Differentiation of continental shelf morphology along the southeast Florida Atlantic coast was based on interpretation of airborne laser bathymetry. The 600-km² shelf study area, which had a shoreline extent of about 160 km and extended up to 10 km offshore, displayed a diverse range of seafloor morphologies that were characteristic of four main alongshore reaches. Reach I (sand flats and karst topography) in the northern part of the study area is terminated southward by the Bahamas Fracture Zone, a major morphotectonic feature. Reach II (sand flats and coral reefs) is characterized by sand flats with diabathic channel fields leeward or shoreward of the Florida Reef Tract, the seaward margin of which occurs along the shelf break on the upper part of the continental slope. Reach III (sand flats, hardgrounds, and coral reefs) is characterized by extensive nearshore rock outcrops that are exposed as bare rock surfaces on the seafloor or are variously mantled by thin veneers of sand that are not thick enough to disguise the underlying rock structure. Reach IV (tidal sand flats and ridges, hardgrounds, and coral reefs) is dominated by tidal features that notably include fields of tidal sand ridges in the lee of the Florida Reef Tract. The barrier reef on the southeast Florida Atlantic coast, which transitions to Florida Keys shelf environments southward, grades northward to drowned karst topography that is overlain by sand sheets and sand waves. Tidal channels and associated bars, deltas, and shoals occur on the interface between Biscayne Bay and the Atlantic Ocean. This reconnaissance-level characterization of continental shelf environments into morphological reaches in a geographic information system platform provides a basis for quantifying spatial distribution patterns of discrete landform units.

Mapping areas of seagrass is important, in part because the extent of seagrass habitat can serve as a general indicator of coastal ecosystem health. While aerial photography and multispectral imagery have commonly been used to map seagrass, digital hyperspectral imagery is at the forefront of current mapping technology in many natural resource applications. In this study, HyMap hyperspectral imagery at 2.9-m resolution was used to map seagrass distribution off Horn Island, Mississippi, and estimate its areal coverage. Seagrass beds and sand-bottom classes were defined based on visual interpretation of the imagery coupled with field observations. Image spectra were sampled for each class in three water-depth zones determined by distance from shore. Supervised image classifications were performed using maximum likelihood, minimum distance to means, and spectral angle mapper methods to compare relative accuracies in mapping seagrass coverage. The maximum likelihood classification produced the highest overall accuracy of 83%. The spectral angle mapper yielded the lowest accuracy due to the predominant influence of water-column optical properties on the apparent spectral characteristics of seagrass and sand bottom.

The ML classification indicated total seagrass coverage of 107 ha. This compared favorably with the results of a separate, independent study based on aerial photography acquired 1 day after the HyMap flyover. For tracking sea-grass coverage in the northern Gulf of Mexico, the mapping of individual seagrass patches at a spatial resolution of at least 3 m is recommended.

Beach profiles surveyed over a period of 18 y (1982 to 2000) at 41 sites were analyzed to assess beach changes, seabed scour, and grain sorting pattern fronting the 5 km long seawall built in 1991 to protect the Rosetta promontory from beach erosion, which had been retreating at a rate of −106 m/y. Although the seawall has succeeded in halting the recession, the shoreline shows adverse erosion at the leeside of the seawall ends (−14.4 m/y) associated with depth scour at a maximum of −0.50 m/y. The erosion along the promontory tip progressively decreases with longshore distance both to the east and to the southwest along the promontory flanks, reverting to accretion on both sides within the promontory saddles and yielding two nodal areas that represents zones where the sediment regime changes from erosion to deposition. Moreover, the seawalls have slightly altered the mean grain sizes of the beach sediment and seabed slope of the surf zone. The overall pattern of beach erosion and seabed scour results from wave refraction–induced longshore sediment transport along the promontory tip. The geographic correspondence between patterns of shoreline and seabed depth changes serve to refine boundaries of littoral subcells of the Rosetta promontory, including sediment paths, sources, sinks, nodal points, and zones of sediment transport convergence and divergence. The morphologic changes along this promontory reflect a combination of factors, including sediment availability, transport pathways from source areas, as well as the impact of protective structures at the Rosetta estuary.

