to the aim of EU RISC-KIT Project. The results of the analysis highlight changes in the geometry of the Magra River mouth, of the coastal profile and bottom features primarily due to variations of the sedimentary budget and secondarily to wave dynamics. This behaviour is characterized by evident river mouth and coastal retreat, beach erosion and sediment bars decay and net accretion under periods of high river sediment discharge and elongate bar formation during relatively fair conditions. In the last century the main change is constituted by the disappearance of the typical constructive seabed delta morphology and the transformation into the current small estuary, with microtidal condition. This small estuary has an upper sector where river processes, sediments and bedforms dominate, a lower sector near the mouth, where wave and tidal processes and marine sediments dominate, and a middle sector, where tidal currents dominate and both river and marine sediments are present.

Modeling invasive alien plant species in river systems: Interaction with native ecosystem engineers and effects on hydro-morphodynamic processes

NASA Astrophysics Data System (ADS)

van Oorschot, M.; Kleinhans, M. G.; Geerling, G. W.; Egger, G.; Leuven, R. S. E. W.; Middelkoop, H.

2017-08-01

Invasive alien plant species negatively impact native plant communities by out-competing species or changing abiotic and biotic conditions in their introduced range. River systems are especially vulnerable to biological invasions, because waterways can function as invasion corridors. Understanding interactions of invasive and native species and their combined effects on river dynamics is essential for developing cost-effective management strategies. However, numerical models for simulating long-term effects of these processes are lacking. This paper investigates how an invasive alien plant species affects native riparian vegetation and hydro-morphodynamics. A morphodynamic model has been coupled to a dynamic vegetation model that predicts establishment, growth and mortality of riparian trees. We introduced an invasive alien species with life-history traits based on Japanese Knotweed (Fallopia japonica), and investigated effects of low- and high propagule pressure on invasion speed, native vegetation and hydro-morphodynamic processes. Results show that high propagule pressure leads to a decline in native species cover due to competition and the creation of unfavorable native colonization sites. With low propagule pressure the invader facilitates native seedling survival by creating favorable hydro-morphodynamic conditions at colonization sites. With high invader abundance, water levels are raised and sediment transport is reduced during the growing season. In winter, when the above-ground invader biomass is gone, results are reversed and the floodplain is more prone to erosion. Invasion effects thus depend on seasonal above- and below ground dynamic vegetation properties and persistence of the invader, on the characteristics of native species it replaces, and the combined interactions with hydro-morphodynamics.

Multi-scale variability of storm Ophelia 2017: The importance of synchronised environmental variables in coastal impact.

PubMed

Guisado-Pintado, Emilia; Jackson, Derek W T

2018-07-15

Low frequency, high magnitude storm events can dramatically alter coastlines, helping to relocate large volumes of sediments and changing the configuration of landforms. Increases in the number of intense cyclones occurring in the Northern Hemisphere since the 1970s is evident with more northward tracking patterns developing. This brings added potential risk to coastal environments and infrastructure in northwest Europe and therefore understanding how these high-energy storms impact sandy coasts in particular is important for future management. This study highlights the evolution of Storm (formally Hurricane) Ophelia in October 2017 as it passed up and along the western seaboard of Ireland. The largest ever recorded Hurricane to form in the eastern Atlantic, we describe, using a range of environmental measurements and wave modelling, its track and intensity over its duration whilst over Ireland. The impact on a stretch of sandy coast in NW Ireland during Storm Ophelia, when the winds were at their peak, is examined using terrestrial laser scanning surveys pre- and post-storm to describe local changes of intertidal and dune edge dynamics. During maximum wind conditions (>35 knots) waves no >2m were recorded with an oblique to parallel orientation and coincident with medium to low tide (around 0.8m). Therefore, we demonstrate that anticipated widespread coastal erosion and damage may not always unfold as predicted. In fact, around 6000m 3 of net erosion occurred along the 420m stretch of coastline with maximum differences in beach topographic changes of 0.8m. The majority of the sediment redistribution occurred within the intertidal and lower beach zone with some limited dune trimming in the southern section (10% of the total erosion). Asynchronous high water (tide levels), localised offshore winds as well as coastline orientation relative to the storm winds and waves plays a significant role in reducing coastal erosional impact. Copyright © 2018 Elsevier B.V. All rights reserved.

Beach-ridge sedimentology as an archive of terrestrial climate change: Insights from a geochemical and stratigraphic study of the Tijucas Strandplain, southern Brazil

NASA Astrophysics Data System (ADS)

Krask, J. L.; Hein, C. J.; Galy, V.; FitzGerald, D.; Henrique de Fontoura Klein, A.

2017-12-01

Whereas millennial-scale variations in climate forcing drives changes in terrestrial processes, which are in turn directly linked to fluvial sediment loads (e.g., weathering and erosion), the impact of decadal- to centennial- scale climate fluctuations on downstream coastal sedimentation patterns and landscape evolution remains unclear. Specifically, the connection between long-term (decades or more) precipitation seasonality and sediment export from river systems has not been established. This study examines the manner in which sub-millennial-scale fluctuations in precipitation over river catchments may be recorded in coastal progradational sedimentary archives. The 5-km wide Tijucas Strandplain (southern Brazil) formed over the last 5800 years through the rapid reworking of sediment discharged from the Tijucas River in a regime of falling sea level. In an overall regime shift from sand- to mud- dominance (linked to a long-term reduction in wave energy caused by bay shoaling) are nearly 70 distinct transitions between shore-parallel sand- and mud- dominated facies. Bulk organic carbon and terrestrial plant-wax fatty acid stable hydrogen (δD) and carbon (δ13C) isotopic measurements from sediments from select sandy and muddy ridges across the plain reveal that these two sedimentological regimes are geochemically distinct. Specifically, waxes from sediments deposited during periods of sandy progradation had δD values, on average, >10 ‰ higher than those from mud-dominated periods, indicating that these sedimentary units reflect different hydroclimatic conditions within the river drainage basin at the time of deposition. Comparison of plant wax isotopic signatures of river, bay, and beach sediments during the current period of mud-dominated progradation reveals a close correlation with earlier periods of mud deposition within the Tijucas Strandplain. Thus, decadal- to centennial- scale sedimentologic transitions within the plain are interpreted to reflect climate-driven changes in mud export rates, as product of modifications in river basin vegetation and soil formation and erosional processes.

Spatial and temporal patterns of shoreline change of a 280-km high-energy disrupted sandy coast from 1950 to 2014: SW France

NASA Astrophysics Data System (ADS)

Castelle, Bruno; Guillot, Benoit; Marieu, Vincent; Chaumillon, Eric; Hanquiez, Vincent; Bujan, Stéphane; Poppeschi, Coline

2018-01-01

A dataset of 15 geo-referenced orthomosaics photos was generated to address long-term shoreline change along approximately 270 km of high-energy sandy coast in SW France between 1950 and 2014. The coast consists of sandy beaches backed by coastal dunes, which are only disrupted by two wide tidal inlets (Arcachon and Maumusson), a wide estuary mouth (Gironde) and a few small wave-dominated inlets and coastal towns. A time and spatially averaged erosion trend of 1.12 m/year is found over 1950-2014, with a local maximum of approximately 11 m/year and a maximum local accretion of approximately 6 m/year, respectively. Maximum shoreline evolutions are observed along coasts adjacent to the inlets and to the estuary mouth, with erosion and accretion alternating over time on the timescale of decades. The two inlet-sandspit systems of Arcachon and Maumusson show a quasi-synchronous behaviour with the two updrift coasts accreting until the 1970s and subsequently eroding since then, which suggests that shoreline change at these locations is controlled by allocyclic mechanisms. Despite sea level rise and the well-established increase in winter wave height over the last decades, there is no capture of significant increase in mean erosion rate. This is hypothesized to be partly the result of relevant coastal dune management works from the 1960s to the 1980s after a long period of coastal dune disrepair during and after the Second World War. This study suggests that long-term shoreline change of high-energy sandy coasts disrupted by inlets and/or estuaries is complex and needs to consider a wide range of parameters including, non-extensively, waves, tides, inlet dynamics, sea level rise, coastal dune management and coastal defences, which challenges the development of reliable long-term coastal evolution numerical models.

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

Establishing physiographic provinces for an integrative approach of the coastal zone management - The case of Rhodes Island, Aegean Sea, Greece

NASA Astrophysics Data System (ADS)

Anagnostou, Vasileios; Angelos Hatiris, Georgios; Sioulas, Andreas

2017-04-01

The coastal zone is a dynamic natural system affected by terrestrial and marine processes as well as human intervention. The sediments derived by the land and supplied by the adjacent catchment are reworked and distributed according to the prevailing hydrodynamic regime. Based on inland and coastal physiography of Rhodes Island, six (6) main Physiographic Provinces were identified, which incorporate 56 main drainage basins and 168 interfluves. Moreover, the variety of coastal types was mapped and the total length of the island's coastline ( 285 km) was measured by using geospatial tools (ArcGIS and Google Earth). The coastline is comprised of depositional sandy beaches (44.5%), rocky coasts (47%) and coasts altered from anthropogenic constructions (8.5%). The Physiographic Provinces were defined in order to facilitate an Integrated Coastal Zone Management (ICZM) scheme for Rhodes Island and also adaptation measures. Overexploitation of the island's natural coastal environment by the tourism industry, mainly in the northern and northeastern parts of the island, left a series of adverse effects on the coastal area, such as erosion of beaches, water and energy overconsumption and land degradation.

Coastal barrier stratigraphy for Holocene high-resolution sea-level reconstruction

PubMed Central

Costas, Susana; Ferreira, Óscar; Plomaritis, Theocharis A.; Leorri, Eduardo

2016-01-01

The uncertainties surrounding present and future sea-level rise have revived the debate around sea-level changes through the deglaciation and mid- to late Holocene, from which arises a need for high-quality reconstructions of regional sea level. Here, we explore the stratigraphy of a sandy barrier to identify the best sea-level indicators and provide a new sea-level reconstruction for the central Portuguese coast over the past 6.5 ka. The selected indicators represent morphological features extracted from coastal barrier stratigraphy, beach berm and dune-beach contact. These features were mapped from high-resolution ground penetrating radar images of the subsurface and transformed into sea-level indicators through comparison with modern analogs and a chronology based on optically stimulated luminescence ages. Our reconstructions document a continuous but slow sea-level rise after 6.5 ka with an accumulated change in elevation of about 2 m. In the context of SW Europe, our results show good agreement with previous studies, including the Tagus isostatic model, with minor discrepancies that demand further improvement of regional models. This work reinforces the potential of barrier indicators to accurately reconstruct high-resolution mid- to late Holocene sea-level changes through simple approaches. PMID:27929122

Coastal barrier stratigraphy for Holocene high-resolution sea-level reconstruction.

PubMed

Costas, Susana; Ferreira, Óscar; Plomaritis, Theocharis A; Leorri, Eduardo

2016-12-08

The uncertainties surrounding present and future sea-level rise have revived the debate around sea-level changes through the deglaciation and mid- to late Holocene, from which arises a need for high-quality reconstructions of regional sea level. Here, we explore the stratigraphy of a sandy barrier to identify the best sea-level indicators and provide a new sea-level reconstruction for the central Portuguese coast over the past 6.5 ka. The selected indicators represent morphological features extracted from coastal barrier stratigraphy, beach berm and dune-beach contact. These features were mapped from high-resolution ground penetrating radar images of the subsurface and transformed into sea-level indicators through comparison with modern analogs and a chronology based on optically stimulated luminescence ages. Our reconstructions document a continuous but slow sea-level rise after 6.5 ka with an accumulated change in elevation of about 2 m. In the context of SW Europe, our results show good agreement with previous studies, including the Tagus isostatic model, with minor discrepancies that demand further improvement of regional models. This work reinforces the potential of barrier indicators to accurately reconstruct high-resolution mid- to late Holocene sea-level changes through simple approaches.

Environmental strategies: A case study of systematic evaluation

NASA Astrophysics Data System (ADS)

Sherman, Douglas J.; Garès, Paul A.

1982-09-01

A major problem facing environmental managers is the necessity to effectively evaluate management alternatives. Traditional environmental assessments have emphasized the use of economic analyses. These approaches are often deficient due to difficulty in assigning dollar values to environmental systems and to social amenities. A more flexible decisionmaking model has been developed to analyze management options for coping with beach erosion problems at the Sandy Hook Unit of Gateway National Recreation Area in New Jersey. This model is comprised of decision-making variables which are formulated from a combination of environmental and management criteria, and it has an accept-reject format in which the management options are analyzed in terms of the variables. Through logical ordering of the insertion of the variables into the model, stepwise elimination of alternatives is possible. A hierarchy of variables is determined through estimating work required to complete an assessment of the alternatives for each variable. The assessment requiring the least work is performed first so that the more difficult evaluation will be limited to fewer alternatives. The application of this approach is illustrated with a case study in which beach protection alternatives were evaluated for the United States National Park Service.

Storm Observations of Persistent Three-Dimensional Shoreline Morphology and Bathymetry Along a Geologically Influenced Shoreface Using X-Band Radar (BASIR)

NASA Astrophysics Data System (ADS)

Brodie, K. L.; McNinch, J. E.

2008-12-01

Accurate predictions of shoreline response to storms are contingent upon coastal-morphodynamic models effectively synthesizing the complex evolving relationships between beach topography, sandbar morphology, nearshore bathymetry, underlying geology, and the nearshore wave-field during storm events. Analysis of "pre" and "post" storm data sets have led to a common theory for event response of the nearshore system: pre-storm three-dimensional bar and shoreline configurations shift to two-dimensional, linear forms post- storm. A lack of data during storms has unfortunately left a gap in our knowledge of how the system explicitly changes during the storm event. This work presents daily observations of the beach and nearshore during high-energy storm events over a spatially extensive field site (order of magnitude: 10 km) using Bar and Swash Imaging Radar (BASIR), a mobile x-band radar system. The field site contains a complexity of features including shore-oblique bars and troughs, heterogeneous sediment, and an erosional hotspot. BASIR data provide observations of the evolution of shoreline and bar morphology, as well as nearshore bathymetry, throughout the storm events. Nearshore bathymetry is calculated using a bathymetry inversion from radar- derived wave celerity measurements. Preliminary results show a relatively stable but non-linear shore-parallel bar and a non-linear shoreline with megacusp and embayment features (order of magnitude: 1 km) that are enhanced during the wave events. Both the shoreline and shore-parallel bar undulate at a similar spatial frequency to the nearshore shore- oblique bar-field. Large-scale shore-oblique bars and troughs remain relatively static in position and morphology throughout the storm events. The persistence of a three-dimensional shoreline, shore-parallel bar, and large-scale shore-oblique bars and troughs, contradicts the idea of event-driven shifts to two- dimensional morphology and suggests that beach and nearshore response to storms may be location specific. We hypothesize that the influence of underlying geology, defined by (1) the introduction of heterogeneous sediment and (2) the possible creation of shore-oblique bars and troughs in the nearshore, may be responsible for the persistence of three-dimensional forms and the associated shoreline hotspots during storm events.

Observations and modeling of surf zone transverse finger bars at the Gold Coast, Australia

NASA Astrophysics Data System (ADS)

Ribas, F.; Doeschate, A. ten; de Swart, H. E.; Ruessink, B. G.; Calvete, D.

2014-08-01

The occurrence and characteristics of transverse finger bars at Surfers Paradise (Gold Coast, Australia) have been quantified with 4 years of time-exposure video images. These bars are attached to the inner terrace and have an oblique orientation with respect to the coastline. They are observed during 24 % of the study period, in patches up to 15 bars, with an average lifetime of 5 days and a mean wavelength of 32 m. The bars are observed during obliquely incident waves of intermediate heights. Bar crests typically point toward the incoming wave direction, i.e., they are up-current oriented. The most frequent beach state when bars are present (43 % of the time) is a rhythmic low-tide terrace and an undulating outer bar. A morphodynamic model, which describes the feedback between waves, currents, and bed evolution, has been applied to study the mechanisms for finger bar formation. Realistic positive feedback leading to the formation of the observed bars only occurs if the sediment resuspension due to roller-induced turbulence is included. This causes the depth-averaged sediment concentration to decrease in the seaward direction, enhancing the convergence of sediment transport in the offshore-directed flow perturbations that occur over the up-current bars. The longshore current strength also plays an important role; the offshore root-mean-square wave height and angle must be larger than some critical values (0.5 m and 20∘, respectively, at 18-m depth). Model-data comparison indicates that the modeled bar shape characteristics (up-current orientation) and the wave conditions leading to the bar formation agree with data, while the modeled wavelengths and migration rates are larger than the observed ones. The discrepancies might be because in the model we neglect the influence of the large-scale beach configuration.

A new Stygarctus (Arthrotardigrada: Stygarctidae) from Japan, with entangled seminal receptacle ducts.

PubMed

Fujimoto, Shinta

2014-03-27

Stygarctus ayatori sp. nov. (Arthrotardigrada: Stygarctidae), is described from a sandy beach located at Okinoshima, Tateyama Bay, Boso Peninsula, Honshu, Japan. The most prominent characters were observed in the female genital structure, with the seminal receptacle ducts forming a three-dimensional entanglement near the exterior opening, and internal thickening situated peripheral to the gonopore and between the gonopore and anus. The new species is distinguished from the congeners by these characters; excluding S. abornatus McKirdy et al., 1976 for which there is no information on the genital structure. However, S. ayatori sp. nov. and S. abornatus can be differentiated by the presence of dorsal spines on the former species, which are absent from the latter.

A model integrating longshore and cross-shore processes for predicting long-term shoreline response to climate change

USGS Publications Warehouse

Vitousek, Sean; Barnard, Patrick; Limber, Patrick W.; Erikson, Li; Cole, Blake

2017-01-01

We present a shoreline change model for coastal hazard assessment and management planning. The model, CoSMoS-COAST (Coastal One-line Assimilated Simulation Tool), is a transect-based, one-line model that predicts short-term and long-term shoreline response to climate change in the 21st century. The proposed model represents a novel, modular synthesis of process-based models of coastline evolution due to longshore and cross-shore transport by waves and sea-level rise. Additionally, the model uses an extended Kalman filter for data assimilation of historical shoreline positions to improve estimates of model parameters and thereby improve confidence in long-term predictions. We apply CoSMoS-COAST to simulate sandy shoreline evolution along 500 km of coastline in Southern California, which hosts complex mixtures of beach settings variably backed by dunes, bluffs, cliffs, estuaries, river mouths, and urban infrastructure, providing applicability of the model to virtually any coastal setting. Aided by data assimilation, the model is able to reproduce the observed signal of seasonal shoreline change for the hindcast period of 1995-2010, showing excellent agreement between modeled and observed beach states. The skill of the model during the hindcast period improves confidence in the model's predictive capability when applied to the forecast period (2010-2100) driven by GCM-projected wave and sea-level conditions. Predictions of shoreline change with limited human intervention indicate that 31% to 67% of Southern California beaches may become completely eroded by 2100 under sea-level rise scenarios of 0.93 to 2.0 m.

A model integrating longshore and cross-shore processes for predicting long-term shoreline response to climate change

NASA Astrophysics Data System (ADS)

Vitousek, Sean; Barnard, Patrick L.; Limber, Patrick; Erikson, Li; Cole, Blake

2017-04-01

We present a shoreline change model for coastal hazard assessment and management planning. The model, CoSMoS-COAST (Coastal One-line Assimilated Simulation Tool), is a transect-based, one-line model that predicts short-term and long-term shoreline response to climate change in the 21st century. The proposed model represents a novel, modular synthesis of process-based models of coastline evolution due to longshore and cross-shore transport by waves and sea level rise. Additionally, the model uses an extended Kalman filter for data assimilation of historical shoreline positions to improve estimates of model parameters and thereby improve confidence in long-term predictions. We apply CoSMoS-COAST to simulate sandy shoreline evolution along 500 km of coastline in Southern California, which hosts complex mixtures of beach settings variably backed by dunes, bluffs, cliffs, estuaries, river mouths, and urban infrastructure, providing applicability of the model to virtually any coastal setting. Aided by data assimilation, the model is able to reproduce the observed signal of seasonal shoreline change for the hindcast period of 1995-2010, showing excellent agreement between modeled and observed beach states. The skill of the model during the hindcast period improves confidence in the model's predictive capability when applied to the forecast period (2010-2100) driven by GCM-projected wave and sea level conditions. Predictions of shoreline change with limited human intervention indicate that 31% to 67% of Southern California beaches may become completely eroded by 2100 under sea level rise scenarios of 0.93 to 2.0 m.

