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At least 271 records · Page 15Linked to original sources
USGS2006

Reconnaissance investigation of Caribbean extreme wave deposits — Preliminary observations, interpretations, and research directions

This report presents an overview of preliminary geological investigations and recommended future research activities in the Caribbean region pertaining to coastal hazards with an emphasis on establishing tsunami risk for U.S. territories. Fieldwork was conducted in March 2006 on the islands of Bonaire, Puerto Rico, and Guadeloupe to evaluate the stratigraphic records of extreme wave deposits as possible indicators of paleotsunami recurrence. Morphological, sedimentological, and stratigraphic evidence indicate that shore-parallel coral rubble deposits composed of coarse clasts and sand that are 10s of meters wide and several meters thick are depositional complexes that have accumulated for a few centuries or millennia, and are not entirely the result of one or a few tsunamis as previously reported. The origins of boulder fields on elevated rock platforms of the Caribbean islands are more complicated than the origins of ridge complexes because boulder fields can be constructed by either storm waves or tsunamis. What is needed now for more conclusive interpretations is a systematic sedimentological approach to deposit analysis and a set of criteria for distinguishing between coarse clast storm and tsunami deposits. Assembling more field data from other Caribbean islands, analyzing stratigraphic deposits on Puerto Rico and Bonaire, and investigating boulder field deposits resulting from a historical tsunami can accomplish this. Also needed are improved sediment transport models for coarse clasts that can be used to estimate the competence and capacity of tsunamis and storms waves and to determine whether a deposit likely was created by a tsunami or extreme storm. Improved models may also be useful for reconstructing the magnitude of extreme wave events.

Puerto Rico↗
USGS1999

Simulation of ground-water flow and movement of the freshwater-saltwater interface in the New Jersey coastal plain

The confined aquifers of the New Jersey Coastal Plain are sands that range in thickness from 50 to 600 feet and are separated by confining units. The confining units are composed of silts and clays that range in thickness from 500 to 1,000 feet. The aquifers are recharged by precipitation on their outcrop areas. This water then flows laterally downdip and vertically to the deeper confined aquifers. The confined aquifers ultimately discharge to the Raritan and Delaware Bays and to the Atlantic Ocean. In 1988, ground-water withdrawals from confined and unconfined New Jersey Coastal Plain aquifers were approximately 345 million gallons per day, more than 75 percent of which was pumped from the confined aquifers. These withdrawals have created large cones of depression in several Coastal Plain aquifers near populated areas, particularly in Camden and Monmouth Counties. The continued decline of water levels in confined aquifers can cause saltwater intrusion, reduce stream discharge near the outcrop areas, and threaten the quality of the ground-water supply. SHARP, a quasi-three-dimensional finite-difference computer model that can simulate freshwater and saltwater flow, was used to simulate the ground-water flow system in the New Jersey Coastal Plain, including the location and movement of the freshwater-saltwater interface in nine aquifers and eight intervening confining units. The freshwater-saltwater interface is defined as the hypothetical line seaward of which the chloride concentration is equal to or greater than 10,000 milligrams per liter. Model simulations were used to estimate the location and movement of the freshwater-saltwater interface resulting from (1) eustatic sea-level changes over the past 84,000 years, (2) ground-water withdrawals from 1896 through 1988, (3) and future ground-water withdrawals from 1988 to 2040 from Coastal Plain aquifers. Simultion results showed that the location and movement of the freshwater-saltwater interface are more dependent on the historical sea level than on the stresses imposed on the flow system by ground-water withdrawals from the Coastal Plain aquifers from 1896 to 1988. Results of a predictive simulation in which pumpage from existing wells was increased by 30 percent indicate that additional withdrawals from each of the eight confined aquifers in the Coastal Plain would broaden and deepen the existing cones of depression and result in significant drawdowns from the 1988 potentiometric surfaces. Drawdowns of 30 feet were simulated at the center of the cone of depression in the Upper, Middle, and Lower Potomac-Raritan-Magothy aquifers in Camden and Ocean Counties. Simulated drawdowns exceeded 80 feet at the center of the cone of depression in the Wenonah-Mount Laurel and Englishtown aquifers in Monmouth County. Drawdowns of 30 feet were simulated in the lower Kirkwood-Cohansey and confined Kirkwood aquifers in Cape May County. Simulation results showed that the increase in ground-water withdrawals would result in only minimal movement of the freshwater-saltwater interface by 2040, despite large drawdowns.

