Assessing the Sustainability of Groundwater Resources Using Water Exploitation and Green Water Scarcity Indicators

Sustainability of groundwater resources means ensuring the permanent availability of essential groundwater services for a long-time. This research was conducted to investigate the sustainability of groundwater resources in the prohibited plain of Behshahr- Bandar-e-Gaz by using water expoliation and green water scarcity indices. Initially, the green water deficit index was calculated based on the concept of water footprint. The water exploitation index was obtained according to the long-term average of annual fresh water resources based on the components of well and qanat discharge, total recharge and return flow. The indices were calculated for the common cropping pattern of the region (spring wheat and rice) for a 33-year period (1982- 2015). The green water deficit index was 2.68 and 2.54 for spring wheat and rice cropping system, respectively. Also, the water exploitation index was 18 percent and 17.8 percent, respectively. Increase in evapotranspiration under spring wheat cropping reduced soil water content and ultimately led to excessive instability of groundwater resources in the study area. Based on the results, the use of water expoliation index can improve the sustainability of groundwater resources in Behshahr Bandar-e-Gaz plain rather than the green water scarcity index.