Relative sea level and coastal environments in arctic Alaska during Marine Isotope Stage 5

NASA Astrophysics Data System (ADS)

Farquharson, L. M.; Mann, D. H.; Jones, B. M.; Rittenour, T. M.; Grosse, G.; Groves, P.

2015-12-01

Marine Isotope Stage (MIS) 5 was characterized by marked fluctuations in climate, the warmest being MIS 5e (124-119 ka) when relative sea level (RSL) stood 2-10 m higher than today along many coastlines. In northern Alaska, marine deposits now 5-10 m above modern sea level are assigned to this time period and termed the Pelukian transgression (PT). Complicating this interpretation is the possibility that an intra-Stage 5 ice shelf extended along the Alaskan coast, causing isostatic depression along its grounded margins, which caused RSL highs even during periods of low, global RSL. Here we use optically stimulated luminescence (OSL) to date inferred PT deposits on the Beaufort Sea coastal plain. A transition from what we interpret to be lagoonal mud to sandy tidal flat deposits lying ~ 2.75 m asl dates to 113+/-18 ka. Above this, a 5-m thick gravelly barrier beach dates to 95 +/- 20 ka. This beach contains well-preserved marine molluscs, whale vertebrae, and walrus tusks. Pleistocene-aged ice-rich eolian silt (yedoma) blanket the marine deposits and date to 57.6 +/-10.9 ka. Our interpretation of this chronostratigraphy is that RSL was several meters higher than today during MIS 5e, and lagoons or brackish lakes were prevalent. Gravel barrier beaches moved onshore as local RSL rose further after MIS 5e. The error range of the OSL age of the barrier-beach unit spans the remaining four substages of MIS 5; however, the highstand of RSL on this arctic coastline appears to occurr after the warmest part of the last interglacial and appears not to be coeval with the eustatic maximum reached at lower latitudes during MIS 5. One possibility is that RSL along the Beaufort Sea coast was affected by isostatic depression caused by an ice shelf associated with widespread, intra-Stage 5 glaciation that was out of phase with lower latitude glaciation and whose extent and timing remains enigmatic.

Measuring the spatial variation in surface moisture on a coastal beach with an infra-red terrestrial laser scanner

NASA Astrophysics Data System (ADS)

Smit, Yvonne; Donker, Jasper; Ruessink, Gerben

2016-04-01

Coastal sand dunes provide essential protection against marine flooding. Consequently, dune erosion during severe storms has been studied intensively, resulting in well-developed erosion models for use in scientific and applied projects. Nowadays there is growing awareness that similarly advanced knowledge on dune recovery and growth is needed to predict future dune development. For this reason, aeolian sand transport from the beach into the dunes has to be investigated thoroughly. Surface moisture is a major factor limiting aeolian transport on sandy beaches. By increasing the velocity threshold for sediment entrainment, pick-up rates reduce and the fetch length increases. Conventional measurement techniques cannot adequately characterize the spatial and temporal distribution of surface moisture content required to study the effects on aeolian transport. Here we present a new method for detecting surface moisture at high temporal and spatial resolution using the RIEGL VZ-400 terrestrial laser scanner (TLS). Because this TLS operates at a wavelength near a water absorption band (1550 nm), TLS reflectance is an accurate parameter to measure surface soil moisture over its full range. Three days of intensive laser scanning were performed on a Dutch beach to illustrate the applicability of the TLS. Gravimetric soil moisture samples were used to calibrate the relation between reflectance and surface moisture. Results reveal a robust negative relation for the full range of possible surface moisture contents (0% - 25%). This relation holds to about 80 m from the TLS. Within this distance the TLS typically produces O(106-107) data points, which we averaged into soil moisture maps with a 0.25x0.25 m resolution. This grid size largely removes small moisture disturbances induced by, for example, footprints or tire tracks, while retaining larger scale trends. As the next step in our research, we will analyze the obtained maps to determine which processes affect the spatial and temporal surface-moisture variability.

Terrestrial laser scanning of anthropogenic beach berms for urban flood defense

NASA Astrophysics Data System (ADS)

Sanders, B. F.; Schubert, J.; Gallien, T.; Shakeri Majd, M.

2013-12-01

Globally, over 20 million people reside below present high tide levels and as many as 200 million are vulnerable to flooding during extreme events. In California, coastal flooding is driven by a combination of factors such as high astronomical tides, waves, storm surge, and other fluctuations such as those caused by the El Nino Southern Oscillation (ENSO), and climate change is likely to exacerbate those factors testing the limits of coastal flood defenses. Beaches provide natural flood protection during storms by mitigating the effects of high water levels and wave runup, and a process known as beach berming can be used to temporarily enhance the ability of beaches to withstand overtopping. In cases where beaches serve as primary protection for development, anthropogenic berms may represent an attractive management option for temporarily addressing future flood hazards. Terrestrial laser scanning (TLS) or lidar has emerged as a valuable technology for capturing the three dimensional geometry of complex surfaces and objects, and in the context of coastal flood prediction mobile TLS could prove invaluable by quickly mapping beach topography before an imminent flood threat and reducing associated uncertainties in coastal flood forecasting systems. The research presented here highlights the results of a field campaign to document the initial conditions and dynamic erosion of anthropogenic berms using TLS. On three occasions in February and March of 2012, a prototype berm was constructed on the foreshore of the city of Newport Beach, CA at low tide, and was scanned to document its initial shape, and then scanned in near-continuous fashion with the rising tide to characterize its subsequent erosion. The purpose is two-fold: (1) to measure the performance of the TLS system relative to accuracy and assess strengths and drawbacks that are likely to bear on the suitability of this technology to support flood prediction as described above, and (2) to develop a better understanding of how typical southern California berms respond to hydrodynamic stresses (rising tides and waves). Near continuous scanning leads to a 4D model (3 spatial coordinates plus time) of the berm that documents its gradual erosion, including a characterization of how the berm crest and volume change over time, which offers primary data on how anthropogenic berms can be expected to perform during a flood event. Results reveal that TLS, when referenced to a temporary bench mark leveled to within 1.5 cm by RTK-GPS, achieves an absolute vertical accuracy of less than 3 cm (VRMSE) with a scan resolution of 10 cm or finer. In regards to berm morphodynamics, a near-linear increase in tide elevation over two hours caused a non-linear lowering of the berm crest with time, characterized first by a gradual and then by a rapid change. The overall erosion of the berm correlates best with the swash elevation in relation to the berm toe elevation. Across the three berm experiments, erosion begins when the swash elevation is about 13% below the toe of the berm, relative to the initial berm height, and the berm is overtopped when the swash elevation is 25-30% of the initial berm height and the berm is 70-75% eroded by volume.

Dune Morphodynamics on a Semi-Arid, Wave-Dominated Barrier Island: South Padre Island, Texas

NASA Astrophysics Data System (ADS)

Del Angel, D. C.; Gibeaut, J. C.

2012-12-01

Spatial and temporal dune accretion along the barrier island of South Padre Island (SPI),Texas was examined using a combination of field measurements and lidar elevation data. Volume change rates derived from the data were compared to potential sediment transport rates derived from Hsu's (1974 & 1977) model using local wind-gauge data. A statistical model was then used to investigate controls on foredune accretion. Dune volume change was estimated from cross-shore profile measurements acquired during the summer of 2009, spring of 2010, and fall of 2010. For summer 2009 to spring 2010, dune volume change ranged from -18 to 12.5 m^3/m. The onshore potential drift for the same time period was estimated to be 6.6 m^3/m. In comparison, volume change ranged from -5.5 to 5.3 m^3/m for spring to fall 2010 with most dunes experiencing erosion. The estimated onshore drift was much higher at 22.5 m^3/m. The high drift potential associated with the spring and summer months is attributed to the predominant wind direction and the occurrence of tropical storms. Dune volume change was also observed on a longer time scale using lidar DEMs for the years 2000, 2005, and 2009. From 2000 to 2005, most natural dunes experienced accretion with a mean of 17.67 m^3/m, whereas between 2005 and 2009, the majority of dunes experienced volume loss with a mean change of -4.16 m^3/m. Overall, the mean volume change from 2000 to 2009 was 13.51 m^3/m. Onshore drift for 2000 to 2005 was estimated to be 16.44 m^3/m, which is a good approximation to the observed volume change. In contrast, onshore drift for 2000 to 2009 was estimated to be 80.4 m^3/m, which is substantially higher than the mean volume change observed during the period. The discrepancy between the modeled and observe value is partly due to dune volume loss from storm surge erosion. In addition, there was a significant increase in onshore drift potential from 2006 to 2008. Stepwise backward regression was used to find significant correlations (p-values < 0.01) between observed values in dune volume change and beach and dune morphometric parameters. Examined parameters include beach width, beach height, beach slope, shoreline orientation, the long-term rate of shoreline displacement, and aeolian dune form (washover terrace, dune terrace, dune ridge and active dunes). Model results show that dune type, beach width, and shoreline orientation were significant contributors. A hierarchical partitioning method provided further insight by showing that dune type explains most of the variation (57%), followed by beach width (30%) and lastly, orientation (< 2%). Based on the volumetric change analysis, results observed from 2000 to 2005 provide a good estimate of the average dune accretion for SPI because of the low impact of storms. But, from the wind models, potential transport has yearly fluctuations which can affect accretion rates. Furthermore, accretion will continue to be interrupted by the periodic occurrence of storms. Spatial variability of dune volume change is related to the existing dune form and beach morphology as evidenced by the statistical analysis. It is expected that the relative occurrence of washovers, terraces, ridges, and active dunes will vary in time as storms, drought and anthropogenic stresses change.

Geomorphology of the Chippewa River delta of Glacial Lake Saginaw, central Lower Michigan, USA

NASA Astrophysics Data System (ADS)

Connallon, Christopher B.; Schaetzl, Randall J.

2017-08-01

We introduce, characterize, and interpret the geomorphic history of a relict, Pleistocene-aged delta of the Chippewa River in central Lower Michigan. The broad, sandy Chippewa delta developed into various stages of Glacial Lake Saginaw, between ca. ≈ 17 and 15 ka·BP (calibrated ages). Although the delta was first identified in 1955 on a statewide glacial geology map, neither its extent nor its Pleistocene history had been previously determined. The delta is typically forested, owing to its wet, sandy soils, which stand out against the agricultural fields of the surrounding, loamy lake plain sediments. The delta heads near the city of Mt Pleasant and extends eastward onto the Saginaw Lowlands, i.e., the plain of Glacial Lake Saginaw. Data from 3285 water well logs, 180 hand augered sites, and 185 points randomly located in a GIS on two-storied (sand over loam) soils were used to determine the extent, textural properties, and thickness of the delta. The delta is ≈ 18 km wide and ≈ 38 km long and is sandy throughout. Deltaic sediments from neighboring rivers that also drained into Glacial Lake Saginaw merge with the lower Chippewa delta, obscuring its boundary there. The delta is thickest near the delta's head and in the center, but thins to 1-2 m or less on its eastern margins. Mean thicknesses are 2.3-2.9 m, suggestive of a thin sediment body, frequently impacted by the waves and fluctuating waters of the lakes. Although beach ridges are only weakly expressed across the delta because of the sandy sediment, the coarsest parts of the delta are generally coincident with some of these inferred former shorezones and have a broad, incised channel that formed while lake levels were low. The thick upper delta generally lies above the relict shorelines of Glacial Lakes Saginaw and Arkona (≈ 17.1 to ≈ 16 ka·BP), whereas most of the thin, distal delta is associated with Glacial Lake Warren (≈ 15 ka·BP). Together, these data suggest that the Chippewa delta formed and prograded as lake levels in the Saginaw Lowlands alternated and episodically fell. The result is a delta that is comparatively thin, expansive, and sandy. In some places, these sands have subsequently been reworked into fields of small parabolic dunes.

How does a tidal embayment morphodynamically react on sea level rise?

NASA Astrophysics Data System (ADS)

van der Wegen, Mick

2010-05-01

Conditions for (assumed) equilibrium in tidal embayments have been studied extensively in the past years with morphodynamic 1D models (Van Dongeren and De Vriend, 1994; Schuttelaars and de Swart, 1996, 2000; Lanzoni and Seminara, 2002) and 2D models (Hibma et al. [2003], Van der Wegen and Roelvink [2008]) Van der Wegen et al 2008). The current research addresses the impact of sea level rise on tidal embayments. Although effects of sea level rise may only become apparent after decades, the character of the embayment can change considerably. Examples are the (dis)appearance or re-allocation of intertidal flats, increased tidal resonance, shift from sediment export to import, deepening of channel area and other related (ecological) parameters. The research applies a 2D morphodynamic model (Delft3D) in an idealized environment. The model is based on the 2 D shallow water equations, the Engelund -Hansen transport formula and includes bed slope effects, drying and flooding procedures and an advanced morphodynamic update scheme (Roelvink 2006). The initial condition of the bathymetry is generated by 3000 years of morphodynamic calculations in a 80 km long and 2.5 km wide rectangular tidal embayment under constant M2 tidal forcing conditions (Van der Wegen and Roelvink [2008]). After this period sea level rise gradually developing towards a rate of 0.4 m/century is added to the boundary conditions. Model results describe development towards less intertidal area and a transition from an exporting system to a importing system. Model results are evaluated in terms of M2, M4 and M6 tidal constituents as well as against Vs/Vc (shoal volume over channel volume) versus a/h (amplitude over water depth) relationship as proposed by Friedrichs and Aubrey (1988). Although the model describes morphodynamic development in a strongly idealized environment the results can provide an excellent tool to systematically study the impact of sea level rise in tidal embayments as well as the time scales of dominant underlying resulting transport mechanisms and processes. DISSANAYAKE, D.M.P.K; RANASINGHE, R. and ROELVINK, J.A., 2009. Effect of Sea Level Rise in tidal inlet evolution: a numerical modelling approach. Journal of Coastal Research, SI 56 (Proceedings of the 10th International Coastal Symposium), pg - pg. Lisbon, Portugal. Friedrichs, C. T., and D. G. Aubrey (1988), Non-linear tidal distortion in shallow well mixed estuaries: A synthesis, Estuarine Coastal Shelf Sci.,27, 521- 545, doi:10.1016/0272-7714(88)90082-0. Hibma, A., H.M. Schuttelaars, and H. J. de Vriend (2003b), Initial formation and long-term evolution of channel-shoal patterns in estuaries, in Proc. 3rd RCEM conf.edited by A. Sánchez -Acrilla and A. Bateman, pp. 740-760, IAHR., Barcelona, Spain. Lanzoni, S., and G. Seminara (2002), Long-term evolution and morphodynamic equilibrium of tidal channels, J. Geophys. Res., 107(C1), 3001, doi:10.1029/2000JC000468. Roelvink, J. A. (2006), Coastal morphodynamic evolution techniques, J. Coastal Eng., 53, 177-187. Schuttelaars, H. M., and H. E. De Swart (1996), An idealized long termmorphodynamic model of a tidal embayment, Eur. J. Mech. B Fluids, 15(1), 55-80. Schuttelaars, H. M., and H. E. De Swart (2000), Multiple morphodynamic equilibria in tidal embayments, J. Geophys. Res., 105(C10), 24,105 - 24,118. Van Dongeren, A. D., and H. J. De Vriend (1994), A model of morphological behaviour of tidal basins, Coastal Eng., 22, 287- 310. van der Wegen, M., and J. A. Roelvink (2008), Long-term morphodynamic evolution of a tidal embayment using a twodimensional, process-based model, J. Geophys. Res., 113, C03016, doi:10.1029/2006JC003983 van der Wegen, M., Z. B. Wang, H. H. G. Savenije, and J. A. Roelvink (2008), Long-term morphodynamic evolution and energy dissipation in a coastal plain, tidal embayment, J. Geophys. Res., 113, F03001, doi:10.1029/2007JF000898

National assessment of shoreline change: A GIS compilation of vector shorelines and associated shoreline change data for the sandy shorelines of Kauai, Oahu, and Maui, Hawaii

USGS Publications Warehouse

Romine, Bradley M.; Fletcher, Charles H.; Genz, Ayesha S.; Barbee, Matthew M.; Dyer, Matthew; Anderson, Tiffany R.; Lim, S. Chyn; Vitousek, Sean; Bochicchio, Christopher; Richmond, Bruce M.

2012-01-01

Sandy ocean beaches are a popular recreational destination, and often are surrounded by communities that consist of valuable real estate. Development is increasing despite the fact that coastal infrastructure may be repeatedly subjected to flooding and erosion. As a result, the demand for accurate information regarding past and present shoreline changes is increasing. Working with researchers from the University of Hawaii, investigators with the U.S. Geological Survey's National Assessment of Shoreline Change Project have compiled a comprehensive database of digital vector shorelines and shoreline-change rates for the islands of Kauai, Oahu, and Maui, Hawaii. No widely accepted standard for analyzing shoreline change currently exists. Current measurement and rate-calculation methods vary from study to study, precluding the combination of study results into statewide or regional assessments. The impetus behind the National Assessment was to develop a standardized method for measuring changes in shoreline position that is consistent from coast to coast. The goal was to facilitate the process of periodically and systematically updating the measurements in an internally consistent manner. A detailed report on shoreline change for Kauai, Maui, and Oahu that contains a discussion of the data presented here is available and cited in the Geospatial Data section of this report.

The National assessment of shoreline shange—A GIS compilation of vector shorelines and associated shoreline change data for the Pacific Northwest coast

USGS Publications Warehouse

Kratzmann, Meredith G.; Himmelstoss, Emily A.; Ruggiero, Peter; Thieler, E. Robert; Reid, David

2013-01-01

Sandy ocean beaches are a popular recreational destination and are often surrounded by communities that consist of valuable real estate. Development along sandy coastal areas is increasing despite the fact that coastal infrastructure may be repeatedly subjected to flooding and erosion. As a result, the demand for accurate information regarding past and present shoreline changes is increasing. Investigators with the U.S. Geological Survey's National Assessment of Shoreline Change Project have compiled a comprehensive database of digital vector shorelines and rates of shoreline change for the Pacific Northwest coast including the states of Washington and Oregon. No widely accepted standard for analyzing shoreline change currently exists. Current measurement and methods for calculating rates of change vary from study to study, precluding the combination of study results into statewide or regional assessments. The impetus behind the national assessment was to develop a standardized method that is consistent from coast to coast for measuring changes in shoreline position. The goal was to facilitate the process of periodically and systematically updating the measurements in an internally consistent manner. A detailed report on shoreline change for the Pacific Northwest coast that contains a discussion of the data presented here is available and cited in the Geospatial Data section of this report.

Characteristics and environmental carrying capacities of coastal area in Yogyakarta Special Region for aquaculture

NASA Astrophysics Data System (ADS)

Triyatmo, B.; Rustadi; Priyono, S. B.

2018-03-01

The purpose of this study were to determine characteristics and environmental carrying capacities of coastal area in Yogyakarta Special Region for aquaculture. This study was conducted in 2015 by characterizing land and water dynamics, land use, and the suitability of coastal environments for aquaculture. Evaluation on the coastal environments suitability for aquaculture ponds was based on the landforms, soil properties, water quality and land. Selection of coastal locations for aquaculture development was based on the level of suitability of coastal environment. The results showed that the coastal in Kulon Progo and Bantul Regencies were characterized by sand dune and beach ridge with sandy soil texture, while in Gunungkidul Regency was characterized by limestone hill with rocky texture. Water sources of the coastal area were the sea, river, and ground water with the salinity of 31–37, 7–11, 7–31 ppt and pH of 7.4–8.4 7.0–8.2 and 7.4–9.9, respectively. The coastal lands were used for seasonal/annual planting, ponds, fish landing sites, tourism areas and conservation areas. The coastal carrying capacity was rather suitable for aquaculture, especially in the sandy soil area. Aquaculture in that area can be done intensively for shrimp (Litopenaeus vannamei), using biocrete (biological material) or plastic sheet.

Evaluation of NYC's Coastal Vulnerability and Potential Adaptation Strategies in the Wake of Hurricane Sandy

NASA Astrophysics Data System (ADS)

Miller, S. M.; Foti, R.; Montalto, F. A.

