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## Conceptual models >## Constant-head test |

Constant-head test

1. Aquifers of infinite lateral extent

Assumptions:

✓aquifer is confined, isotropic, of infinite lateral extent;

✓two leakage concepts can be considered: accounting and not accounting for leakage;

✓drawdown is estimated in the aquifer at any distance from the pumping well;

✓hydraulic head in the pumping well is constant during the test period;

✓storage capacity of the pumping well is included.

a b c

Conceptual model sketches for constant-head test analysis: nonleaky confined aquifer (a); leaky confined aquifer (b ); unconfined aquifer (c). For leaky aquifer some other positions of aquifers and aquitards can be considered.

2. Radially heterogeneous aquifer

Assumptions:

✓general conditions for constant-head tests in nonleaky and leaky aquifers of infinite lateral extent;

✓a circular boundary along the external contour of the aquifer;

✓the pumping well is located in the center of the circular aquifer.

Radially heterogeneous aquifer: cross-section and plan view

Pumping regimes:

One well pumped at a constant drawdown

Pumping

References

Hantush M.S. Nonsteady flow to flowing wells of leaky aquifers // Journal of Geophysical Research. 1959. Vol. 64, N 8. P. 1043–1052.

Hantush M.S. Hydraulics of wells // Advances in Hydroscience / Edited by Ven Te Chow. New York; London: Academic Press, 1964. Vol. 1. P. 281–432.

Sternberg Y.M. Some approximate solutions of radial flow problems // Journal of Hydrology. 1969. Vol. 33, N 2. P. 158–166.

Yang S.-Y., Yeh H.-D. A novel analytical solution for constant-head test in a patchy aquifer // International Journal for Numerical and Analytical Methods in Geomechanics. 2006. Vol. 30, N 12. P. 1213–1230.

Mishra S., Guyonnet D. Analysis of observation-well response during constant-head testing // Ground Water. 1992. Vol. 30, N 4. P. 523–528.

Chen C.-S., Chang C.-C. Well hydraulics theory and data analysis of the constant head test in an unconfined aquifer with the skin effect // Water Resources Research. 2003. Vol. 39, N 5, 1121, doi:10.1029/2002WR001516.