Principal component analysis was used to identify dominant patterns of change in morphology of five recent LIDAR surveys of Shinnecock Inlet. The first principal component accounted for 55% of the ebb shoal variability over a period of 6 years (21 June 1994 through 3 July 2000) and identified three accretionary features: (1) an updrift bar complex, (2) a downdrift bypass bar, and (3) shore perpendicular bars along the downdrift barrier. The evolution of these features, accounted for in the first principal component, appears to be the result of both a natural deflection of the main ebb channel and realignment of the channel by dredging. Evidence of channel migration is seen in comparison of 14 sequential historical photographs of the inlet from 24 September 1938 to 22 April 1997. This study also documents that sand waves (length = 100 to 200 m) within the outer channel region were displaced because of variations in incident wave climate.

One of the issues identified in natural resources management leading to overexploitation has to do with a limited or weak legislative framework. The aim was to analyze a quantitative approach evaluating the contribution of different legislative instruments of Mexico on coastal ecosystems sustainability. A case study was employed, and a practical appraisal method that allows identification of sustainability criteria embedded in the legislative instruments was generated. Forty-three Mexican legislative instruments were evaluated, and 60 sustainability attributes were considered. Trends and consistency regarding objectives, times of law application, orientation to systems or to resources, legal and institutional interactions, scientific support, unpredicted impacts of productive activities (non-regulated) and performance evaluation were analyzed. A multivariate analysis was performed to map the interrelations among legislative instruments. On a global scale, legislative instruments only fit in 25% of global sustainability attributes when compared with the two references defined as ideal. Multiple objectives and some systemic approaches were well represented among the analyzed instruments, and regulation of some coastal areas and ecosystems, such as reefs, need to be deeply strengthened. It can be concluded that the proposed approach is useful to obtain a rapid appraisal to evaluate the overall contribution of legislative instruments on ecosystems sustainability. This information will guide legislative authorities in the development of instruments that could strengthen legislative framework in order to efficiently promote ecosystems sustainability.

An experiment was designed to test if the contamination of intensely used beaches by solid wastes could be correlated to the presence of users. Profiles perpendicular to the water line were marked on Boa Viagem Beach, Recife City, Pernambuco, Brazilian Northeast. The solid waste items collected within these profiles at days of high user frequency revealed that some items might be used as flags for the presence (and contribution to the contamination) of users on the beach. Such items especially abundant were plastic cups and drinking straws. The contamination of the beach has the same qualitative character at all sites at all times. However, the amount of flag items changes according to the more intense use of the beach, especially during summer weekends and sociocultural events, when use reaches its maximum intensity.

A sand deficit on Florida's Atlantic coast affects sea turtle nesting, dune ecosystems, and storm protection. Ecological benefits of restoring very large deficits could exceed ecological costs. Dredging and beach nourishment databases revealed sand disposal dynamics and deficit size. Dredge-and-fill activities increased after 1950, peaked in the 1980s, then declined somewhat. Most sand disposal accompanied channel and harbor deepening; little was primarily for beach nourishment. Until the 1970s most dredged material was placed outside the coastal sand-sharing system (offshore and upland). After 1970, beach and nearshore disposal rapidly increased, but generally involved sand already within the system. Moreover, offshore and upland disposal did not immediately decline. To date, little sand has been returned. By 2003, net removal totaled ∼130 × 10⁶ m³. Channels and harbors increased by ∼70 × 10⁶ m³, leaving 60 × 10⁶ m³ of standing sand deficit. Jetties could have redistributed another 70 × 10⁶ m³ from beaches and dunes to inlet shoals. Overall, loss of beaches and dunes could approach 130 × 10⁶ m³. Engineering responses to past objections have improved both habitat suitability and longevity of nourished beaches. Through field trials and adaptive management principles, ecologists could now develop beach nourishment into a management tool to rebuild lost habitat, restore the sand deficit, and stockpile additional sand before nonessential channels and harbors are allowed to refill. With large projects, sand from offshore, upland, and ebb shoal sites and natural wave energy for stable beach building, beach and dune habitat can be restored within decades, better preparing threatened animals for rising sea level.

