Optimal Reservoir Operation under Climate Change Based on a Probabilistic Approach

Abstract

Recently, climate change and global warming issues with rapid global population growth and socioeconomic development have increased water demand and caused more pressure on water resources. Reservoirs in semiarid regions have always played a role in alleviating water scarcity. This study presents an improved approach to investigating the resilience of vulnerable reservoirs using a probabilistic technique for water resource management under climate change by simultaneously considering integrative elements, namely rainfall-runoff processing, agricultural water management, reservoir operation, and uncertainty analysis. To this end, the study investigates the climate change impacts on optimal operation of Jarreh reservoir in southwest of Iran, for the period from 2025 to 2054. A risk assessment based on multimodel ensemble scenarios is used to deal with uncertainties in climate change projection. The results indicated an increase in the mean annual temperature in the range of 1.1–1.7°C, and irregular changes (both decreases and sometimes increases) in the long-term mean monthly precipitation in the study area. In addition, an annual increase of the agricultural water volume demand is also expected by a factor of 1.18–1.47. The results also showed that the average long-term reservoir inflow volume would decrease by 13–41% under the future scenarios. The reservoir operation model has been developed based on minimizing the sum of square water allocation using the differential evolution algorithm (DEA). The modeling results depicted reduced reliability and increased vulnerability of the reservoir in the future relative to the base period. Reduced reliabilities of 41–13% (39–7%) are expected under A2 (B1) scenario for the critical and ideal conditions, respectively. The results of this study can be used in adaptation scenarios to reduce vulnerability and improve the water resources performance.