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At least 829 records · Page 46Linked to original sources
USGS2009

Polar bear maternal den habitat in the Arctic National Wildlife Refuge, Alaska

Polar bears ( Ursus maritimus ) give birth during mid-winter in dens of ice and snow. Denning polar bears subjected to human disturbances may abandon dens before their altricial young can survive the rigors of the Arctic winter. Because the Arctic coastal plain of Alaska is an area of high petroleum potential and contains existing and planned oil field developments, the distribution of polar bear dens on the plain is of interest to land managers. Therefore, as part of a study of denning habitats along the entire Arctic coast of Alaska, we examined high-resolution aerial photographs (n = 1655) of the 7994 km 2 coastal plain included in the Arctic National Wildlife Refuge (ANWR) and mapped 3621 km of bank habitat suitable for denning by polar bears. Such habitats were distributed uniformly and comprised 0.29% (23.2 km 2 ) of the coastal plain between the Canning River and the Canadian border. Ground-truth sampling suggested that we had correctly identified 91.5% of bank denning habitats on the ANWR coastal plain. Knowledge of the distribution of these habitats will help facilitate informed management of human activities and minimize disruption of polar bears in maternal dens.

Alaska↗
USGS2023

Physicochemical coastal groundwater dynamics between Kauhakō Crater lake and Kalaupapa settlement, Moloka‘i, Hawai‘i

Land-based sources of groundwater pollution can be a critical threat to coral reefs, and a better understanding of “ridge-to-reef” water movement is required to advance management and coral survival in the Anthropocene. In this study a more complete understanding of the geological, atmospheric, and oceanic drivers behind coastal groundwater exchange on the Kalaupapa peninsula, on Moloka‘i, Hawai‘i, is obtained by analyzing high resolution geochemical and geophysical time-series data. In concert with multiyear water level analyses, a tidally and precipitation-driven groundwater connection between Kauhakō Crater lake and submarine groundwater discharge (SGD) fluxes are demonstrated. Results include an average discharge rate of 190 cm d −1 and the detection of water-flow pathways past cesspools that likely contribute to higher nutrient loading near the SGD sites. This underlines the importance of managing anthropogenic nutrients that enter the shallow freshwater lens such as through cesspools and are consequently discharged via SGD onto coral reef habitats.

Hawai'i↗
USGS2010

Seasonal and spatial distribution patterns of finfish and selected invertebrates in coastal lagoons of northeastern Florida, 2002-2004

The U.S. Geological Survey conducted a survey of juvenile fisheries resources, in cooperation with the St. Johns River Water Management District and Volusia County, to establish baseline data on spatial and temporal distribution patterns of estuarine fish. The survey was conducted from November 2001 to March 2005 and the baseline data established for the survey in the Northern Coastal Basins were collected from January 2002 to December 2004. The study area included the bar-built estuaries ranging from just north of St. Augustine, Florida, south to Ponce de Leon Inlet. Sampling protocols developed by the Florida Fish and Wildlife Research Institute for their statewide Fisheries Independent Monitoring (FIM) program were replicated to allow for comparability with FIM program results. Samples were collected monthly from randomly selected stations based on a geographically stratified design. Finfish and selected invertebrates were collected using a 21.3-meter center-bag seine with a 3-millimeter mesh, and a 6.1-meter otter trawl with a 3-millimeter mesh liner. Total estimated fish and selected invertebrate densities were similar to estimates from FIM projects in adjacent areas and were characterized by similar dominant species. Preliminary analysis indicates that observed species distribution patterns were mainly a function of proximity to the three inlets within the study area. The two regions encompassing the northern Tolomato River and the Tomoka River and Basin are farthest from inlets and appear to function as oligohaline nursery areas. Those two areas had the greatest estimated densities of shellfish and juvenile sciaenid (drum) species associated with oligohaline waters (for example, Micropogonias undulatus, Sciaenops ocellatus and Cynoscion nebulosus). Samples near inlets, and between the two northern inlets, had greater estimated densities of species limited to euhaline waters, including juvenile clupeids collected at relatively high abundance and species of marine strays collected in low abundance. Based on correspondence analysis, seasonal variation dominated the ordination of seine samples and spatial variation dominated the ordination of trawl samples; this was due to differences in the number and timing of taxa found near inlets versus oligohaline regions. The absence of seagrass habitat in the Northern Coastal Basins is reflected by the absence of a seagrass-fish assemblage.

Scientific Investigations Report↗
USGS2014

Mercury bioaccumulation in estuarine wetland fishes: Evaluating habitats and risk to coastal wildlife

Estuaries are globally important areas for methylmercury bioaccumulation because of high methylmercury production rates and use by fish and wildlife. We measured total mercury (THg) concentrations in ten fish species from 32 wetland and open bay sites in San Francisco Bay Estuary (2005–2008). Fish THg concentrations (μg/g dry weight ± standard error) differed by up to 7.4× among estuary habitats. Concentrations were lowest in open bay (0.17 ± 0.02) and tidal wetlands (0.42 ± 0.02), and highest in managed seasonal saline wetlands (1.27 ± 0.05) and decommissioned high salinity salt ponds (1.14 ± 0.07). Mercury also differed among fishes, with Mississippi silversides (0.87 ± 0.03) having the highest and longjaw mudsuckers (0.37 ± 0.01) the lowest concentrations. Overall, 26% and 12% of fish exceeded toxicity benchmarks for fish (0.20 μg/g wet weight) and piscivorous bird (0.30 μg/g wet weight) health, respectively. Our results suggest that despite managed wetlands' limited abundance within estuaries, they may be disproportionately important habitats of Hg risk to coastal wildlife.