2015-12-01

New York City's coastlines are a mosaic of remnant natural habitat, man-made wetlands, manicured parkland, public beaches, housing, and industrial centers, all of which are extremely vulnerable to flooding, storm surge, and damaging wave action. Risks are projected to increase overtime as sea levels rise, population grows, and the frequency and severity of extreme events increases. In order to protect its citizens and infrastructure, New York City is planning to invest 20 billion into a coastal protection plan, including 200 million towards wetlands creation and restoration. Focusing on the role of wetlands and parkland in reducing damages during Hurricane Sandy, our study seeks to identify the primary causes of coastal vulnerability and to provide guidelines for the design of coastal protection measures. Our findings show that most of the small, fragmented NYC's wetlands did not provide significant protection from the violence of the hurricane. Large stretches of wetlands and parkland, on the other hand, were found to exacerbate storm surge along the coast, but did reduce surge penetration further inland. Much of the protection provided by wetlands and coastal green sites was in the form of cost avoidance. Wetlands existed in the most heavily hit areas and so averted damages that would have occurred if those areas had been developed. Our results suggest that, when positioned in the highest risk areas, coastal green infrastructure such as wetlands and parklands can reduce coastal flood risks associated with extreme events like Hurricane Sandy. Policy would ideally prioritize conservation, restoration, and enhancement of large contiguous areas of wetlands in the lowest elevation areas of the city. Where low-lying coastal development cannot be relocated, the risk of damage from storm surges is best reduced by elevating critical infrastructure.

Biogeochemical Controls on Biodegradation of MC252 Oil:Sand Aggregates on a Rapidly Eroding Coastal Headland Beach

NASA Astrophysics Data System (ADS)

Pardue, J.; Elango, V.; Urbano, M.; Lemelle, K.

2012-12-01

The research described below was conducted on Fourchon Beach, a coastal headland consisting of nine miles of fairly pristine sandy beaches and dunes, backed by wetlands and tidal channels, located between Belle Pass tidal inlet on the west and Elmer's Island on the east in Lafourche Parish, Louisiana. MC252 oil first arrived in large quantities on Fourchon Beach on or around May 20, 2010. A unique oil form created under these conditions was an aggregate of sand and emulsified oil, typically 0.1-10 cm in diameter, termed small surface residue balls (SSRBs). The work from this project made critical measurements on the factors controlling biodegradability of these SSRB aggregates. SSRB aggregates were sampled across transects perpendicular to the beach from the intertidal to the supratidal. Areas in the supratidal that were sampled initially were set aside for research purposes and not altered by any clean-up activities. Chemical composition of SSRBs was measured including concentrations of n-alkanes, PAHs, hopanes, nutrients (nitrate, nitrite, ammonium and orthophosphate measured on water extracts of SSRBs), and electron acceptor concentrations (O2 microprofiles measured on intact SSRBs and sulfate). Physical characterization of the SSRBs including length and area dimensions, mass, density, porosity, moisture content, and salinity using standard methods. Microbial characterization of SSRBs was also conducted using denaturing gradient gel electrophoresis and sequencing of dominant bands. SSRBs were sampled from various locations across the beach profile deposited by 2 significant tropical events in 2010; Hurricane Alex and TS Bonnie, and one event in 2011, TS Lee. Sampling focused on comparing and contrasting impacts of biogeochemistry on weathering of oil stranded in three beach microenvironments; supratidal surface; subtidal subsurface which is permanently inundated and intertidal subsurface samples which are intermittently inundated. The three types of oil are dramatically different in appearance and have a distinctive chemical signature indicative of different rates of weathering. Supratidal surface samples were depleted in n-alkanes and lower-molecular weight PAHs. Geochemically, aggregates located in these environments had low salinities (1.3-1.5 ppt), O2 at near saturation throughout the aggregates and nutrient concentrations (N and P) significantly lower than SSRBs deposited in the intertidal and subtidal. Intertidal and subtidal subsurface oil samples were characterized by elevated nutrient concentrations and salinities consistent with regular seawater inundation. Complete inundation leads to O2 consumption in the aggregates after several days. Despite the presence of elevated nutrients, PAHs and n-alkanes were comparatively unweathered in the subtidal subsurface samples consistent with O2 limitations. Sequences of known PAH degraders were isolated from the supratidal and intertidal aggregates. The results to be presented support the hypothesis that SSRBs deposited at different locations on the beach have different biogeochemical characteristics . These characteristics are due, in part, to their location on the landscape.

Effect of soil texture, tailwater height, and pore-water pressure on the morphodynamics of migrating headcuts in upland concentrated flows

USDA-ARS?s Scientific Manuscript database

Rill and gully erosion in upland and agricultural areas can result in significant soil degradation worldwide, and headcuts are the primary mechanism by which this landscape dissection occurs. Experiments were conducted to further examine the morphodynamic behavior of actively migrating headcuts in u...

Field scale test of multi-dimensional flow and morphodynamic simulations used for restoration design analysis

USGS Publications Warehouse

McDonald, Richard R.; Nelson, Jonathan M.; Fosness, Ryan L.; Nelson, Peter O.; Constantinescu, George; Garcia, Marcelo H.; Hanes, Dan

2016-01-01

Two- and three-dimensional morphodynamic simulations are becoming common in studies of channel form and process. The performance of these simulations are often validated against measurements from laboratory studies. Collecting channel change information in natural settings for model validation is difficult because it can be expensive and under most channel forming flows the resulting channel change is generally small. Several channel restoration projects designed in part to armor large meanders with several large spurs constructed of wooden piles on the Kootenai River, ID, have resulted in rapid bed elevation change following construction. Monitoring of these restoration projects includes post- restoration (as-built) Digital Elevation Models (DEMs) as well as additional channel surveys following high channel forming flows post-construction. The resulting sequence of measured bathymetry provides excellent validation data for morphodynamic simulations at the reach scale of a real river. In this paper we test the performance a quasi-three-dimensional morphodynamic simulation against the measured elevation change. The resulting simulations predict the pattern of channel change reasonably well but many of the details such as the maximum scour are under predicted.

Geomorphology and anthropogenic impact including military constraints in a microtidal wave-dominated embayment in south western Sardinia (Porto Pino beach, SCI ITB040025, Mediterranean Sea). Implications for beach management.

NASA Astrophysics Data System (ADS)

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

2016-04-01

The coastal zones of the Mediterranean have undergone increasing pressure over the last century. The intensifying coastal development and the increasing tourist impact have led to an intense transformation of the coastlines and adjacent marine areas. The beach and the coastal dune play an important role in protecting the coastline. Thus, the study of its geomorphological evolution and of its anthropic modification is fundamental in order to adopt the best management practices. In this regard, the LIFE Project (LIFE13NAT/IT/001013) SOSS DUNES (Safeguard and management Of South-western Sardinian Dunes) aims to safeguard the dune habitats and the beach system in a site belonging to the Natura 2000 network, an EUwide network of nature protection areas established under the 1992 Habitats Directive. This project is focused on a microtidal wave-dominated embayment located in south western Sardinia (Italy, Mediterranean Sea) called Porto Pino beach comprised in the SCI (Site of Community Importance) "Promontory, dunes and wetland of Porto Pino (ITB040025)". This research aims to investigate the geomorphological processes, the evolution and the main human impacts on Porto Pino beach as an useful tool for both conservation and coastal management. The coastal area of Porto Pino is represented by sandy shorelines extending for a total length of 5 km characterized by a wide primary and secondary dune systems, a backshore wetland lagoon and marsh area arranged parallel to the coastline. This littoral area can be ideally divided into three parts: the first, about 600 m long, in the north-west part characterized by the highest human pressure due to touristic activity on the foredunes and deposition of beach wrack; the second part in the south-east, about 1100 m long, characterized by a complex dune system (primary and secondary foredunes); and the third southernmost part included in a military area, about 3300 m long, characterized by transgressive dune system with low human impact. The coastal dunes vulnerability status of this three parts was assessed using the Dune Vulnerability Index (DVI) based on 57 variables that described geomorphological condition, marine influence, aeolian influence, vegetation condition, and human effects. Results reveal the lowest vulnerability value in the area undergone military constraints. Blowouts, breaches in the coastal dune system and deflation areas are observed in the first and second part where there is the greatest human transit to allow users access of the beach. The main pressures and threats identified that determine significant impacts on dune habitats are: transit of vehicles in the dune with the subsequent degradation of vegetation and the triggering of deflation processes; setting of infrastructure on the dune; removal of seagrass banquettes. In particular, the impact of trucks used to remove banquettes is significant on subaerial beach morphology. This traffic flattens the berms, modifies sand permeability and reduces organic sediment input to the shore. This study has allowed to highlight the geomorphological processes, the anthropic pressure and the coastal dune vulnerability of this coastal area in order to mitigate the impacts.

Morphodynamics: Rivers beyond steady state

NASA Astrophysics Data System (ADS)

Church, M.; Ferguson, R. I.

2015-04-01

The morphology of an alluvial river channel affects the movement of water and sediment along it, but in the longer run is shaped by those processes. This interplay has mostly been investigated empirically within the paradigm of Newtonian mechanics. In rivers, this has created an emphasis on equilibrium configurations with simple morphology and uniform steady flow. But transient adjustment, whether between equilibrium states or indefinitely, is to be expected in a world in which hydrology, sediment supply, and base level are not fixed. More fundamentally, water flows and all the phenomena that accompany them are inherently unsteady, and flows in natural channels are characteristically nonuniform. The morphodynamics of alluvial river channels is the striking consequence. In this paper, we develop the essential connection between the episodic nature of bed material transport and the production of river morphology, emphasizing the fundamental problems of sediment transport, the role of bar evolution in determining channel form, the role of riparian vegetation, and the wide range of time scales for change. As the key integrative exercise, we emphasize the importance of physics-based modeling of morphodynamics. We note consequences that can be of benefit to society if properly understood. These include the possibility to better be able to model how varying flows drive morphodynamic change, to understand the influence of the sediments themselves on morphodynamics, and to recognize the inherent necessity for rivers that transport bed material to deform laterally. We acknowledge pioneering contributions in WRR and elsewhere that have introduced some of these themes.

A Wireless Sensor Network for the Real-Time Remote Measurement of Aeolian Sand Transport on Sandy Beaches and Dunes

PubMed Central

Cappelli, Irene; Mecocci, Alessandro; Alquini, Fernanda

2018-01-01

Direct measurements of aeolian sand transport on coastal dunes and beaches is of paramount importance to make correct decisions about coast management. As most of the existing studies are mainly based on a statistical approach, the solution presented in this paper proposes a sensing structure able to orient itself according to wind direction and directly calculate the amount of wind-transported sand by collecting it and by measuring its weight. Measurements are performed remotely without requiring human action because the structure is equipped with a ZigBee radio module, which periodically sends readings to a local gateway. Here data are processed by a microcontroller and then transferred to a remote data collection centre, through GSM technology. The ease of installation, the reduced power consumption and the low maintenance required, make the proposed solution able to work independently, limiting human intervention, for all the duration of the expected experimental campaign. In order to analyze the cause-effect relationship between the transported sand and the wind, the sensing structure is integrated with a multi-layer anemoscope-anemometer structure. The overall sensor network has been developed and tested in the laboratory, and its operation has been validated in field through a 48 h measurement campaign. PMID:29518060

National assessment of shoreline change: historical change along the north coast of Alaska, U.S.-Canadian border to Icy Cape

USGS Publications Warehouse

Gibbs, Ann E.; Richmond, Bruce M.

2015-01-01

Similar to the earlier reports in this series, this report summarizes the methods of analysis, documents and describes the results of the analysis, and explains historical trends and rates of shoreline change. This Alaska shoreline change assessment differs from previously published shoreline change assessments in that: (1) only two historical shorelines (from the 1940s and 2000s eras) were available for the Alaska study area whereas four or more shorelines (from 1850 to 2002) were available for the other assessments and, thus, only end-point rates for one long-term analysis period are reported here, compared to a combination of long-term and short-term rates as reported in other studies; (2) modern (2000s era) shorelines in this study represent a visually derived land-water interface position versus an elevation based, tidally referenced shoreline position; and (3) both exposed open-ocean and sheltered mainland-lagoon shorelines and rates of change are included in this study compared to other locations where only exposed open-ocean sandy shorelines or bluff edges were evaluated. No distinction was made between sand or gravel beaches, and the base of the unconsolidated coastal bluff was considered the shoreline where no fronting beach existed.

Preliminary study of soil liquefaction hazard at Terengganu shoreline, Peninsular Malaysia

NASA Astrophysics Data System (ADS)

Hashim, H.; Suhatril, M.; Hashim, R.

2017-06-01

Terengganu is a shoreline state located in Peninsular Malaysia which is a growing hub for port industries and tourism centre. The northern part offers pristine settings of a relax beach areas whereas the southern part are observed to be a growing centre for development. The serious erosion on soil deposit along the beach line presents vulnerable soil condition to soil liquefaction consists of sandy with low plasticity and shallow ground water. Moreover, local earthquake from nearby fault have present significant tremors over the past few years which need to be considered in the land usage or future development in catering the seismic loading. Liquefaction analysis based on field standard penetration of soil is applied on 546 boreholes scattered along the shoreline areas ranging 244 km of shoreline stretch. Based on simplified approach, it is found that more than 70% of the studied areas pose high liquefaction potential since there are saturated loose sand and silt deposits layer ranges at depth 3 m and up to 20 m. The presence of clay deposits and hard stratum at the remaining 30% of the studied areas shows good resistance to soil liquefaction hence making the area less significant to liquefaction hazard. Result indicates that liquefaction improving technique is advisable in future development of shoreline areas of Terengganu state.

Maturation, fecundity, and intertidal spawning of Pacific sand lance in the northern Gulf of Alaska

USGS Publications Warehouse

Robards, Martin D.; Piatt, John F.; Rose, G.A.

1999-01-01

Pacific sand lance Ammodytes hexapterus in Kachemak Bay, Alaska, showed no sexual dimorphism in length-to-weight (gonad-free) ratio or length-at-age relationship. Most matured in their second year, males earlier in the season than females, but females (31%) attained a higher gonadosomatic index than males (21%). Sand lance spawned intertidally once each year in late September and October on fine gravel or sandy beaches soon after the seasonal peak in water temperatures. Sand lance in Cook Inlet and Prince William Sound displayed similar maturation schedules. Schools were dominated 2: 1 by males as they approached the intertidal zone at a site where spawning has taken place for decades. Sand lance spawned vigorously in dense formations, leaving scoured pits in beach sediments. Fecundity of females (93–199 mm) was proportional to length, ranging from 1468 to 16 081 ova per female. About half of the overall spawning school fecundity was derived from age group 1 females (55% of the school by number). Spawned eggs were 1·02 mm in diameter, demersal, slightly adhesive, and deposited in the intertidal just below the waterline. Sand lance embryos developed over 67 days through periods of intertidal exposure and sub-freezing air temperatures.

The whale barnacle Cryptolepas rhachianecti (Cirripedia: Coronulidae), a phoront of the grey whale Eschrichtius robustus (Cetacea: Eschrichtiidae), from a sandy beach in The Netherlands.

PubMed

Bosselaers, Mark; Collareta, Alberto

2016-08-22

An isolated compartment of a whale barnacle is herein described from Recent beach deposits in Zoutelande (Walcheren, The Netherlands). This specimen is identified as belonging to the extant coronulid species Cryptolepas rhachianecti, currently known as an epizoic symbiont of the grey whale Eschrichtius robustus. This find represents the first occurrence of C. rhachianecti outside the North Pacific, and the first one as a (sub)fossil. In view of the fact that E. robustus, which is currently confined to the North Pacific, is known as a subfossil from the northeastern Atlantic between late Late Pleistocene (c. 45,000 years ago) and historical (c. 1700 AD) times, we propose a similar (late Quaternary) age for the isolated compartment. The find indicates that the extinct late Quaternary northeastern Atlantic population of E. robustus was infected by Cryptolepas rhachianecti. Our find is, therefore, compatible with the hypothesis of an ancient grey whale migration route running between the subtropical/temperate waters of the northeast Atlantic (or Mediterranean Basin), and the cold waters of the Baltic Sea (or southern Arctic Ocean), through the southern North Sea. Finally, we discuss the systematic placement of the fossil barnacle species Cryptolepas murata and propose the possibility of its removal from the genus Cryptolepas pending further investigations.

Ground penetrating radar and differential global positioning system data collected in April 2016 from Fire Island, New York

USGS Publications Warehouse

Forde, Arnell S.; Bernier, Julie C.; Miselis, Jennifer L.

2018-02-22

Researchers from the U.S. Geological Survey (USGS) conducted a long-term coastal morphologic-change study at Fire Island, New York, prior to and after Hurricane Sandy impacted the area in October 2012. The Fire Island Coastal Change project objectives include understanding the morphologic evolution of the barrier island system on a variety of time scales (months to centuries) and resolving storm-related impacts, post-storm beach response, and recovery. In April 2016, scientists from the USGS St. Petersburg Coastal and Marine Science Center conducted geophysical and sediment sampling surveys on Fire Island to characterize and quantify spatial variability in the subaerial geology with the goal of subsequently integrating onshore geology with other surf zone and nearshore datasets.  This report, along with the associated USGS data release, serves as an archive of ground penetrating radar (GPR) and post-processed differential global positioning system (DGPS) data collected from beach and back-barrier environments on Fire Island, April 6–13, 2016 (USGS Field Activity Number 2016-322-FA). Data products, including unprocessed GPR trace data, processed DGPS data, elevation-corrected subsurface profile images, geographic information system files, and accompanying Federal Geographic Data Committee metadata are available for download.

A Wireless Sensor Network for the Real-Time Remote Measurement of Aeolian Sand Transport on Sandy Beaches and Dunes.

PubMed

Pozzebon, Alessandro; Cappelli, Irene; Mecocci, Alessandro; Bertoni, Duccio; Sarti, Giovanni; Alquini, Fernanda

2018-03-08

Direct measurements of aeolian sand transport on coastal dunes and beaches is of paramount importance to make correct decisions about coast management. As most of the existing studies are mainly based on a statistical approach, the solution presented in this paper proposes a sensing structure able to orient itself according to wind direction and directly calculate the amount of wind-transported sand by collecting it and by measuring its weight. Measurements are performed remotely without requiring human action because the structure is equipped with a ZigBee radio module, which periodically sends readings to a local gateway. Here data are processed by a microcontroller and then transferred to a remote data collection centre, through GSM technology. The ease of installation, the reduced power consumption and the low maintenance required, make the proposed solution able to work independently, limiting human intervention, for all the duration of the expected experimental campaign. In order to analyze the cause-effect relationship between the transported sand and the wind, the sensing structure is integrated with a multi-layer anemoscope-anemometer structure. The overall sensor network has been developed and tested in the laboratory, and its operation has been validated in field through a 48 h measurement campaign.

Morphodynamics and Sediment Transport on the Huanghe (Yellow River) Delta: Work in Progress

NASA Astrophysics Data System (ADS)

Kineke, G. C.; Calson, B.; Chadwick, A. J.; Chen, L.; Hobbs, B. F.; Kumpf, L. L.; Lamb, M. P.; Ma, H.; Moodie, A. J.; Mullane, M.; Naito, K.; Nittrouer, J. A.; Parker, G.

2017-12-01

Deltas are perhaps the most dynamic of coastal landforms with competing processes that deliver and disperse sediment. As part of the NSF Coastal SEES program, an interdisciplinary team of scientists from the US and China are investigating processes that link river and coastal sediment transport responsible for morphodynamic change of the Huanghe delta- an excellent study site due to its high sediment load and long history of natural and engineered avulsions, that is, abrupt shifts in the river course. A fundamental component of the study is a better understanding of sediment transport physics in a river system that transports mostly silt. Through theory and data analysis, we find that fine-grained rivers fail to develop full scale dunes, which results in faster water flow and substantially larger sediment fluxes as compared to sandy rivers (e.g. the Mississippi River). We also have developed new models for sediment-size dependent entrainment that are needed to make longer term predictions of river sedimentation patterns. On the delta front, we are monitoring the high sediment flux to the coast, which results in steep foresets and ideal conditions for off-shore sediment delivery via gravity flows. These constraints on sediment transport are being used to develop new theory for where and when rivers avulse - including the effects of variable flood discharge, sediment supply, and sea level rise -and how deltas ultimately grow through repeated cycles of lobe development. Flume experiments and field observations are being used to test these models, both in the main channel of the Huanghe and in channels abandoned after historic avulsions. Abandoned channels and floodplains are now dominated by coastal sediment transport through a combination of wave resuspension and tidal transport, settling lag and reverse estuarine circulation. Finally, the field and laboratory tested numerical models are being used as inputs to define a cost curve for efficient avulsion management of the Huanghe delta by minimizing expected flood-damage cost. Taken together, these studies can inform management policies and promote consideration of the natural evolution of deltas to achieve sustainability.

