Water supply risk analysis of Panjiakou reservoir in Luanhe River basin of China and drought impacts under environmental change

This study investigates the impacts of drought on water supply risk of Panjiakou reservoir in Luanhe River basin of China under environmental change by using a copula-based streamflow series generation approach. To understand how nonstationarity of runoff sequence influences water supply risk, reservoir performance metrics including reliability (time-based and volume-based), resilience, vulnerability, drought risk index (DRI), and sustainability index (SUI) are evaluated with 1956-1979 and 1980-2016 inflows of Panjiakou reservoir, respectively. The results indicated that the prolonged and severe drought may seriously affect the safety of water supply. From two results of generated streamflow time series, the reliability reduction rate reached 58.3% (0.773 to 0.322) when water supply assurance rate was 75% and ecological water level was minimum. Perturbing the copula parameter will make it possible to increase the drought durations and deficits for Panjiakou reservoir to analyze drought impacts on water supply. Based on the reservoir performance metrics, the analysis for Panjiakou reservoir showed that the trend of drought in the future made water supply reliability (time-based and volume-based), resilience, and SUI decrease, but vulnerability and DRI increase, which means the water supply system security became more vulnerable in the future. These results make it easy for decision makers to understand how drought influences future planning and management of Panjiakou reservoir.