New Jersey↗
USGS2022

Sea-level rise and warming mediate coastal groundwater discharge in the Arctic

Groundwater discharge is an important mechanism through which fresh water and associated solutes are delivered to the ocean. Permafrost environments have traditionally been considered hydrogeologically inactive, yet with accelerated climate change and permafrost thaw, groundwater flow paths are activating and opening subsurface connections to the coastal zone. While warming has the potential to increase land-sea connectivity, sea-level change has the potential to alter land-sea hydraulic gradients and enhance coastal permafrost thaw, resulting in a complex interplay that will govern future groundwater discharge dynamics along Arctic coastlines. Here, we use a recently developed permafrost hydrological model that simulates variable-density groundwater flow and salinity-dependent freeze-thaw to investigate the impacts of sea-level change and land and ocean warming on the magnitude, spatial distribution, and salinity of coastal groundwater discharge. Results project both an increase and decrease in discharge with climate change depending on the rate of warming and sea-level change. Under high warming and low sea-level rise scenarios, results show up to a 58% increase in coastal groundwater discharge by 2100 due to the formation of a supra-permafrost aquifer that enhances freshwater delivery to the coastal zone. With higher rates of sea-level rise, the increase in discharge due to warming is reduced to 21% as sea-level rise decreased land-sea hydraulic gradients. Under lower warming scenarios for which supra-permafrost groundwater flow was not established, discharge decreased by up to 26% between 1980 and 2100 for high sea-level rise scenarios and increased only 8% under low sea-level rise scenarios. Thus, regions with higher warming rates and lower rates of sea-level change (e.g. northern Nunavut, Canada) will experience a greater increase in discharge than regions with lower warming rates and higher rates of sea-level change. The magnitude, location and salinity of discharge have important implications for ecosystem function, water quality, and carbon dynamics in coastal zones.

Environmental Research Letters↗
USGS2024

Participatory engagement to reduce communication gaps

Underserved communities, especially those in coastal areas in Puerto Rico, face significant threats from natural hazards such as hurricanes and rising sea levels. Limited funding hinders the investment in costly mitigation measures, increasing exposure to natural disasters. Providing coastal resources and data products through effective communication mechanisms is fundamental to improving the well-being of these underserved coastal communities. The overall objectives of the pilot effort to engage and connect with underserved coastal communities in Puerto Rico were the following: (1) compile a comprehensive database of the projects and resources relevant to natural hazards in Puerto Rico; (2) foster connections with Puerto Rican interested parties to better understand their priorities regarding coastal hazards and provide them with pertinent U.S. Geological Survey (USGS) resources; and (3) identify knowledge gaps to guide future USGS projects in Puerto Rico. Here we outline our participatory engagement framework and process, along with two specific resources developed with the information collected from this effort. These resources are available in English and Spanish and consist of user-friendly, non-technical information products. Among them are: (1) a website where users can learn about USGS research on landslides, hurricanes, earthquakes, water resources, coastal hazards, tsunamis, and ecosystem hazards and environmental contaminants, and (2) a geonarrative highlighting shoreline changes in Puerto Rico with sections on historical shoreline trends, hurricane impacts, and potential solutions that could help protect communities and mitigate coastal hazards. Continuing participatory engagement in future projects could enhance the accessibility and usability of natural hazards resources within the community.

