Sensitivity Analysis of Groundwater Flow: Paper presented at the Nordic Hydrological Conference (Kalmar, Sweden, August - 1990)

A numerical model developed for sensitivity analysis of groundwater flow is presented. Sensitivity analysis is a useful complementary aid for groundwater flow modelling to assess the importance of various governing flow parameters to the behaviour of any specific flow problem. Two different methods are considered: One is called the direct method and the other the adjoint method. In the direct method the sensitivity equations are obtained by directly differentiating the flow equations with respect to the parameters, while in the adjoint method they are obtained by a variational technique. The numerical method for solving the groundwater flow equation and the sensitivity equations are based on the Galerkin finite element method. The sensitivity model developed was applied to a simple flow problem, in which the sensitivity of the piezometric head as well as various flux performance measures to perturbations of the permeability of various layers of the flow domain were analyzed. The following performance measures were considered: The piezometric head, the Darcy flux at selected regions and the total influx into a tunnel system.