Geology of the Woods Hole area, Massachusetts; the story behind the landscape

USGS Publications Warehouse

Hutchinson, D.R.; Schwarzman, Beth

2001-01-01

The geologic story of the Woods Hole area, Cape Cod, Mass., was written by glacial ice during the last ice age and edited by the ocean waves. If you learn to read today's landscape, you can see the fascinating history it records. The features of Cape Cod, from the ponds and cranberry bogs to the gently sloping sandy uplands and rocky, irregular hills to the beaches, result from the glacial processes that built the cape and the marine processes that still shape it. Many geologists since the late 19th century have contributed to telling this story. The U.S. Geological Survey has studied the geology of Cape Cod in order to provide people with objective scientific data that can be applied to wise stewardship of the land and coasts.

Crocodilian Nest in a Late Cretaceous Sauropod Hatchery from the Type Lameta Ghat Locality, Jabalpur, India

PubMed Central

Srivastava, Rahul; Patnaik, Rajeev; Shukla, U. K.; Sahni, Ashok

2015-01-01

The well-known Late Cretaceous Lameta Ghat locality (Jabalpur, India) provides a window of opportunity to study a large stable, near shore sandy beach, which was widely used by sauropod dinosaurs as a hatchery. In this paper, we revisit the eggs and eggshell fragments previously assigned to lizards from this locality and reassign them to crocodylomorphs. Several features point to a crocodilian affinity, including a subspherical to ellipsoidal shape, smooth, uneven external surface, discrete trapezoid shaped shell units with wide top and narrow base, basal knobs and wedge shaped crystallites showing typical inverted triangular extinction under crossed nicols. The crocodylomorph eggshell material presented in this paper adds to the skeletal data of these most probably Cretaceous-Eocene dryosaurid crocodiles. PMID:26641665

The Outer Banks of North Carolina

USGS Publications Warehouse

Dolan, Robert; Lins, Harry F.; Smith, Jodi Jones

2016-12-27

The Outer Banks of North Carolina are excellent examples of the nearly 300 barrier islands rimming the Atlantic and Gulf coasts of the United States. These low, sandy islands are among the most dynamic natural landscapes occupied by man. Beach sands move offshore, onshore, and along the shore in the direction of the prevailing longshore currents. In this way, sandy coasts continuously adjust to different tide, wave, and current conditions and to rising sea level that causes the islands to migrate landward.Despite such changes, barrier islands are of considerable environmental importance. The Outer Banks are home to diverse natural ecosystems that are adapted to the harsh coastal environment. Native species tend to be robust and many are specifically adapted to withstand salt spray, periodic saltwater flooding, and the islands’ well-drained sandy soil. The Outer Banks provide an important stopover for birds on the Atlantic flyway, and many species inhabit the islands year round. In addition, Outer Banks beaches provide an important nesting habitat for five endangered or threatened sea turtle species.European explorers discovered North Carolina’s barrier islands in the 16th century, although the islands were not permanently settled until the middle 17th century. By the early 19th century, shipbuilding and lumber industries were among the most successful, until forest resources were depleted. Commercial fishing eventually followed, and it expanded considerably after the Civil War. By the Great Depression, however, little industry existed on the Outer Banks. In response to the effects of a severe hurricane in 1933, the National Park Service and the Civilian Conservation Corps proposed a massive sand-fixation program to stabilize the moving sand and prevent storm waves from sweeping across the entire width of some sections of the islands. Between 1933 and 1940, this program constructed sand fencing on 185 kilometers (115 miles) of beach and planted grass seedlings, trees, and shrubs.In 1937, Congress authorized the Cape Hatteras National Seashore, which was established in 1953. The national seashore preserved one of the world’s best examples of a barrier island environment, and minimized the effect of erosion that was becoming a serious problem. In 1966, Congress authorized the Cape Lookout National Seashore to ensure that Core and Shackleford Banks would not undergo major development and could be preserved in their natural state.The rate of population growth along the Outer Banks in recent decades has been among the highest in North Carolina. More important, however, has been the growth in vacationers—in 2008, more than a quarter of a million visitors during a typical week. Municipalities now need to provide services to a transient population as much as six times as large as their permanent resident population.Although human activities have dominated the landscape changes observed on the Outer Banks for the past century or two, these changes must be understood in the context of the prevailing atmospheric, oceanic, and geologic processes that have governed the form and function of these islands for thousands of years. It is these natural processes that imbue the Outer Banks with their unique and dichotomous qualities of tranquility and tumult. In the presence of human occupation, it is these same processes that make the islands one of the highest natural-hazard risk zones along the Eastern Seaboard of the United States.

Morphodynamic data assimilation used to understand changing coasts

USGS Publications Warehouse

Plant, Nathaniel G.; Long, Joseph W.

2015-01-01

Morphodynamic data assimilation blends observations with model predictions and comes in many forms, including linear regression, Kalman filter, brute-force parameter estimation, variational assimilation, and Bayesian analysis. Importantly, data assimilation can be used to identify sources of prediction errors that lead to improved fundamental understanding. Overall, models incorporating data assimilation yield better information to the people who must make decisions impacting safety and wellbeing in coastal regions that experience hazards due to storms, sea-level rise, and erosion. We present examples of data assimilation associated with morphologic change. We conclude that enough morphodynamic predictive capability is available now to be useful to people, and that we will increase our understanding and the level of detail of our predictions through assimilation of observations and numerical-statistical models.

The impact of tourism and personal leisure transport on coastal environments: A review

NASA Astrophysics Data System (ADS)

Davenport, John; Davenport, Julia L.

2006-03-01

Coastal tourism started in the 19th Century and has increased in non-linear fashion ever since, stimulated by a combination of developments in transport technology and rising prosperity. Initially, mainly national in character, the introduction of roll-on, roll-off ferries and inexpensive air transport caused an exponential 28-fold rise in international tourism between 1950 and the start of the 21st Century. This review considers the impact of tourism at two levels: (1) that created by the sheer numbers of tourists and their demands ('mass tourism and transport') and (2) that resulting from individual, often novel, forms of transport ('personal leisure transport'). Under (1), the consequences of the construction of coastal resorts and roads, marinas and jetties for habitat fragmentation and reduced biodiversity are described. Next, the effects of large cruise ships (now some 250 in number) are considered, particularly in relation to unregulated pollution and the delivery of substantial numbers of tourists to remote destinations. Thirdly, the literature related to disturbance caused by intertidal trampling by tourists on rocky/sandy shores is reviewed, followed by a section devoted to the unappreciated effects of beach 'cleaning' (i.e. removal of natural strandlines as well as litter) that is practiced throughout the world's sandy beach resorts. Finally, the potentially positive area of coastal ecotourism is considered, but evidence is assembled to highlight the problems associated with too high a demand. Under (2), the impact of a range of personal leisure transport modes is considered. These range from relatively innocuous pursuits (e.g. swimming, surfing, sailboarding and dinghy sailing), to an extremely popular sport (SCUBA diving) that is marketed for its environmentally-friendly nature, yet causes measurable deterioration in the world's coral ecosystems despite good management practices. The impact of motorboats is considered, particularly in the context of transmission of non-native species, while the highly polluting and disturbing technology of 'personal watercraft' is evaluated. Finally, the uncontrolled emergence of new 'extreme sports' (e.g. 'coasteering', kitesurfing) is identified as a future problem.

Geologic history of Cape Cod, Massachusetts

USGS Publications Warehouse

,

1976-01-01

Cape Cod, a sandy peninsula built mostly during the Ice Age, juts into the Atlantic Ocean like a crooked arm. Because of its exposed location, Cape Cod was visited by many early explorers. Although clear-cut evidence is lacking, the Vikings may have sighted this land about 1,000 years ago. It was visited by Samuel de Champlain in 1605, and his detailed descriptions and charts have helped present-day scientists to determine the rate of growth of Nauset Beach marsh and Nauset spit. Bartholomew Gosnold, a lesser known explorer, settled for a short time on the Elizabeth Islands to the southwest and gave Cape Cod its name in 1602. The Pilgrims first landed in America on the tip of Lower Cape Cod after they were turned back from their more southerly destination by shoals between Cape Cod and Nantucket Island. On Cape Cod they found potable water and food and had their first fight with the natives. The Pilgrims, however, decided that this land was too isolated, too exposed, and too sandy to support them, and they sailed across Cape Cod Bay to establish Plymouth. These features remain today. Small villages are separated by large areas of forest, dune, beach, and marsh. This unspoiled natural beauty makes Cape Cod one of the most favored vacation areas for the people living in the thickly settled Northeastern States. Cape Cod is of particular interest to geologists because it was formed by glaciers very recently in terms of geologic time. During the Great Ice Age, (the Pleistocene Epoch which began 2 to 3 million years ago), glaciers advanced from the north into the temperate regions of the Earth. Glacial ice covered the land at least four times. Each advance was accompanied by a worldwide lowering of sea level because the source of the ice was water from the seas. When the glaciers melted, the climate and sea level were probably much like they are today. In fact, some scientists believe that the Earth is presently between glacial episodes and that ice once again will advance across the land.

Temporal variation in life-history traits of the clam Tivela mactroides (Bivalvia: Veneridae): Density-dependent processes in sandy beaches

NASA Astrophysics Data System (ADS)

Turra, Alexander; Petracco, Marcelo; Amaral, A. Cecilia Z.; Denadai, Márcia R.

2014-10-01

Temporal variation in the structure and dynamics of a population of Tivela mactroides was examined over two periods (2003-2004 and 2007-2008) in the southern part of Caraguatatuba Bay, southeastern Brazil. During the first period from January 2003 to October 2004, sampling was conducted monthly. Sampling in the second period was performed in the summer (January and February 2007 and 2008) and winter (July and August 2007 and 2008). The von Bertalanffy growth function was applied to estimate growth parameters for both periods from length-frequency distributions. Production was determined using the mass-specific growth rate method. Results indicated that the mean abundance (±SE) of T. mactroides varied sharply between the two periods, with an increase of almost 150 times from 2003 to 2004 (8.67·102 ± 0.83·102 ind m-1) to 2007-2008 (1.25·105 ± 3.33·104 ind m-1). The higher abundance in the second period was related to successful recruitment events. While the mean biomass and the production were higher in the second (5.43 ± 0.87 kg AFDM m-1 and 7.89 kg AFDM m-1 yr-1) than in the first period (0.18 ± 0.02 kg AFDM m-1 and 0.18 kg AFDM m-1 yr-1), lower values of shell length, curvature parameter, asymptotic length of the VBGF, and the growth index phi-prime in 2007-2008 (17.57 ± 1.35 mm; K = 0.40 yr-1; L∞ = 38.60 mm, ϕ‧ = 2.78) than in 2003-2004 (26.21 ± 1.21 mm; K = 1.00 yr-1; L∞ = 40.75 mm, ϕ‧ = 3.22) were related to a strongly density-dependent growth process in the second period. The oscillation in growth observed in the second, but not in the first period also indicates a process of density-dependent growth. These sharp temporal variations in population parameters of T. mactroides suggest the occurrence of density-dependent processes, and reinforce the importance of these processes in structuring sandy-beach populations.

Large-eddy simulation of sand dune morphodynamics

NASA Astrophysics Data System (ADS)

Khosronejad, Ali; Sotiropoulos, Fotis; St. Anthony Falls Laboratory, University of Minnesota Team

2015-11-01

Sand dunes are natural features that form under complex interaction between turbulent flow and bed morphodynamics. We employ a fully-coupled 3D numerical model (Khosronejad and Sotiropoulos, 2014, Journal of Fluid Mechanics, 753:150-216) to perform high-resolution large-eddy simulations of turbulence and bed morphodynamics in a laboratory scale mobile-bed channel to investigate initiation, evolution and quasi-equilibrium of sand dunes (Venditti and Church, 2005, J. Geophysical Research, 110:F01009). We employ a curvilinear immersed boundary method along with convection-diffusion and bed-morphodynamics modules to simulate the suspended sediment and the bed-load transports respectively. The coupled simulation were carried out on a grid with more than 100 million grid nodes and simulated about 3 hours of physical time of dune evolution. The simulations provide the first complete description of sand dune formation and long-term evolution. The geometric characteristics of the simulated dunes are shown to be in excellent agreement with observed data obtained across a broad range of scales. This work was supported by NSF Grants EAR-0120914 (as part of the National Center for Earth-Surface Dynamics). Computational resources were provided by the University of Minnesota Supercomputing Institute.

Observations of storm morphodynamics using Coastal Lidar and Radar Imaging System (CLARIS): Importance of wave refraction and dissipation over complex surf-zone morphology at a shoreline erosional hotspot

NASA Astrophysics Data System (ADS)

Brodie, Katherine L.

Elevated water levels and large waves during storms cause beach erosion, overwash, and coastal flooding, particularly along barrier island coastlines. While predictions of storm tracks have greatly improved over the last decade, predictions of maximum water levels and variations in the extent of damage along a coastline need improvement. In particular, physics based models still cannot explain why some regions along a relatively straight coastline may experience significant erosion and overwash during a storm, while nearby locations remain seemingly unchanged. Correct predictions of both the timing of erosion and variations in the magnitude of erosion along the coast will be useful to both emergency managers and homeowners preparing for an approaching storm. Unfortunately, research on the impact of a storm to the beach has mainly been derived from "pre" and "post" storm surveys of beach topography and nearshore bathymetry during calm conditions. This has created a lack of data during storms from which to ground-truth model predictions and test hypotheses that explain variations in erosion along a coastline. We have developed Coastal Lidar and Radar Imaging System (CLARIS), a mobile system that combines a terrestrial scanning laser and an X-band marine radar system using precise motion and location information. CLARIS can operate during storms, measuring beach topography, nearshore bathymetry (from radar-derived wave speed measurements), surf-zone wave parameters, and maximum water levels remotely. In this dissertation, we present details on the development, design, and testing of CLARIS and then use CLARIS to observe a 10 km section of coastline in Kitty Hawk and Kill Devil Hills on the Outer Banks of North Carolina every 12 hours during a Nor'Easter (peak wave height in 8 m of water depth = 3.4 m). High decadal rates of shoreline change as well as heightened erosion during storms have previously been documented to occur within the field site. In addition, complex bathymetric features that traverse the surf-zone into the nearshore are present along the southern six kilometers of the field site. In addition to the CLARIS observations, we model wave propagation over the complex nearshore bathymetry for the same storm event. Data reveal that the complex nearshore bathymetry is mirrored by kilometer scale undulations in the shoreline, and that both morphologies persist during storms, contrary to common observations of shoreline and surf-zone linearization by large storm waves. We hypothesize that wave refraction over the complex nearshore bathymetry forces flow patterns which may enhance or stabilize the shoreline and surf-zone morphology during storms. In addition, our semi-daily surveys of the beach indicate that spatial and temporal patterns of erosion are strongly correlated to the steepness of the waves. Along more than half the study site, fifty percent or more of the erosion that occurred during the first 12 hours of the storm was recovered within 24 hours of the peak of the storm as waves remained large (>2.5 m), but transitioned to long period swell. In addition, spatial variations in the amount of beach volume change during the building portion of the storm were strongly correlated with observed wave dissipation within the inner surf zone, as opposed to predicted inundation elevations or alongshore variations in wave height.

Dune formation on the Cooper Creek floodplain, Strzelecki Desert, Australia - first results of morphodynamic simulations

NASA Astrophysics Data System (ADS)

Kryger, Mateusz; Bubenzer, Olaf; Parteli, Eric

2017-04-01

Linear Dunes, which align longitudinally to the resultant wind vector, are the prevailing type of the south-north trending and partially vegetated dunes in the Strzelecki Desert, Australia. However, particularly on the Cooper Creek floodplain near Innamincka, striking complex dune features consisting of transversely oriented east-west trending dunes occur. These transverse dunes extend over several kilometers and are superimposed by linear dunes that elongate northwards and are separated by sandy swales. The aeolian features in the Strzelecki Desert are the result of interrelated late quaternary aeolian and fluvial activity and serve, thus, as archives providing information about variations in palaeoclimate and potential changes in fluvial sediment supply and wind strength and directionality. However, since the dunes are currently mostly stabilized by vegetation, it is uncertain whether their formation can be explained by the contemporary wind systems. To understand the dynamic processes underlying the genesis of the dune field in the Strzelecki Desert, the role of vegetation and the wind regimes leading to the observed dune patterns must be elucidated. Here we investigate the formative processes of the dune features occurring on the Cooper Creek floodplain by means of morphodynamic modeling of aeolian sand transport and dune formation in presence of vegetation growth. Our simulations show that a source-bordering dune can be formed out of the sediments of seasonally exposed sandbars of the palaeo-Cooper system by a unidirectional wind, which explains the emergence of the transverse dunes in the field. Moreover, a shift in the wind regime to obtuse bidirectional wind flows combined with a rapid decrease in the vegetation cover leads to the formation of linear dunes on the surface and in the lee of the transverse dunes. These linear dunes elongate over several kilometers downwind as a result of the seasonal wind changes. The dune shapes obtained in our simulations agree well with the real dune morphologies when a low vegetation growth rate is applied in the model. Although geochronological investigations, reported in the literature, on the Cooper Creek floodplain did not show the linear dunes declining in age downwind (which suggests the adjacent swales or the transverse dune to be the sediment source), our simulations show that strikingly similar linear dune morphologies can be obtained by sediment influx due to saltation alone. In this case, the bars of the palaeo-Cooper system might as well have served as the sediment source for the formation of the linear dunes. Therefore, our results suggest that a long-distance transport extension model could also explain the linear dune formation, while previous geochronological investigations supported the wind-rift vertical extension and wind-rift vertical accretion models. The morphodynamic simulations may thus not only help to reconstruct the palaeoenvironment of the northern Strzelecki Desert, but also provide insights for the interpretation of the sediment archives located on the Cooper Creek alluvial fan.

Dunes Around Khnifiss Lagoon (Tarfaya, SW of Morocco): Composition, Itinerary In Dune Fields, Effects on Dunes' Colours and Morphodynamic

NASA Astrophysics Data System (ADS)

Adnani, M.; Azzaoui, M. A.; Elbelrhiti, H.; Ahmamou, M.; Masmoudi, L.

2015-12-01

Dunes around Khnifiss lagoon (28° 3'N, 12°13'W) show different colors ranging from black at the beach, whitish yellow in transverse dunes near the beach to reddish at the mega barchans situated few kilometers in the SW. The scientific question is about the abundance of different dunes in the same environmental conditions. The present work aims to investigate the factors that influence dunes color change, and then at which degree these factors could control dunes stability. To highlight the difference in color observed at the dune fields then to characterize dunes mineralogy, Landsat TM images were used in addition to mineralogical analysis that was carried out for the black grains samples originated from megabarchans. Optic Microscope and SEM- EDS data was adopted, in addition to physico-chemical analysis provided by Electronic Microprobe. Grain size and shape analysis were conducted to characterize the different types of grains of sand. 3/1 Landsat image band ratio allowed iron oxide distinction, the results revealed the importance of iron oxide concentration. Furthermore, mineralogical and physico-chemical analysis revealed (i) a high grade of oxides (Rutile, Ilmenite, Magnetite, Ulvöspinel) in samples, (ii) silicates (Quartz, Clinopyroxene, feldspar, Zircon), (iii) phosphate (apatite) and (iv) carbonate (calcite). The grain size analysis of the sand originated from the megabarchans reveals that there are three populations of sand. Black grains with a diameter less than 100μm and dominated by the magnetite, red ones composed mainly by the quartz with diameter between 100 and 180 μm and grains with diameter more than 180 μm are white and composed by carbonates. The threshold of motion of these different grains was calculated. It shows that these different grains have the same threshold of motion, which means that the grain size compensates the density. This explains the abundance of different populations of sand in the same environment. The dominance of iron oxides justified the color black in sand. However, the whitish yellow and reddish color observed in dunes could be attributed to iron oxide clay coating, produced under weathering conditions, covering the grains of quartz. Key words: black sand, Landsat, Iron Oxide, Khnifiss beach, megadunes, Tarfaya, Morocco

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.

