Ground-water-flow model of the Shenandoah Valley, Virginia and West Virginia

Problem - Increasing development within the Shenandoah Valley in recent years has placed additional demands on the region’s water resources. The sedimentary rocks in the Valley have been compressed and folded by tectonic forces to form a 5-km deep basin. Ground water, a principal component of the available water supply, flows through fractures in the sedimentary and crystalline rocks that underlie the Valley. Bedding fractures in the rocks are angled downward along the dip of the folds, allowing ground water to penetrate deeply below land surface—fresh water is obtained from wells over 800 ft deep in the Valley.

Objectives - Develop a ground-water-flow model to simulate movement of ground water and estimate the rate of flow and values of hydraulic properties of the rocks that control the movement of ground water. Develop a novel approach using SUTRA3D to represent hydraulic connections along bedding planes that conform to the generalized dip of the bedding by specifying the directions of the principal hydraulic connections within each part of the modeled area.

Benefits - The completed ground-water model will serve as a framework for further hydrologic studies in the Valley by simulating directions and rates of flow throughout the region. The approach used to represent fracture connections in this study could also be used to simulate ground-water flow in similar geologic terrains, such as other parts of the Valley and Ridge province in Pennsylvania, Virginia and West Virginia, and the Newark basin in New Jersey.