Type‐Curve Analysis of Time‐Draw down Data for Partially Penetrating Wells in Unconfined Anisotropic Aquifers

ABSTRACT With the aid of a computer, and using an iterative alternating‐direction implicit method, a numerical solution is sought for the unsteady‐state radial flow to partially penetrating wells pumping at a constant rate from an unconfined anisotropic aquifer. These solutions are used to generate a series of theoretical type curves valid for individual aquifer‐test situations characterized by particular combinations of two constants Q = (P r /P z ) (m/r w ) 2 and C 2 = (Sy/S s m) and particular well penetration. The aquifer‐test data requirements are the time‐drawdown data and at least two pairs of observation wells, one of the pair tapping well‐screen depths and the other tapping water‐table depths. The parameters that are identified are the lateral permeability, vertical permeability, specific storage and specific yield of the aquifer. The use of the type curves is illustrated by an example.