Flow reduction effect on fish habitat below water diversion—A case study of the Central Yunnan Water Diversion Project

Abstract

With the implementation of large-scale water diversion projects, the reduction of river flow in water diversion areas may impact the ecological environment of the river. In this study, we used integrated hydrodynamic, habitat, and risk modeling methods to produce an ecological risk time series based on the consequences of departures from the optimum environmental flow range of a river, quantifying the extent to which flow regulation affects fish habitats. Taking the water diversion project in central Yunnan as an example, we used this method to produce a risk time series of fish habitats. This time series shows that the ecological risk increases when the river flow deviates from the optimal range of environmental flow. The degree of risk is different in different periods: in wet years, the risk is negligible; in normal years, the risk is between acceptable and critical, and in dry years, the risk is above critical. The research results can provide a basis for the optimal allocation of water resources to meet environmental flow requirements.