Changes in reliability–resilience–vulnerability-based watershed health under climate change scenarios in the Efin Watershed, Iran

摘要

Abstract Numerous factors, such as the occurrence of climate change and severe droughts, affect the ability of watersheds to provide their expected services. However, the changeability of the watershed health under climate change has not adequately considered. Accordingly, the Reliability (Rel), Resilience (Res), and Vulnerability (Vul) of the Efin Watershed to drought due to climate change have been evaluated in the present study. To this end, the current climatic data of three rainfall stations for the period of 2006–2020 and the rainfall data of the two climatic scenarios of the Representative Concentration Pathways (RCPs) 4.5 and 8.5 of the second generation Canadian Earth System Model (CanESM2) related to the report five of the Intergovernmental Panel on Climate Change for the period of 2027–2055 were used. The rainfall data were initially extracted and then, downscaled using the data modification method of the mentioned scenarios and based on the Inverse Weighted Distance (IDW) method at the sub-watershed scale. Drought characteristics in the study area were then determined using the monthly Standardized Precipitation Index (SPI). Rel, Res, and Vul indices were then calculated employing the geometric mean for different sub-watersheds in the base and future periods. The results showed that rainfall under climate change scenarios RCPs 4.5 and 8.5 from 2027 through 2055 would increase by 31.74 and 29.79, respectively. Mean Rel, Res, and Vul indices in the base period were estimated at 0.73, 0.52, and 0.34, which would change to 0.73, 0.56, and 0.29 under RCP4.5 and 0.74, 0.53, and 0.27 under RCP8.5. It was further found that the overall watershed health index would decrease from 0.46 to 0.42 under the RCP4.5 climate scenario and 0.43 under the RCP8.5 climate scenario. The present findings would help watershed managers and decision-makers adopt necessary managerial measures.