Integrating geophysical techniques to study a small confined aquifer

Abstract

A small nature preserve in Ohio (U.S.A.) has an unusually cool environment due to artesian springs supplying cold ground water. This cool environment supports a collection of rare plants and animals. To understand the water supply so that it can be protected from encroaching development, a series of geophysical studies have been conducted over an extended period of time. The techniques include seismic refraction, seismic reflection, gravity, magnetics, and resistivity. These were supported by drilling and hydrochemical analyses. The results of these studies show that the nature preserve sits on the edge of a major buried valley which has been filled with outwash and till. The ground water appears to flow from a high area in the northeast through an outwash layer which is capped by till. Near the nature preserve later glacial advances caused erosion of channels through the till layer. These channels were back filled with permeable sand and gravel which allowed the cold confined ground water to upwell and cool the nearby areas.