A Simulation/Optimization approach to manage groundwater resources in the Gaza aquifer (Palestinian Territories) under climate change conditions

Abstract

"The Gaza aquifer is the main source of water for agricultural, domestic, and industrial uses in the Gaza Strip. The rapid increase on water demand due to continuous population growth has led to water scarcity and contamination by seawater intrusion (SWI). urthermore, current projections of future climatic conditions (IPCC, 2007) point to potential decreases in available water, both inflows and outflows. A numerical assessment of SWI in the Gaza coastal aquifer under climate induced changes has been carried out by means of the CODESA-3D model of density-dependent variably saturated flow and salt transport in groundwater. The model was calibrated and validated in the period 1935-2010 and then used to simulate the response of the hydrological basin to actual and future scenarios of climate change obtained from different regional circulation models. The results clearly show that, if current pumping rates are maintained, seawater intrusion will worsen. To manage sustainable aquifer development under effective recharge operations and water quality constraints, a decision support system based on a simulation/optimization (S/O) approach was applied to the Gaza study site over the period 2011-2040, incorporating two conflicting objectives by a penalty method: maximizing pumping rates from the aquifer wells while limiting the salinity of the water withdrawn. The S/O approach is based on coupling the CODESA-3D model with Carroll’s (1996) Genetic Algorithm (GA) Driver. The resulting coastal aquifer management model identified the optimum spatial distribution of pumping rates at the control wells, providing for a general increase in water table levels and a decrease in the total extracted salt mass while keeping total abstraction rates relatively constant, with reference to non-optimized conditions."