San Juan↗
USGS2020

Influence of demand and capacity in transportation simulations of short-notice, distant-tsunami evacuations

Distant tsunamis require short-notice evacuations in coastal communities to minimize threats to life safety. Given the available time to evacuate and potential distances out of hazard zones, coastal transportation planners and emergency managers can expect large proportions of populations to evacuate using vehicles. A community-wide, short-notice, distant-tsunami evacuation is challenging because it creates a sudden, significant, and concentrated demand on road-network systems. Transportation planners and emergency managers need methods to help them determine if a road network can handle an evacuation surge and if not, where interventions can best reduce overall clearance times. We use the coastal community of Bay Farm Island (City of Alameda, California, USA) and the distant-tsunami threat posed by Aleutian-Alaskan earthquakes as a case study to explore the use of agent-based, transportation simulation to support short-notice, tsunami-evacuation planning. Results demonstrate how vehicle simulation can characterize network performance during a tsunami evacuation in the absence of real-world measurements of vehicle demand and flow. Changes in vehicle demand had the greatest influence on reductions in clearance times and recommended reductions varied based on time of day. Doubling the capacity of certain road segments based on traditional vehicle-capacity ratios and level-of-service thresholds reduced overall clearance time in some cases but increased it in other cases. The proposed simulation approach can serve as an analytical foundation for future efforts to characterize distant-tsunami evacuations in other coastal communities throughout the world.

California↗
USGS2022

Presence of the herbaceous marsh species Schoenoplectus americanus enhances surface elevation gain in transitional coastal wetland communities exposed to elevated CO2 and sediment deposition events

Coastal wetlands are dynamic ecosystems that exist along a landscape continuum that can range from freshwater forested wetlands to tidal marsh to mudflat communities. Climate-driven stressors, such as sea-level rise, can cause shifts among these communities, resulting in changes to ecological functions and services. While a growing body of research has characterized the landscape-scale impacts of individual climate-driven stressors, little is known about how multiple stressors and their potential interactions will affect ecological functioning of these ecosystems. How will coastal wetlands respond to discrete climate disturbances, such as hurricane sediment deposition events, under future conditions of elevated atmospheric CO 2 ? Will these responses vary among the different wetland communities? We conducted experimental greenhouse manipulations to simulate sediment deposition from a land-falling hurricane under future elevated atmospheric CO 2 concentrations (720 ppm CO 2 ). We measured responses of net primary production, decomposition, and elevation change in mesocosms representing four communities along a coastal wetland landscape gradient: freshwater forested wetland, forest/marsh mix, marsh, and mudflat. When Schoenoplectus americanus was present, above- and belowground biomass production was highest, decomposition rates were lowest, and wetland elevation gain was greatest, regardless of CO 2 and sediment deposition treatments. Sediment addition initially increased elevation capital in all communities, but post-deposition rates of elevation gain were lower than in mesocosms without added sediment. Together these results indicate that encroachment of oligohaline marshes into freshwater forested wetlands can enhance belowground biomass accumulation and resilience to sea-level rise, and these plant-mediated ecosystem services will be augmented by periodic sediment pulses from storms and restoration efforts.

Plants↗
USGS2017

Final Report fr critical thresholds and ecosystem services for coastal ecological and human climate adaptation

Understanding how climate change will impact natural and human communities is a crucial part of decision making and management related to the protection of our coasts. As the effects of climate change on ecological communities grow, the possibility of crossing tipping points or thresholds of viability increases the potential for rapid and possibly irreversible changes in ecosystems. Therefore, understanding thresholds related to climate change is critical for facilitating conservation and management actions, which could help to prevent more costly and possibly catastrophic effects in the future. As part of a broad effort to synthesize and deliver coastal resilience information through the Landscape Conservation Cooperatives (LCCs), Climate Science Centers, states, and other partners along the Atlantic and Gulf Coasts, we synthesized existing quantitative threshold information for 45 priority coastal fish, wildlife, and plant species and habitats in response to sea level rise and storm projections. Additional information was synthesized on climate change adaptation actions that can increase the persistence and resilience of species and their habitats and how these actions relate to human community resilience. In addition to two peer-reviewed manuscripts, results from these synthesis efforts were disseminated online through easily accessible, topic-specific web pages in the Massachusetts Wildlife Climate Action Tool (climateactiontool.org) to make this information more easily accessible to stakeholders across the region. The compilation and dissemination of species and habitat threshold information will help to develop a more comprehensive understanding of how natural systems will respond to climate change and how land and resource management decisions could potentially help these species.