California↗
USGS2023

Estuarine salinity extremes: Using the Coastal Salinity Index to quantify the role of droughts, floods, hurricanes, and freshwater flow alteration

In the face of accelerating climate change, advancing understanding of how extreme climatic events influence estuarine salinities can help to inform resource management. Extreme salinities driven by droughts, hurricanes, floods, and freshwater flow alterations can lead to ecological transformations in estuarine ecosystems. Here, we applied the Coastal Salinity Index (CSI; Conrads and Darby 2017) to 22 years (1998–2020) of salinity data in a Louisiana estuary (Barataria Estuary, USA) to elucidate the impacts of extreme events on estuarine salinities. The CSI is an index to quantify salinity patterns at a specific location through long-term averages and deviations from historical average conditions. We calculated and compared CSI values for four stations distributed along an estuarine salinity gradient. We identified 10 events between 1998 and 2020 that produced extreme salinities, including two droughts, four hurricanes, three floods, and one freshwater diversion. The droughts of 2000 and 2006 caused surface water salinities to increase substantially throughout the estuary. The effects of hurricanes were highly variable, with some storms leading to elevated salinities throughout the entire estuary (e.g., Hurricanes Katrina and Rita in 2005), whereas other storms led to elevated salinities for some but not all stations (e.g., Hurricanes Gustav and Ike in 2008 or Hurricane Isaac in 2012). The opening of a freshwater river diversion in 2010 contributed to fresher conditions throughout the estuary and appeared to reduce or eliminate the increases in salinity that normally occur during the summer, although these effects were short-lived. Mississippi River floods in 2008, 2011, and 2019 reduced salinities throughout the estuary, but the effects were most pronounced in the lower estuary compared to the upper estuary. Collectively, our results advance understanding of the influence of extreme events on estuarine salinity regimes. Our analyses also highlight the value of the CSI for identifying periods with extreme salinities (i.e., extreme high or low salinities) via calculations that place salinity levels within and across estuaries within a historical context.

Louisiana↗
USGS2016

Assessment of groundwater availability in the Northern Atlantic Coastal Plain aquifer system From Long Island, New York, to North Carolina

