Pumping Optimization for Saltwater Intrusion Management in a Coastal Aquifer with Combined Use of Sharp Interface and Density Dependent Models

Abstract

AbstractCoastal areas are densely populated due to socioeconomic benefits and in turn also have a greater demand for fresh water. This ever-increasing demand for fresh water can be met by coastal aquifers, which act as large reservoirs of freshwater. Excessive and unmanaged pumping from coastal aquifer allows the salt water to flow inward encroaching on the voids created by the pumping of freshwater. This phenomenon is called saltwater intrusion. To stop the saltwater intrusion, an optimal pumping strategy needs to be adopted. Simulation models are generally linked with an optimization algorithm to develop an optimal pumping strategy for management of saltwater intrusion. Sharp interface based simulation models are often used which are computationally inexpensive but lacks in prediction accuracy, as it does not incorporate the effects of dispersion and diffusion. Density dependent simulation models include the effect of dispersion and diffusion, but have a very high computational budget in evaluating an optimal pumping strategy. To overcome above-mentioned limitation a new methodology is developed, where a density dependent model is used in conjunction with a sharp interface model to derive an optimal density ratio, such that interface obtained using this density ratio implicitly accommodated the effect of dispersion and diffusion in a sharp interface model. The performance of the developed methodology is evaluated for three hypothetical scenarios of saltwater intrusion. The performance evaluation results show the applicability of the methodology for management of saltwater intrusion while maximizing fresh water pumping in coastal aquifers.KeywordsGroundwater modellingCoastal aquifer managementPumping optimizationSaltwater intrusionDensity dependent modelSharp interface model