Delineating the Impact of Climate Change on Precipitation and Groundwater Level Fluctuations in A Semi-Arid Region of Iran

In this study, the impacts of climate change on Kashan’s groundwater resources were assessed by utilizing outputs from general circulation models (GCMs) and downscaled precipitation data using the SDSM model. For downscaling, the CanESM۲ model was applied under the RCP۲.۶, RCP۴.۵, and RCP۸.۵ scenarios to determine precipitation values for future periods. Subsequently, we developed a groundwater model of the aquifer in both steady-state and transient modes using the MODFLOW code within the GMS modeler, based on the hydrological and hydrogeological conditions of the Kashan aquifer. The results of climate downscaling under the CanESM۲ model in two scenarios indicated that precipitation percentages during the simulated period of the aquifer (۲۰۱۷-۲۰۲۳) under the RCP۲.۶, RCP۴.۵, and RCP۸.۵ scenarios were ۱.۱۷%, ۱۱.۷۷%, and ۱۴.۰۱%, respectively. The reduced precipitation percentages in the climate scenarios of the aquifer model and the magnitude of changes in the water table level for the three scenarios were estimated over ۸۳-time steps. The changes in the water table level during the base period (۲۰۱۶) indicated a decrease of ۰.۰۶۹ m, ۰.۷۵ m, and ۰.۷۸ m compared to the previous seven-year simulation (۲۰۱۶-۲۰۲۳) at the last time step in the RCP۲.۶, RCP۴.۵, and RCP۸.۵ scenarios, respectively. In light of these climate changes, climate parameter alterations directly correlate with recharge, which could be managed through appropriate water table exploitation practices. Such management necessitates a robust program to compensate for reservoir depletion and mitigate further intensification of water table decline in the area.

کلیدواژه ها:

climate change ، SDSM ، Groundwater resources ، Kashan aquifer ، MODFLOW