A new global coastal database has been developed within the context of the DINAS-COAST project. The database covers the world's coasts, excluding Antarctica, and includes information on more than 80 physical, ecological, and socioeconomic parameters of the coastal zone. The database provides the base data for the Dynamic Interactive Vulnerability Assessment modelling tool that the DINAS-COAST project has produced. In order to comply with the requirements of the modelling tool, it is based on a data model in which all information is referenced to more than 12,000 linear coastal segments of variable length. For efficiency of data storage, six other geographic features (administrative units, countries, rivers, tidal basins or estuaries, world heritage sites, and climate grid cells) are used to reference some data, but all are linked to the linear segment structure. This fundamental linear data structure is unique for a global database and represents an efficient solution to the problem of representing and storing coastal data. The database has been specifically designed to support impact and vulnerability analysis to sea-level rise at a range of scales up to global. Due to the structure, consistency, user-friendliness, and wealth of information in the database, it has potential wider application to analysis and modelling of the world's coasts, especially at regional to global scales.

The purpose of the paper is to characterize mollusk stranding on the northern coast of Buenos Aires, and to determine the mechanisms of alteration induced by storm surges on the infralittoral macroinvertebrates as well as on the morphosedimentary feature of the beach. The most common living organisms stranded on the beach were Adelomelon brasiliana and their free giant egg capsules, Amiantis purpurata, Atrina seminuda, Buccinanops duartei, Buccinanops gradatum, Buccinanops monilifer, Donax hanleyanus, Mesodesma mactroides, Mytilus edulis platensis, Tivella isabelleana, and Zidona dufresnei. Shells of Mactra isabelleana and Glycymeris longior were also found.

Three mechanisms were responsible for strandings on the emerged beach: (i) storm surges related to a decrease in the wave-cut level, (ii) swell conditions with infralittoral organism remobilization in the following 7 days, and (iii) shell bar migration. The high abundance of shells found at the emerged beach is due to Mactra isabelleana, although no living individuals were found during the 6 years of survey. The predominance of G. longior shells resulted from their shape, thickness, and hardness, enriching the beach sediments. This is in contrast to other species (D. hanleyanus, Mytilus edulis platensis, and Mesodesma mactroides) whose shells cannot endure exposure to the transport and weather conditions in the swash zone and on the emerged beach.

The intact condition of shells immediately after the storm indicate that they were transported from greater depths where the death of the organisms occured. This is indicated by the simultaneous presence of live stranded individuals and empty shells of the same species (T. isabelleana, Amiantis purpurata, Adelomelon brasiliana, Z. dufresnei, B. gradatum, and Mytilus edulis platensis). Between 35% and 65% of the sand are shell fragments, mostly of deeper water species. The variation in mean grain size, sorting, and skewness among samplings is attributed to shell fragmentation, while the mode remained invariable. Most of the intact shells supplied by the storm were reworked in the swash zone. The percentage of bioclasts remained invariable for 5 months and fell within the interval of 0–0.5 phi.

In this paper, I report on the use of geographic information systems as a highly efficient tool in modeling wind-transported sand along sandy beaches. Programming with Visual Basic in ArcGIS reduces time and represents results easily on spatial maps. The study area is located in the southwestern part of Sinai Peninsula, Egypt, with a long shoreline extending about 180 km on the Gulf of Suez. Representative sand samples were collected along the study area, and beach and wind records were derived from the El-Tor meteorological station. Sand samples were mechanically analyzed, and wind data were classed in order to allow wind direction and intensity analysis. Aster images at 15-m resolution were processed for coastline measurements. Kadib formula components were subjected to Visual Basic code to modulate the wind-transported sand landward and seaward along the Qaa Plain with the use of ArcGIS software. The study area is characterized by an excess of annual landward transport of sand than seaward transport, depending on the wind energy and direction, along with the orientation of the beach segments rather than the length of each coast segment. Also, the study area is characterized by greater amounts of sand collected northward than southward.