Executive Summary The U.S. Geological Survey began a multiyear regional assessment of groundwater availability in the Northern Atlantic Coastal Plain (NACP) aquifer system in 2010 as part of its ongoing regional assessments of groundwater availability of the principal aquifers of the Nation. The goals of this national assessment are to document effects of human activities on water levels and groundwater storage, explore climate variability effects on the regional water budget, and provide consistent and integrated information that is useful to those who use and manage the groundwater resource. As part of this nationwide assessment, the USGS evaluated available groundwater resources within the NACP aquifer system from Long Island, New York, to northeastern North Carolina. The northern Atlantic Coastal Plain physiographic province depends heavily on groundwater to meet agricultural, industrial, and municipal needs. The groundwater assessment of the NACP aquifer system included an evaluation of how water use has changed over time; this evaluation primarily used groundwater budgets and development of a numerical modeling tool to assess system responses to stresses from future human uses and climate trends. This assessment focused on multiple spatial and temporal scales to examine changes in groundwater pumping, storage, and water levels. The regional scale provides a broad view of the sources and demands on the system with time. The sub-regional scale provides an evaluation of the differing response of the aquifer system across geographic areas allowing for closer examination of the interaction between different aquifers and confining units and the changes in these interactions under pumping and recharge conditions in 2013 and hydrologic stresses as much as 45 years in the future. By focusing on multiple scales, water-resource managers may utilize this study to understand system response to changes as they affect the system as a whole. The NACP aquifer system extends from Long Island to northeastern North Carolina, and includes aquifers primarily within New York, New Jersey, Delaware, Maryland, Virginia, and North Carolina. The seaward-dipping sedimentary wedge that underlies the northern Atlantic Coastal Plain physiographic province forms a complex groundwater system. Although the NACP aquifer system is recognized by the U.S. Geological Survey as one of the smallest of the 66 principal aquifer systems in the Nation, it ranks 13th overall in terms of total groundwater withdrawals and is 7th in population served. Despite abundant precipitation [about 45 inches per year (in/yr)], the supply of fresh surface water in this region is limited because many of the surface waters in this area are brackish estuaries, contributing to why many communities in the northern Atlantic Coastal Plain physiographic province rely heavily on groundwater to meet their water needs. Increases in population and changes in land use during the past 100 years have resulted in diverse increased demands for freshwater throughout the northern Atlantic Coastal Plain physiographic province with groundwater serving as a vital source of drinking water for the nearly 20 million people who live in the region. Total groundwater withdrawal in 2013 was estimated to be about 1,300 million gallons per day (Mgal/d) and accounts for about 40 percent of the drinking water supply with the densely populated areas tending to have the highest rates of withdrawals and, therefore, being most susceptible to effects from these withdrawals over time. Water levels in many of the confined aquifers are decreasing by as much as 2 feet per year (ft/yr) in response to extensive development and subsequent increased withdrawals throughout the region. Total water-level decreases (drawdowns) are more than 100 feet (ft) in some aquifers from their predevelopment (before 1900) levels. These drawdowns extend across state lines and under the Chesapeake and Delaware Bays, creating the potential for interstate aquifer management issues. Regional water-resources managers in the northern Atlantic Coastal Plain physiographic province face challenges beyond competing local domestic, industrial, agricultural, and environmental demands for water. Large changes in regional water use have made the State-level management of aquifer resources more difficult because of hydrologic effects that extend beyond State boundaries. The northern Atlantic Coastal Plain physiographic province is underlain by a wedge of unconsolidated to partially consolidated sediments that are typically thousands of feet thick along the coastline with a maximum thickness of about 10,000 ft near the edge of the continental shelf. The NACP aquifer system consists of nine confined aquifers and nine confining units capped by an unconfined surficial aquifer that is bounded laterally from the west by the contact between Coastal Plain sediments and the upland Piedmont bedrock. This aquifer system extends to the east to the limit of the Continental Shelf, however, the boundary between fresh and saline groundwater is considered to be much closer to the shoreline and varies vertically by aquifer. Precipitation over the region for average conditions from 2005 to 2009 is about 61,800 Mgal/d, but about 70 percent of it is lost to evapotranspiration resulting in an inflow of about 19,600 Mgal/d entering the groundwater system as aquifer recharge. Most of this recharge enters the aquifer system and flows through the shallow unconfined aquifer and either discharges to streams or directly to coastal waters without reaching the deep, confined aquifer system. In addition to recharge from precipitation, other sources of water include the return of wastewater from domestic septic systems of about 240 Mgal/d, about 60 Mgal/d of water released from storage in the confined system, and about 30 Mgal/d of lateral inflow at the boundary between freshwater and saltwater in response to pumping for conditions in 2013. The outflow needed to balance the inflows was subdivided between streamflow, discharge to tidal portions of streams, and coastal discharge. The hydrologic budget developed for current [2013] conditions determined that 93 percent of the total outflow was to surface waters with about 70 percent divided evenly between streamflow and shallow coastal discharge and 23 percent as discharge to tidal waters. The remaining 7 percent of the total outflow components include withdrawals from both the surficial and confined aquifers of the groundwater system. The groundwater availability assessment of the NACP aquifer system highlights the importance of analyses at both the regional and local scales to understand how changes in land use, water use, and climate have affected groundwater resources and how these resources may change in the future. The investigation included assessments of the regional changes in water levels and budgets across State lines, the importance of considering storage change in the confining units, the response of the aquifer system to a continuation of current [2013] hydrologic stresses into the future, and the potential effects of climate change and sea-level rise on the aquifer system. The Potomac aquifer group includes two of the most widely used aquifers in the NACP aquifer system, the Potomac-Patapsco and Potomac-Patuxent regional aquifers, providing about 24 percent of the total groundwater used in the region. Withdrawals from large pumping centers in this deep, confined aquifer group have resulted in substantial decreases in water-levels across state lines, particularly between southern Virginia and northeastern North Carolina as well as between southern New Jersey and northern Delaware where water levels in the Potomac-Patapsco aquifer have decreased by as much as 200 ft and 50 ft, respectively from predevelopment to current [2013] conditions. This response in water levels also is reflected in changes in water budgets where, for example, about 20 percent of the total response to pumping in Virginia is met by inducing flow from adjacent States. Understanding and quantifying these hydrologic effects that extend beyond State boundaries is critical for the State- and regional-level management of aquifer resources. The cumulative storage loss from the intervening confining units throughout the entire NACP aquifer system was about 35 percent of the total storage loss from predevelopment to current [2013] conditions. In geographic areas such as Delmarva Peninsula, Maryland, and New Jersey, the water released from storage in the confining units makes up the majority of the total storage release from the groundwater system and is becoming proportionally more important over time as the surficial aquifer approaches equilibrium with respect to pumping and recharge stresses as of 2013. Storage loss from the confining units is of particular concern because, unlike in the sands that comprise the confined aquifers, water removed from the clayey confining unit sediments cannot be replenished as these units gradually compress. This non-recoverable storage loss, if great enough, can result in land subsidence where these units are thick and the release from storage is relatively large and contributes to increased concerns for sea-level rise in areas such as the lower portion of the Chesapeake Bay. Groundwater usage increased dramatically in the NACP aquifer system during post-World War II era from the mid-1940s to early the 1980s, with withdrawals increasing from about 400 Mgal/d to more than 1,300 Mgal/d. Although groundwater withdrawals have been relatively constant since the early 1980s, about half of the total groundwater withdrawn from the NACP aquifer system since 1900 was withdrawn in the past 30 years. An analysis of the response of the groundwater system to a continuation of the current [2013] pumping for an additional 30 years into the future shows that the flow system continues to adjust in terms of changes in water budget components, water levels, and the boundary between freshwater and saltwater as it approaches equilibrium. The largest change in water budget components is the reduction in the amount of water released from storage. Across the entire NACP aquifer system, the reduction of storage release from 7 to 4 percent of the total water budget change is accounted for by reductions in groundwater discharge to streams and coastal waters. Locally, a similar response is calculated for each of the geographic areas except for Virginia where the amount of water released from storage accounts for about 25 percent of the total change in water budget. This finding suggests that the groundwater flow system in Virginia is not approaching equilibrium under the current [2013] stresses and, therefore, water levels will continue to decrease even if the pumping remains constant. An analysis of the change in water levels in the Potomac-Patapsco aquifer as pumping is continued 30 years into the future reveals that the largest decreases in water levels throughout the NACP aquifer system will occur in the southern Virginia and northeastern North Carolina parts of the study area. It is these areas that also see the greatest potential for increased lateral movement of saline groundwater in the deep, confined portion of the groundwater flow system in response to a continuation of the current [2013] pumping rates. The potential effects of long-term climate change and variability on the hydrologic system and availability of water resources in the NACP aquifer system continue to be of serious societal concern. These concerns include the effects of changes in aquifer recharge and in sea-level rise on the groundwater flow system. An assessment of the potential effects of a prolonged drought during current [2013] pumping conditions indicated that the reductions in recharge associated with droughts, including additional irrigation withdrawals required to meet increased crop water demand, have the greatest effects on water levels and streamflows in the surficial aquifer, and changes in water levels in the confined aquifers primarily resulted from the increased withdrawals associated with increased irrigation pumping; this response was most apparent in the Delmarva Peninsula. These results suggest that water levels may not be susceptible to the effects of droughts in the confined aquifers of the NACP aquifer system not used for irrigation, unlike in the unconfined surficial aquifer. A second analysis also was conducted to assess the effects of sea-level rise on the groundwater system throughout the northern Atlantic Coastal Plain physiographic province because recent analyses of the relative rates of sea-level rise along the Atlantic coast indicate that the Mid-Atlantic region represents a hot spot with anomalously higher rates of sea-level rise than observed elsewhere in the United States. Groundwater levels rose from 0 to 3 ft in response to a 3-ft simulated change in sea-level position, with the largest response occurring along the shoreline and away from non-tidal streams. About 37 percent (or 10,000 square miles) of the area of the northern Atlantic Coastal Plain physiographic province may experience about a 0.5-ft or more increase in water levels with the 3-ft increase in sea-level position, whereas about 18 percent (almost 5,000 square miles) of land of the northern Atlantic Coastal Plain physiographic province may experience a 2-ft or more increase in water levels with the 3-ft increase in sea-level position. These increases in the water table are of particular concern in low-lying areas where the unsaturated (vadose) zone is already thin, thus creating concerns for groundwater inundation of subsurface infrastructure, such as basements, septic systems, and subway systems. This increase in the water table also will likely alter the distribution of groundwater discharge to surface-water bodies thus increasing groundwater flow to streams that would have otherwise discharged directly to coastal waters. Throughout the NACP aquifer system, this redistribution of groundwater discharge results in an additional 2 percent of base flow in streams. Although the increases in groundwater discharge to streams (and corresponding decreases in discharge to coastal waters) calculated for the entire NACP aquifer system and its geographic areas represent only a small increase compared with current [2013] conditions, this redistribution of groundwater discharge from the coast to streams locally can alter the delivery of freshwater input to coastal receiving waters and have ecohydrological implications on the sensitive ecosystems which rely on a balance of groundwater discharge and surface-water flow.

