Optimizing Operating Rules for a Reservoir System in Northern China Considering Ecological Flow Requirements and Water Use Priorities

One of the most common ways of operating a reservoir system is to follow preestablished rules that specify the allowable releases at different time points of a year. Reservoir operating rules traditionally focus on human water uses such as flood control, water supply, hydroelectric power generation, and recreation, without fully considering downstream ecological requirements. At present, a key challenge is how to carry out multipurpose coordinated operations under the premise of restoring the flow regime for downstream ecosystems while maintaining (or minimizing interruptions to) the original water use benefits. To deal with this challenge, this paper presents a case study of a reservoir system in northern China (the Luan River Basin). The ecological flow requirements are estimated using Indicators of Hydrologic Alteration (IHA); water supply priorities for domestic, aquatic ecosystem, and agricultural uses are quantified and incorporated as constraints into a simulation-optimization model to optimize the operation. Reservoir storage allocation and water supply to the various requirements will be determined simultaneously under various inflow conditions. The modeling results demonstrate the effectiveness in identifying solutions to improve downstream river ecosystems while maintaining existing human water use benefits.