Time-Varying Discrete Hedging Rules for Drought Contingency Plan Considering Long-Range Dependency in Streamflow

This study proposed a simple and efficient method for developing time-varying discrete hedging rules. The novelty of the proposed methodology is that long-range streamflow traces are inserted into the sequent peak processes in order to reflect long-lasting drought events, which is rarely considered, during the development of the hedging rules. The developed rules were evaluated with three performance indices (risk, resiliency, and vulnerability) across a wide range of synthetic streamflow scenarios that represent changes in the annual mean streamflow and the long-range streamflow dependency. Boryung Dam, located in South Korea, was used as a case study. As a result, the developed hedging rules reflecting long-range streamflow traces led to enhanced reservoir operation performance results in terms of resiliency and vulnerability indices. The developed hedging rules outperformed the reference hedging rules, especially under dry conditions. When there was a strong long-range dependency in streamflow, the superiority of the developed hedging rules was found to be remarkable. Since the proposed methodology is relatively simple, it will be easy for dam operators to understand and implement discrete hedging rules at different sites.