Coupled Groundwater Drought and Water Scarcity Index for Intensively Overdrafted Aquifers

Abstract

Drought and water scarcity are key aspects in the management of groundwater resources in regions with excessive withdrawal. In this paper, groundwater drought, water scarcity, and their compound impact were analyzed based on a new evaluation index in overdrafted aquifers. Groundwater drought analysis was performed using the standardized groundwater index (SGI) on the naturalized groundwater level time series. For this purpose, the MODFLOW groundwater simulation tool and a surrogate artificial neural network model were adopted to obtain the time series of the naturalized groundwater level in Qazvin plain, central Iran, over the 1966–2016 period. Moreover, a water scarcity index, namely the deficit rate (DR), and a droughtwater scarcity (DWS) index were introduced. Results showed that abstraction could cause a severe negative trend in the groundwater level in comparison with natural causes (i.e., drought). Furthermore, use of the DWS index revealed that the safe yield of the Qazvin aquifer was about 44% of the existing abstraction volume. It is concluded that the DWS index represents a comprehensive criterion in water resource assessment and groundwater safe yield computations.