Optimal Extraction of Water from Regional Aquiferunder Salinization

Abstract

A model for the optimal management of a regional aquifer under salinization is developed. The objectives of management are to maximize the total amount of water pumped for use and to minimize the total amount of salt extracted with the water. The model is based on a combination of simulation and an optimization routine, run iteratively. The simulation model uses a finite-element formulation for the flow and a streamline upwind Petrov-Galerkin formulation for the transport and computes the gradient of the state variables (heads and concentrations) with respect to the decision variables (pumping rates at wells). The gradients are then used in a Bundle-Trust nonsmooth optimization procedure to achieve an improved solution. The process ends when termination criteria are met, resulting in a good solution, which cannot be claimed to be the global optimum. The procedure is demonstrated on a 600-km