Analysis of Spatiotemporal Variations of Groundwater Drought, Case Study: Karun Watershed

Drought as one of the natural disasters has a major impact on parts of an ecosystem. Although it cannot be prevented, its negative effects can be mitigated by some measures. Considering the high importance of groundwater resources in the country, the study of hydrogeological droughts and factors affecting groundwater drawdown is essential for the management of these vital resources. In order to investigate the impact of droughts on each other, the groundwater level variations and evaluation of the groundwater drought in Karun watershed were analyzed using GRI and SDI drought indices over a ten-year statistical period (2008-2018). The results showed a correlation between GRI and SDI indices in most regions of the study areas. Although in some cases, the impact of hydrological drought on groundwater is delayed by 6 months to one year. Low correlation between two hydrological and groundwater drought indices and the high correlation between GRI and groundwater abstraction indicated that drawdown in the aquifers cannot be the sole cause of drought, rather, in some cases, excessive abstraction is more effective. Overall, the GRI indices are more obvious in the southeast and west of the Karun watershed during the ten-year statistical period. In the final years of this period the northern side of the basin has also been affected by more severe droughts, which also has a correlation with the values of the SDI indices.