Report↗
USGS2012

Restoration of freshwater cypress-tupelo wetlands in the southeastern U.S. following severe hurricanes

Freshwater forested wetlands commonly occur in the lower Coastal Plain of the southeastern US with baldcypress ( Taxodium distichum [L.] L.C. Rich.) and water tupelo ( Nyssa aquatica L.) often being the dominant trees. Extensive anthropogenic activities combined with eustatic sea-level rise and land subsidence have caused widespread hydrological changes in many of these forests. In addition, hurricanes (a common, although aperiodic occurrence) cause wide-spread damage from wind and storm surge events, with impacts exacerbated by human-mediated coastal modifications ( e.g. , dredging, navigation channels, etc.). Restoration of forested wetlands in coastal areas is important because emergent canopies can greatly diminish wind penetration, thereby reducing the wind stress available to generate surface waves and storm surge that are the major cause of damage to coastal ecosystems and their surrounding communities. While there is an overall paucity of large-scale restoration efforts within coastal forested wetlands of the southeastern US, we have determined important characteristics that should drive future efforts. Restoration efforts may be enhanced considerably if coupled with hydrological enhancement, such as freshwater, sediment, or sewage wastewater diversions. Large-scale restoration of coastal forests should be attempted to create a landscape capable of minimizing storm impacts and maximizing wetland sustainability in the face of climate change. Planting is the preferred regeneration method in many forested wetland sites because hydrological alterations have increased flooding, and planted seedlings must be protected from herbivory to enhance establishment. Programs identifying salt tolerance in coastal forest tree species need to be continued to help increase resilience to repetitive storm surge events.

Alabama, Delaware, Florida, Georgia, Louisiana, Mi↗
USGS2017

Assessing the impacts of future climate conditions on the effectiveness of winter cover crops in reducing nitrate loads into the Chesapeake Bay Watershed using SWAT model

Winter cover crops (WCCs) have been widely implemented in the Coastal Plain of the Chesapeake Bay watershed (CBW) due to their high effectiveness at reducing nitrate loads. However, future climate conditions (FCCs) are expected to exacerbate water quality degradation in the CBW by increasing nitrate loads from agriculture. Accordingly, the question remains whether WCCs are sufficient to mitigate increased nutrient loads caused by FCCs. In this study, we assessed the impacts of FCCs on WCC nitrate reduction efficiency on the Coastal Plain of the CBW using Soil and Water Assessment Tool (SWAT) model. Three FCC scenarios (2085 – 2098) were prepared using General Circulation Models (GCMs), considering three Intergovernmnental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) greenhouse gas emission scenarios. We also developed six representative WCC implementation scenarios based on the most commonly used planting dates and species of WCCs in this region. Simulation results showed that WCC biomass increased by ~ 58 % under FCC scenarios, due to climate conditions conducive to the WCC growth. Prior to implementing WCCs, annual nitrate loads increased by ~ 43 % under FCC scenarios compared to the baseline scenario (2001 – 2014). When WCCs were planted, annual nitrate loads were substantially reduced by ~ 48 % and WCC nitrate reduction efficiency water ~ 5 % higher under FCC scenarios relative to the baseline. The increase rate of WCC nitrate reduction efficiency varied by FCC scenarios and WCC planting methods. As CO2 concentration was higher and winters were warmer under FCC scenarios, WCCs had greater biomass and therefore showed higher nitrate reduction efficiency. In response to FCC scenarios, the performance of less effective WCC practices (e.g., barley, wheat, and late planting) under the baseline indicated ~ 14 % higher increase rate of nitrate reduction efficiency compared to ones with better effectiveness under the baseline (e.g., rye and early planting), due to warmer temperatures. According to simulation results, WCCs were effective to mitigate nitrate loads accelerated by FCCs and therefore the role of WCCs in mitigating nitrate loads is even more important in the given FCCs.

