Identifying and Assessing Robust Water Allocation Plans for Deltas Under Climate Change

Water scarcity threatens economic growth, social cohesion, and environmental sustainability in many deltas. This situation is likely to worsen due to future climate change. To reduce water scarcity and limit salt water intrusion in deltas, many countries have launched policies to allocate water resources. However, it is difficult to develop long-term adaptive water management policies due to large uncertainties. In this paper, we present a Robust Assessment Model for Water Allocation (RAMWA) to support decision making about water release of different key reservoirs under future climate change. The model was applied in the Pearl River basin, China to improve reservoir management, to ensure sufficient flow into the delta to reduce salt intrusion, and to provide sufficient freshwater for human and industrial consumption. Results show that performance of the existing water allocation plans reduces under climate change, as the plans are unable to sustain the required minimum river discharge. However alternatives generated by a Generic Evolutionary Algorithm (GEA) suggest that new plans can be developed which ensure minimum flows into the delta under most future climate change scenarios. The GEA plans perform better than existing plans because rather than following a fixed allocation schedule, the optimal water release for each reservoir is recalculated every 10 days based on observed discharge and storage in key reservoirs.