Showing papers in "Journal of Coastal Research in 2004"

Flow Resistance and Associated Sedimentary Processes in a Spartina maritima Salt-Marsh

Abstract: The vertical accretion of salt marshes is mainly due to flow reduction and wave damping by vegetation. However, the details of the hydrodynamics are only partially understood, and have been studied mainly in the laboratory. This study presents detailed field investigations of the water flow in a Spartina maritima salt-marsh in the Ria Formosa, a shallow, meso-tidal lagoon in Southern Portugal. Detailed velocity profiles were obtained within and above the 30 cm high canopy using a high-precision velocimeter. Results show that the influence of the bottom becomes negligible a few centimetres above the bed, and that the flow depends on the vegetation density at each level of the canopy. When the canopy is partially emergent or is only slightly submerged, the upward increase of horizontal velocity is roughly linear. A more drastic flow reduction exists when the canopy is well submerged, with a slow, nearly constant velocity in the denser part of the canopy and a faster, logarithmic shaped velocity pro...

Decadal Scale Patterns in Beach Oscillation and Rotation Narrabeen Beach, Australia—Time Series, PCA and Wavelet Analysis

Abstract: Twenty-six years of monthly beach profiles located along 3.6 km Narrabeen beach were analyzed using time series, principle components (PCA) and wavelet analysis. The time series reveal both beach oscillation (erosion-accretion) and rotation between the boundary headlands. The rotation phenomenon is confirmed by the 2nd PCA component, explaining 58% of the remaining data variance. The scale of beach oscillation is on the order of 70 m, with 30 m of this oscillation attributed to beach rotation. Continuous wavelet transform analysis identified decadal scale patterns in beach response. This analysis indicates that variability in ensemble beach width and beach rotation exhibit long-term non-stationary variability. Longer-term cycles of behavior in overall beach erosion/accretion and beach rotation appear to coincide with each other, while short term fluctuations suggest a variety of physical processes are responsible for beach width variation and the interannual rotation phenomenon.

Coastal Classification: Systematic Approaches to Consider in the Development of a Comprehensive Scheme

Abstract: Many different kinds of classification have been applied to coasts in attempts to characterize dominant features in terms of physical or biological properties, modes of evolution, or geographic occurrence. Some of the earlier general classifications were broad in scope but lacked specificity while other specialized systems were narrowly focused, providing uneven coverage of taxonomic units for coastlines of the world. Due to more comprehensive study of coasts and the increasing availability of information, especially digital formats in GIS frameworks, integrated and systematic approaches to coastal classification are favored. The complex demands of today require sophisticated solutions to overlapping and interrelated problems in the littoral, as facilitated by organization of biophysical parameters into a coherent whole or universal scheme. The developmental approach to a new comprehensive classification system is thus proposed for the coastal fringe, a swath zone 5 to 10 km wide across the shore...

Influence of Seagrasses on Water Quality in Shallow Regions of the Lower Chesapeake Bay

Abstract: The influence of seagrasses on water quality was investigated seasonally from permanent stations located along transects across vegetated and formerly vegetated sites in shoal regions of the Chesapeake Bay National Estuarine Research Reserve in Virginia. The effect of the seagrass bed on conditions inside compared to outside the bed varied seasonally and could be related to bed biomass and development. During spring (April to June), the rapidly growing seagrass bed was a sink for nutrients, suspended inorganic particles, and phytoplankton, whereas during the summer, as bed dieback progressed, resuspension and release of nutrients were observed. Reductions in suspended particle concentrations and light attenuation were generally not measurable until bed biomass exceeded 50–100 gdm/m2 or 25–50% vegetative cover. During April, when nitrate levels in adjacent channel waters were observed to be highest (>10 μM), rapid uptake, equivalent to 48% of nitrogen requirements for seagrass growth, reduced inor...

Tourism-generated earnings in the coastal zone: a regional analysis.