Delaware, Maryland, New Jersey, New York, North Ca↗
USGS2011

Monitoring habitat restoration projects: U.S. Fish and Wildlife Service Pacific Region Partners for Fish and Wildlife Program and Coastal Program Protocol

The U.S. Fish and Wildlife Service's (FWS) Pacific Region (Region 1) includes more than 158 million acres (almost 247,000 square miles) of land base in Idaho, Oregon, Washington, Hawai`i, the Commonwealth of the Northern Mariana Islands, American Samoa, Guam, the Republic of Palau, the Federated States of Micronesia, and the Republic of the Marshall Islands. Region 1 is ecologically diverse with landscapes that range from coral reefs, broadleaf tropical forests, and tropical savannahs in the Pacific Islands, to glacial streams and lakes, lush old-growth rainforests, inland fjords, and coastal shoreline in the Pacific Northwest, to the forested mountains, shrub-steppe desert, and native grasslands in the Inland Northwest. Similarly, the people of the different landscapes perceive, value, and manage their natural resources in ways unique to their respective regions and cultures. The Partners for Fish and Wildlife Program (Partners Program) and Coastal Program work with a variety of partners in Region 1 including individual landowners, watershed councils, land trusts, Soil and Water Conservation Districts, non-governmental organizations, Tribal governments, Native Hawaiian organizations, and local, State, and Federal agencies. The Partners Program is the FWS's vanguard for working with private landowners to voluntarily restore and conserve fish and wildlife habitat. Using non-regulatory incentives, the Partners Program engages willing partners to conserve and protect valuable fish and wildlife habitat on their property and in their communities. This is accomplished by providing the funding support and technical and planning tools needed to make on-the-ground conservation affordable, feasible, and effective. The primary goals of the Pacific Region Partners Program are to: Promote citizen and community-based stewardship efforts for fish and wildlife conservation Contribute to the recovery of at-risk species, Protect the environmental integrity of the National Wildlife Refuges, Contribute to the implementation of the State Comprehensive Wildlife Conservation Strategies, and Help achieve the objectives of the National Fish Habitat Partnerships and regionally based bird conservation plans (for example, North American Waterfowl Management Plan, U.S. Pacific Island Shorebird Conservation Plans, Intermountain West Regional Shorebird Plan, etc.). The Partners Program accomplishes these priorities by: Developing and maintaining strong partnerships, and delivering on-the-ground habitat restoration projects designed to reestablish habitat function and restore natural processes; Addressing key habitat limiting factors for declining species; Providing corridors for wildlife and decrease impediments to native fish and wildlife migration; and Enhancing native plant communities by reducing invasive species and improving native species composition. The Coastal Program is a voluntary fish and wildlife conservation program that focuses on watershed-scale, long-term collaborative resource planning and on-the-ground restoration projects in high-priority coastal areas. The Coastal Program conducts planning and restoration work on private, State, and Federal lands, and partnerships with other agencies-Native American Tribes, citizens, and organizations are emphasized. Coastal Program goals include restoring and protecting coastal habitat, providing technical and cost-sharing assistance where appropriate, supporting community-based restoration, collecting and developing information on the status of and threats to fish and wildlife, and using outreach to promote stewardship of coastal resources. The diversity of habitats and partners in Region 1 present many opportunities for conducting restoration projects. Faced with this abundance of opportunity, the Partners Program and Coastal Program must ensure that limited staffing and project dollars are allocated to benefit the highest priority resources and achieve the highest quality results for Federal trust species. In 2007, the Partners Program and Coastal Program developed a Strategic Plan to guide program operations and more efficiently conserve habitat by focusing partnership building and habitat improvement actions within 35 Partners Program Focus Areas and 9 Coastal Program Focus Areas (U.S. Fish and Wildlife Service, 2010). The Strategic Plan also contains four other goals: broaden and strengthen partnerships; improve information sharing and communications; enhance workforce; and increase accountability to ensure that program resources are used efficiently and effectively. This protocol will help achieve all goals of the Strategic Plan.

