Hantush-Jacob Step Drawdown Test Solution for Leaky Confined Aquifers
Description
A mathematical solution by Hantush and Jacob (1955) is useful for determining the hydraulic properties (transmissivity and storativity) of leaky confined aquifers. Analysis involves matching the solution to drawdown data collected during a step test. The Hantush and Jacob step-drawdown test solution also includes linear and nonlinear well losses for the pumping well (Jacob 1947; Rorabaugh 1953; Ramey 1982).
AQTESOLV provides visual and automatic methods for matching the Theis step test solution to step-drawdown test data. This easy-to-use and intuitive software promotes rapid and accurate determination of aquifer properties.
Assumptions
The following assumptions apply to the use of the Hantush and Jacob step test solution:
- aquifer has infinite areal extent
- aquifer is homogeneous, isotropic and of uniform thickness
- pumping well is fully or partially penetrating
- aquifer is leaky confined
- flow is unsteady
- water is released instantaneously from storage with decline of hydraulic head
- diameter of pumping well is very small so that storage in the well can be neglected
- aquitards have infinite areal extent, uniform vertical hydraulic conductivity and uniform thickness
- aquitards are overlain or underlain by an infinite constant-head plane source
- aquitards are incompressible (no storage)
- flow in the aquitards is vertical
Solution Options
AQTESOLV provides the following options for the Hantush and Jacob step test solution:
- variable pumping rates
- multiple pumping wells
- multiple observation wells
- partially penetrating wells
- boundaries
References
Hantush, M.S. and C.E. Jacob, 1955. Non-steady radial flow in an infinite leaky aquifer, Am. Geophys. Union Trans., vol. 36, pp. 95-100.
Jacob, C.E., 1947. Drawdown test to determine effective radius of artesian well, Trans. Amer. Soc. of Civil Engrs., vol. 112, paper 2321, pp. 1047-1064.
Ramey, H.J., 1982. Well-loss function and the skin effect: A review. In: Narasimhan, T.N. (ed.) Recent trends in hydrogeology, Geol. Soc. Am., special paper 189, pp. 265-271.
Rorabaugh, M.J., 1953. Graphical and theoretical analysis of step-drawdown test of artesian well, Proc. Amer. Soc. Civil Engrs., vol. 79, separate no. 362, 23 pp.
Bear, J., 1979. Hydraulics of Groundwater, McGraw-Hill, New York, 569p.
See also: solution methods, pumping tests