Abstract: Over the past thirty years, the coastal counties have shifted from traditional maritime activities such as fishing and boating, to a more service-oriented, and tourism-dependent economy. A key to economic growth in the coastal states has been the strength of the travel and tourist industry. This study links a regional model of tourism-generated earnings to a GIS model to quantify the relationship between the relative size of the travel and tourism sector in each county and the county's proximity to the coast. We find that tourism-related earnings, as a percent of total earnings, are concentrated in counties that lie within forty km (25 miles) of the Atlantic, Gulf and Pacific coasts of the United States. In contrast, the share of earnings attributable to tourism is not sensitive to distance from the coast for counties that are further than forty km (25 miles) inland. The literature on beach quality suggests that coastal tourism is dependent on clean, broad and sandy beaches. Key unanswered questi...

Using Sea Level Rise Projections for Urban Planning in Australia

Abstract: This study deals with incorporating predictions of sea level rise into practical municipal planning. Predictions of global mean sea level rise can be made with more confidence than many other aspects of climate change science. The world has warmed in the past century, and as a result global mean sea level has risen and is expected to continue to rise. Even so, there are significant uncertainties regarding predictions of sea level. These arise from two main sources: the future amount of greenhouse gases in the atmosphere, and the ability of models to predict the impact of increasing concentrations of greenhouse gases. Current knowledge regarding the effect of global warming on sea level rise is reviewed. Global mean sea level is expected to rise by 3–30 cm by 2040, and 9–88 cm by 2100. An important remaining uncertainty is the future contribution of surface water storage (for example, lakes and reservoirs) to changes in sea level. In addition, there are also significant local sea level effects tha...

Sustainable Coastal Policy Developments in The Netherlands. A Systematic Approach Revealed

Abstract: VAN KONINGSVELD, M. and MULDER, J.P.M., 2004. Sustainable coastal policy developments in the Netherlands. A systematic approach revealed. Journal of Coastal Research, 20(2), 375-385. West Palm Beach (Florida), ISSN 07490208. Policy development is a dynamic and cyclic process characterised by successive stages of development, implementation and evaluation. Throughout this process, interaction between science and coastal management plays an important role. An illustration is given in this paper, based on an analysis of the history of coastal policy in the Netherlands over the last two decades. Evaluation in 1995 of the coastal policy of Dynamic Preservation, developed during the late 80’s and implemented in 1990, led to a redefinition in 2000. Implementation in 2001, of a sustainable coastal policy in the Netherlands with both a small- and a large-scale approach, is the result. The analysis in this paper indicates that the successful development and implementation of coastal policy in the Netherlands, is related to the use of a systematic ‘frame of reference’; characteristics are explicit definitions of both strategic and operational objectives applied in a 4-step decision recipe of (1) a quantitative state concept, (2) a bench marking procedure, (3) a procedure for CZM measures or intervention and (4) an evaluation procedure. Applications of this frame of reference show its high potential to better integrate coastal science and coastal policy and -management and to stimulate co-operation.

Importance of Storm Events in Controlling Ecosystem Structure and Function in a Florida Gulf Coast Estuary

Abstract: From 8/95 to 2/01, we investigated the ecological effects of intra- and inter-annual variability in freshwater flow through Taylor Creek in southeastern Everglades National Park. Continuous monitoring and intensive sampling studies overlapped with an array of pulsed weather events that impacted physical, chemical, and biological attributes of this region. We quantified the effects of three events representing a range of characteristics (duration, amount of precipitation, storm intensity, wind direction) on the hydraulic connectivity, nutrient and sediment dynamics, and vegetation structure of the SE Everglades estuarine ecotone. These events included a strong winter storm in November 1996, Tropical Storm Harvey in September 1999, and Hurricane Irene in October 1999. Continuous hydrologic and daily water sample data were used to examine the effects of these events on the physical forcing and quality of water in Taylor Creek. A high resolution, flow-through sampling and mapping approach was used to...