Techniques and Methods↗
USGS2019

Perspective: Developing flow policies to balance the water needs of humans and wetlands requires a landscape scale approach inclusive of future scenarios and multiple timescales

Maintenance of the natural flow regime is essential for continued wetland integrity; however, the flow regime is greatly influenced by both natural and anthropogenic forces. Wetlands may be particularly susceptible to altered flow regimes as they are directly impacted by water flows at a variety of time scales. In Puerto Rico, contemporary water management is decreasing freshwater recharge to wetlands and contributes to the salinization of important coastal wetlands as sea levels rise. Further, downscaled climate models predict an increase in drought frequency, intensity, and duration by mid-century. Conflicts over water allocation seem imminent between human and ecological needs. Current minimum flow policies are insufficient given the complexities of ecosystem processes and the changes in precipitation patterns and sea level rise that are expected in the future. Improved flow policies need to be established that reflect the functional relationships between specific representative ecological resources and components of the natural flow regime across all relevant time scales. Similarly, flow policies need to be developed within a landscape scale to implicitly address the socio-ecological trade-offs as well as the complexities of water management. Multi-disciplinary collaborations will be essential for increasing our resiliency to anticipated future changes.

Wetlands↗
USGS2024

Simulation of groundwater flow in the Long Island, New York regional aquifer system for pumping and recharge conditions from 1900 to 2019

The U.S. Geological Survey has developed a transient, groundwater-flow model that simulates hydrologic conditions in the Long Island aquifer system as part of an ongoing (since 2016) multiyear, cooperative investigation with the New York State Department of Environmental Conservation. The goals of this investigation are to assist stakeholders and resource managers to evaluate the response of the hydrologic system to changes in future hydraulic stresses. Responses in the hydrologic system include changes in water levels in the hydrogeologic units; discharge to streams, coastal waters, and subsurface infrastructure; and the extent of saline groundwater in the aquifers. Hydraulic stresses include future water-supply management and changes in land use and infrastructure. The numerical model synthesizes a diverse set of physiographic, geologic, climatic, land-use, and historical population, water use, and infrastructure data to physically represent the Long Island aquifer system from land surface to bedrock and to simulate annual hydrologic conditions between 1900 and 2019. A three-dimensional hydrogeologic framework was developed from existing and recently collected borehole geologic and geophysical data collected as part of a companion drilling program. Water-transmitting properties of the principal aquifer sediments were defined in three dimensions from new and existing lithologic logs. The distribution of recharge from precipitation was estimated from landscape characteristics and climate data. Anthropogenic recharge from wastewater, leaky infrastructure, and storm runoff were estimated from population, infrastructure, and pumping data. Water-use data, including well locations, depths, and pumping rates, were obtained from historical sources and records and used to estimate pumping stresses continuously in time and space, at an annual average time scale. The data were incorporated into a three-dimensional numerical model using the U.S. Geological Survey finite difference modeling code MODFLOW 6; the model encompassed all of Long Island and surrounding surface waters and simulated historical hydrologic conditions from 1900 to 2019. The calibration process involved trial and error adjustments using prior knowledge to improve general fit to observations followed by an inverse calibration to update and optimize input parameters, using an iterative ensemble smoother algorithm implemented in PEST++ version 5.0. This resulted in a model that generally was in good agreement with observed, dynamically varying hydrologic conditions from 1900 to 2019. The calibrated model was used to develop two base-case models for scenario testing of future, hypothetical conditions where one represented average-annual conditions, and one represented average-seasonal conditions from 2010 to 2019. The model representing average-annual conditions was modified further to represent an alternate sea-level position of 6 feet above the North American Vertical Datum of 1988, and the model representing average-seasonal conditions was modified to represent the average seasonal effects of a 5-year drought imposed upon current hydrologic conditions. Recharge is the sole source of water to the aquifer system; groundwater discharges to coastal water and streams and is withdrawn by pumped wells. Model-estimated annual recharge ranged from about 11 inches in 1965 to 41 inches in 1983. On average, from 2010 to 2019, about 23 percent of water was pumped from wells, and about 47 and 27 percent discharged to coastal waters and streams, respectively; the remaining 4 percent was water that moved into storage in the aquifer matrix. Water levels on Long Island vary naturally during time in response to changes in recharge; the amount of variation is largest in the interior of the island, in areas with highest water table altitudes near groundwater divides and lowest near streams and the coastal waters. The total range of water table altitudes on Long Island between 1900 and 2019 ranged from near 0 to more than 70 feet in western parts of Long Island. The largest range in altitudes is in New York City and is associated with areas of large historical withdrawals between the 1920s and the late 1980s. Water table altitudes generally varied by less than 10 feet in eastern Suffolk County, where the aquifer is under more natural conditions. Saltwater intrusion is of great concern on Long Island, particularly in western Long Island where both the unconfined and confined parts of the aquifer system have been intruded in response to large-scale groundwater withdrawals; however, the volume of freshwater in the islandwide aquifer system only has changed by about 5 percent between 1900 and 2019. The decadal change in the freshwater volume was largest during the early and mid-20th century, corresponding to the largest historical pumping, but that volume change did not exceed 1 percent. The negligible change in freshwater volume suggests that saltwater intrusion as of 2019 was limited at an islandwide scale but continues to occur in local areas of Queens and Nassau Counties, adversely affecting current water supplies and limiting future water supplies for affected communities. The regional groundwater model developed for this investigation is a tool that can be used to help determine the viability of current and future water supplies at a regional scale and can be used to support development of additional models at finer scale to support more focused assessments of groundwater sustainability.