During Hurricane Ivan (2004), dunes in undeveloped sections of northwest Florida were significantly reduced in height through direct wave erosion and the transfer of sediment to the backbarrier by overwash. The poststorm morphology of the island consists of a narrow beach face, multiple breach corridors, a washover terrace, and a remnant secondary dune that was further eroded in 2005 by Tropical Storm Arlene and Hurricanes Dennis and Katrina. The redevelopment of this dune will direct the response of the island to future storms, but the mechanisms of posthurricane dune recovery are unclear, particularly in this low-energy coastal environment. The recovery is further complicated by a swale that was created through a knickpoint effect on an adjacent road. The swale was reinforced when the road surface was removed and as a berm developed during the recovery of the beach face.

Field observations suggest that sediment transport across the narrow beach face and berm is limited by a lag of shells and gravel from the pre-Ivan roadbed. As a consequence, sediment input to the dune is relatively minor with onshore winds, despite the presence of fans deposited during frontal storms in the swale behind the berm. The resulting sediment transport gradient across the seaward slope of the dune is more reflective of the expanding fetch than topographic acceleration and the drag imposed by the sparse vegetation. In contrast, there is a larger sediment input to the dune during offshore winds in response to the larger fetch across the washover terrace, despite the presence of a lag. It is concluded that posthurricane dune recovery in this area is strongly dependent on the deposition of sediment during frontal storms and the resulting development of a sand ramp through the swale. This will increase both the availability of sediment and the fetch for winds directly or obliquely onshore.

The lower 9 km of the Buffalo River that flows into the eastern end of Lake Erie has been designated by the International Joint Commission as a Great Lakes area of concern (AoC) because of poor water quality, degraded riparian and river habitat, and contaminated sediments—impairments related to a long history of contamination from the industrial legacy of the past century. As a designated AoC, attention is presently focused on sediment remediation, an endeavor requiring an assessment of the relationship between sediment transport processes and sediment contaminant concentrations. In 1990 a pilot sediment trend analysis (STA) revealed an upriver return of sediments from the mouth of the Buffalo River as far as 5 km inland. A complete STA conducted in 2004 confirmed the upriver transport regime. Examination of river discharge and Lake Erie water levels demonstrated that lake seiches occur at far greater frequencies than river discharges of a magnitude capable of transporting sediment. Thus the river is behaving in a similar manner to an estuary with seiche rather than tidal waves responsible for driving fine-grained sediments in an inland direction. The dynamic behavior of the sediments as determined by STA correlated well with the expected contaminant levels contained in the sediments of the main river channel. The findings are used to establish a conceptual understanding of the river that requires extreme river flows to transport sediments to its mouth, after which sediments recently deposited from plumes discharging into Lake Erie are reentrained and transported upriver by seiche activity. Such an understanding is of considerable importance in sediment remediation as contaminants are also in a constant state of recycling both up and down the lower 5 km of the Buffalo River.

The ichthyofauna of the Manche-à-Eau mangrove lagoon was regularly sampled in 2002 with a fixed net at seven stations during 4 months corresponding to two hydrological seasons. Physicochemical variables (depth, temperature, salinity, dissolved oxygen, pH) and population descriptors (species and family richness, density and biomass) were measured. The Whitefield and the well-being indexes were calculated to appreciate species equilibrium. Canonical correspondence analysis and generalized linear models were used to link species assemblages to physicochemical variables and to search for a special link with salinity. A total of 30,733 individuals belonging to 34 species and 23 families were collected. The Gerreidae, Clupeidae, Engraulidae, Scianidae, and Sparidae represented almost 98% of the total number of individuals. Our results show that organization of the fish assemblages in the lagoon is poorly dependent on salinity, whereas dissolved oxygen, temperature, and pH could have a stronger role. Looking at response curves to salinity change, most fishes species appeared to be visitors, either temporarily present or regular migrators. Only a few species compose the year-round resident population. They have a high patrimonial value and could be considered bioindicator species for long-term studies (e.g., of global change and natural or anthropogenic disturbances). The Euclidean distance and biomass variables were not useful descriptors of confinement and biological zonation in the lagoon, whereas the negative gradient of specific richness, number of individuals, Whitefield index, and index of well-being better described confinement. On the basis of these last parameters, biological zonation in the Manche-à-Eau lagoon was established and is provided.