Salt Marsh Morphodynamics: an Investigation of Tidal Flows and Marsh Channel Equilibrium

Abstract: Although numerous field studies have evaluated flow and transport processes in salt marsh channels, the overall role of channels in delivering and removing material from salt marsh platforms is still poorly characterised. In this paper, we consider this issue based on a numerical hydrodynamic model for a prototype marsh system and on a field survey of the cross-sectional geometry of a marsh channel network. Results of the numerical simulations indicate that the channel transfers approximately three times the volume of water that would be estimated from mass balance considerations alone. Marsh platform roughness exerts a significant influence on the partitioning of discharge between the channel and the marsh platform edge, alters flow patterns on the marsh platform due to its effects on channel-to-platform transfer and also controls the timing of peak discharge relative to marsh-edge overtopping. Although peak channel discharges and velocities are associated with the flood tide and marsh inundation, a larger volume of water is transferred by the channel during ebb flows, a portion of which transfer takes place after the tidal height is below the marsh platform. Detailed surveys of the marsh channels crossing a series of transects at Upper Stiffkey Marsh, north Norfolk, England, show that the total channel cross-sectional area increases linearly with catchment area in the inner part of the marsh, which is consistent with the increase in shoreward tidal prism removed by the channels. Toward the marsh edge, however, a deficit in the total cross-sectional area develops, suggesting that discharge partitioning between the marsh channels and the marsh platform edge may also be expressed in the morphology of marsh channel systems.

Mapping Shoreline Position Using Airborne Laser Altimetry

Abstract: This paper examines the feasibility of using LIDAR surveys to update existing historical shoreline data sets by comparing contour shorelines and the high water line (HWL) at eight study locations in North and South Carolina. The analysis was based on airborne LIDAR topography and orthoimagery collected simultaneously during June 2000. The popular method of digitizing the wet-dry line from orthoimagery was used to measure the HWL. Contour shorelines were derived by using the previous high tide (HW), the mean high water datum (MHW), and the mean higher high water datum (MHHW) of nearby tide gauges. A method was developed to quantitatively compare the positions of the HWL and the contour shorelines in a GIS. The mean high water and mean higher high water contour shoreline positions were the best match to the high water line at 7 of 8 locations, and differed by less than 5.4 meters from the digitized high water line positions. This difference is well within the errors associated with past methods for measuring shoreline position. Therefore, it is deemed practical to use LIDAR data to estimate the HWL.

Impacts of Marine Aggregate Dredging on Benthic Macrofauna off the South Coast of the United Kingdom

Abstract: A survey of benthic macrofauna in the vicinity of a coastal marine aggregate dredging site off the south coast of UK was carried out in 1999. The object of the survey was to determine impact of marine aggregate dredging on community composition, the extent of impact outside the boundaries of the dredge site, and the rate of recolonization and recovery of the fauna following cessation of dredging. Part of the site was intensively dredged by vessels at anchor whilst other parts were less intensively exploited by trailer dredger. The impact of dredging within the intensively exploited anchor dredge site was limited to the dredged area. Impacts included a suppression of species variety, population density and biomass, as well as differences in species composition compared with the surrounding deposits. In contrast, trailer dredging had no impact on community composition of macrofauna within the dredge site. No suppression of benthic community structure was recorded beyond 100 m from the dredge site. ...