New York↗
USGS2020

Spatially referenced models of streamflow and nitrogen, phosphorus, and suspended-sediment loads in the southeastern United States

Spatially Referenced Regression On Watershed attributes (SPARROW) models were applied to describe and estimate mean-annual streamflow and transport of total nitrogen (TN), total phosphorus (TP), and suspended sediment (SS) in streams and delivered to coastal waters of the southeastern United States on the basis of inputs and management practices centered near 2012, the base year of the model. Previously published TN and TP models for 2002 served as a starting point and reference for comparison. The datasets developed for the 2012 models not only represent updates of previous conditions but also incorporate new approaches for characterizing sources and transport processes that were not available for previous models. Variability in streamflow across the southeastern United States was explained as a function of precipitation adjusted for evapotranspiration, spring discharge, and municipal and domestic wastewater discharges to streams. Results from the streamflow model were used as input to the water-quality SPARROW models, and areas with large streamflow prediction errors—urban areas and karst areas—were used to provide guidance on where additional data are needed to improve routing of flow. Variability in TN transport in Southeast streams was explained by the following five sources in order of decreasing mass contribution to streams: atmospheric deposition, agricultural fertilizer, municipal wastewater, manure from livestock, and urban land. Variable rates of TN delivery from source to stream were attributed to variation among catchments in climate, soil texture, and vegetative cover, including the extent of cover crops in the watershed. Variability in TP transport in Southeast streams was explained by the following six sources in order of decreasing mass contribution to streams: parent-rock minerals, urban land, manure from livestock, municipal wastewater, agricultural fertilizer, and phosphate mining. Varying rates of TP delivery were attributed to variation in climate, soil erodibility, depth to water table, and the extent of conservation tillage practices in the watershed. Variability in SS transport in Southeast streams was explained by variable sediment export rates for different combinations of land cover and geologic setting (for upland sources of sediment) and by gains in stream power caused by longitudinal changes in channel hydraulics (for channel sources of sediment). Sediment yields for the transitional land cover (shrub, scrub, herbaceous, and barren) varied widely depending on geologic setting and on agricultural land cover. Varying rates of SS delivery, like those for TP, were attributed to variation in climate, soil erodibility, and the extent of conservation tillage practices in the watershed, as well as to areal extent of canopy land cover in the 100-meter buffer along the channel. Relatively large uncertainty, compared to the other three models, for almost all the SS source coefficients indicates the need for caution when interpreting the results from the sediment model. TN, TP, and SS inputs to streams from sources were balanced in the models with losses from physical processes in streams and reservoirs and with water withdrawals. The losses in streams and reservoirs along with withdrawals removed 35, 44, and 65 percent of the TN, TP, and SS load, respectively, that entered streams before reaching coastal waters.

Scientific Investigations Report↗
USGS2025

Estimated hydrogeologic, spatial, and temporal distribution of self-supplied domestic groundwater withdrawals for aquifers of the Virginia Coastal Plain

Water use from private-domestic wells accounts for nearly 40 percent of total groundwater withdrawals in the Virginia Coastal Plain Physiographic Province (henceforth called the Virginia Coastal Plain). However, because self-supplied domestic water use generally falls below the Virginia Department of Environmental Quality (VDEQ) reporting and management threshold of 300,000 gallons per month, quantifying these withdrawals is challenging. This report builds upon the foundation of previous U.S. Geological Survey investigations by providing revised techniques to improve estimates of the aquifer source, spatial distribution, and monthly magnitude of these groundwater withdrawals. The aquifer sources of private-domestic wells in the Virginia Coastal Plain were estimated by cross-referencing 8,264 well records from the VDEQ and the Virginia Department of Health to a digital model of the Virginia Coastal Plain hydrogeologic framework. This analysis highlights the regional importance of the Yorktown-Eastover, Potomac, and surficial aquifers. Collectively, these three aquifers account for 80 percent of self-supplied domestic groundwater withdrawals. The population using self-supplied domestic water was estimated using census blocks, well-use ratios, building footprints, and land-use and land-cover data to produce a high-resolution, disaggregated, raster-based dataset. This approach improves upon previous models at the census-block or road-network scale by reducing the low-density spread of the self-supplied domestic population across undeveloped areas and concentrating the population and its corresponding water use in the areas where it is most likely to occur. Results show that an estimated 475,332 people comprise the 2020 self-supplied domestic population of the Virginia Coastal Plain, an increase of 5.7 percent since 2010, and the greatest concentrations of self-supplied domestic population surround large cities. Estimates could be further refined with the addition of current and complete spatial data on public water-system service areas. The quantity of water used by the self-supplied domestic population was estimated by modifying published state per-capita water-use coefficients with the corresponding monthly variability assessed from Virginia Coastal Plain public water-system withdrawal data. This analysis estimates an average increase of 12 percent from June through August and an average decrease of 8 percent from December through March from the baseline annual average of 80 gallons per day per capita, which generally matches similar studies in the eastern United States. The application of these revised methodologies for the estimation of private-domestic wells and the self-supplied domestic population improves understanding of domestic groundwater use in the Virginia Coastal Plain across hydrogeologic, spatial, and temporal scales. These revisions help better inform water-resource managers and decision makers and support higher resolution groundwater modeling. Furthermore, these methods are transferrable to other areas where self-supplied domestic water withdrawals are important to the overall water budget.

Virginia↗
USGS2023

Trends and population estimate of the threatened Buff-breasted Sandpiper Calidris subruficollis wintering in coastal grasslands of southern Brazil

Information about population sizes, trends, and habitat use is key for species conservation and management. The Buff-breasted Sandpiper Calidris subruficollis (BBSA) is a long-distance migratory shorebird that breeds in the Arctic and migrates to south-eastern South America, wintering in the grasslands of southern Brazil, Uruguay, and Argentina. Most studies of Nearctic migratory species occur in the Northern Hemisphere, but monitoring these species at non-breeding areas is crucial for conservation during this phase of the annual cycle. Our first objective was to estimate trends of BBSA at four key areas in southern Brazil during the non-breeding season. We surveyed for BBSA and measured vegetation height in most years from 2008/09 to 2019/20. We used hierarchical distance sampling models in which BBSA abundance and density were modelled as a function of vegetation height and corrected for detectability. Next, we used on-the-ground surveys combined with satellite imagery and habitat classification models to estimate BBSA population size in 2019/20 at two major non-breeding areas. We found that abundance and density were negatively affected by increasing vegetation height. Abundance fluctuated five- to eight-fold over the study period, with peaks in the middle of the study (2014/15). We estimated the BBSA wintering population size as 1,201 (95% credible interval [CI]: 637–1,946) birds in Torotama Island and 2,232 (95% CI: 1,199–3,584) in Lagoa do Peixe National Park during the 2019/20 austral summer. Although no pronounced trend was detected, BBSA abundance fluctuated greatly from year to year. Our results demonstrate that only two of the four key areas hold high densities of BBSA and highlight the positive effect of short grass on BBSA numbers. Short-grass coastal habitats used by BBSA are strongly influenced by livestock grazing and climate, and are expected to shrink in size with future development and climatic changes.

