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WATER RESOURCES RESEARCH,
VOL. 43,
W07417,
doi:10.1029/2006WR005597,
2007
A method to estimate groundwater depletion from confining layers
L. F. Konikow
U.S. Geological Survey, Reston, Virginia, USA
C. E. Neuzil
U.S. Geological Survey, Reston, Virginia, USA
Abstract
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 (S s ) 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.
Received 6
October
2006;
accepted 19
April
2007;
published 13
July
2007.
Keywords: groundwater;
confining layer;
depletion.
Index Terms: 1828 Hydrology: Groundwater hydraulics; 1836 Hydrology: Hydrological cycles and budgets (1218, 1655); 1876 Hydrology: Water budgets.
Read Full Article (file size: 544992 bytes) Cited by
Citation: Konikow, L. F., and C. E. Neuzil
(2007),
A method to estimate groundwater depletion from confining layers,
Water Resour. Res.,
43,
W07417,
doi:10.1029/2006WR005597.
This paper is not subject to U.S. copyright. Published in 2007 by the
American Geophysical Union.
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