Water resources management considering groundwater instability affected by climate change scenarios

In the present study, using GMS and MODFLOW code, a model of Khorramabad aquifer (Iran) was developed under unsteady conditions with considering the climate change (as a study innovation) in scenarios of RCP26 (optimistic) and RCP85 (pessimistic) based on results of CNRM-CM5 global climate model (Centre National de Recherches Me´te´orologiques—phase 5 of the Coupled Model). Using surface runoff data and computational level output from GMS, an integrated model was created in WEAP. According to scenarios of RCP26 and RCP85 for periods (2040-2069) and (2070-2099), the climate change effects on surface water and groundwater were evaluated. Results showed that water level calculated by GMS was obtained with high accuracy in calibration period (RMSR = 1.42 meter, MSR = 0.85 meter) and in verification period (MAE = 0.88, r = 0.98 and NSE = 0.97), which was in agreement with observed water levels of wells in region. The water level in RCP26 (2040-2069 and 2070-2099) compared to observed water level, on average, decreased by 0.154 meter and 1.175 meter, respectively, and in RCP85 for the same period, a decrease of 0.621 meter and 0.753 meter of calculated water level was observed compared to baseline. Then, allocation of surface water and groundwater resources to consumption sectors (agricultural, urban and industrial sectors) was analyzed using WEAP. Results showed that the lowest deficit of water resources in all sectors occurred in RCP26 (2040-2069) with a value of 7% and the highest deficit occurred in RCP85 (2070-2099) with a value of 180% compared to baseline.