Bird Conservation International↗
USGS2022

Great Lakes spatial priorities study

Spatial data about the bathymetry, habitat characteristics, underlying geology, and other features of the ocean and inland seas are essential for decision-making. Marine research and management organizations use these data to help ensure safe navigation, promote sustainable fisheries, extract energy, and protect marine habitats in the coastal and ocean waters of the U.S. Exclusive Economic Zone (EEZ) and Laurentian Great Lakes. Many of these organizations may have overlapping or shared mapping interests without knowing it. In a multi-jurisdictional planning environment, it can be challenging and cumbersome to determine where other entities have shared or overlapping mapping interests, especially across a transnational region such as the Great Lakes. State and provincial governments, federal governments, academia, tribes and First Nations, and other stakeholders from both the U.S. and Canada all have mapping interests across Great Lakes waters. Identifying and communicating target geographies for new data collection that are shared among multiple organizations can both help to avoid redundancy of new mapping efforts, and create opportunities for greater efficiency through collaboration. To address this issue, a spatial priorities study was conducted using a geospatial tool developed by the National Ocean Services National Centers for Coastal and Ocean Science (NCCOS). The tool provided an easy-to-use online interface in which programs can identify their priorities in a simple and straightforward way. This study asked representatives of Great Lakes management and science organizations to identify the areas for which they needed maps of lakebed features on a near-term, mid-term, and long-term timeframe, and why. Then, the responses were analyzed and overlaid to determine areas of shared mapping need and opportunity and to determine the types of map products needed. The analysis revealed high interest among multiple organizations in discrete geographies including the Minnesota and Wisconsin shoreline from Duluth to the eastern extent of the Bayfield Peninsula, Green Bay in Lake Michigan, and the southern coastlines of Lake Erie and Lake Ontario, the St. Marys River, and the northern Lake Superior coastal waters near Grand Portage, MN. Lower priority mapping interest were distributed widely across all lakes, but tended to be concentrated in nearshore areas (<30 m depth). The analysis also indicated that the top mapping justifications were Habitat/biota/natural area, Benthic exploration, Commercial and recreational fishing, and Scientific research. The top desired map product types were Elevation, Substrate/sub-bottom geologic characterization, and Habitat map/characterization, although participants on some lakes noted other less prevalent product types. Following from previously conducted NOAA and non-NOAA Federal spatial prioritization exercises, the results of this regional focus can help mapping organizations better understand how their priorities align with the needs of regional organizations, allow for more efficient coordination and funding, and enable partners to leverage assets and resources to fill their most pressing data and information gaps across Great Lakes waters. The U.S. Mapping Coordination Site hosts the results of this study and other spatial prioritization studies. Through this website, one can interact with the study results along with recent and planned mapping efforts. NOAA intends to update their spatial priorities on a three- to five-year basis. Future studies should strive to expand participation of federal agencies, state and local governments, federally-recognized tribes, academia, and private industry (among other stakeholders) to seek out ocean mapping partnerships in conjunction with the National Ocean Mapping, Exploration and Characterization (NOMEC) goals map once, use many times.”

Great Lakes↗
USGS2022

Action plan for restoration of coral reef coastal protection services: Case study example and workbook

This report was prepared by the U.S. Environmental Protection Agency (USEPA), Office of Research and Development, as part of the Air, Climate and Energy (ACE) research program, with support from Tetra Tech, Inc., and in collaboration with the National Oceanic and Atmospheric Administration, the U.S. Geological Survey, and The Nature Conservancy. The ACE research program provides scientific information and tools to support USEPA’s commitment to clean air, clean water and sustainable natural resources, even as environmental conditions change. A key component of this is the development of sound science to support adaptation. Adaptation involves preparing for and adjusting to the effects of climate change and its interactions with other global and local stressors. Because these effects are diverse, interactive, and difficult to predict, adapting management of natural resources in this context can be very challenging. Coral reefs—which provide valued ecosystem services such as fisheries, coastal protection, and tourism—are threatened by the effects of increased sea surface temperatures, sea level rise, and intensifying storms. These large-scale stressors are interacting with local stressors such as pollution, overfishing, and recreational misuse to drive ongoing and accelerating declines in coral reef ecosystems. Thus, there is a rising urgency to design and implement climate change adaptation measures that will enable reef resilience in the face of these changes. This includes accounting for, and adjusting to, the combined effects of climate change and local stressors in coral reef protection and restoration efforts. The action plan, example case study, and workbook found in this report demonstrate a structured process for integrating climate-smart design considerations into restoration planning using A Manager’s Guide to Coral Reef Restoration Planning and Design. The focus is a hypothetical coral reef restoration project that has a goal of recovering nature-based coastal protection services using restoration interventions. The intent is to provide readers with a completed example of how to use the Guide workbook to inform a draft action plan, centering on the topic of coastal protection as a burgeoning area of interest in coral reef science and management communities. The information in this hypothetical case study is not intended for direct use; rather, it provides a starting point for more detailed planning that would occur in specific places. And while a full review of the current literature on reef restoration methods is outside the scope of this report, readers are encouraged to use the examples herein as well as in the Guide as a jumping-off point for exploring the rapidly growing body of information on methods, techniques, successes, failures, monitoring challenges and future directions of coral reef restoration in a changing world. The workbook, together with the action plan, can serve as a valuable record of the planning thought process as well as a living document for adaptive management, to be updated through time as improved information becomes available.

