A method to estimate groundwater depletion from confining layers
Article first published online: 13 JUL 2007
Copyright 2007 by the American Geophysical Union.
Water Resources Research
Volume 43, Issue 7, July 2007
How to Cite
2007), A method to estimate groundwater depletion from confining layers, Water Resour. Res., 43, W07417, doi:10.1029/2006WR005597., and (
- Issue published online: 13 JUL 2007
- Article first published online: 13 JUL 2007
- Manuscript Accepted: 19 APR 2007
- Manuscript Revised: 30 MAR 2007
- Manuscript Received: 6 OCT 2006
- confining layer;
 Although depletion of storage in low-permeability confining layers is the source of much of the groundwater produced from many confined aquifer systems, it is all too frequently overlooked or ignored. This makes effective management of groundwater resources difficult by masking how much water has been derived from storage and, in some cases, the total amount of water that has been extracted from an aquifer system. Analyzing confining layer storage is viewed as troublesome because of the additional computational burden and because the hydraulic properties of confining layers are poorly known. In this paper we propose a simplified method for computing estimates of confining layer depletion, as well as procedures for approximating confining layer hydraulic conductivity (K) and specific storage (Ss) using geologic information. The latter makes the technique useful in developing countries and other settings where minimal data are available or when scoping calculations are needed. As such, our approach may be helpful for estimating the global transfer of groundwater to surface water. A test of the method on a synthetic system suggests that the computational errors will generally be small. Larger errors will probably result from inaccuracy in confining layer property estimates, but these may be no greater than errors in more sophisticated analyses. The technique is demonstrated by application to two aquifer systems: the Dakota artesian aquifer system in South Dakota and the coastal plain aquifer system in Virginia. In both cases, depletion from confining layers was substantially larger than depletion from the aquifers.