Risk analysis of inflow to the Zayandehrud Dam under historical and future scenarios using reliability, resiliency, and vulnerability indicators: a comparative study of the runoff risk index and runoff risk ranking methods

ABSTRACT Climate change disrupts water cycles, impacting arid regions’ water resources. This study aims to evaluate and rank the risk related to the availability of inflow to the Zayandehrud dam, Isfahan, Iran, under historical and future periods by using reliability, resiliency, and vulnerability criteria. Evaluation and ranking of runoff risk in the upstream Zayandehrud Dam Basin was done using methods based on the Runoff Risk Index (viz., the Weighted Addition Method and the Multiplication Method) and methods based on the Runoff Risk Ranking (viz., Technique for Order of Preference by Similarity to Ideal Solution and Simultaneous Evaluation of Criteria and Alternatives). The subjective, objective, and hybrid methods were used to attribute the weights of the three criteria. The main results revealed that (1) the average monthly runoff during the historical period is lower than in the future periods, specifically, an increase of the runoff of about 30–60% compared to the historical period; (2) in the considered basin, the weight of the resiliency criterion compared to others increased in all periods, indicating the importance of the resiliency of the dam system and the manageability of this system in the conditions of climate change; and (3) the runoff risk in the historical period was higher than in the future period, however, in all periods the runoff risk is in the ‘high risk’ range.