Morphodynamic Behaviour and Sedimentary Variation of Mixed Sand and Gravel Beaches, Suffolk, UK

Abstract: This paper investigates the spatial and temporal variability of three different mixed sand and gravel beaches on the Suffolk coast, U.K. The beaches consist of a highly variable mixture of medium (−3.3 to −3.47 ϕ), moderately sorted gravel (0.85 to 0.78 ϕ), and 15 to 30% coarse (0.47 ϕ) moderately sorted (0.96 ϕ) sand. Above the high water mark beach sediments are predominantly gravel, whilst the sand fraction is concentrated in a planar region of the lower foreshore. The beaches studied exhibit some characteristics of pure gravel beaches, some of pure sand beaches and some which are unique to mixed beaches. Distinctive sedimentary features include a coarser sand fraction and finer gravel fraction, the existence of multi-modality within the gravel fraction, very limited shape sorting, and high spatial and temporal variability. Beach profile responses are similar to those of pure sand and pure gravel beaches, including those changes occurring over semi-diurnal, spring-neap, and seasonal timescales...

The U.S. Minerals Management Service Outer Continental Shelf Sand and Gravel Program: Environmental Studies to Assess the Potential Effects of Offshore Dredging Operations in Federal Waters

Abstract: The U.S. Department of the Interior, Minerals Management Service, provides policy direction relative to the development of all marine mineral resources located beneath Federal waters of the United States. Over the last ten years or so, geological studies encompassing the collection and analysis of seismic, vibracore, and grain size data have been conducted in partnership with coastal States in the Atlantic and Gulf of Mexico to locate suitable sources of compatible sand for beach and coastal restoration. Environmental studies have been initiated to provide biological, physical, and other pertinent information for decisions regarding leasing and use of this resource. Aggregate dredging studies also have been conducted in the event that an offshore aggregate mining operation is proposed in the future. A symposium was held in New Orleans in January 2002 to report results from several studies completed over the past 2 years. The papers prepared for this Special Issue summarize the findings of recentl...

Evidence of Anthropogenic Nitrogen Enrichment of the Littoral Waters of East Central Florida

Abstract: Excessive human-derived nutrient availability has been implicated as a primary driver in the decline of the water quality and biota of coastal ecosystems. In 2003, seven sites along an urbanized section (∼100 km) of the Atlantic littoral coastline in east-central Florida were assessed for the bio-availability of the primary nutrients nitrogen and phosphorus. Ratios of dissolved inorganic nitrogen (DIN = nitrate + nitrite + ammonium) to soluble reactive phosphorus (SRP) in 74 beach water samples averaged 8:1, indicating strong water column nitrogen-limitation. DIN concentrations ranged from 0.69 to 8.11 µM with a grand mean of 2.10 µM, a value two-fold above the reported threshold value of ∼1 µM that saturates growth of Florida red tide, Karenia brevis and macroalgae species utilized in this study, such as Ulva lactuca. The majority (mean = 56%) of this DIN was in the form of ammonium, even during a peak upwelling event in June and August, suggesting the importance of anthropogenic land-based nitr...

Incorporation of a Mass-Conserving Inundation Scheme into a Three Dimensional Storm Surge Model

Abstract: The rapid rise and fall of coastal sea level due to tides and storm surge complicates the application of hydrodynamic models that use constant lateral boundaries in the region where sea level change falls within the tidal range or between the negative and positive surge extremes. In order to enable a hydrodynamic model for use in tidal or surge zones, an inundation and drying scheme must be incorporated into the hydrodynamic model. In this study, a mass-conserving inundation (wetting) and draining (drying) scheme is incorporated into a three-dimensional hydrodynamic model (the Princeton Ocean Model, often referred to as POM) for coastal ocean and estuarine systems. This coupled hydrodynamic and inundation modeling system is tested in an idealized lake/estuarine setting. The results show that: 1) incorporation of the inundation/drying scheme into the POM enabled its application in shallow water systems with time-dependent coastal boundaries; 2) the mass conservation constraint used in the inundati...