Close-range airborne photogrammetry: an effective tool for high-resolution sandy beach morphometric surveys. Examples from embayed beaches in French Guyana.

NASA Astrophysics Data System (ADS)

Brunier, Guillaume; Fleury, Jules; Anthony, Edward; Gardel, Antoine; Dussouillez, Philippe

2015-04-01

Photogrammetric techniques are at a turning point in their history with the development of new algorithms, such as SIFT (Lowe, 1999) for automatic camera alignment and point cloud densification (Furukawa, 2010) integrated in user-friendly end-products. These innovations facilitate the utilization of this technique to study objects with low to mild morphological contrasts at low cost and by non-specialists. It is now possible to produce high-resolution 3D morphometric models, and derived products such as Digital Surface Models (DSM) and Orthophotographs. We conducted three photogrammetric experiments on the embayed beach of Montjoly (4 km long, 100-200 m wide) in Cayenne, French Guyana, in order to quantify morphological changes. The beach is affected by rotation induced by westward migration of mud banks from the Amazon that generate spatio-temporal changes in wave refraction and incident wave angles. The current rotation involves massive erosion of the northern part of the beach (50 m retreat between October 2013 and March 2014) and deposition in the southern sector (50 m advance). We acquired subvertical aerial photographs from a microlight aircraft using a full frame DSLR sensor with a 50 mm lens synchronized with an onboard DGPS, and flew alongshore at low elevation (900 ft). The flight plan included several parallel flight axes with a 50 m interband distance. Meanwhile on the ground, we placed around 30 square targets of 40 cm width georeferenced by RTK-DGPS with centimetre accuracy. These targets served in producing the georeferenced output 3D model. Third, we measured the topography of random points and cross-shore profiles to validate our results and assess the process accuracy. We produced the model and its derived products with user-friendly Agisoft Photoscan© software. We obtained three morphometric models realized in October 2013, March 2014 and October 2014 covering the entire beach. These models were produced at a resolution of 10 cm per pixel and have a mean vertical accuracy less than +/- 5 cm compared to the GPS control points, with a maximum of 20 cm in marginal sectors near vegetation and in the swash zone in low-water conditions. To our knowledge, this is the first time a poorly textured surface composed of sand is reconstructed by photogrammetry, contrast in the studied object being necessary for this method. Our highly accurate photo resolution and pre-processing permitted imaging enough texture to proceed. Morphological features in the upper surf zone such as rip channels, and subaerial features, such as erosion scarps and aeolian forms, clearly appear. The comparison between the DSM validates the estimation of sediment transfers and the rotation process on this beach, unlike traditional beach monitoring with GPS, which involves large uncertainty linked to sparse point acquisition. It can be claimed that photogrammetry is low-cost, user-friendly, and offers new perspectives for non-specialist users in geomorphology and other fields recquiring high-resolution topographic data. It combines the advantages of the reproducibility of GPS topographic surveys and the high density and accuracy of LIDAR, but at very advantageous cost compared to the latter.

Modelling the hydrodynamic and morphosedimentary response of an beach-headland system (Algarve, Southern Portugal)

NASA Astrophysics Data System (ADS)

Horta, João; Oliveira, Sónia; Moura, Delminda

2015-04-01

Future behaviour of beaches within a headland-beach system is of fundamental interest on coastal evolution since they act as a buffer between the waves' attack and the cliffs backing them. The beaches at the cliffs' foot anchored between headlands are space-limited environments to morphosedimentary processes. Additionally, headlands and shore platforms are natural barriers to the alongshore drift. Several attempts to develop numerical expressions to characterize the stability of headland-beach systems have been made based mainly on linear parameters. However, in the sandy areas occur volumetric variations of greater magnitude that changes in the shoreline position in a tidal cycle. This work aims to quantify the balance between the incoming and the lost sediment in two embayed beaches in order to improve knowledge of the sedimentary dynamics of such environments and therefore the evolution of coastal landscapes. The study area is the Algarve coastal karstic landscapes, which raises challenging questions on morphosedimentary processes because it has dozens of stacks and cavities both in the surf zone and in the nearshore that interfere with the littoral current patterns. The field campaigns were performed during spring tide conditions in February and March, 2011. The nearshore wave climate and the current's velocity and direction were measured using respectively a non-vented Level TROLL 700 Pressure Transducer (PT) and an autonomously deployable electro-magnetic current meter (EMCM) Infinity-EM with a data logger. The offshore wave data used was acquired through the Portuguese Hydrographic Institute (IH) at the Faro buoy, located 50 km southeast from the study area. The topographic surveys were performed for a total area of about 1500 m2 using two Global Navigation Satellite System receptors (GPS Trimble R6 and GPS Trimble 5800) in real-time kinematic mode (RTK) with differential global positioning system (DGPS) providing centimetric accuracy. The altimetric values ranged between -2 and +6 m (mean sea level-msl). The automatic determination of the spatial characteristics of the beach morphology results from the GIS tools. The wave and current post processing was made using the STWAVE and Bouss-2D model software. Our results showed that: (i) the shore orientation is the major factor for the height of the waves approaching the coast (considering the same offshore climate) and thus to the wave energy input to transport sediment, (ii) the shore platforms which extend up to -7 m (msl) determine a very irregular pattern of the shoaling waves and distance of the breaking point from the shoreline, (iii) as a consequence of (ii) the rip currents in the surf zone show a very complex pattern and the direction of the sedimentary transport can be opposite to the direction of the incoming waves, (iv) the pattern of the rip currents is highly variable depending on the water depth, (v) the results obtained for volumetric balances showed a negative balance (erosion higher than accretion) at the smaller embayed beach and a positive balance (accretion higher than erosion) at the larger one. This work is a contribution to the PTDC/GEO-GEO/3981/2012 funded by the Portuguese Foundation for Science and Technology.

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.

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.

The implications of variable remigration intervals for the assessment of population size in marine turtles.

PubMed

Hays, G C

2000-09-21

Sea turtles nest on sandy beaches and tend to show high fidelity to specific nesting areas, but, despite this fidelity, the inter-annual variation in nesting numbers may be large. This variation may reflect the fact that turtles do not usually nest in consecutive years. Here, theoretical models are developed in which the interval between successive nesting years (the remigration interval) reflects conditions encountered on the feeding grounds, with good feeding years leading to a reduction in the remigration interval and vice versa. These simple models produce high levels of inter-annual variation in nesting numbers with, on occasion, almost no turtles nesting in some years even when the population is large and stable. The implications for assessing the size of sea turtle populations are considered. Copyright 2000 Academic Press.

Diets and trophic guilds of small fishes from coastal marine habitats in western Taiwan.

PubMed

Egan, J P; Chew, U-S; Kuo, C-H; Villarroel-Diaz, V; Hundt, P J; Iwinski, N G; Hammer, M P; Simons, A M

2017-07-01

The diets and trophic guilds of small fishes were examined along marine sandy beaches and in estuaries at depths <1·5 m in western Taiwan, Republic of China. Copepods were the most frequently identified item in fish guts, indicating they are key prey for the fish assemblages studied. Piscivore, crustacivore, detritivore, omnivore, zooplanktivore and terrestrial invertivore trophic guilds were identified. The zooplanktivore guild contained the most fish species. Maximum prey size consumption was positively correlated with standard length (L S ) in seven species and at the assemblage level and negatively correlated with L S in a single detritivorous species. The diet data and trophic guild scheme produced by this study contribute to an understanding of coastal marine food webs and can inform ecosystem-based fisheries management. © 2017 The Fisheries Society of the British Isles.

The use of genetic programming to develop a predictor of swash excursion on sandy beaches

NASA Astrophysics Data System (ADS)

Passarella, Marinella; Goldstein, Evan B.; De Muro, Sandro; Coco, Giovanni

2018-02-01

We use genetic programming (GP), a type of machine learning (ML) approach, to predict the total and infragravity swash excursion using previously published data sets that have been used extensively in swash prediction studies. Three previously published works with a range of new conditions are added to this data set to extend the range of measured swash conditions. Using this newly compiled data set we demonstrate that a ML approach can reduce the prediction errors compared to well-established parameterizations and therefore it may improve coastal hazards assessment (e.g. coastal inundation). Predictors obtained using GP can also be physically sound and replicate the functionality and dependencies of previous published formulas. Overall, we show that ML techniques are capable of both improving predictability (compared to classical regression approaches) and providing physical insight into coastal processes.

Two Sea-Level Challenges

NASA Astrophysics Data System (ADS)

Galvin, C.

2008-12-01

"No place on the sandy ocean shores of the world has been shown to be eroding because of sea level rise." This statement appeared nearly 19 years ago in bold print at the top of the page in a brief article published in Shore and Beach (Galvin,1990). The term "sea level rise" was defined in 1990 as follows: "In this statement, "sea level rise" has the meaning that the average person on the street usually attaches to that term. That is, sea level is rising; not, as in some places like the Mississippi River delta, land level is sinking." While still a subject of controversy, it is now (2008) increasingly plausible (Tornqvist et al,2008) that damage from Hurricane Katrina was significantly worse on the Mississippi River delta because floodwaters exploited wetlands and levees whose elevations had been lowered by decades of compaction in the underlying soil. (1) "Sea level" commonly appears in the literature as "relative sea level rise", occurring that way in 711 publications between 1980 and 2009 (GeoRef database on 8 Sep 08). "Relative sea level rise" does not appear in the 2005 AGI Glossary. The nearest Glossary term is "relative change in sea level", but that term occurs in only 12 publications between 1980 and 2009. The Glossary defines this term in a sequence stratigraphy sense, which infers that "relative sea level rise" is the sum of bottom subsidence and eustatic sea level rise. In plain English, "relative sea level rise" means "water depth increase". For present day coastal environments, "relative sea level rise" is commonly used where eustatic sea level rise is less than subsidence, that is, where the magnitude of actual sea level rise is smaller than the magnitude of subsidence. In that situation, "relative sea level rise" misleads both the average person and the scientist who is not a coastal geologist. Thus, the first challenge is to abandon "relative sea level rise" in favor of "water depth increase", in order that the words accurately descibe what happens. It would further clarify popular understanding if the term "actual sea level rise" were used in place of "eustatic sea level rise". (2)Geologists have approximated the the practice of paleontologists and biologists in establishing type examples of important geological features. This is a useful practice. A graduate geologist holds in mind clear conceptions of "beach cusps", "drumlin fields", "birdfoot deltas", and "igneous sills" based on seeing field examples accepted by professional geologists as representative of these features. However, although publications frequently report that sea level rise erodes a particular beach, no one identifies a type beach where that cause has been proven to produce the alleged effect. At the type beach, it is necessary to show that sea level is rising, and that the beach erodes primarily from this sea level rise, rather than from interrupted longshore transport. Thus, the second challenge is to identify a type ocean beach proven to erode because of sea level rise.

National Assessment Of Shoreline Change: Part 2, Historical Shoreline Changes And Associated Coastal Land Loss Along The U.S. Southeast Atlantic Coast

USGS Publications Warehouse

Morton, Robert A.; Miller, Tara L.

2005-01-01

EXECUTIVE SUMMARY Beach erosion is a chronic problem along most open-ocean shores of the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information regarding past and present trends and rates of shoreline movement. There is also a need for a comprehensive analysis of shoreline movement that is consistent from one coastal region to another. To meet these national needs, the U.S. Geological Survey is conducting an analysis of historical shoreline changes along open-ocean sandy shores of the conterminous United States and parts of Hawaii and Alaska. One purpose of this work is to develop standard repeatable methods for mapping and analyzing shoreline movement so that periodic updates regarding coastal erosion and land loss can be made nationally that are systematic and internally consistent. This report on states comprising the Southeast Atlantic Coast (east Florida, Georgia, South Carolina, North Carolina) represents the second in a series that already includes the Gulf of Mexico and will eventually include the Northeast Atlantic Coast, Pacific Coast, and parts of Hawaii and Alaska. The report summarizes the methods of analysis, interprets the results, provides explanations regarding the historical and present trends and rates of change, and describes how different coastal communities are responding to coastal erosion. Shoreline change evaluations are based on comparing three historical shorelines with a recent shoreline derived from lidar (Light Detection and Ranging) topographic surveys. The historical shorelines generally represent the following periods: 1800s, 1920s-1930s, and 1970s, whereas the lidar shoreline is 1998-2002. Long-term rates of change are calculated using four shorelines (1800s to lidar shoreline), whereas short-term rates of change are calculated for the most recent period (1970s to lidar shoreline). The historical rates of change presented in this report represent past conditions and therefore are not intended for predicting future shoreline positions or rates of change. Rates of erosion for the Southeast Atlantic region were generally highest in South Carolina along barrier islands and headland shores associated with the Santee delta. Erosion was also rapid along some barrier islands in North Carolina. Highest rates of erosion in Florida were generally localized around tidal inlets. The most stable Southeast Atlantic beaches were along the east coast of Florida where low wave energy and frequent beach nourishment minimized erosion. Some beach segments in Florida accreted as a result of net longshore drift convergence around Cape Canaveral and around tidal inlets that were stabilized by jetties. Seawalls, riprap revetments, and groins were constructed in all the Southeast Atlantic states as initial community responses to long-term beach erosion. Although some states, such as Florida, still permit shoreline stabilization structures, beach nourishment has become the preferred method of mitigating long-term erosion. Beach nourishment is common in all of the Southeast Atlantic states except Georgia.

Coupling Solute and Fine Particle Transport with Sand Bed Morphodynamics within a Field Experiment

NASA Astrophysics Data System (ADS)

Phillips, C. B.; Ortiz, C. P.; Schumer, R.; Jerolmack, D. J.; Packman, A. I.

2017-12-01

Fine suspended particles are typically considered to pass through streams and rivers as wash load without interacting with the bed, however experiments have demonstrated that hyporheic flow causes advective exchange of fine particles with the stream bed, yielding accumulation of fine particle deposits within the bed. Ultimately, understanding river morphodynamics and ecosystem dynamics requires coupling both fine particle and solute transport with bed morphodynamics. To better understand the coupling between these processes we analyze a novel dataset from a controlled field experiment conducted on Clear Run, a 2nd order sand bed stream located within the North Carolina coastal plain. Data include concentrations of continuously injected conservative solutes and fine particulate tracers measured at various depths within the stream bed, overhead time lapse images of bed forms, stream discharge, and geomorphological surveys of the stream. We use image analysis of bed morphodynamics to assess exchange, retention, and remobilization of solutes and fine particles during constant discharge and a short duration experimental flood. From the images, we extract a time series of bedform elevations and scour depths for the duration of the experiment. The high-resolution timeseries of bed elevation enables us to assess coupling of bed morphodynamics with both the solute and fine particle flux during steady state mobile bedforms prior to the flood and to changing bedforms during the flood. These data allow the application of a stochastic modeling framework relating bed elevation fluctuations to fine particle residence times. This combined experimental and modeling approach ultimately informs our ability to predict not only the fate of fine particulate matter but also associated nutrient and carbon dynamics within streams and rivers.

Barrier island morphodynamic classification based on lidar metrics for north Assateague Island, Maryland

USGS Publications Warehouse

Brock, John C.; Krabill, William; Sallenger, Asbury H.

2004-01-01

In order to reap the potential of airborne lidar surveys to provide geological information useful in understanding coastal sedimentary processes acting on various time scales, a new set of analysis methods are needed. This paper presents a multi-temporal lidar analysis of north Assateague Island, Maryland, and demonstrates the calculation of lidar metrics that condense barrier island morphology and morphological change into attributed linear features that may be used to analyze trends in coastal evolution. The new methods proposed in this paper are also of significant practical value, because lidar metric analysis reduces large volumes of point elevations into linear features attributed with essential morphological variables that are ideally suited for inclusion in Geographic Information Systems. A morphodynamic classification of north Assategue Island for a recent 10 month time period that is based on the recognition of simple patterns described by lidar change metrics is presented. Such morphodynamic classification reveals the relative magnitude and the fine scale alongshore variation in the importance of coastal changes over the study area during a defined time period. More generally, through the presentation of this morphodynamic classification of north Assateague Island, the value of lidar metrics in both examining large lidar data sets for coherent trends and in building hypotheses regarding processes driving barrier evolution is demonstrated

Dynamic equilibrium behaviour observed on two contrasting tidal flats from daily monitoring of bed-level changes

NASA Astrophysics Data System (ADS)

Hu, Zhan; van der Wal, Daphne; Cai, Huayang; van Belzen, Jim; Bouma, Tjeerd J.

2018-06-01

Dynamic equilibrium theory (DET) has been applied to tidal flats to systematically explain intertidal morphological responses to various distributions of bed shear stress (BSS). However, it is difficult to verify this theory with field observations because of the discrepancy between the idealized conceptions of theory and the complex reality of intertidal dynamics. The core relation between intertidal morphodynamics and BSS distribution can be easily masked by noise in complex datasets, leading to conclusions of insufficient field evidence to support DET. In the current study, hydrodynamic and morphodynamic data were monitored daily for one year on two tidal flats with contrasting wave exposures. BSS distribution was obtained by validated numerical models. Tidal flat dynamic equilibrium behaviour and BSS were linked via Empirical Orthogonal Function (EOF) analysis. We show that the principal morphodynamic modes corresponded well with the respective modes of BSS found at both sites. Tide-induced BSS was the dominant force at both sites, regardless of the level of wave exposure. The overall erosional and steepening trend found at the two flats can be attributed to the prevailing action of tidal forcing and reduced sediment supply. Hence, EOF analysis confirmed that tidal flat morphodynamics are consistent with DET, providing both field and model evidence to support this theory.

The Hidden Microplastics: New Insights and Figures from the Thorough Separation and Characterization of Microplastics and of Their Degradation Byproducts in Coastal Sediments.

PubMed

Ceccarini, Alessio; Corti, Andrea; Erba, Francesca; Modugno, Francesca; La Nasa, Jacopo; Bianchi, Sabrina; Castelvetro, Valter

2018-05-15

The environmental pollution by plastic debris directly dispersed in or eventually reaching marine habitats is raising increasing concern not only for the vulnerability of marine species to ingestion and entanglement by macroscopic debris, but also for the potential hazards from smaller fragments down to a few micrometer size, often referred to as "microplastics". A novel procedure for the selective quantitative and qualitative determination of organic solvent soluble microplastics and microplastics degradation products (<2 mm) in shoreline sediments was adopted to evaluate their concentration and distribution over the different sectors of a Tuscany (Italy) beach. Solvent extraction followed by gravimetric determination and chemical characterization by FT-IR, Pyrolysis-GC-MS, GPC and 1 H NMR analyses showed the presence of up to 30 mg microplastics in 1 kg sand, a figure corresponding to about 5.5 g of generally undetected and largely underestimated microplastics in the upper 10 cm layer of a square meter of sandy beach ! The extracted microplastic material was essentially polystyrene and polyolefin byproducts from oxidative degradation and erosion of larger fragments, with accumulation mainly above the storm berm. Chain scission and oxidation processes cause significant variations in the physical and chemical features of microplastics, promoting their adsorption onto sand particles and thus their persistence in the sediments.

Comparative Transcriptome Analysis of the Cosmopolitan Marine Fungus Corollospora maritima Under Two Physiological Conditions

PubMed Central

Velez, Patricia; Alejandri-Ramírez, Naholi D.; González, María C.; Estrada, Karel J.; Sanchez-Flores, Alejandro; Dinkova, Tzvetanka D.

