Holistic Approach to Sustainable Groundwater Management in Semi-arid Regions

Abstract

Owing to rational deep understanding of intrinsic nature of groundwater as common pool and decayable resources, together with, lack of withdrawal control by local states, groundwater depletion has been incredibly under consistent withdrawal. Under these circumstances, attempts have been made by users to maximize withdrawal without considering any limitation on account of lack of reliable withdrawal pattern. In this research, sustainable management of groundwater in south western part of Tehran plain has been evaluated by coupling simulation and optimization models of cooperative and non-cooperative approaches. The MODFLOW model and the Artificial Neural Network model are used for simulation of different scenarios after calibration and validation. Then, a non-linear optimization model is used for optimal allocation of groundwater to different water users. Results indicate that users may gain more benefit in early years of withdrawal in non-cooperative approach. However, this may have an adverse effect which implies a decreasing trend in the benefit in such a way that it reaches null in long term period, as this is reflected by dramatic drawdown of groundwater level and its depletion. In cooperative approach, rate of withdrawal from aquifer is determined by considering renewable water volume, together with, groundwater table drawdown constraint. In this approach, water users may gain less benefit than non-cooperative in early years of withdrawal, however, that will offset in 50 years period by means of more benefit.