An experimental investigation of floc characteristics in a diffusive turbulent flow

Abstract: GRATIOT, N, and MANNING, AJ, 2004 An experimental investigation of floc characteristics in a diffusive turbulent flow Journal of Coastal Research, SI 41, pg-pg Ferrara (Italy), ISSN 0749-0208 The work presented aimed at investigating the influence of the physical processes effecting mud flocculation in a grid stirred experiment Two natural muds from the Gironde estuary (organic and another with the organic content removed) and mud from the Tamar estuary (organic) were used to examine the influence of the biological and chemical compositions on interparticular collision efficiency (ie stickiness) For every experiment, the mean sediment concentration were deduced from extracted water samples and by optical methods The turbulent shearing was estimated from high frequency measurements of the velocity profile Floc size and settling velocity were obtained by high resolution video observational techniques The study showed that particles are advected with the large scale turbulent eddies from low to high turbulent shearing regions It does not imply an instantaneous response and floc properties remained predominantly homogeneous in the water column of the experimental tank From the measurements made, it is therefore possible to conclude that time scales associated to the turbulent transport are much smaller than the ones associated to flocculation processes As sediment concentrations increased up to 8 gl -1 , the increase in particle collision frequency enhanced the flocculation process to such a high degree that only a small percentage of the total floc population fell within the microfloc (< 120 μm) size range Flocculation is especially significant for trials with organic muds and the effect of floc break-up by inter-particular collisions was not observed, at all shear and concentration levels, during our study The Gironde mud with the organic components neutralised produced only a minor number of flocs, at all shear and suspended concentration combinations, which exceeded the pre-sieving mesh size of 125 μm This highlights the important role organic matter plays in the flocculation of natural cohesive sediments This paper compares the distribution of size and settling velocity of macroflocs and microflocs and mean floc properties for the different sediment types under the various experimental concentration and shear ranges The findings highlight how floc properties change in response to their ambient environment

CZM applications of Argus coastal imaging at the Gold Coast, Australia

Abstract: A video-based ARGUS coastal imaging system is being used at the northern Gold Coast, Australia to monitor and quantify the regional-scale coastal response to sand nourishment and construction of the world-first Gold Coast artificial (surfing) reef. This automated monitoring system is used to obtain hourly daylight images from four cameras that combined provide continuous coverage of 4.5 km of the coast. Digital image processing techniques are then applied on a routine (weekly to monthly) basis to extract a range of CZM information from the growing image database. Analyses include: the mapping of changing shoreline position (and hence beach width); the measurement of three-dimensional inter-tidal morphology and resulting changes in subaerial sand volume; and the comparison of wave breaking frequency at the reef and adjacent nearshore bars, to quantify enhanced recreational surfing opportunities at the reef site. Based upon the results of image analysis, to date (January 2003) an additional 20–30 m...

Shoreline Changes and Near Shore Processes Along Ennore Coast, East Coast of South India

Abstract: The study region located north of Chennai city on the East coast of India is facing shoreline erosion/accretion related problems after the introduction of Ennore Port during 2001. For the present study 25 km of coastal stretch has been taken up, which comprises Ennore port region, natural sandy beaches of Kattupalli Island, which is a turtle breeding ground and Ennore Creek and Pulicat Lake inlets, with a total coastal settlement population of 25,000 people. After the introduction of breakwaters for the port, beach erosion and accretion are considered as critical problems, resulting in damages to the natural set up of the coastal region in the study area. Analyses of coastal dynamics and vulnerable zones of erosion and accretion along the coast were performed during the present study which are highly useful for the development of strategies for beach erosion/accretion management. Four major categories of shoreline changes were observed in the study region, viz., 1) Beach accretion south of Ennore...

Classification of Coasts

Abstract: The simplest description of a given coast requires a minimum of three terms, embracing the following: (1) material (hard/soft; soluble or otherwise); (2) agencies (erosive/constructive; physical, chemical, biological, and geographic setting [latitude, exposure, fetch]), and (3) historical factors (time scale: geotectonic, glacioisostatic, eustatic, steric, anthropic). Deductive reasoning based on instrumental data such as tide gauges frequently lead to misleading conclusions, in that most are located in the northern hemisphere (land-dominated), near river mouths (variable runoff), sediment compaction, crustal lowering, coriolis effect of geostrophic current variation, and excessively short data spans (< 100 yr). Climatic oscillation influences sea level on all scales from ENSO (El Nino Southern Oscillation) and NAO (North Atlantic Oscillation) up to 1500 yr or more. Satellite observations furnish only the briefest “snap-shots.” Classifications based on perceived “relative” relationships such as s...