2015-01-01

Marine sandy beaches represent dynamic environments often subject to harsh conditions and climate fluctuations, where natural and anthropogenic inputs of freshwater from fluvial and pluvial sources alter salinity, which has been recognized as a key variable affecting the distribution of aquatic organisms and influencing critical physiological processes. The marine arenicolous fungus Corollospora maritima is a worldwide-distributed saprobe that has been reported to present tolerance to freshwater. Here, we present a transcriptome analysis that will provide the first insight of the genomic content for this fungus and a gene expression comparison between two different salinity conditions. We also identified genes that are candidates for being differentially expressed in response to environmental variations on salinity during the fungal growth. The de novo reconstruction of C. maritima transcriptome Illumina sequencing provided a total of 14,530 transcripts (16 megabases). The comparison between the two growth conditions rendered 103 genes specifically overexpressed in seawater, and 132 genes specifically up-regulated under freshwater. Using fungal isolates collected from different beaches, the specific environmental regulation of particular transcript differential expression was confirmed by RT-qPCR. To our knowledge, this is the first analysis that explores the marine fungus C. maritima molecular responses to overcome freshwater stress, and these data could shed light to understand the fungal adaptation and plasticity mechanisms to the marine habitat. PMID:26116293

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.

Metrics for assessing the performance of morphodynamic models of braided rivers at event and reach scales

NASA Astrophysics Data System (ADS)

Williams, Richard; Measures, Richard; Hicks, Murray; Brasington, James

2017-04-01

Advances in geomatics technologies have transformed the monitoring of reach-scale (100-101 km) river morphodynamics. Hyperscale Digital Elevation Models (DEMs) can now be acquired at temporal intervals that are commensurate with the frequencies of high-flow events that force morphological change. The low vertical errors associated with such DEMs enable DEMs of Difference (DoDs) to be generated to quantify patterns of erosion and deposition, and derive sediment budgets using the morphological approach. In parallel with reach-scale observational advances, high-resolution, two-dimensional, physics-based numerical morphodynamic models are now computationally feasible for unsteady, reach-scale simulations. In light of this observational and predictive progress, there is a need to identify appropriate metrics that can be extracted from DEMs and DoDs to assess model performance. Nowhere is this more pertinent than in braided river environments, where numerous mobile channels that intertwine around mid-channel bars result in complex patterns of erosion and deposition, thus making model assessment particularly challenging. This paper identifies and evaluates a range of morphological and morphological-change metrics that can be used to assess predictions of braided river morphodynamics at the timescale of single storm events. A depth-averaged, mixed-grainsize Delft3D morphodynamic model was used to simulate morphological change during four discrete high-flow events, ranging from 91 to 403 m3s-1, along a 2.5 x 0.7 km reach of the braided, gravel-bed Rees River, New Zealand. Pre- and post-event topographic surveys, using a fusion of Terrestrial Laser Scanning and optical-empirical bathymetric mapping, were used to produce 0.5 m resolution DEMs and DoDs. The pre- and post-event DEMs for a moderate (227m3s-1) high-flow event were used to calibrate the model. DEMs and DoDs from the other three high-flow events were used for model assessment using two approaches. First, "morphological" metrics were applied to compare observed and predicted post-event DEMs. These metrics include measures of confluence and bifurcation node density, bar shape, braiding intensity, and topographic comparisons using a form of the Brier Skill Score and cumulative frequency distributions of rugosity. Second, "morphological change" metrics were used to compare observed and predicted morphological change. These metrics included the extent of the morphologically active area, pairwise comparisons of morphological change (using kappa and fuzzy kappa statistics), and comparisons between vertical morphological change magnitude and elevation distribution. Results indicate that those metrics that assess characteristic features of braiding, rather than making direct comparisons, are most useful for assessing reach-scale braided river morphodynamic models. Together, the metrics indicate that there was a general affinity between observed and predicted braided river morphodynamics, both during small and large magnitude high-flow events. These results thus demonstrate how high-resolution, reach-scale, natural experiment datasets can be used to assess the efficacy of morphological models in predicting realistic patterns of erosion and deposition. This lays the foundation for the development and assessment of decadal scale morphodynamic models and their use in adaptive river basin management.

Activation and synchronization of the oscillatory morphodynamics in multicellular monolayer

PubMed Central

Lin, Shao-Zhen; Li, Bo; Lan, Ganhui; Feng, Xi-Qiao

2017-01-01

Oscillatory morphodynamics provides necessary mechanical cues for many multicellular processes. Owing to their collective nature, these processes require robustly coordinated dynamics of individual cells, which are often separated too distantly to communicate with each other through biomaterial transportation. Although it is known that the mechanical balance generally plays a significant role in the systems’ morphologies, it remains elusive whether and how the mechanical components may contribute to the systems’ collective morphodynamics. Here, we study the collective oscillations in the Drosophila amnioserosa tissue to elucidate the regulatory roles of the mechanical components. We identify that the tensile stress is the key activator that switches the collective oscillations on and off. This regulatory role is shown analytically using the Hopf bifurcation theory. We find that the physical properties of the tissue boundary are directly responsible for synchronizing the oscillatory intensity and polarity of all inner cells and for orchestrating the spatial oscillation patterns inthe tissue. PMID:28716911

Morphodynamics of submarine channel inception revealed by new experimental approach

PubMed Central

de Leeuw, Jan; Eggenhuisen, Joris T.; Cartigny, Matthieu J. B.

2016-01-01

Submarine channels are ubiquitous on the seafloor and their inception and evolution is a result of dynamic interaction between turbidity currents and the evolving seafloor. However, the morphodynamic links between channel inception and flow dynamics have not yet been monitored in experiments and only in one instance on the modern seafloor. Previous experimental flows did not show channel inception, because flow conditions were not appropriately scaled to sustain suspended sediment transport. Here we introduce and apply new scaling constraints for similarity between natural and experimental turbidity currents. The scaled currents initiate a leveed channel from an initially featureless slope. Channelization commences with deposition of levees in some slope segments and erosion of a conduit in other segments. Channel relief and flow confinement increase progressively during subsequent flows. This morphodynamic evolution determines the architecture of submarine channel deposits in the stratigraphic record and efficiency of sediment bypass to the basin floor. PMID:26996440

Post-Hurricane Sandy coastal oblique aerial photographs collected from Cape Lookout, North Carolina, to Montauk, New York, November 4-6, 2012

USGS Publications Warehouse

Morgan, Karen L.M.; Krohn, M. Dennis

2014-01-01

The U.S. Geological Survey (USGS) conducts baseline and storm response photography missions to document and understand the changes in vulnerability of the Nation's coasts to extreme storms. On November 4-6, 2012, approximately one week after the landfall of Hurricane Sandy, the USGS conducted an oblique aerial photographic survey from Cape Lookout, N.C., to Montauk, N.Y., aboard a Piper Navajo Chieftain (aircraft) at an altitude of 500 feet (ft) and approximately 1,000 ft offshore. This mission was flown to collect post-Hurricane Sandy data for assessing incremental changes in the beach and nearshore area since the last survey in 2009. The data can be used in the assessment of future coastal change. The photographs provided here are Joint Photographic Experts Group (JPEG) images. The photograph locations are an estimate of the position of the aircraft and do not indicate the location of the feature in the images. These photos document the configuration of the barrier islands and other coastal features at the time of the survey. Exiftool was used to add the following to the header of each photo: time of collection, Global Positioning System (GPS) latitude, GPS longitude, keywords, credit, artist (photographer), caption, copyright, and contact information. Photographs can be opened directly with any JPEG-compatible image viewer by clicking on a thumbnail on the contact sheet. Table 1 provides detailed information about the GPS location, image name, date, and time each of the 9,481 photographs were taken, along with links to each photograph. The photographs are organized in segments, also referred to as contact sheets, and represent approximately 5 minutes of flight time. In addition to the photographs, a Google Earth Keyhole Markup Language (KML) file is provided and can be used to view the images by clicking on the marker and then clicking on either the thumbnail or the link above the thumbnail. The KML files were created using the photographic navigation files.

Physical linkages between an offshore canyon and surf zone morphologic change

NASA Astrophysics Data System (ADS)

Hansen, Jeff E.; Raubenheimer, Britt; Elgar, Steve; List, Jeffrey H.; Lippmann, Thomas C.

2017-04-01

The causes of surf zone morphologic changes observed along a sandy beach onshore of a submarine canyon were investigated using field observations and a numerical model (Delft3D/SWAN). Numerically simulated morphologic changes using four different sediment transport formulae reproduce the temporal and spatial patterns of net cross-shore integrated (between 0 and 6.5 m water depths) accretion and erosion observed in a ˜300 m alongshore region, a few hundred meters from the canyon head. The observations and simulations indicate that the accretion or erosion results from converging or diverging alongshore currents driven primarily by breaking waves and alongshore pressure gradients. The location of convergence or divergence depends on the direction of the offshore waves that refract over the canyon, suggesting that bathymetric features on the inner shelf can have first-order effects on short-term nearshore morphologic change.

USGS: Science at the intersection of land and ocean

USGS Publications Warehouse

Myers, M.D.

2009-01-01

The US Geological Survey (USGS) conducts an ongoing national assessment of coastal change hazards in order to help protect lives and support management of coastal infrastructure and resources. The research group rapidly gathers to investigate coastal changes along the Gulf Coast's sandy beaches after each hurricane to examine the magnitude and variability of impacts. This investigation helps to protect the environment and the American people by preparing maps that show the extreme coastal change. It also posts online video and still photography and LIDAR (light detection and ranging) survey data after each storm, to provide a clear picture of the devastated area. The USGS provides data to understand changing coastal vulnerabilities so that informed decisions can be made to protect disaster affected areas and its resources. Earth scientists in the USGS are learning more about coastal dynamics, determining changes, and improving the ability to forecast how coastal environments will respond to the next storm.

Short-term changes in mobile dunes at Port Alfred, South Africa

NASA Astrophysics Data System (ADS)

Lubke, Roy A.; Sugden, Jean

1990-03-01

Development along the western beachfront of Port Alfred, which is situated along a sandy shoreline, increased markedly in the 1960s as the coastal town became a popular holiday resort. This development included the removal of coastal vegetation, which resulted in the destabilization of dunes and migration of sand westerly onto the road, West Beach parking lot, and lawns of the cabanas. Sand traps were constructed to collect sand blowing across the dunes over set periods, and the net sand movement along the mobile dune belt was calculated using Hunter's equation. The dunes show an easterly movement of sand at a rate of 3.5 m/yr, which is comparable with figures recorded along other areas of this coastline. Considering the wind regime and amount of sand movement along this coast, it is inappropriate to clear vegetation and develop within the dune region.

The development of a probabilistic approach to forecast coastal change

USGS Publications Warehouse

Lentz, Erika E.; Hapke, Cheryl J.; Rosati, Julie D.; Wang, Ping; Roberts, Tiffany M.

2011-01-01

This study demonstrates the applicability of a Bayesian probabilistic model as an effective tool in predicting post-storm beach changes along sandy coastlines. Volume change and net shoreline movement are modeled for two study sites at Fire Island, New York in response to two extratropical storms in 2007 and 2009. Both study areas include modified areas adjacent to unmodified areas in morphologically different segments of coast. Predicted outcomes are evaluated against observed changes to test model accuracy and uncertainty along 163 cross-shore transects. Results show strong agreement in the cross validation of predictions vs. observations, with 70-82% accuracies reported. Although no consistent spatial pattern in inaccurate predictions could be determined, the highest prediction uncertainties appeared in locations that had been recently replenished. Further testing and model refinement are needed; however, these initial results show that Bayesian networks have the potential to serve as important decision-support tools in forecasting coastal change.

Simulations of dredged sediment spreading on a Posidonia oceanica meadow off the Ligurian coast, Northwestern Mediterranean.

PubMed

Capello, M; Cutroneo, L; Ferranti, M P; Budillon, G; Bertolotto, R M; Ciappa, A; Cotroneo, Y; Castellano, M; Povero, P; Tucci, S

2014-02-15

The sandy deposits from dredging can have negative effects on the environment such as increase in suspended solids in the water column and their consequent transport. An experimental study was conducted to characterize water masses, dynamics, and sedimentation rates on the Ligurian continental shelf (Italy), where both a sand deposit, that could be used for beach nourishment, and a nearby Posidonia oceanica meadow coexist. The environmental plan provides a mathematical simulation of the sediment-dispersion to evaluate the possible impact on the meadow. It has been calculated that the dredging could double the concentration of suspended particles, but its scheduling will preclude a sediment accumulation. All the information obtained from this work will be used to study the environmental feasibility of the sand deposit exploitation and as starting point for drawing up the monitoring plan in case of dredging. Copyright © 2013 Elsevier Ltd. All rights reserved.

KSC00pp0325

NASA Image and Video Library

2000-03-10

The Orange Crusher team (282) works on their robot, which is named Rust Bot, during the FIRST competition. The team of students from Lake Howell, Winter Springs and Orange Christian Private high schools was co-sponsored by NASA Kennedy Space Center, Matern Professional Engineering The Foundation, Control Technologies, Lucent Technologies and Sandy Engineering. Students from all over the country are at the KSC Visitor Complex for the FIRST (For Inspiration and Recognition of Science and Technology) Southeast Regional competition March 9-11 in the Rocket Garden. Teams of high school students are testing the limits of their imagination using robots they have designed, with the support of business and engineering professionals and corporate sponsors, to compete in a technological battle against other schools' robots. Of the 30 high school teams competing, 16 are Florida teams co-sponsored by NASA and KSC contractors. Local high schools participating are Astronaut, Bayside, Cocoa Beach, Eau Gallie, Melbourne, Melbourne Central Catholic, Palm Bay, Rockledge, Satellite, and Titusvill

KSC-00pp0325

NASA Image and Video Library

2000-03-10

The Orange Crusher team (282) works on their robot, which is named Rust Bot, during the FIRST competition. The team of students from Lake Howell, Winter Springs and Orange Christian Private high schools was co-sponsored by NASA Kennedy Space Center, Matern Professional Engineering The Foundation, Control Technologies, Lucent Technologies and Sandy Engineering. Students from all over the country are at the KSC Visitor Complex for the FIRST (For Inspiration and Recognition of Science and Technology) Southeast Regional competition March 9-11 in the Rocket Garden. Teams of high school students are testing the limits of their imagination using robots they have designed, with the support of business and engineering professionals and corporate sponsors, to compete in a technological battle against other schools' robots. Of the 30 high school teams competing, 16 are Florida teams co-sponsored by NASA and KSC contractors. Local high schools participating are Astronaut, Bayside, Cocoa Beach, Eau Gallie, Melbourne, Melbourne Central Catholic, Palm Bay, Rockledge, Satellite, and Titusvill

Morphodynamics of an Anthropogenically Altered Dual-Inlet System: John’s Pass and Blind Pass, West-Central Florida, USA

DTIC Science & Technology

2012-01-01

and Estuarine Environments: Sedimentology , Geomorphology and Geoarchaeology, 175. Geological Society London Special Publication, pp. 293–303. Davis Jr...1996. Geomorphic variability and morphologic and sedimentologic controls on tidal inlets. Journal of Coastal Research 23, 47–71. FitzGerald, D.M., 2011...Morphodynamics and facies architecture of tidal inlets and tidal deltas. In: Davis, R.A., Dalrymple, R.W. (Eds.), Principles of Tidal Sedimentology

Is “morphodynamic equilibrium” an oxymoron?

USGS Publications Warehouse

Zhou, Zeng; Coco, Giovanni; Townend, Ian; Olabarrieta, Maitane; van der Wegen, Mick; Gong, Zheng; D'Alpaos, Andrea; Gao, Shu; Jaffe, Bruce E.; Gelfenbaum, Guy R.; He, Qing; Wang, Yaping; Lanzoni, Stefano; Wang, Zhengbing; Winterwerp, Han; Zhang, Changkuan

2017-01-01

Morphodynamic equilibrium is a widely adopted yet elusive concept in the field of geomorphology of coasts, rivers and estuaries. Based on the Exner equation, an expression of mass conservation of sediment, we distinguish three types of equilibrium defined as static and dynamic, of which two different types exist. Other expressions such as statistical and quasi-equilibrium which do not strictly satisfy the Exner conditions are also acknowledged for their practical use. The choice of a temporal scale is imperative to analyse the type of equilibrium. We discuss the difference between morphodynamic equilibrium in the “real world” (nature) and the “virtual world” (model). Modelling studies rely on simplifications of the real world and lead to understanding of process interactions. A variety of factors affect the use of virtual-world predictions in the real world (e.g., variability in environmental drivers and variability in the setting) so that the concept of morphodynamic equilibrium should be mathematically unequivocal in the virtual world and interpreted over the appropriate spatial and temporal scale in the real world. We draw examples from estuarine settings which are subject to various governing factors which broadly include hydrodynamics, sedimentology and landscape setting. Following the traditional “tide-wave-river” ternary diagram, we summarize studies to date that explore the “virtual world”, discuss the type of equilibrium reached and how it relates to the real world.

An extreme breaching of a barrier spit: insights on large breach formation and its impact on barrier dynamics

NASA Astrophysics Data System (ADS)

Iulian Zăinescu, Florin; Vespremeanu-Stroe, Alfred; Tătui, Florin

2017-04-01

In this study, we document a case of exceptionally large natural breaching of a sandy spit (Sacalin barrier, Danube delta) using Lidar data and satellite imagery, annual (and seasonal) surveys of topography and bathymetry on successive cross-barrier profiles, and hourly datasets of wind and waves. The breach morphology and dynamics was monitored and described from its inception to closure, together with its impact on the adjoining features (upper shoreface, back-barrier lagoon, downdrift coast) and on the local sediment budgets. Breaching is first observed to occur on a beach-length of 0.5 km in April 2012 and two years later reached 3.5 km (May 2014). The barrier translates to a recovery stage dominated by continuous back-barrier deposition through subaqueous cross-breach sediment transport. Soon, the barrier widening triggers a negative feedback which limits the back-barrier sediment transfer. As a result, back-barrier deposition decreases whilst the barrier aggradation through overwash becomes more frequent. The event was found to be a natural experiment which switched the barrier's decadal evolution from low cross-shore transport to high cross-shore transport over the barrier. Although previously considered as constant, the cross-shore transport recorded during the large breach lifespan is an order of magnitude larger than in the non-breach period. 3 x 106 m3 of sediment were deposited in three years which is equivalent to the modelled longshore transport in the region. Nevertheless, the sediment circuits are more complex involving exchanges with the upper shoreface, as indicated by the extensive erosion down to -4m. In the absence of tides, the Sacalin breach closed naturally in 3 years and brings a valuable contribution on how breaches may evolve, as only limited data has been internationally reported until now. The very high deposition rate of sediment in the breach is a testimony of the high sediment volumes supplied by the longshore transport and the high sediment release through shoreface retreat, and resulted in widening the barrier to a maximum of 1 km. Since the newly-formed barrier shoreline got displaced backward up to 500 m, this reveals that barrier breaching is an important mechanism which significantly accelerates the landward migration of the barrier system and is a proof of the highly nonlinear morphodynamics involved in the barrier island translation. We demonstrate that the 2012-2015 event was an example of complex barrier breaching which has a substantial influence on the longer-term evolution of the spit. Studies of breaching help us understand the barrier evolution and will help coastal erosion risk management policy makers undertake better decisions on barrier management practice.

Agglomeration of a comprehensive model for the wind-driven sand transport at the Belgian Coast

NASA Astrophysics Data System (ADS)

Strypsteen, Glenn; Rauwoens, Pieter

2016-04-01

Although a lot of research has been done in the area of Aeolian transport, it is only during the last years that attention has been drawn to Aeolian transport in coastal areas. In these areas, the physical processes are more complex, due to a large number of transport limiting parameters. In this PhD-project, which is now in its early stage, a model will be developed which relates the wind-driven sand transport at the Belgian coast with physical parameters such as the wind speed, humidity and grain size of the sand, and the slope of beach and dune surface. For the first time, the interaction between beach and dune dynamics is studied at the Belgian coast. The Belgian coastline is only 67km long, but densely populated and therefore subject to coastal protection and safety. The coast mostly consists of sandy beaches and dikes. Although, still 33km of dunes exist, whose dynamics are far less understood. The overall research approach consists of three pathways: (i) field measurements, (ii) physical model tests, and (iii) numerical simulations. Firstly and most importantly, several field campaigns will provide accurate data of meteo-marine conditions, morphology, and sand transport events on a wide beach at the Belgian Coastline. The experimental set-up consists of a monitoring station, which will provide time series of vegetation cover, shoreline position, fetch distances, surficial moisture content, wind speed and direction and transport processes. The horizontal and vertical variability of the event scale Aeolian sand transport is analyzed with 8 MWAC sand traps. Two saltiphones register the intensity and variations of grain impacts over time. Two meteo-masts, each with four anemometers and one wind vane, provide quantitative measurements of the wind flow at different locations on the beach. Surficial moisture is measured with a moisture sensor. The topography measurements are typically done with laser techniques. To start, two sites are selected for measurement campaigns: one consists of the typical beach - dike system, a second site involves the dunes. First results of the measured data will be presented at the conference, together with a comparison to empirical correlations available in literature. Next to the field measurements, we propose physical model tests to provide data that is difficult to measure in the field. They will be used to determine the shear velocity and critical shear velocity in function of the transport flux. The effect of surficial moisture, vegetation and morphologic landforms will also be investigated in the model tests. Numerical simulations will provide a better insight in the physical processes of the Aeolian events and will be validated with the experimental results from the field campaigns and the physical model tests. The ultimate goal of the PhD is to obtain a sand transport model for the Belgian Coast, which can be used to assess the stability of nourishments in a quantitative matter, but it also will gain a better insight in the beach and dune interactions with the changing climate.

