SWAIN, LINDSAY A., U.S. Geological Survey, Richmond, VA

ABSTRACT: Hydrogeological Characteristics of the Bedrock Aquifers in the Appalachian Valley and Ridge, Piedmont, and Blue Ridge Physiographic Provinces of the Eastern and Southeastern United States

In 1988, the U.S. Geological Survey began a regional study of the aquifer systems within the Appalachian Valley and Ridge, Piedmont, and Blue Ridge physiographic provinces. The project area covers more than 142,000 sq mi of the eastern and southeastern United States from the northern border of New Jersey to Birmingham, Alabama.

The principal study objectives were to delineate, describe, and quantify the hydrogeologic terranes, and the significant characteristics of the groundwater flow systems within the bedrock aquifers. In the regional approach to accomplish these objectives, the hydrogeologic framework and groundwater conditions in each province were evaluated. In the localized approach, representative basins were intensively studied and their hydrogeologic characteristics were quantified by means of groundwater modeling.

Preliminary findings indicate that maximum discharge of wells in the Valley and Ridge, Piedmont, and Blue Ridge provinces are 8000, 2200, and 830 gal/min, respectively. Median nondomestic discharges of wells in each of these provinces are 37 (4287 wells), 30 (8100 wells), and 20 (668 wells) gal/min, respectively. In the crystalline rocks of the Piedmont and Blue Ridge provinces, the median well discharge is greater in the southern half of the study area than in the northern half. However, in the sedimentary rocks of the Mesozoic rift zones within the Piedmont province, well discharge generally decreases from north to south. At some locations in crystalline rocks in the Piedmont, zones of high yield have been identified between depths of 350 and 650 ft.

AAPG Search and Discovery Article #90995©1993 AAPG Eastern Section Meeting, Williamsburg, Virginia, September 19-21, 1993.