Dependence of Total Longshore Sediment Transport Rates on Incident Wave Parameters and Breaker Type

Abstract: Experiments were conducted in the Large-scale Sediment Transport Facility (LSTF) at the U.S. Army Engineer Research and Development Center to investigate the importance of wave height, period, and breaker type (spilling and plunging breakers) on total rate of longshore sediment transport (LST) and the cross-shore distribution of LST. Estimates computed by the CERC formula and Kamphius were compared to the accurately measured total LST rates. Several K-values were used with the CERC formula, including the recommended value of 0.39 and calculated values by Kamphuis and Readshaw, Ozhan, Bailard, and Del Valle et al. The recommended K-value and most of the calculated K-values overpredicted the measured total LST rates, but methods that included parameters to indicate breaker type gave good estimates. The Kamphuis and Readshaw equation, in which K is a function of surf similarity parameter, gave consistent estimates with measurements. The Kamphuis equation, which includes wave period and beach slope t...

Potential Implications of Sea-Level Rise for France

Abstract: Concern is growing in France about climate change and the related issue of accelerated sea-level rise (ASLR). Although a national vulnerability assessment has not been produced, available information is sufficient to clearly identify the coastal zones which are at risk. On the Mediterranean coast, the most vulnerable area corresponds to the deltaic plain of the Rhone River, chiefly because of human actions (e.g., shortage of sediment supply as a result of dam construction; river embankments). Coastal erosion, lowland flooding, and ground water salinisation are the main impacts expected from ASLR. The Languedoc coastal barriers will move landward faster than at present, thus jeopardising dense tourist facilities. On the Atlantic coast, enhanced erosion of the Aquitaine sandy beaches is expected. Existing salt marshes do not appear threatened because mud sedimentation from soil erosion is active, but reclaimed areas will be at risk of flooding. Moderate salt intrusion is expected into the Loire est...

Grain-Size Analysis and Characterization of Sedimentary Environments of The United Arab Emirates Coastal Area

Abstract: There are no previously published granulometric studies of the sediments from the coastal areas of the UAE. In this study one hundred and forty-four beach sediment samples were collected from coastal districts of seven emirates (Abu Dhabi, Dubai, Sharjah, Ajman, Umm Al-Quwain, Ras Al-Khaimah and Fujairah) for the purposes of grain size analysis and province delineation. A range of grain size data analysis methods, such as bivariate scatter plots and discrimination functions, were employed in the interpretation of the environments and mechanisms of sediment deposition. Multivariate statistical analysis was also used to discriminate between different coastal zones. The Arabian Gulf coast can be divided into the following three provinces: a) Abu Dhabi/Dubai province, b) Sharjah/Ajman/Umm Al-Quwain province and c) Ras Al-Khaimah province. The Gulf of Oman coast can be divided into the following four provinces: a) Rol Diba Province, b) Dadnah/Aqqa province, c) Khor Fakkan province and d) Fujairah prov...

Physical Impacts of Marine Aggregate Dredging on Seabed Resources in Coastal Deposits

Abstract: A detailed study of the seabed surrounding dredge pits created during the mining of marine aggregate from a small licence off the south coast of the United Kingdom (“Licence Area 122/3”) has been completed. Over 350 km of high-resolution sidescan sonar imagery and 177 sediment samples have been obtained over a study area extending 10 km either side of the dredge zone (representing one full tidal excursion) in order to identify far-field effects on both physical and biological resources of the seabed. The physical results presented here for Area 122/3 clearly show that the physical impact of dredging (without screening) on the seabed is limited to a zone within approximately 300 m downtide of the dredge area. This will generally be within the dredge licence boundary due to operational procedures. There is no evidence of suspended sediments falling to the seabed beyond this zone and causing significant changes, which may be manifested as infilling of small pits by fine sediments, siltation within c...

