Digital elevations and extents of regional hydrogeologic units in the Northern Atlantic Coastal Plain aquifer system (ver. 1.1, January 2021)

A digital model of the sedimentary Northern Atlantic Coastal Plain aquifer system is composed of 20 rasters and hydrogeologic unit extent polygons. Rasters describe the top elevations of regional aquifers and confining units at a resolution of 2640 feet (1/2 mile). The rasters are clipped to the extent polygons, which represent the spatial extents of the hydrogeologic units onshore and several miles offshore. This three-dimensional hydrogeologic model was constructed as part of a U.S. Geological Survey Groundwater Resources Program study of groundwater availability in the Northern Atlantic Coastal Plain (NACP) aquifer system, including parts of New York, New Jersey, Delaware, Maryland, Virginia, and North Carolina. Digital elevations of major regional aquifers and confining units were compiled from published digital elevation models (DEM) of various parts of the NACP aquifer system to provide a consistent regional model of hydrogeologic unit geometries. The many studies incorporated within these data include the interpretation and analysis of thousands of well logs and other related information spanning at least a century of study. These regional units are derived from published unit-elevation contours interpreted by geologists at the state and local level, and incorporate little additional interpretation of unit elevations beyond the correlation of individual units across geographic boundaries and some extrapolation of units to the edges of the modeled area. This regionally consistent hydrogeologic framework was used as the foundation of a MODFLOW groundwater flow model of the NACP, which informed modifications to the regional hydrogeologic units that have now been incorporated into the framework data. A related digital elevation model (DEM) for the Northern Atlantic Coastal Plain (NACP) from Long Island New York to northeastern North Carolina represents the elevation of the topographic and bathymetric surface at a uniform horizontal grid spacing of 100 feet and vertical units of 1 (integer) foot. The land-surface elevations are derived from U.S. Geological Survey 30-meter National Elevation Dataset (NED), and the bathymetric elevations are derived from 3 arc-second (90-meter-nominal) National Oceanic and Atmospheric Administration (NOAA) U.S. Coastal Relief Model (CRM).