Decrease of habitat, coastal erosion, and shoreline changes are recent issues for coastal management. In this study, an algorithm which extracts coastlines efficiently and automatically by processing low- or medium-resolution satellite images has been developed. The junction of sea and land is a common result yielded by the automatic coastline extraction method.

In this study, CORONA (1963), IRS-1D (2000), and LANDSAT-7 (2001) satellite images for the same region in Istanbul, Turkey were used. A novel algorithm was developed for automatic coastline extraction. The algorithm is encoded in a C environment. The results of automatic coastline extraction obtained from different images were compared to the results derived from manual digitizing. Random control points which are seen on every image were used.

The average differences of selected points were calculated. Obtained results from selected points were rendered as 3 pixels on the CORONA and IRS-1D images and as 2 pixels on the LANDSAT-7 image. These show that the differences are similar, although different images were used. On the other hand, the results are acceptable compared to manual digitizing.

Padre Island is the longest of five barrier islands occurring along the Texas Gulf Coast. South Padre Island is separated from the northern two-thirds of the island by the Mansfield Channel. The composition and pattern of vegetation on South Padre Island are relatively well known, but data on the interrelationship of dune and vegetation stability are lacking. We hypothesized that (1) there should be an inverse relationship between elevation change and percent cover on transects across the nearshore dunes of South Padre Island; and (2) percent cover, species composition, and species importance should be most stable where elevation change was least. We tested these hypotheses using three study sites differing in vegetation abundance. Elevation measurements were taken at 1.0-m intervals along three transects at each site using survey-grade Global Positioning System equipment. Vegetation abundance was determined in 10-m intervals along each transect. No sites or topographic zones were devoid of elevation change. Even a site that had a mean percent cover of 65.1% had a mean elevation change of 15.6 cm. However, cover does not have to be great to provide considerable stability. There was no significant difference in elevation change at Site 1, where cover was 57%, and Site 2, where cover was only 12.5%. As hypothesized, there was a significant inverse correlation between elevation change and percent cover when analyzed over all transects and sites, but the relationship did not hold for all sites or topographic zones when these were examined separately. Lack of correlation may be due to differences among sites and zones in the number of different perturbations and their intensities and frequencies. Only Site 2 showed a significant difference in percent cover between the initial and final samples. Species composition and importance were more stable where elevation changes were low.

In macrotidal estuaries, a tidal bore may form during spring tide conditions when the flood tide is confined to a narrow channel. Most field occurrences showed well-defined undulations behind the leading wave, that is, an undular bore process. Herein, detailed free-surface and turbulence measurements were performed beneath undular bore fronts using side-looking acoustic Doppler velocimetry and nonintrusive free-surface measurement devices in a laboratory channel. Undular bores were observed for Froude numbers less than 1.7, which compared favourably with past studies. Velocity measurements with a temporal resolution of 50 Hz showed a marked effect of the bore passage. Longitudinal velocities were characterised by rapid flow deceleration at all vertical elevations, while large fluctuations of transverse velocities were recorded beneath the front. Turbulent Reynolds stress data highlighted high levels in the lower flow region, including next to the bed. Maximum normal and tangential turbulent stresses were observed immediately upstream of and at wave crests.