A Modelling Study of Coastal Upwelling Driven by Wind and Meanders of the Brazil Current

Abstract: A numerical model is used to investigate coastal upwelling in the South Brazil Bight. The wind in the area is predominantly from the northeast, especially in summer, which is upwelling favorable. Reversals of the wind direction are frequent and intense during the winter, due to the passage of frontal systems. The offshore circulation is dominated by the Brazil Current, which flows southward meandering around the 200 m isobath. Significant shelf-break upwelling has being associated with Brazil Current cyclonic meanders. To assess the relative importance of the two processes in the pumping of South Atlantic Central Water (SACW) onto the continental shelf, three cases are analyzed: (1) wind-driven upwelling; (2) upwelling induced by Brazil Current meanders and (3) both effects acting together. The results show that in the coastal area upwelling/downwelling is mainly caused by the wind, whereas the cyclonic meanders of the Brazil Current are the dominant mechanism in the generation of vertical velocities over the shelf break and slope. This meander-induced upward motion brings the SACW to shallower depths, where it is influenced by the wind. In this situation, when both effects act together, the SACW penetrates all the way to the coast.

Stratigraphy of Back-Barrier Coastal Dunes, Northern North Carolina and Southern Virginia

Abstract: Ground penetrating radar studies of four representative active back-barrier dunes, combined with radiocarbon and photon-stimulated-luminescence dating techniques and soils analysis, reveal phases of alternating dune activity and stabilization along the North Carolina–Virginia coast. Two smaller dunes represent only the current phase of dune activity. Two larger dunes preserve evidence of three phases of dune development (ca. 740, 1260 and 1810 AD) and intervening phases of soil development. Climate, particularly moisture conditions, played a part in the timing of dune activity and stabilization events. All three dune phases are associated with drier conditions whereas soils formation is associated with humid conditions. Modern (phase 3) dunes are more widespread along the coast and their formation is attributed to a combination of dry conditions, increased storminess associated with the Little Ice Age, and rising sea level. Tidal inlet closing and storm overwash processes likely provided sediment...

Seasonal Dynamics of a Microtidal Pocket Beach with Posidonia oceanica Seabeds (Mallorca, Spain)

Abstract: In this work, we analyze the seasonal evolution of a Mediterranean pocket beach and its response to different storm episodes. Magalluf, an intermediate medium sand beach located in the Bay of Palma (Balearic Islands) was monitored by topographic levelling during 14 months. Near the beach, a Posidonia oceanica meadow covers most of the seabed and appears to influence the cross-shore beach adjustment. The low variability observed during the sampling period was perturbed by two storm events that caused significant beach evolution and sediment transport. The first storm gave rise to waves from the SE, significant height = 2.4 m, cross-shore sediment transport and along-shore net sediment exchange that resulted in decreased dry beach extension to a minimum. The second storm was characterized by strong northeasterly winds and generated a set-up of 0.5 m and a nearshore drift reversal that redistributed sediment from the berm crest to the beach face, thereby increasing beach extension. Results from nume...