An Efficient and Imperfect Model for Gravel-Bed Braided River Morphodynamics: Numerical Simulations as Exploratory Tools

NASA Astrophysics Data System (ADS)

Kasprak, A.; Brasington, J.; Hafen, K.; Wheaton, J. M.

2015-12-01

Numerical models that predict channel evolution through time are an essential tool for investigating processes that occur over timescales which render field observation intractable. However, available morphodynamic models generally take one of two approaches to the complex problem of computing morphodynamics, resulting in oversimplification of the relevant physics (e.g. cellular models) or faithful, yet computationally intensive, representations of the hydraulic and sediment transport processes at play. The practical implication of these approaches is that river scientists must often choose between unrealistic results, in the case of the former, or computational demands that render modeling realistic spatiotemporal scales of channel evolution impossible. Here we present a new modeling framework that operates at the timescale of individual competent flows (e.g. floods), and uses a highly-simplified sediment transport routine that moves volumes of material according to morphologically-derived characteristic transport distances, or path lengths. Using this framework, we have constructed an open-source morphodynamic model, termed MoRPHED, which is here applied, and its validity investigated, at timescales ranging from a single event to a decade on two braided rivers in the UK and New Zealand. We do not purport that MoRPHED is the best, nor even an adequate, tool for modeling braided river dynamics at this range of timescales. Rather, our goal in this research is to explore the utility, feasibility, and sensitivity of an event-scale, path-length-based modeling framework for predicting braided river dynamics. To that end, we further explore (a) which processes are naturally emergent and which must be explicitly parameterized in the model, (b) the sensitivity of the model to the choice of particle travel distance, and (c) whether an event-scale model timestep is adequate for producing braided channel dynamics. The results of this research may inform techniques for future morphodynamic modeling that seeks to maximize computational resources while modeling fluvial dynamics at the timescales of change.

Megascours: the morphodynamics of large river confluences

NASA Astrophysics Data System (ADS)

Dixon, Simon; Sambrook Smith, Greg; Nicholas, Andrew; Best, Jim; Bull, Jon; Vardy, Mark; Goodbred, Steve; Haque Sarker, Maminul

2015-04-01

River confluences are wildly acknowledged as crucial controlling influences upon upstream and downstream morphology and thus landscape evolution. Despite their importance very little is known about their evolution and morphodynamics, and there is a consensus in the literature that confluences represent fixed, nodal points in the fluvial network. Confluences have been shown to generate substantial bed scours around five times greater than mean depth. Previous research on the Ganges-Jamuna junction has shown large river confluences can be highly mobile, potentially 'combing' bed scours across a large area, although the extent to which this is representative of large confluences in general is unknown. Understanding the migration of confluences and associated scours is important for multiple applications including: designing civil engineering infrastructure (e.g. bridges, laying cable, pipelines, etc.), sequence stratigraphic interpretation for reconstruction of past environmental and sea level change, and in the hydrocarbon industry where it is crucial to discriminate autocyclic confluence scours from widespread allocyclic surfaces. Here we present a wide-ranging global review of large river confluence planforms based on analysis of Landsat imagery from 1972 through to 2014. This demonstrates there is an array of confluence morphodynamic types: from freely migrating confluences such as the Ganges-Jamuna, through confluences migrating on decadal timescales and fixed confluences. Along with data from recent geophysical field studies in the Ganges-Brahmaputra-Meghna basin we propose a conceptual model of large river confluence types and hypothesise how these influence morphodynamics and preservation of 'megascours' in the rock record. This conceptual model has implications for sequence stratigraphic models and the correct identification of surfaces related to past sea level change. We quantify the abundance of mobile confluence types by classifying all large confluences in the Amazon and Ganges-Brahmaputra-Meghna basins, showing these two basins have contrasting confluence morphodynamics. For the first time we show large river confluences have multiple scales of planform adjustment with important implications for infrastructure and interpretation of the rock record.

Ecological concerns following Superstorm Sandy: stressor level and recreational activity levels affect perceptions of ecosystem

PubMed Central

2015-01-01

Coastal habitats are vulnerable to storms, and with increasing urbanization, sea level rise, and storm frequency, some urban populations are at risk. This study examined perceptions of respondents in coastal and central New Jersey to Superstorm Sandy, including: 1) concerns about ecological resources and effects (open-ended question), 2) information sources for ecology of the coast (open-ended), and 3) ratings of a list of ecological services as a function of demographics, location (coastal, central Jersey), stressor level (power outages, high winds, flooding) and recreational rates. “Wildlife” and “fish” were the ecological concerns mentioned most often, while beaches and dunes were most often mentioned for environmental concerns. Television, radio, and web/internet were sources trusted for ecological information. The data indicate 1) stressor level was a better predictor of ratings of ecological services than geographical location, but days engaged in recreation contributed the most to variations in ratings, 2) ecological services were rated the highest by respondents with the highest stressor levels, and by those from the coast, compared to others, 3) Caucasians rated ecological services higher than all others, and 4) recreational rates were highest for coastal respondents, and ratings for ecological services increased with recreational rates. Only 20 % of respondents listed specific ecological services as one of their three most important environmental concerns. These data will be useful for increasing preparedness, enhancing educational strategies for shore protection, and providing managers and public policy makers with data essential to developing resiliency strategies. PMID:27011729

Vulnerability of sandy coasts to climate change and anthropic pressures: methodology and preliminary results

NASA Astrophysics Data System (ADS)

Idier, D.; Poumadère, M.; Vinchon, C.; Romieu, E.; Oliveros, C.

2009-04-01

1-INTRODUCTION Climate change is considered in the latest reports of the Intergovernmental Panel on Climate Change IPCC (2007) as unequivocal. Induced vulnerability of the system is defined as "the combination of sensitivity to climatic variations, probability of adverse effects, and adaptive capacity". Substantial methodological challenges remain, in particular estimating the risk of adverse climate change impacts and interpreting relative vulnerability across diverse situations. As stated by the IPCC, the "coastal systems should be considered vulnerable to changes in climate". In these areas, amongst the most serious impacts of sea-level rise (Nicholls, 1996) are erosion and marine inundation. Thus, the coast of metropolitan France, being composed of 31% sandy coasts, is potentially vulnerable, as it has been qualitatively assessed on the pilot coasts of Aquitaine and Languedoc-Roussillon in the RESPONSE project (Vinchon et al., 2008). Within the ANR VULSACO project (VULnerability of SAndy COast to climate change and anthropic pressure), the present day erosion tendencies as well as the potentially future erosion trends are investigated. The main objectives are to: (1) assess indicators of vulnerability to climate change for low-lying linear sandy coastal systems, from the shore to the hinterland, facing undergoing climate change and anthropic pressure until the 2030s; and (2) identify the aggravating or improving effect of human pressure on this vulnerability. This second issue is sometimes considered as a main driver of coastal risks. The methodology proposed in the project considers anthropic adaptation (or not) by putting decision makers in front of potential modifications of the physical system, to study the decision process and the choice of adaptation (or not). The coastal system is defined by its morphology, its physical characteristics and its land use. The time scales will range from short-term (days to weeks, e.g. time scale of extreme events) to medium-term (decades), whereas the space scales range from several tens of meters to several tens of kilometers. The project is based on the study of representative coastal units: 4 sites characterised by low-lying linear sandy beaches but different, representative, hydrodynamic and socio-economic environments. These sites are located in: Mediterranean Sea (Lido of Sète), Atlantic coast (Truc Vert beach and Noirmoutier island) and English channel coast (Est of Dunkerque). Each of these sites is studied following the same methodology, on both the physical and socio-economic dimensions, the aim being to identify vulnerability indicators regarding climate change and anthropic pressure. 2 - METHODOLOGY The work is based on the following methodology, for every site: 1) The compartments of the unit are defined: shoreface, coastline, backshore, hinterland, from a physical and socio-economical point of view. 2) The available data are analysed in order to provide some information on the present trend of the coastal unit, regarding climate change and anthropic pressure, but also to support the model validation. 3) The vulnerability is studied. On one hand, the socio-economic dimension is assessed and, in a risk governance perspective, stake holders are identified and involved. This part of the project combines the study of social perceptions of dangers along with a deliberative workshop. On the other hand, numerical models of the physical behaviour of shoreface and coastline are applied. The selected models cover a time scale from short-term (storm time scale) to long-term (decades). Then, vulnerability can be studied: the vulnerability of coast/beach is defined and studied based on in-situ observations and model results. Most of these models needs some forcing conditions (waves at the boundary of the computational domains for instance). The present day conditions can be potentially modified by climate change. However, the model and literature review on climate change show that the few prediction of wave conditions available for the future deal mainly with the significant wave height, and not so much with the wave direction or period. To compensate this lack of knowledge, a sensitivity study is done to get information on the possible changes within the next decades (2030). It consists in studying the influence of a modification in the characteristics of the present day forcing conditions(like waves) within a reasonable magnitude order. 4) The anthropic pressure is taken into account as a modulator of the physical vulnerability. In each context, participative techniques are used to involve representatives of the main stakeholder groups into decision-making simulations. The scenario of a storm in 2030 is adopted to provide structured interactions during the workshop. Along with socio-economic projections, this simulation relies upon a fictive journal article written on the basis of the model outputs. These methodological choices aim at better understanding how decisions are made by stake holders dealing with risks and scientific uncertainty. Some applied results on the study sites will be presented at the EGU. ACKNOWLEDGEMENTS The VULSACO project is financially supported by the ANR (French National Research Agency) within the Vulnérabilité-Milieux-Climat programm.

Can human activities alter the drowning fate of barrier islands?

NASA Astrophysics Data System (ADS)

Lorenzo-Trueba, J.; Ashton, A. D.; Jin, D.; Hoagland, P.; Kite-Powell, H.

2012-12-01

Low-lying coastal barriers face an uncertain future over the coming century and beyond as sea levels rise, with many projections suggesting end-of-century rates of sea-level rise as high or higher than 1 cm/yr. Geologically, such rates of sea-level rise have been experienced several thousand years ago and we can use our understanding of geological processes and sedimentary evidence to help unravel the dynamics of natural barriers experiencing sea-level rise. Along many modern coastal barriers, however, anthropic change, such as beach nourishment, dune construction, and emplacement of hard structures, plays a dominant role in coastline dynamics. A fundamental question to be addressed is whether human activities intended to preserve infrastructure and beach recreation may make wholesale collapse, or 'drowning,' of barrier systems more likely. Here we present a numerical modeling tool that couples natural processes and the human responses to these changes (and the subsequent of human responses on natural processes). Recent theoretical model development suggests that barriers are intrinsically morphodynamic features, responding to sea-level rise in complex ways through the interactions of marine processes and barrier overwash. Undeveloped coastal barriers would therefore respond to an accelerated sea-level rise in complex, less predictable manners than suggested by existing long-term models. We have developed a model that examines non-equilibrium cross-shore evolution of barrier systems at decadal to centennial temporal scales, focusing on the interactions between processes of shoreface evolution and overwash deposition. Model responses demonstrate two means of barrier collapse during sea-level rise: 'height drowning', which occurs when overwash fluxes are insufficient to maintain the landward migration rate required to keep in pace with sea-level rise, and 'width drowning', which occurs when the shoreface response is insufficient to maintain the barrier geometry during landward migration. The model also demonstrates the potential for discontinuous shoreline retreat, with alternating periods of barrier stability and rapid migration, even for constant rates of sea-level rise. Anthropic activities can strongly interact with these behaviors. In particular, considering only cross-shore processes, beach nourishment activities widen the beach and can affect shoreface fluxes, and dune building, which curtails the overwash process, can potentially enhance barrier drowning by reducing overwash fluxes. Furthermore, coastal protection activities of adjacent communities or even individual property holders can be uncoordinated or coordinated, with their effects coupled along the coast through coastal reorientation and gradients in alongshore sediment transport. In the coordinated framework, owners act in concert to alter the barrier based upon community benefits, whereas in the non-coordinated framework owners alter only their own property. Another important role in management is the perception of future sea-level-rise-associated losses—communities manage their coast differently depending on their adopted forecast for sea-level rise. We find that coordinated behavior coupled with natural processes can substantially affect the drowning scenarios from the individual decision-making process.

Laboratory modeling of edge wave generation over a plane beach by breaking waves

NASA Astrophysics Data System (ADS)

Abcha, Nizar; Ezersky, Alexander; Pelinovsky, Efim

2015-04-01

Edge waves play an important role in coastal hydrodynamics: in sediment transport, in formation of coastline structure and coastal bottom topography. Investigation of physical mechanisms leading to the edge waves generation allows us to determine their effect on the characteristics of spatially periodic patterns like crescent submarine bars and cusps observed in the coastal zone. In the present paper we investigate parametric excitation of edge wave with frequency two times less than the frequency of surface wave propagating perpendicular to the beach. Such mechanism of edge wave generation has been studied previously in a large number of papers using the assumption of non-breaking waves. This assumption was used in theoretical calculations and such conditions were created in laboratory experiments. In the natural conditions, the wave breaking is typical when edge waves are generated at sea beach. We study features of such processes in laboratory experiments. Experiments were performed in the wave flume of the Laboratory of Continental and Coast Morphodynamics (M2C), Caen. The flume is equipment with a wave maker controlled by computer. To model a plane beach, a PVC plate is placed at small angle to the horizontal bottom. Several resistive probes were used to measure characteristics of waves: one of them was used to measure free surface displacement near the wave maker and two probes were glued on the inclined plate. These probes allowed us to measure run-up due to parametrically excited edge waves. Run-up height is determined by processing a movie shot by high-speed camera. Sub-harmonic generation of standing edge waves is observed for definite control parameters: edge waves represent themselves a spatial mode with wavelength equal to double width of the flume; the frequency of edge wave is equal to half of surface wave frequency. Appearance of sub-harmonic mode instability is studied using probes and movie processing. The dependence of edge wave exponential growth rate index on the amplitude of surface wave is found. On the plane of parameters (amplitude - frequency) of surface wave we have found a region corresponding parametric instability leading to excitation of edge waves. It is shown that for small super criticalities, the amplitude of edge wave grows with amplitude of surface wave. For large amplitude of surface wave, wave breaking appears and parametric instability is suppressed. Such suppression of instability is caused by increasing of turbulent viscosity in near shore zone. It was shown that parametric excitation of edge wave can increase significantly (up to two times) the maximal run-up. Theoretical model is developed to explain suppression of instability due to turbulent viscosity. This theoretical model is based on nonlinear mode amplitude equation including terms responsible for parametric forcing, frequency detuning, nonlinear detuning, linear and nonlinear edge wave damping. Dependence of coefficients on turbulent viscosity is discussed.

National Assessment of Shoreline Change: Part 1, Historical Shoreline Changes and Associated Coastal Land Loss Along the U.S. Gulf of Mexico

USGS Publications Warehouse

Morton, Robert A.; Miller, Tara L.; Moore, Laura J.

2004-01-01

EXECUTIVE SUMMARY Beach erosion is a chronic problem along most open-ocean shores of the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information regarding past and present trends and rates of shoreline movement. There is also a need for a comprehensive analysis of shoreline movement that is consistent from one coastal region to another. To meet these national needs, the U.S. Geological Survey is conducting an analysis of historical shoreline changes along open-ocean sandy shores of the conterminous United States and parts of Hawaii and Alaska. One purpose of this work is to develop standard repeatable methods for mapping and analyzing shoreline movement so that periodic updates regarding coastal erosion and land loss can be made nationally that are systematic and internally consistent. This report on states bordering the Gulf of Mexico (Florida, Alabama, Mississippi, Louisiana, and Texas) represents the first in a series that will eventually include the Atlantic Coast, Pacific Coast, and parts of Hawaii and Alaska. The report summarizes the methods of analysis, interprets the results, provides explanations regarding the historical and present trends and rates of change, and describes how different coastal communities are responding to coastal erosion. Shoreline change evaluations are based on comparing three historical shorelines with a recent shoreline derived from lidar (Light Detection and Ranging) topographic surveys. The historical shorelines generally represent the following periods: 1800s, 1920s-1930s, and 1970s, whereas the lidar shoreline is 1998-2002. Long-term rates of change are calculated using all four shorelines (1800s to lidar shoreline), whereas short-term rates of change are calculated for the most recent period (1970s to lidar shoreline). The historical rates of change presented in this report represent past conditions and therefore are not intended for predicting future shoreline positions or rates of change. Rates of erosion for the Gulf of Mexico region are generally highest in Louisiana along barrier island and headland shores associated with the Mississippi delta. Erosion is also rapid along some barrier islands and headlands in Texas, and barrier islands in Mississippi are migrating laterally. Highest rates of erosion in Florida are generally localized around tidal inlets. The most stable Gulf beaches are along the west coast of Florida where low wave energy and frequent beach nourishment minimize erosion. Some beach segments in Texas have accreted as a result of net longshore drift convergence, and around tidal inlets that have been stabilized by long jetties. Seawalls and riprap revetments were constructed in all the Gulf Coast states as initial community responses to long-term beach erosion. Although some states, such as Florida, still permit shoreline stabilization structures, beach nourishment has become the preferred method of mitigating long-term erosion.

Sediment heterogeneity and mobility in the morphodynamic modelling of gravel-bed braided rivers

NASA Astrophysics Data System (ADS)

Singh, Umesh; Crosato, Alessandra; Giri, Sanjay; Hicks, Murray

2017-06-01

The effects of sediment heterogeneity and sediment mobility on the morphology of braided rivers are still poorly studied, especially when the partial sediment mobility occurs. Nevertheless, increasing the bed sediment heterogeneity by coarse sediment supply is becoming a common practice in river restoration projects and habitat improvement all over the world. This research provides a step forward in the identification of the effects of sediment sorting on the evolution of sediment bars and braiding geometry of gravel-bed rivers. A two-dimensional morphodynamic model was used to simulate the long-term developments of a hypothetical braided system with discharge regime and morphodynamic parameters derived from the Waimakariri River, New Zealand. Several scenarios, differing in bed sediment heterogeneity and sediment mobility, were considered. The results agree with the tendencies already identified in linear analyses and experimental studies, showing that a larger sediment heterogeneity increases the braiding indes and reduces the bars length and height. The analyses allowed identifying the applicability limits of uniform sediment and variable discharge modelling approaches.

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.

Offshore Sand Resource Needs, Data Availability and Revaluation, and Beach Nourishment Projects in North Carolina

NASA Astrophysics Data System (ADS)

Conery, I.; Walsh, J. P.

2016-12-01

Storms and sea-level rise continue to impact the dynamic coastlines of North Carolina. Since the coastal region is economically critical to the state and yields numerous ecosystem services, many towns have planned beach nourishment projects. However, offshore sands compatible for nourishment are limited, and project costs fluctuate with borrow source proximity to the shoreline. Hurricane Sandy (2012) caused high water levels and waves resulting in localized overwash and erosion in the northeastern part of NC. In response, to effectively meet the rising nourishment demands for recovery after future storm events and for long-term resiliency, the Bureau of Ocean Energy Management (BOEM) recognized the need to compile and consolidate all geophysical and geologic information in federal waters (3-8 nm) along the East Coast states. A GIS database was created for NC using bathymetric, seismic reflection, sediment and other relevant data from federal, state and private entities. Information will be accessible to the public, coastal planners and managers to allow for informed decision-making and cost-effective project planning. Priority regions for seismic and core collection were determined based on data gaps and needs across the state. In addition, potential sand resource thickness and volume in northeastern NC were revaluated using comparisons of several overlapping datasets. Shoreline volume losses were calculated using long-term erosion rates and compared to historic and future nourishment projects. Finally, tourism-based revenue by town was evaluated and related to short and long-term nourishment costs.