The former U.S. Navy range at Vieques Island (Puerto Rico, United States) is now the largest national wildlife refuge in the Caribbean. We investigated the geomorphology and benthic assemblage structure to understand the status of the coral reefs. Coral assemblages were quantified at 24 sites at Vieques and at 6 sites at St. Croix, U.S. Virgin Islands. These sites were chosen to represent the major zones of reef geomorphology. Sites consisted of two or three 21-m-long photo-quadrate belt transects. The results revealed surprisingly little differentiation in the coral assemblages within and between reefs of comparable geomorphological and oceanographic setting at Vieques and St. Croix. At Vieques, the Acropora palmata zone was almost completely lost, and it was severely reduced at St. Croix, presumably primarily due to diseases and hurricane impacts since the 1970s. Subtle, but nonsignificant, differences with respect to the nature of the shelf margin (north adjacent to the bank, south adjacent to the open sea) and depth zone were observed at Vieques. At St. Croix, benthic assemblages differed more between depth zones but not between north and south. Effects of natural disturbances were severe at Vieques, outweighing impacts of past military activity—which were present but not quantitatively discernible at our scale of sampling. Germs and storms, rather than bombs (and associated naval activities), primarily seem to have taken the worst toll on corals at both Vieques and St. Croix.

We consider the effect of decadal climate change on the historic wave climate of the Southern California Bight (SCB) using a 50 year hindcast record (1948–98) for waves generated in the North Pacific winter. Deep-water wave height, period, and direction are examined with respect to the Southern Oscillation Index (SOI) and the Pacific Decadal Oscillation (PDO). Storms occurring during strong La Niña intervals, when the SOI is greater than 1.0, concurrent with either a cool or warm phase of the PDO, are indistinguishable in wave character. In marked contrast, wave conditions arising from storms during strong El Niño intervals, when the SOI is less than −1.0, concurrent with the PDO cool phase (1948–77), differ greatly from wave conditions of storms during strong El Niño intervals concurrent with the PDO warm phase (1978–98). Our statistical analyses characterize the deep-water winter wave climate as consistent during La Niña intervals (mean values H_s =3.3 m, T_s =13.0 s, α =293°, for the highest 5% of waves), but variable during El Niño intervals depending on PDO phase (H_s =3.64 m, T_s =13.8 s, α =292°during the PDO cool phase, and H_s =4.82 m, T_s =15.1 s, α =284°during the PDO warm phase, for the highest 5% of waves). The dominant characteristics for the different operational modes of wave climate determined in this study provide realistic inputs for numerical models aimed at understanding past and future coastal change within the SCB. Simulating WAves Nearshore (SWAN)-modeled wave transformations for the southern portion of the Oceanside littoral cell show that nearshore wave heights during westerly wave conditions are roughly twice those of northwesterly wave conditions for the same deep-water wave heights and periods, indicating increasing wave energy flux at the beach during the westerly storm-source conditions by an average of 320% (74 kW/m vs. 23 kW/m).

The Atchafalaya Bay system consists of a series of five shallow bays in southern Louisiana (U.S.A.) that are dominated by the circulation of the Atchafalaya River plume. Winter cold fronts have a significant impact on the resuspension and transport of sediments in this region, and a better understanding of the circulation during these events is absolutely necessary for determining the sediment transport patterns of the Atchafalaya Bay system and the adjacent shelf area. Understanding the circulation of this region is also crucial for environmental studies as well. This work describes the implementation of the Navy Coastal Ocean Model (NCOM), a three-dimensional numerical circulation model for tide, river, and wind-forced circulation in the Atchafalaya Bay system. The model has a cell size (Δx) of ∼800 m and is nested to a northern Gulf of Mexico model (Δx ∼5000 m), which is itself nested to the global NCOM (Δx =1/8°). Atmospheric forcing is supplied by the Navy Operational Global Atmospheric Prediction System (NOGAPS) (Δx =1°). These models are used to simulate the hydrodynamics of the Atchafalaya Bay system and Atchafalaya river plume between December 1997 and January 1998 during the passage of three winter cold fronts. The water levels, salinity, and currents predicted by NCOM are in reasonable agreement with available measurements and tide-gauge elevation data. Errors in ebb tides and wind-driven circulation are attributable to uncertainties in the bathymetry and the low spatial and temporal resolution of the NOGAPS wind fields.