Chesapeake Bay↗
USGS2005

Multiple-Aquifer Characterization from Single Borehole Extensometer Records

Measurement and analysis of aquifer-system compaction have been used to characterize aquifer and confining unit properties when other techniques such as flow modeling have been ineffective at adequately quantifying storage properties or matching historical water levels in environments experiencing land subsidence. In the southeastern coastal plain of Virginia, high-sensitivity borehole pipe extensometers were used to measure 24.2 mm of total compaction at Franklin from 1979 through 1995 (1.5 mm/year) and 50.2 mm of total compaction at Suffolk from 1982 through 1995 (3.7 mm/year). Analysis of the extensometer data reveals that the small rates of aquifer-system compaction appear to be correlated with withdrawals of water from confined aquifers. One-dimensional vertical compaction modeling indicates measured compaction is the result of nonrecoverable hydrodynamic consolidation of the fine-grained confining units and interbeds, as well as recoverable compaction and expansion of coarse-grained aquifer units. The calibrated modeling results indicate that nonrecoverable specific storage values decrease with depth and range from 1.5 x 10-5/m for aquifer units to 1.5 x 10-4/m for confining units and interbeds. The aquifer and Potomac system recoverable specific storage values were all estimated to be 4.5 x 10-6/m, while the confining units and interbeds had values of 6.0 x 10-6/m. The calibrated vertical hydraulic conductivity values of the confining units and interbeds ranged from 6.6 x 10-4 m/year to 2.0 x 10-3 m/year. These parameter values will be useful in future management and modeling of ground water in the Virginia Coastal Plain.

Ground Water↗
USGS2012

Nearshore morphology, benthic structure, hydrodynamics, and coastal groundwater discharge near Kahekili Beach Park, Maui, Hawaii

This report presents a brief summary of recent fieldwork conducted off Kahekili Beach Park, Maui, Hawaii, the site of the newly established U.S. Coral Reef Task Force priority study area at Kaanapali and the Hawaii Department of Land and Natural Resources, Division of Aquatic Resources, Kahekili Herbivore Fisheries Management Area (HFMA). The goals of this fieldwork are to provide new baseline information to help guide future studies and to provide first insights into rates and drivers of coastal groundwater discharge and associated constituent loadings into the priority study area's coastal waters. This study presents the first swath acoustic mapping information, in situ oceanographic instrument measurements, and coastal groundwater discharge estimates at this site based on the submarine groundwater discharge tracer radon-222 ( 222 Rn). Coastal groundwater discharge rates ranged from about 22 to 50 centimeters per day, depending on proximity of the sampling mooring to the primary discharge vent. The water chemistry of the discharging groundwater was at times dramatically different than ambient seawater. For example, at the primary vent site at Kahekili, the concentrations of total dissolved nitrogen (TDN), dissolved silicate (DSi), and total dissolved phosphorus (TDP) in the discharging groundwater were 43.75 micromolar (μM), 583.49 μM, and 12.04 μM, respectively. These data extend our basic understanding of the morphology, benthic structure, and oceanographic setting of this vent site and provide a first estimate of the magnitude and physical forcings of submarine groundwater discharge and associated trace metals and nutrient loads here.

