Abstract:Ground-water recharge potential maps show land areas characterized by their abilities to transmit water from land surface to a depth of 20 feet. The basic methods for mapping ground-water recharge potential are presented in Delaware Geological Survey Open File Report No. 34 (Andres, 1991) and were developed specifically for the geohydrologic conditions present in the Coastal Plain of Delaware.
Purpose:Recharge maps are being used in state and county resource protection programs. The maps are also being used in digital ground-water flow modeling and geologic mapping research.
Supplemental Information:Original scale 1:24,000 The only modification to the published method (Andres, 1991) is that flow-net analysis is not used to discriminate recharge areas from discharge areas. As a result recharge potential has been mapped for almost all land areas not depicted as water, swamp, or marsh on U. S. Geological Survey 1:24,000 topographic maps. In addition, a systematic methodology for mapping areas that have undergone significant filling, excavation, or regrading could not be developed, hence, recharge potentials are not assigned to these areas. Approximately 10 years of field, laboratory, and GIS work were invested in producing recharge potential maps. Over 6900 well and test boring logs and more than 400 descriptions of outcrops and hand auger borings were used for mapping in Kent and Sussex counties. About 600 of these were test borings drilled and logged by staff of the Delaware Geological Survey for this project. Another 580 well and test boring logs were used for a complimentary mapping project in New Castle County. Single-well aquifer tests were completed in nearly 200 wells to establish the relationships between earth material and hydraulic properties that are the bases for recharge potential characterization. More than 500 grain size distribution tests were run on outcrop and borehole samples to test the accuracy of field descriptions.

Progress:Complete
Update Frequency:As needed

Theme Keywords:None, water resources, resource protection, ground water, recharge, geoscientificInformation, environment
Place Keywords:Delaware, Kent County, Sussex County, Assawoman Bay, Bombay Hook, Bethany Beach, Bennetts Pier, Burrsville, Cape Henlopen, Clayton, Delmar, Dover, Ellendale, Fairmount, Frankford, Frederica, Georgetown, Greenwood, Harrington, Harbeson, Hebron, Hickman, Kenton, Laurel, Lewes, Little Creek, Marydel, Milford, Mispillion River, Milton, Millington, Millsboro, Pittsville, Rehoboth Beach, Seaford East, Selbyville, Seaford West, Sharptown, Smyrna, Sudlersville, Trap Pond, Whaleysville, Wyoming

Access Constraints:None.
Usage Constraints:These maps, which were developed through the application of generally accepted geologic principles and practices represent our knowledge at the time of production. They were derived through interpretation of site-specific boring and outcrop exposure data located across the map area. Thus, the lines on the map and cross section must be considered on the basis of the scale at which they are shown and the data from which they were derived. Because specific subsurface conditions between individual data points are not certain, precise location of any individual map feature requires investigation on a more detailed scale. Data used in constructing the map are available at the Survey offices.