A Biological and Physical Monitoring Program to Evaluate Long-term Impacts from Sand Dredging Operations in the United States Outer Continental Shelf

Abstract: NAIRN, R.; JOHNSON, J.A.; HARDIN, D., and MICHEL, J., 2004. A biological and physical monitoring program to evaluate long-term impacts from sand dredging operations in the United States Outer Continental Shelf. Journal of Coastal Research, 20(1), 126‐137. West Palm Beach (Florida), ISSN 0749-0208. The Minerals Management Service (MMS) International Activities and Marine Minerals Division is charged with management of Federal Outer Continental Shelf (OCS) sand and gravel resources that would be used for beach nourishment to repair storm damage and protect against sea-level rise. To reduce environmental damage associated with long-term and large-scale use of these resources, a project was funded by MMS to design a comprehensive physical and biological monitoring program for sand-mining activities. An initial task of this project was performance of a literature review to determine where information gaps existed regarding the effects of sand mining and which physical processes and biological resources should be the focus of monitoring. Based upon the literature review and a conference with other investigators, the monitoring program was designed to include the following elements: benthic communities and their trophic relationships to fishes, marine mammals and wildlife (operational monitoring), sediment sampling and analysis, wave monitoring and modeling, bathymetric and substrate surveys, and shoreline monitoring and modeling. Protocols were developed for these elements to ensure consistency of methods among studies. The two primary physical impacts of concern are changes to the sea bed resulting in changes to the erosion and sedimentation processes along the shore and changes to the sea bed that would have a direct and significant impact on the biological environment. The most important biological impacts from dredging to be monitored in this program are changes in benthic secondary production and trophic transfer to fishes.

Distribution and Abundance of Submerged Aquatic Vegetation and Trapa natans in the Hudson River Estuary

Abstract: Submerged aquatic vegetation (SAV) is widely recognized as an important habitat and indicator of water quality in large rivers and estuaries. Despite the perceived importance, system-wide assessments of cover, susceptibility to change, and ecological functioning are rare because of the geographical scope and multi-disciplinary expertise required. A collaboration between scientists, estuarine managers, and environmental educators was initiated to map the SAV and the Eurasian water chestnut (Trapa natans) in the Hudson River estuary from Hastings-on-Hudson north to Troy, New York. These groups provided diverse scientific and estuarine management expertise to enable the first broad delimitation of SAV in the Hudson and sampling of beds to describe abundance, biomass, and species composition and to address management and education needs and opportunities. The areal extent of SAV based on a combination of 1995 and 1997 photographs in the study area was 1,802 hectares (4,453 acres), ∼6% of the river ar...

A Set of 3-D Nested Models for Tidal Propagation from the Argentinean Continental Shelf to the Río de la Plata Estuary—Part I. M2

Abstract: As a contribution to the UNDP/GEF project ‘Environmental Protection of the Rio de la Plata and its Maritime Front’, the three-dimensional primitive equation Hamburg Shelf Ocean Model is being implemented for forecasting purposes. As a first step a study of the tidal propagation was done. Data for the estuary were gained through a set of three one-way nested models. Simulations were started with a large-scale model covering the Argentinean and Uruguayan and part of the Brazilian continental shelves. This model provides boundary conditions to a smaller scale model of the Rio de la Plata and adjacent continental shelf, which in turn is used to force a small-scale high-resolution model of the Rio de la Plata estuary. Model sensitivity to different boundary conditions and to model parameters was investigated. Solutions are not sensitive to the two different boundary conditions tested, derived from global data assimilating models. It results also not sensitive to lateral diffusion but to bottom frictio...

Beach-Dune Interactions in Nourishment Areas along the Dutch Coast

Abstract: The impact of beach nourishment on the development of coastal dunes was studied along the Dutch coast. A database of annual cross-shore profiles was analysed to derive volumetric changes associated with aeolian and hydrodynamic processes. The database covered a period of 15 years. Beach nourishment projects that were carried out arbitrarily within this time-span were selected, and the volumetric changes occurring on the selected sites were statistically related to the number of years following nourishment. An overall negative sand budget was found for the supratidal zone of the nourished sites. A substantial part of the sand was blown to the foredunes. One year after nourishment, this amount increased significantly. At the same time, the supratidal beach was eroded more. In the second and third year after nourishment, the erosion of the higher parts of the nourishment decreased. In the foredune, dune toe erosion due to storm surges was usually negligible until the fourth year following beach nour...