SEDL / STP / STP963-EB / STP44881S

A Geologic and Flow-System-Based Rationale for Ground-Water Sampling

Urban, JB
Geologist and hydrologist, Northeast Watershed Research Center, USDA-ARS, University Park, PA

Gburek, WJ
Geologist and hydrologist, Northeast Watershed Research Center, USDA-ARS, University Park, PA

Pages: 14    Published: Jan 1988

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Abstract

Representative measurements of ground water require a sampling protocol based on the physical and hydraulic properties of the geologic materials. Measurements must be made within the context of the site and areal ground-water flow systems. A multizone geologic system in east-central Pennsylvania is used as an example of instrumentation by geologic and hydrologic criteria. Geology is that of a weathered, fractured, sedimentary rock mantle overlying deeper, less fractured, sedimentary rock strata.

The focus of this paper is on describing the domain of and controls on ground-water flow within the shallow (<15 m) and deep (15 to 100 m) fracture systems. A systematic approach, using commonly available information, identifies the areal extent, depth, hydraulic conductivity distribution, and paths of ground-water flow in the two systems. This approach was tested within a 7.4-km² watershed and at stream-valley cross sections. The findings indicate that ground-water quality distribution is accurately portrayed in both settings if the sampling scheme is based on geologic and flow system controls. Ground-water sampling wells must be located, and their data interpreted, by grouping according to geology and the ground-water flow system elements of recharge, lateral flow, and discharge zones.