Infragravity wave generation and dynamics over a mild slope beach : Experiments and numerical computations

NASA Astrophysics Data System (ADS)

Cienfuegos, R.; Duarte, L.; Hernandez, E.

2008-12-01

Charasteristic frequencies of gravity waves generated by wind and propagating towards the coast are usually comprised between 0.05Hz and 1Hz. Nevertheless, lower frequecy waves, in the range of 0.001Hz and 0.05Hz, have been observed in the nearshore zone. Those long waves, termed as infragravity waves, are generated by complex nonlinear mechanisms affecting the propagation of irregular waves up to the coast. The groupiness of an incident random wave field may be responsible for producing a slow modulation of the mean water surface thus generating bound long waves travelling at the group speed. Similarly, a quasi- periodic oscillation of the break-point location, will be accompained by a slow modulation of set-up/set-down in the surf zone and generation and release of long waves. If the primary structure of the carrying incident gravity waves is destroyed (e.g. by breaking), forced long waves can be freely released and even reflected at the coast. Infragravity waves can affect port operation through resonating conditions, or strongly affect sediment transport and beach morphodynamics. In the present study we investigate infragravity wave generation mechanisms both, from experiments and numerical computations. Measurements were conducted at the 70-meter long wave tank, located at the Instituto Nacional de Hidraulica (Chile), prepared with a beach of very mild slope of 1/80 in order to produce large surf zone extensions. A random JONSWAP type wave field (h0=0.52m, fp=0.25Hz, Hmo=0.17m) was generated by a piston wave-maker and measurements of the free surface displacements were performed all over its length at high spatial resolution (0.2m to 1m). Velocity profiles were also measured at four verticals inside the surf zone using an ADV. Correlation maps of wave group envelopes and infragravity waves are computed in order to identify long wave generation and dynamics in the experimental set-up. It appears that both mechanisms (groupiness and break-point oscillation) are clearly present in this experiment while spectral analysis evidences the reorganization of energy density from the original narrow spectrum into the infragravity band. This experiment provides an opportunity to test numerical models that would in principle be able to reproduce infragravity wave generation and dynamics. We compare numerical results (free surface and velocities) produced by a fully nonlinear Boussinesq model including breaking and runup to the experimental data and show that the complex infragravity wave dynamics is adequately reproduced by the model.

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.

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.

The 1960 tsunami on beach-ridge plains near Maullín, Chile: Landward descent, renewed breaches, aggraded fans, multiple predecessors

USGS Publications Warehouse

Atwater, Brian F.; Cisternas, Marco; Yulianto, E.; Prendergast, A.; Jankaew, K.; Eipert, A.; Fernando, Warnakulasuriya; Tejakusuma, Iwan; Schiappacasse, Ignacio; Sawai, Yuki

2013-01-01

The Chilean tsunami of 22 May 1960 reamed out a breach and built up a fan as it flowed across a sparsely inhabited beach-ridge plain near Maullín, midway along the length of the tsunami source. Eyewitnesses to the flooding, interviewed mainly in 1988 and 1989, identified levels that the tsunami had reached on high ground, trees, and build- ings. The maximum levels fell, from about 10 m to 2 m, between the mouth of the tidal Río Maullín and an inundation limit nearly 5 km inland across the plain. Along this profile at Caulle, where the maximum flow depth was a few meters deep, airphotos taken in 1961 show breaches across a road on a sandy beach ridge. Inland from one of these breaches is a fan with branched distributaries. Today its breach holds a pond that has been changing into a marsh. The 1960 fan deposits, as much as 60 cm thick, are traceable inland for 120 m from the breach. They rest on a pasture soil above two additional sand bodies, each atop its own buried soil. The earlier of the pre-1960 sand bodies probably dates to AD 1270-1400, in which case its age is not statistically different from that of a sand sheet previously dated elsewhere near Maullín. The breach likely originated then and has been freshened twice. Evidence that the breach was freshened in 1960 includes a near-basal interval of cobble-size clasts of sediment and soil, most of them probably derived from the organic fill of pre-1960 breach. The cobbly interval is overlain by sand with ripple-drift laminae that record landward flow. The fan of another breach near Maullín, at Chanhué, also provides stratigraphic evidence for recurrent tsunamis, though not necessarily for the repeated use of the breach. These findings were anticipated a half century ago by descrip- tion of paired breaches and fans that the 1960 Chilean tsunami produced in Japan. Breaches and their fans may provide lasting evidence for tsunami inundation of beach-ridge plains. The breaches might be detectable by remote sensing, and the thickness of the fan deposits might help them outlast an ordinary tsunami sand sheet. Keywords: Tsunami, Erosion, Deposition, Hazard, Chile.

Nitrogen transformations along a shallow subterranean estuary

NASA Astrophysics Data System (ADS)

Couturier, Mathilde; Tommi-Morin, Gwendoline; Sirois, Maude; Rao, Alexandra; Nozais, Christian; Chaillou, Gwénaëlle

2017-07-01

The transformations of chemical constituents in subterranean estuaries (STEs) control the delivery of nutrient loads from coastal aquifers to the ocean. It is important to determine the processes and sources that alter nutrient concentrations at a local scale in order to estimate accurate regional and global nutrient fluxes via submarine groundwater discharge (SGD), particularly in boreal environments, where data are still very scarce. Here, the biogeochemical transformations of nitrogen (N) species were examined within the STE of a boreal microtidal sandy beach located in the Magdalen Islands (Quebec, Canada). This study revealed the vertical and horizontal distribution of nitrate (NO3-), nitrite (NO2-), ammonia (NH4+), dissolved organic nitrogen (DON) and total dissolved nitrogen (TDN) measured in beach groundwater during four spring seasons (June 2011, 2012, 2013 and 2015) when aquifer recharge was maximal after snowmelt. Inland groundwater supplied high concentrations of NOx and DON to the STE, whereas inputs from seawater infiltration were very limited. Non-conservative behaviour was observed along the groundwater flow path, leading to low NOx and high NH4+ concentrations in the discharge zone. The long transit time of groundwater within the beach (˜ 166 days), coupled with oxygen-depleted conditions and high carbon concentrations, created a favourable environment for N transformations such as heterotrophic and autotrophic denitrification and ammonium production. Biogeochemical pathways led to a shift in nitrogen species along the flow path from NOx-rich to NOx-poor groundwater. An estimate of SGD fluxes of N was determined to account for biogeochemical transformations within the STE based on a N-species inventory and Darcy's flow. Fresh inland groundwater delivered 37 mol NOx yr-1 per metre of shoreline and 63 mol DON m-1 yr-1 to the STE, and NH4+ input was negligible. Near the discharge zone, the potential export of N species was estimated around 140, 1.5 and 33 mol yr-1 per metre of shoreline for NH4+, NOx and DON respectively. In contrast to the fresh inland groundwater, the N load of beach groundwater near the discharge zone was dominated by NH4+ and DON. Our study shows the importance of tidal sands in the biogeochemical transformation of the terrestrial N pool. This local export of bioavailable N probably supports benthic production and higher trophic levels leading to its rapid transformation in surface sediments and coastal waters.

The influence of bed friction variability due to land cover on storm-driven barrier island morphodynamics

USGS Publications Warehouse

Passeri, Davina L.; Long, Joseph W.; Plant, Nathaniel G.; Bilskie, Matthew V.; Hagen, Scott C.

2018-01-01

Variations in bed friction due to land cover type have the potential to influence morphologic change during storm events; the importance of these variations can be studied through numerical simulation and experimentation at locations with sufficient observational data to initialize realistic scenarios, evaluate model accuracy and guide interpretations. Two-dimensional in the horizontal plane (2DH) morphodynamic (XBeach) simulations were conducted to assess morphodynamic sensitivity to spatially varying bed friction at Dauphin Island, AL using hurricanes Ivan (2004) and Katrina (2005) as experimental test cases. For each storm, three bed friction scenarios were simulated: (1) a constant Chezy coefficient across land and water, (2) a constant Chezy coefficient across land and depth-dependent Chezy coefficients across water, and (3) spatially varying Chezy coefficients across land based on land use/land cover (LULC) data and depth-dependent Chezy coefficients across water. Modeled post-storm bed elevations were compared qualitatively and quantitatively with post-storm lidar data. Results showed that implementing spatially varying bed friction influenced the ability of XBeach to accurately simulate morphologic change during both storms. Accounting for frictional effects due to large-scale variations in vegetation and development reduced cross-barrier sediment transport and captured overwash and breaching more accurately. Model output from the spatially varying friction scenarios was used to examine the need for an existing sediment transport limiter, the influence of pre-storm topography and the effects of water level gradients on storm-driven morphodynamics.

A Coordinated USGS Science Response to Hurricane Sandy

NASA Astrophysics Data System (ADS)

Jones, S.; Buxton, H. T.; Andersen, M.; Dean, T.; Focazio, M. J.; Haines, J.; Hainly, R. A.

2013-12-01

In late October 2012, Hurricane Sandy came ashore during a spring high tide on the New Jersey coastline, delivering hurricane-force winds, storm tides exceeding 19 feet, driving rain, and plummeting temperatures. Hurricane Sandy resulted in 72 direct fatalities in the mid-Atlantic and northeastern United States, and widespread and substantial physical, environmental, ecological, social, and economic impacts estimated at near $50 billion. Before the landfall of Hurricane Sandy, the USGS provided forecasts of potential coastal change; collected oblique aerial photography of pre-storm coastal morphology; deployed storm-surge sensors, rapid-deployment streamgages, wave sensors, and barometric pressure sensors; conducted Light Detection and Ranging (lidar) aerial topographic surveys of coastal areas; and issued a landslide alert for landslide prone areas. During the storm, Tidal Telemetry Networks provided real-time water-level information along the coast. Long-term networks and rapid-deployment real-time streamgages and water-quality monitors tracked river levels and changes in water quality. Immediately after the storm, the USGS serviced real-time instrumentation, retrieved data from over 140 storm-surge sensors, and collected other essential environmental data, including more than 830 high-water marks mapping the extent and elevation of the storm surge. Post-storm lidar surveys documented storm impacts to coastal barriers informing response and recovery and providing a new baseline to assess vulnerability of the reconfigured coast. The USGS Hazard Data Distribution System served storm-related information from many agencies on the Internet on a daily basis. Immediately following Hurricane Sandy the USGS developed a science plan, 'Meeting the Science Needs of the Nation in the Wake of Hurricane Sandy-A U.S. Geological Survey Science Plan for Support of Restoration and Recovery'. The plan will ensure continuing coordination of internal USGS activities as well as enhancing our work with other agencies. The data, information, and tools that are being produced by implementing this plan will: (1) further characterize impacts and changes, (2) guide mitigation and restoration of impacted communities and ecosystems, (3) inform a redevelopment strategy aimed at developing resilient coastal communities and ecosystems, (4) improve preparedness and responsiveness to the next hurricane or similar coastal disaster, and (5) enable improved hazard assessment, response, and recovery for future storms along the hurricane prone shoreline of the United States. The activities outlined in the plan are organized in five themes based on impact types and information needs. These USGS science themes are: Theme 1: Coastal topography and bathymetry. Theme 2: Impacts to coastal beaches and barriers. Theme 3: Impacts of storm surge and estuarine and bay hydrology. Theme 4: Impacts on environmental quality and persisting contaminant exposures. Theme 5: Impacts to coastal ecosystems, habitats, and fish and wildlife. The major emphases in the implementation of this plan are interacting with stakeholders to better understand their specific data and information needs, engaging with other Federal agencies and non-governmental agencies to encourage collaboration and avoid duplication, defining the best way to make information available, and providing applications of USGS science and expertise to support decision-making.

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

Sobocinski, Kathryn; Johnson, Gary; Sather, Nichole

This document is the first annual report for the study titled 'Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta in the Lower Columbia River'. Hereafter, we refer to this research as the Tidal Freshwater Monitoring (TFM) Study. The study is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, U.S. Army Corps of Engineers, U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act as a result of operation of the Federal Columbia River Power System (FCRPS). The project ismore » performed under the auspices of the Northwest Power and Conservation Council's Columbia Basin Fish and Wildlife Program. The goal of the 2007-2009 Tidal Freshwater Monitoring Study is to answer the following questions: In what types of habitats within the tidal freshwater area of the lower Columbia River and estuary (LCRE; Figure 1) are yearling and subyearling salmonids found, when are they present, and under what environmental conditions?1 And, what is the ecological importance2 of shallow (0-5 m) tidal freshwater habitats to the recovery of Upper Columbia River spring Chinook salmon and steelhead and Snake River fall Chinook salmon? Research in 2007 focused mainly on the first question, with fish stock identification data providing some indication of Chinook salmon presence at the variety of habitat types sampled. The objectives and sub-objectives for the 2007 study were as follows: (1) Habitat and Fish Community Characteristics-Provide basic data on habitat and fish community characteristics for yearling and subyearling salmonids at selected sites in the tidal freshwater reach in the vicinity of the Sandy River delta. (1a) Characterize vegetation assemblage percent cover, conventional water quality, substrate composition, and beach slope at each of six sampling sites in various tidal freshwater habitat types. (1b) Determine fish community characteristics, including species composition, abundance, and temporal and spatial distributions. (1c) Estimate the stock of origin for the yearling and subyearling Chinook salmon captured at the sampling sites using genetic analysis. (1d) Statistically assess the relationship between salmonid abundance and habitat parameters, including ancillary variables such as temperature and river stage. (2) Acoustic Telemetry Monitoring-Assess feasibility of applying Juvenile Salmon Acoustic Telemetry System (JSATS) technology to determine migration characteristics from upriver of Bonneville Dam through the study area (vicinity of the Sandy River delta/Washougal River confluence). (2a) Determine species composition, release locations, and distributions of JSATS-tagged fish. (2b) Estimate run timing, residence times, and migration pathways for these fish. Additionally, both objectives serve the purpose of baseline research for a potential tidal rechannelization project on the Sandy River. The U.S. Forest Service, in partnership with the Bonneville Power Administration and the U.S. Army Corps of Engineers, is currently pursuing reconnection of the east (relict) Sandy River channel with the current channel to improve fish and wildlife habitat in the Sandy River delta. Our study design and the location of sampling sites in this reach provide baseline data to evaluate the potential restoration.« less

Process-based, morphodynamic hindcast of decadal deposition (1856-1887) and erosion (1951-1983) patterns in San Pablo Bay, California

NASA Astrophysics Data System (ADS)

Wegen, M. V.; Jaffe, B. E.; Roelvink, J.

2009-12-01

The objective of the current research is to hindcast decadal morphodynamic development in San Pablo Bay, California, USA using a process-based, numerical model, Delft3D. Experience gained in the current research will be ultimately used to model future morphodynamic changes in San Pablo Bay under different scenarios of climate change. Delft3D is run in 3D mode including wind waves, salt and fresh water interaction, sand and mud fractions and applies a sophisticated morphodynamic update scheme [Roelvink (2006)]. Model outcomes are evaluated against measured bathymetric developments [Cappiella (1999), Jaffe et al (2007)] and include an extensive sensitivity analysis on model parameter settings. In the 19th century more than 250 million cubic meters of sediment was deposited in San Pablo Bay because of the increased sediment load associated with hydraulic gold mining activities. When mining stopped and dam construction regulated river flows and trapped sediment upstream early 20th century, San Pablo Bay showed an eroding trend. Focus of the hindcast is on the 1856 to 1887 depositional period and on the 1951 to 1983 erosional period. The results of the model heavily depend on parameter settings related to sediment transport, bed composition and boundary conditions schematization. A major handicap is that the (historic) values of these parameters are not known in detail. Recommendations by Ganju et al. (2008) are used to overcome this problem. The results show, however, that applying best-guess model parameter settings can predict decadal morphodynamic developments reasonably well in San Pablo Bay. From all varied settings sediment concentration, river discharge and waves have the most significant effect on deposition volumes, whereas waves have the most impact on sediment distribution within San Pablo Bay. For the depositional period Brier Skill Scores have values around 0.25 with a maximum of 0.43 (qualified as ‘good’) although higher values (up to 0.65) were obtained in sub-areas of San Pablo Bay. Modeling the erosional period is more sensitive to bed composition data and leads to worse results. This is partly attributed to the fact that morphodynamic change was much smaller than during the depositional period. The research is part of larger project, CASCaDE (http://cascade.wr.usgs.gov/). CASCaDE is supported by the U.S Geological Survey’s Priority Ecosystems Science program and the CALFED Bay/Delta Program. Cappiella, K., Malzone, C. , Smith R., Jaffe, B.E., 1999. Sedimentation and bathymetric change in Suisun Bay 1876-1990. USGS Open File Report, 9-563. Ganju, N.K., Knowles, N., and Schoellhamer, D.H., in 2008, Temporal downscaling of decadal sediment load estimates to a daily interval for use in hindcast simulations. Journal of Hydrology, v. 349, p. 512-523. Jaffe, B.E., Smith R.E. and Foxgrover A.C., 2007. Anthropogenic influence on sedimentation and intertidal mudflat change in San Pablo Bay, California: 1856-1983. Estuarine, Coastal and Shelf Science 73 175-187. Roelvink, J. A. (2006), Coastal morphodynamic evolution techniques, J. Coastal Eng., 53, 177-187.

Testing coastal DRR in current and climate change scenarios - Artificial winter dune system in a highly touristic beach in the Northern Adriatic.

NASA Astrophysics Data System (ADS)

Duo, Enrico; Armaroli, Clara

2017-04-01

Artificial dunes are common features built along the coast of the Emilia-Romagna region (Italy) that act as temporary protections during the stormy season in order to prevent damages and inundation to the structures located on the backshore. The RER coast is in fact characterised by low sandy beaches that are exploited for tourism and where beach huts are permanently present on the rear part of the beach. While scientists and regional managers already provided proofs of the capacity of the artificial dunes to lower the hazard component, any study has never investigated their direct impacts in the current (CS) and climate change scenarios (CCS). The RISC-KIT project (www.risckit.eu) provided a methodology for testing DRRs at local level integrating hydro-morphological numerical modelling with a Bayesian Network to assess the consequences of extreme events for different scenarios. The approach was applied at the beach of Lido degli Estensi and Spina (Comacchio, Italy) in the Emilia-Romagna coast. It is a highly touristic area with concessions directly facing the sea, providing sun-and-beach tourism services during summer time, and private residences, commercial activities and hotels at the seafront. The flooding and erosion hazards were analyzed, along with their impacts. A 2DH XBeach model was built and forced with a large number of triangular storms, representative of many different representative combinations of waves' and total water level's ranges observed at regional level. Flooding and erosion results were input into a Bayesian Network which included, as feeding variables categories, deep water boundary conditions (including the CCS trigger), receptors (type and location of assets at the coast), hazard intensity affecting the receptors, impacts and DRR. Therefore, it was possible to integrate a flood damage curve and an erosion potential damage function for the analyzed receptors (beach concessions and residential/commercial buildings), in order to calculate the direct impacts. The artificial dune system was implemented, as representative of the DRR scenario, modifying the topography through the DuneMaker 2.0 Matlab tool. The CCS was implemented through a predicted RSLR under RCP8.52050. The results evidenced that the DRR positively influenced both flooding and erosion hazard intensities distributions. The impacts for the CS showed that, potentially: 20% of residential and commercial buildings and 90% of concessions will be preserved from flood impacts; more than 50% of concessions will be preserved from erosion impacts. The impacts of the CCS evidenced that, potentially: 65% of residential and commercial buildings and 95% of concessions will be preserved from flood impacts; more than 30% of concessions will be preserved from erosion. The positive effect on coastal extreme storm impacts of the implementation of the artificial dunes was evidenced and quantified in comparison with current and climate change scenarios without any DRR implemented. Ongoing studies on the artificial winter dunes, comparing field drone observations and numerical modelling, are being implemented starting from October 2016. Besides, the methodology, if properly adapted, can be applied for any type of DRR, as demonstrated by the RISC-KIT project. It is able to help managers in comparing DRR solutions or strategic alternatives.