EPA Report↗
USGS2025

Understanding abundances and behaviors of shorebirds in coastal Louisiana

Barrier islands provide resources and ecological services that are integral to economic and environmental interests, such as protection of coastal infrastructure and provision of wildlife habitat. Over time, barrier islands may become eroded and experience land loss, which can require management actions to restore island integrity. Barrier island restoration can create or modify habitats, which can impact the organisms depending on them. Our objective was to understand how the abundance and behaviors of a suite of shorebird species responded to restoration and habitat factors at two restored sites in coastal Louisiana (USA). For five focal species, we used abundance from the breeding and non-breeding seasons as well as breeding, foraging, and maintenance behaviors as response variables in boosted regression tree models to determine the importance of various geospatial and remotely sensed predictor variables related to restoration. Across sites and species, remotely sensed variables, particularly a brightness index, tended to be more important than restoration phases as predictors of bird abundance and behavior. Our results suggest that sediment composition, moisture, and vegetative cover are related to shorebird coastal habitat selection, although the direction and strength of relationships differ among these variables and our focal species. Tying these remote sensing metrics to restoration design and management actions can help land managers better understand factors that attract and benefit birds. Additional research can advance understanding in how remote sensing can be used to monitor the availability of functional habitats for shorebirds.

BioRxiv↗
USGS2013

Trends and causes of historical wetland loss in coastal Louisiana

Wetland losses in the northern Gulf Coast region of the United States are so extensive that they represent critical concerns to government environmental agencies and natural resource managers. In Louisiana, almost 3,000 square kilometers (km 2 ) of low-lying wetlands converted to open water between 1956 and 2004, and billions of dollars in State and Federal funding have been allocated for coastal restoration projects intended to compensate for some of those wetland losses. Recent research at the St. Petersburg Coastal and Marine Science Center (SPCMSC) focused on understanding the physical processes and human activities that contributed to historical wetland loss in coastal Louisiana and the spatial and temporal trends of that loss. The physical processes (land-surface subsidence and sediment erosion) responsible for historical wetland loss were quantified by comparing marsh-surface elevations, water depths, and vertical displacements of stratigraphic contacts at 10 study areas in the Mississippi River delta plain and 6 sites at Sabine National Wildlife Refuge (SNWR) in the western chenier plain. The timing and extent of land loss at the study areas was determined by comparing historical maps, aerial photographs, and satellite imagery; the temporal and spatial trends of those losses were compared with historical subsidence rates and hydrocarbon production trends.

Louisiana↗
USGS2020

Local sea level rise information sheets for Texas, Louisiana, Mississippi, Alabama and Florida

Two Pagers for Federally Managed Lands The Northern Gulf of Mexico Sentinel Site Cooperative partnered with individuals at the U.S. Geological Survey’s Wetland and Aquatic Research Center and the U.S. Fish and Wildlife Service to produce customized two-pager information sheets for federal coastal refuges, parks, and reserves across the northern Gulf of Mexico (i.e., sea-level rise sensitive federally-managed lands within Texas, Louisiana, Alabama, Mississippi, and Florida). The project was funded by the Department of the Interior Southeast Climate Adaptation Science Center, and the project team included Bogdan Chivoiu (Cherokee Nation Technologies at USGS), Michael Osland (USGS), Renee Collini (Northern Gulf of Mexico Sentinel Site Cooperative), Sara Martin (Northern Gulf of Mexico Sentinel Site Cooperative), Benjamin Wilson (NAS Science Policy Fellow at USFWS) and John Tirpak (USFWS). The project team is grateful to the many individuals that provided helpful comments on earlier drafts of these two pagers.

Texas, Louisiana, Mississippi, Alabama, Florida↗
USGS2017

Linear and nonlinear effects of temperature and precipitation on ecosystem properties in tidal saline wetlands

Climate greatly influences the structure and functioning of tidal saline wetland ecosystems. However, there is a need to better quantify the effects of climatic drivers on ecosystem properties, particularly near climate-sensitive ecological transition zones. Here, we used climate- and literature-derived ecological data from tidal saline wetlands to test hypotheses regarding the influence of climatic drivers (i.e., temperature and precipitation regimes) on the following six ecosystem properties: canopy height, biomass, productivity, decomposition, soil carbon density, and soil carbon accumulation. Our analyses quantify and elucidate linear and nonlinear effects of climatic drivers. We quantified positive linear relationships between temperature and above-ground productivity and strong positive nonlinear (sigmoidal) relationships between (1) temperature and above-ground biomass and canopy height and (2) precipitation and canopy height. Near temperature-controlled mangrove range limits, small changes in temperature are expected to trigger comparatively large changes in biomass and canopy height, as mangrove forests grow, expand, and, in some cases, replace salt marshes. However, within these same transition zones, temperature-induced changes in productivity are expected to be comparatively small. Interestingly, despite the significant above-ground height, biomass, and productivity relationships across the tropical–temperate mangrove–marsh transition zone, the relationships between temperature and soil carbon density or soil carbon accumulation were not significant. Our literature review identifies several ecosystem properties and many regions of the world for which there are insufficient data to fully evaluate the influence of climatic drivers, and the identified data gaps can be used by scientists to guide future research. Our analyses indicate that near precipitation-controlled transition zones, small changes in precipitation are expected to trigger comparatively large changes in canopy height. However, there are scant data to evaluate the influence of precipitation on other ecosystem properties. There is a need for more decomposition data across climatic gradients, and to advance understanding of the influence of changes in precipitation and freshwater availability, additional ecological data are needed from tidal saline wetlands in arid climates. Collectively, our results can help scientists and managers better anticipate the linear and nonlinear ecological consequences of climate change for coastal wetlands.

Ecosphere↗