589 - Can We Better Balance the Drought Risk and Flood Risk Tradeoff By Climate-informed Reservoir Operation?

Jordan Lake Reservoir, primarily built as a flood mitigation structure in North Carolina, is also critical for meeting local water demand while maintaining the downstream water quality. Historically, this reservoir has undergone frequent drought events. Further, our preliminary analysis found the reservoir to be highly vulnerable to drought risk in future given the expected increase in water demand and potential changes in climate if operated under the existing policy. As additional water demand and increased frequency of extremes stresses Jordan Lake reservoir, effective reservoir operation is crucial to meet the overall water release needs with the desired reliability while keeping the flood risk low simultaneously. In the existing reservoir operation policy, flood storage volumes are fixed across months, and thus it neither accounts for monthly variation in inflows and flood flows coming into the reservoir, nor does it adapt to potential changes in climate. In our work, we propose an alternate reservoir operation policy that estimates the flood storage for each month over a period of operation and adapts to potential changes in monthly reservoir inflows and flood flows in future. We compare the two operation policies, current and proposed, for historical, and for different scenarios of target release and potential climate change. The proposed alternate reservoir operation policy yields very high target release reliability compared to the existing for most of the considered scenarios of changes in water demand and climate. Flood protection reliability of the alternate policy is slightly lower than the existing policy. The developed framework can assist reservoir managers in selecting an operation policy based on the net gain in drought and flood risks tradeoff under different climate and water demand scenarios.