  An analytical solution is developed for three-dimensional flow towards a
partially penetrating large-diameter well in an unconfined aquifer bounded
below by an aquitard of finite or semi-infinite extent. The analytical solution
is derived using Laplace and Hankel transforms, then inverted numerically.
Existing solutions for flow in leaky unconfined aquifers neglect the
unsaturated zone following an assumption of instantaneous drainage assumption
due to Neuman [1972]. We extend the theory of leakage in unconfined aquifers by
(1) including water flow and storage in the unsaturated zone above the water
table, and (2) allowing the finite-diameter pumping well to partially penetrate
the aquifer. The investigation of model-predicted results shows that leakage
from an underlying aquitard leads to significant departure from the unconfined
solution without leakage. The investigation of dimensionless time-drawdown
relationships shows that the aquitard drawdown also depends on unsaturated zone
properties and the pumping-well wellbore storage effects.
