Assessment of the Ecological Reservoir Operation in the Yangtze Estuary Based on the Salinity Requirements of the Indicator Species

Abstract

AbstractIn conventional reservoir operations, energy and economic benefits are typically optimized, and ecosystem values are only addressed as constraints. To reduce the negative influence of reservoir operation on the downstream ecological environment, ecological targets should be incorporated into reservoir operations. The concept of environmental flow was developed to define the quantity, quality and timing of water flows that are required to sustain freshwater and estuarine ecosystems. Based on the salinity requirements of the indicator species and the relationship between salinity and the freshwater inflows, environmental flows for the Yangtze Estuary were determined. Subsequently, an ecological reservoir operation model was established that incorporated the ecological target for the protection of the Qingcaosha water source; the Non‐dominated Sorting Genetic Algorithm II was applied to the model. Three typical periods of wet, normal and dry years were selected, and the operation results were analysed for the downstream Datong cross‐section and the environmental flows. The results showed that joint scheduling should be performed for the reservoirs upstream of the Yangtze Estuary. In June of wet and normal years, the current run‐off of the Datong should be reduced by 13.5% and 5%, respectively. In July and September of wet years, current run‐off should be reduced by 30.6% and 25.5%, respectively, as these reductions will not negatively affect the drinking‐water sources. The results of this study should provide guidance in decision‐making to improve the operation of the Three Gorges Reservoir. Copyright © 2015 John Wiley & Sons, Ltd.