Groundwater management in arid and semi-arid regions

In recent decades, there has been an increasing demand for water, particularly in arid and semi-arid areas of Iran, resulting in excessive use of waters, more specifically groundwater resources. The present study aims at optimizing the use of groundwater and determining the optimal pumping rate (OPR) of wells in an appropriate manner. First, a hydrodynamic groundwater model, known as MODFLOW, was developed, calibrated, and verified. Subsequently, the model was linked to a multi-objective evolutionary algorithm (MOEA), and the objective functions were defined as the maximization of net benefit from agricultural products and minimization of the groundwater table drawdown, using the non-dominated sorting genetic algorithm version II (NSGA-II). Then, the optimal policies were derived considering three scenarios of water and power consumption management (NEXUS) in terms of base price, 50% reduction, and 50% increase in the base price. The replacement of a 50% reduction in costs scenario with the status quo showed an increase of up to 10% in the benefits gained from agricultural crops and, consequently, a 16% increase in groundwater table drawdown. On the other hand, the scenario of a 50% increase in costs resulted in a 10% reduction in benefits and a 51% increase in the groundwater level. There is a positive correlation between electricity prices and the sustainability of aquifers. Nevertheless, it led to economic instability caused by the loss of farmers’ income. To follow the Subsidy Reform Plan (SRP), subsidy to agricultural products was recommended to be provided as an optimal policy to ensure sustainable groundwater withdrawal and food security.