A system identification methodology, applicable to calibration of confined and unconfined (under certain constraints) aquifer models described by two dimensional parabolic partial differential equations, has been developed. A computer program (in FORTRAN IV) simulating an aquifer using an alternating direction implicit-iterative procedure which has been obtained from the U.S. Geological Survey was utilized as a component in the system identification effort. Work has been completed on the formulation and coding of a digital computer software package (in FORTRAN V) capable of estimating the values of transmissivity, as a function of location within the aquifer. The identification methodology has been successfully applied to the parameter identification of an aquifer model simulating the behavior of a real aquifer system.