Theis Solution for Nonleaky Confined Aquifers
Description
The Theis (1935) solution (nonequilibrium method) is useful for determining the hydraulic properties (transmissivity and storativity) of nonleaky confined aquifers. Analysis involves matching the Theis type curve for nonleaky confined aquifers to drawdown data collected during a pumping test (aquifer test). Hantush (1961a; 1961b) extended the Theis nonequilibrium method for partially penetrating wells.
AQTESOLV provides visual and automatic methods for matching the Theis nonequilibrium method to pumping test and recovery test data. This easy-to-use and intuitive aquifer test software promotes rapid and accurate determination of aquifer properties.
AQTESOLV also includes Jacob's correction for partial dewatering of water-table (phreatic) aquifers, thereby allowing use of the Theis solution for unconfined aquifers.
Assumptions
The following assumptions apply to the use of the Theis solution:
- aquifer has infinite areal extent
- aquifer is homogeneous, isotropic and of uniform thickness
- control well is fully or partially penetrating
- flow to control well is horizontal when control well is fully penetrating
- aquifer is nonleaky confined
- flow is unsteady
- water is released instantaneously from storage with decline of hydraulic head
- diameter of control well is very small so that storage in the well can be neglected
Solution Options
AQTESOLV provides the following options for the Theis nonequilibrium method:
- variable pumping rates
- multiple pumping wells
- multiple observation wells
- partially penetrating pumping and observation wells
- boundaries
Benchmark
Comparison of AQTESOLV (blue line) and published Theis (1935) w(u) well function values (symbols).
References
Theis, C.V., 1935. The relation between the lowering of the piezometric surface and the rate and duration of discharge of a well using groundwater storage, Am. Geophys. Union Trans., vol. 16, pp. 519-524.
See also: solution methods, pumping tests