Hawai'i↗
USGS1964

Artesian water in the Malabar coastal plain of southern Kerala, India

The present report is based on a geological and hydrological reconnaissance during 1954 of the Malabar Coastal Plain and adjacent island area of southern Kerala to evaluate the availability of ground water for coastal villages and municipalities and associated industries and the potentialities for future development. The work was done in cooperation with the Geological Survey of India and under the auspices of the U.S. Technical Cooperation Mission to India. The State of Kerala, which lies near the southern tip of India and along the eastern shore of the Caspian Sea, contains a total area of 14,937 square miles. The eastern part of the state is s rugged mountainous highland which attains altitudes of more than 6,000 feet. This highland descends westward through piedmont upland to s narrow coastal plain, which reaches a maximum width of about 16 miles in the latitude of Shertalli. A tropical monsoon rain-forest climate prevails in most of Kerala, and annual rainfall ranges from 65 to 130 inches in the southern part of the coastal plain to as much a 200 inches in the highland. The highland and piedmont upland tracts of Kerala are underlain by Precambrian meamorphic and igneous rocks belonging in large parabola-the so-called Charnockite Series. Beneath ahe coastal plain are semiconsolidated asunconsolidated sedimentary deposits whose age ranges from Miocene to Recent. These deposits include sofa sandstone and clay shale containing some marl or limestone and sand, and clay and pea containing some gravel. The sofa sandstone, sand, and gravel beds constitute important aquifers a depths ranging from a few tens of feet to 400 feet or more below the land surface. The shallow ground war is under water-able or unconfined conditions, but the deeper aquifers contain water under artesian pressure. Near the coast, drilled wells tapping the deeper aquifers commonly flow with artesian heads as much as 10 to 12 feet above the land surface. The draft from existing wells in the coastal belt between Quilon and Alleppy was estimated at 1 to 1 1/2 million imperial gallons a day. However, favorable conations exist for considerable further ground-water development in the coastal plain provided that sufficient attention is given to the potential hazards of saltwater encroachment and local overdevelopment. It is estimated that the overall potential for development of water from wells is probably at least several tens of millions of gallons a day, and perhaps more, in the Malabar Coastal Plain of southern Kera. Such a draft would have to be well dispersed to avoid overdevelopment and salt-war encroachment.

Water Supply Paper↗
USGS2023

Assessing environmental change associated with early Eocene hyperthermals in the Atlantic Coastal Plain, USA

Eocene transient global warming events (hyperthermals) can provide insight into a future warmer world. While much research has focused on the Paleocene–Eocene Thermal Maximum (PETM), hyperthermals of a smaller magnitude can be used to characterize climatic responses over different magnitudes of forcing. This study identifies two events, namely the Eocene Thermal Maximum 2 (ETM2 and H2), in shallow marine sediments of the Eocene-aged Salisbury Embayment of Maryland, based on magnetostratigraphy, calcareous nannofossil, and dinocyst biostratigraphy, as well as the recognition of negative stable carbon isotope excursions (CIEs) in biogenic calcite. We assess local environmental change in the Salisbury Embayment, utilizing clay mineralogy, marine palynology, δ 18 O of biogenic calcite, and biomarker paleothermometry (TEX 86 ). Paleotemperature proxies show broad agreement between surface water and bottom water temperature changes. However, the timing of the warming does not correspond to the CIE of the ETM2 as expected from other records, and the highest values are observed during H2, suggesting factors in addition to p CO 2 forcing have influenced temperature changes in the region. The ETM2 interval exhibits a shift in clay mineralogy from smectite-dominated facies to illite-rich facies, suggesting hydroclimatic changes but with a rather dampened weathering response relative to that of the PETM in the same region. Organic walled dinoflagellate cyst assemblages show large fluctuations throughout the studied section, none of which seem systematically related to CIE warming. These observations are contrary to the typical tight correspondence between climate change and assemblages across the PETM, regionally and globally, and ETM2 in the Arctic Ocean. The data do indicate very warm and (seasonally) stratified conditions, likely salinity-driven, across H2. The absence of evidence for strong perturbations in local hydrology and nutrient supply during ETM2 and H2, compared to the PETM, is consistent with the less extreme forcing and the warmer pre-event baseline, as well as the non-linear response in hydroclimates to greenhouse forcing.

