Uncertainty Evaluation of Reservoir System Performance Indicators Under Climate Change (Case Study: Namroud Dam)

Climate change is one of the major challenges for the management and planning of water resources. Considering the uncertainties can present a more accurate picture of the system state. The present paper evaluated the uncertainty of performance indicators in the reservoir of Namroud Dam, located in the Hablehroud Basin, under climate change in the upcoming period (2021-2040). For this purpose, statistical downscaling for the upcoming period was performed using the output of the EC-EARTH general circulation model under the RCP4.5 and RCP8.5 emission scenarios and the LARS-WG6 model. The basin runoff in the upcoming period was estimated using the IHACRES hydrological model. In addition, the demand changes were calculated taking the future inputs of the climate variables into account. The water resources system was modeled using the WEAP model. Finally, based on the changes in river flow and using the Monte Carlo simulation, this study evaluated the performance uncertainty of the Namroud Dam reservoir under current conditions and climate change. Moreover, it investigated the adaptation strategies to reduce the demand (meeting 85% and 70% of the agricultural demand). The results showed the highest values of the stability index for the 30% reduction in agricultural demand under the RCP4.5 emission scenario. The changes in agriculture in Firoozkooh and Garmsar under this scenario decreased by 20.64% and 34.2%, respectively, although the reduction in demand alone is not sufficient to improve system performance. Compared to other indicators, the stability index changes were more limited and thus more reliable for assessing the system state.