In Part 2 of our application of the Navy coastal ocean model (NCOM) to the Atchafalaya Bay system, we examine the wind- and tide-forced three-dimensional baroclinic circulation of the Lower Atchafalaya and Wax Lake Outlet river plumes. The salinity and the current velocity are examined during a time period when three cold fronts passed over the region. The baroclinic circulation of NCOM was validated for the same time period in Part 1 of this study (Cobb, Keen, and Walker, 2008. Modeling the circulation of the Atchafalaya Bay region, 1: Model description and validation. Journal of Coastal Research, this issue). We find that the westward transport of plume water and the offshore cold-front–induced circulation are determined to a large extent by the alongshore and cross-shore bathymetric structure. Wind-driven plume water moves parallel to the alongshore bathymetric contours unless forced to mix with higher salinity water by strong cross-shore directed winds. The mixing of plume water with offshore water occurs over bathymetric shoals during periods of strong post-frontal winds. This mixing process involves the offshore transport of plume water over the entire water column in addition to the strong surface transport. The model results for offshore circulation are in qualitative agreement with past observations. In addition, the hydrodynamic processes that control the salinity fronts in Vermilion and West Cote Blanche Bays, areas where the model salinity was validated in Part 1, are examined as well.

Hurricane Katrina scoured the seaward side of Dauphin Island, Alabama, and then deposited the sediment on the back side of the island into a repeating pattern of arc-shaped overwash fans. We set out to determine if sediment sorting operated at the scale of the individual overwash fan during the storm. Variograms and kriging were used to create maps of the topography and sediment patterning in terms of the mean grain size, standard deviation, skewness, and mineral composition. Mantel tests were used to correlate hypothesized directional processes with the patterns. We found that sands near the surface were spatially sorted in a direction consistent with the north-northwesterly forces of Katrina. The spatial distribution was not correlated with the topography. Our results support the concept that horizontal spatial pattern formation primarily begins as the extreme forces of a hurricane subside.

Tide gauges remain the fundamental instrument used to measure water level in the coastal environment. Issues surrounding the calibration and vertical datum control of tide gauges are therefore fundamental in studies involving the determination of absolute sea level and its variation over time. Macquarie Island, located in Australian sub-Antarctic waters (54°30′ S, 158°57′ E), represents one of the few possible locations in the Southern Ocean to observe sea level using traditional tide gauge techniques. The wave and atmospheric climatology of the region, coupled with a rugged coastline, makes the operation of a modern tide gauge installation extremely difficult. To overcome many of these difficulties, researchers use an acoustic gauge operated within an inclined shaft that is drilled through a coastal rocky outcrop. The calibration requirements of the gauge are therefore problematic and require special consideration to enable the accurate calculation of mean sea level and its change over time. We present results from a novel application of a GPS-equipped buoy to achieve an in situ calibration of the tide gauge, solving for scale, vertical offset, and sea state–dependent bias parameters. The methodology provides a new, high precision technique using available instrumentation, allowing users to maximise the oceanographic and geodetic value of tide gauge observations.

An accurate, single-user beach-elevation profile device that relies on lightweight, inexpensive materials is described. The device is used to rapidly survey beach topographic profiles and is appropriate for scientific data collection. The profiler consists of two vertical legs and two horizontal spacer bars in the shape of the pound (#) symbol with a freely rotating arm to determine the horizontal level. The light weight and ease of operation of the apparatus permit profiles to be surveyed in 1-m increments at roughly 2 m/min. Standard deviations of the profiler reading at specific points along a single profile varied between 0.003 and 0.014 m as recorded by four different users. Root-mean-square errors on data along five different cross-shore profiles collected at Rehoboth Beach, Delaware, by the four users were 0.01–0.13 m when compared to standard rod and sighting scope and ground-based light detecting and ranging. Several potential causes for the differences, including intrinsic profiler bias, tilt in the assumed vertical legs, and operator error (that accumulate along the profile), as well as changes in the sediment surface, are discussed.