Optimizing the operation of a hydraulic dam for ecological flow requirements of the You-shui River due to a hydropower station construction

Abstract

River ecosystems are closely linked to flow velocity, depth, water temperature, and river bed substrates, and the alteration of hydrological regime due to dam operation has significant impacts on the river ecosystem. It is critical for river managers to seek the optimal solution to balance the environmental discharge requirement with hydropower production. This study investigated links between hydropower plant generation and stream habitat conditions in the You-shui River, China, and developed an optimization model to obtain the most beneficial solution for both generating capacity and environmental discharge. The typical annual flow rates were determined, and Chinese sucker (Procypris rabaudi) was chosen as the target fish with 4 life stages to represent the habitat suitability situation under the environmental discharge. The optimal model was designed to be a function of the maximum value of the sum of the power generating function and the overall suitability index (OSI) function. The traditional environmental flow scheme and optional plan with 3 other schemes were also calculated for comparison. The results of this model indicate that traditional environmental discharge methods cannot satisfy the requirement of juvenile, adult, and spawning stages of the target fish. The solution of the optional plan can meet the habitat demand but will significantly reduce the hydropower generation. The analysis indicates that the optimal model could well balance the hydropower production and the ecosystem protection in the You-shui River and is therefore recommended as a suitable dam management method.