A structured approach for calibrating steady-state ground-water flow models

A structured approach for calibrating two-dimensional, steady-state ground-water flow models is developed. The first step of the proposed approach is to replace the heterogeneous aquifer with an equivalent homogeneous one using the geometric mean of transmissivities. Then, boundary conditions are adjusted with the aid of a scattergram to reduce bias of the simulated hydraulic head distribution of the equivalent homogeneous aquifer. After the bias is removed, the differences between the simulated mean by hydraulic head and the observed hydraulic head, resulting from small-scale heterogeneities, are then reduced by adjustment of local transmissivity values based on hydrological and geological information. The validity of the proposed procedure was tested for a hypothetical aquifer under idealized conditions and it was then applied to the Avra Valley in southern Arizona to demonstrate its utility in real world scenarios.