Atlantic Coastal Plain↗
USGS2023

Comparison of historic to future without action (FWOA) land change

One of the primary purposes of the 2023 Coastal Master Plan Integrated Compartment Model (ICM) is to forecast potential changes in coastal wetland area under varying environmental and restoration scenarios. To validate the model performance, historical analyses of observed wetland changes are needed for comparison to hindcast model runs. To generate these historical analyses, this effort has analyzed satellite imagery from 1985 through 2020 to form a basis of comparison for the hindcast model results. Wetland change is a dynamic process which varies in time and space as a result of multiple compounding and interacting stressors. Wetland area is a fluid concept which can vary depending upon the definition of “wetland” and environmental conditions at the time of acquisition of imagery utilized to estimate land area. Estimates of wetland area are known to vary by more than +/- 5% as a result of nothing more than water level variability. Often, simplistic wetland change analyses are conducted using simple pre- and post- assessments. These assessments create two wetland classifications at two points in time, difference the two, and assume any change between the two assessments is wetland change. These types of assessments ignore parameters like water level variability, lack temporal resolution to account for said variability, and as such, are often prone to misinterpreting normal environmental variability as wetland change. The wetland area change analyses presented here take a multitemporal approach to assessing wetland area change. Annual classifications were created from 1985-2020, and wetland area trends were fit statistically with lines which generalize trends through time. Additionally, the statistical methods utilized here allow for the calculation of confidence intervals with regard to wetland area, which are vital for the validation of model output. The analyses presented here provide a comprehensive historical analysis of wetland change by hydrologic compartment from 1985 through 2020. More importantly, these analyses provide a basis by which to assess hindcasting scenarios of the master plan model as it relates to wetland area change. The results from this effort can be utilized to assess model performance and quantify the confidence which may be placed in outputs of projected wetland area.

Louisiana↗
USGS2007

Surficial sediment character of the New York-New Jersey offshore continental shelf region: A GIS compilation

Broad continental shelf regions such as the New York Bight are the product of a complex geologic history and dynamic oceanographic processes, dominated by the Holocene marine transgression (>100 m sea-level rise) following the end of the last Pleistocene ice advance ~ 20,000 years ago. The area of the U.S. Exclusive Economic Zone (U.S. EEZ) territory, extending 200 nautical miles seaward from the coast, is larger than the continental U.S. and contains submerged landforms that provide a variety of natural functions and societal benefits, such as: critical habitats for fisheries, ship navigation and homeland security, and engineering activities (i.e. oil and gas platforms, pipeline and cable routes, potential wind-energy-generation sites). Some parts of the continental margins, particularly inner-continental shelf regions, also contain unconsolidated hard-mineral deposits such as sand and gravel that are regarded as potential aggregate resources to meet or augment needs not met by onshore deposits (Williams, 1992). The present distribution of surficial sediment off the northeastern United States is shaped from the deposits left by the last glaciation and reflects the cumulative effects of sediment erosion, transport, sorting, and deposition by storm and tidal processes during the Holocene rise in sea level. As a result, the sediments on the sea floor represent both an historical record of former conditions and a guide to possible future sedimentary environments. The U.S. Geological Survey (USGS) through the Coastal and Marine Geology Program, in cooperation with the University of Colorado and other partners, has compiled extant sediment character and textural data as well as other geologic information on the sea floor from all regions around the U.S. into the usSEABED data system (Reid and others, 2005; Buczkowski and others, 2006; Reid and others, 2006). The usSEABED system, which contains information on sediment grain size and lithology for more than 340,500 stations within the U.S. EEZ. has been developed and populated with data as part of the USGS Marine Aggregate Resources and Processes and the National Benthic Habitats projects in order to provide the base-line data needed to update the current maps of offshore surficial geologic character and sediment distribution. The maps are also used to characterize benthic sea floor environments important for marine ecosystems. U.S. Geological Survey, Data Series 118 (Reid and others, 2005), of the usSEABED data release series, represents the combined efforts of the USGS and several other government agencies to provide a unified resource for accessing and preserving records of U.S. east coast sea floor geologic information and sediment texture data. For this present report, we have chosen to focus on the New York-New Jersey region, an area that has been intensely studied by the USGS for many years to address many complex issues. This report illustrates the uses of the usSEABED database for GIS applications, while offering additional insight into the resources and data available from the USGS and its collaborative institutions. This report is based on data contained in U.S. Geological Survey Data Series 118 (Reid and others, 2005) and shows an assortment of example GIS products that are possible using usSEABED. All data are intended to be GIS-ready and should not require any additional cleanup, formatting, or renaming of fields in order to use the data in a Geographic Information System. This project employs the Environmental Systems Research Institute's (ESRI) ArcView™ software. Many of these maps were made as part of the ongoing USGS study to assess marine aggregate resources offshore New York and New Jersey, but these maps can serve many other purposes. The marine science community, educators, students and others are encouraged to use these data to generate GIS products for their own purposes. The objectives of the Marine Aggregate Resources and Processes project are to produce a series of new geologic maps and reports of the sea floor that will provide scientific insights into the character and geologic development of U.S. continental margins and to use these maps and information to assess the potential availability of offshore sand and gravel resources. The mapping and aggregate resource assessments are being conducted on a national scale using the usSEABED data base as described in Williams and others (2003). Potential uses for these data include: (1) defining the geological variability of the sea floor in relation to benthic habitat diversity; (2) improving our understanding of the processes that control the distribution and transport of bottom sediments and benthic habitats; (3) locating aggregate resources for beach nourishment and industrial applications; and (4) providing a detailed geospatial framework for future marine science research, monitoring, and management activities. The initial assessments are in progress for the New York Bight and Louisiana offshore areas.

