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## Conceptual models > Leaky aquifer > Constant level in the adjacent aquifer >## Infinite leaky aquifer |

Infinite leaky aquifer

Assumptions:

✓leaky aquifer system consists of isotropic aquifers interbedded with aquitards;

✓main aquifer: the aquifer that contains pumping well and where the water drawdown is estimated;

✓adjacent aquifer (may be two aquifers) water level drawdown is constant during the test period;

✓initial water levels in aquifers may be different or coincide;

✓boundary: aquifer has infinite areal extent;

✓pumping well is fully penetrating, located in the main aquifer, its storage capacity is neglected;

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

✓crossflow through the aquitard is vertical;

✓storage of the aquitards is neglected;

✓pumping well storage capacity may be taken into account (see complementary solutions below).

a b

c d

e f

Cross-section of the leaky aquifer system with water level in adjacent aquifers constant during the test period.

a – 3-layered confined aquifer system with a leaky roof; b – the same with a leaky bed; c – 3-layered confined aquifer system with different initial levels in aquifers; d – 3-layered unconfined leaky aquifer system; e, f – 5-layered confined (e) and unconfined (f) aquifer systems with leaky roof and bed. Arrows show flow direction within layers.

Fundamental equation:

Laplace transform solution:

Besides the fundamental equation the following complementary solutions are applied:

1) solution for water level drawdown in the fully penetrating observation well in the leaky aquifer with allowance for the pumping well storage capacity

Laplace transform solution:

2) solution for water level drawdown in the pumping well in leaky aquifer with allowance for the pumping well storage capacity

Laplace transform solution:

3) Hantush’s solution for the aquifer anisotropic on the lateral plane

Pumping regimes:

One well pumped at a constant rate

Pumping

Recovery

One or several wells pumped at a variable rate

Pumping

References

Hantush M.S. Analysis of data from pumping tests in anisotropic aquifers // Journal of Geophysical Research. 1966. Vol. 71, N 2. P. 421–426.

Hantush M.S., Jacob C.E. Non-steady radial flow in an infinite leaky aquifer // Transactions, American Geophysical Union. 1955. Vol. 36, N 1. P. 95–100.

Hantush M.S., Thomas R.G. A method for analyzing a drawdown test in anisotropic aquifers // Water Resources Research. 1966. Vol. 2, N 2. P. 281–285.

Jacob C.E. Radial flow in a leaky artesian aquifer // Transactions, American Geophysical Union. 1946. Vol. 27, N 2. P. 198–205.

Lai R.Y.S., Chen-Wu Su. Nonsteady flow to a large well in a leaky aquifer // Journal of Hydrology. 1974. Vol. 22, N 3/4. P. 333–345.