Ground-water supply
potential and procedures for well-site selection in the upper Cape Fear
River Basin
Article
By C.C. Daniel, III and N.B. Sharpless
Prepared in cooperation with the
North Carolina Department of Natural Resources and Community
Development U.S. Water Resources Council
Abstract
The regolith in the upper Cape Fear River basin, North Carolina,
contains approximately 1.5 billion gallons per square mile of
potentially available ground water. Storage capacity in the
underlying fractured bedrock is low and decreases to nearly zero
below a depth of about 400 feet. Precipitation averaging 45.9
inches per year recharges the ground-water system; about 20
percent of this amount infiltrates to the water table. A site
selection procedure for locating new well sites was developed
from an analysis of rock types, land forms, and drainage
patterns. The mafic volcanics unit is the most productive with
nearly three times as many high-yield wells as the sheared
granite, porphyritic granite, felsic volcanics, mica gneiss, and
diorite. High-yield wells are absent in the mica schist and
argillite units. High-yield wells are most often found in draws
or narrow valleys underlain by thick regolith and
highly-fractured bedrock with a high water table. Drainage
patterns provide clues to the presence or absence of fractured
bedrock. Drilling and testing of test wells demonstrated the
usefulness of site selection criteria for locating, in selected
geologic units, wells with above-averaged yields penetrating
zones of highly-fractured rock at sites with a high water table
and thick regolith.
Citation:
Daniel, C.C., III, and Sharpless, N.B., 1983, Ground-water supply potential and procedures for well-site selection in the upper Cape Fear River Basin: North Carolina Department of Natural Resources and Community Development and U.S. Water Resources Council, 73 p.
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