New Jersey, New York↗
USGS2004

Coastal vulnerability assessment of Olympic National Park to sea-level rise

A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-level rise within Olympic National Park (OLYM), Washington. The CVI scores the following in terms of their physical contribution to sea-level rise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-level rise, shoreline change rates, mean tidal range and mean wave height. The rankings for each variable were combined and an index value calculated for 1-minute grid cells covering the park. The CVI highlights those regions where the physical effects of sea-level rise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-level rise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. The Olympic National Park coast consists of rocky headlands, pocket beaches, glacial-fluvial features, and sand and gravel beaches. The Olympic coastline that is most vulnerable to sea-level rise are beaches in gently sloping areas.

Washington↗
USGS2005

Coastal vulnerability assessment of National Park of American Samoa (NPSA) to sea-level rise

A coastal vulnerability index (CVI) was used to map the relative vulnerability of the coast to future sea-level rise within National Park of American Samoa. The CVI ranks the following in terms of their physical contribution to sea-level rise-related coastal change: geomorphology, regional coastal slope, rate of relative sea-level rise, historical shoreline change rates, mean tidal range and mean significant wave height. The rankings for each input variable were combined and an index value calculated for 500-meter grid cells covering the park. The CVI highlights those regions where the physical effects of sea-level rise might be the greatest. This approach combines the coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, yielding a quantitative, although relative, measure of the park's natural vulnerability to the effects of sea-level rise. The CVI provides an objective technique for evaluation and long-term planning by scientists and park managers. The National Park of American Samoa consists of carbonate sand and coral rubble beaches, rock cliffs and platforms, and back-reef lagoon shorelines. The areas within National Park of American Samoa that are likely to be most vulnerable to sea-level rise are areas of unconsolidated sediment where coastal slope is shallowest and wave energy is high.

American Samoa, National Park of American Samoa↗
USGS2009

Community variations in social vulnerability to Cascadia-related tsunamis in the U.S. Pacific Northwest

Tsunamis generated by Cascadia subduction zone earthquakes pose significant threats to coastal communities in the U. S. Pacific Northwest. Impacts of future tsunamis to individuals and communities will likely vary due to pre-event socioeconomic and demographic differences. In order to assess social vulnerability to Cascadia tsunamis, we adjust a social vulnerability index based on principal component analysis first developed by Cutter et al. (2003) to operate at the census-block level of geography and focus on community-level comparisons along the Oregon coast. The number of residents from blocks in tsunami-prone areas considered to have higher social vulnerability varies considerably among 26 Oregon cities and most are concentrated in four cities and two unincorporated areas. Variations in the number of residents from census blocks considered to have higher social vulnerability in each city do not strongly correlate with the number of residents or city assets in tsunami-prone areas. Methods presented here will help emergency managers to identify community sub-groups that are more susceptible to loss and to develop risk-reduction strategies that are tailored to local conditions. ?? z.

Natural Hazards↗