Research On Dispatching Mode Improving Water Quality Of Three Gorges Reservoir In Non-flood Season

During March-May, water bloom phenomenon has taken place in some parts of the Three Gorges Reservoir's tributaries. The high water level results in the decreases of the flow velocity and turbulence, which leads to the enrichment of nutrient and fast growth of algae. While in non-flood season, Three Gorges Power Station will be in peak-load operation, which will benefit the water exchange between main stream and tributaries and increase the water turbulence and velocity. Therefore, the peak load operation will provide a new way to improve the water quality of tributaries.In the paper, the impact of peak load operation on hydraulics and water quality is researched. The best peak load operation mode for both water quality and power generation is found by establishing the ecological optimal dispatching model. The main research work focuses on the following aspects.First of all, according to the peak-load regulation capacity and the minimum ecological water requirement, the influences of hydraulics and water quality under different water level, different flow and different peak-load regulate amplitude is simulated in the second part of the paper. Then, by analyzing the results, the corresponding flow discharge of different water level under which the velocity of the tributary can reach the critical velocity of suppressing algal growth is obtained.Next, the simple ecological dynamics model reacting to the hydraulics and water quality status in peak-load regulation is set up in the third part of the paper. The model can simulate the nutrient density process of the whole non-flood season, then, the average nutrient density of different dispatching mode is gained.In addition, in the last of the third part, an ecological dispatching model of the Three Gorges Power Station is built. The basic thought is based on the conventional power generation optimal dispatching model, with another one objective function and two constraint conditions added. The objective function is the minimum of the TP nutrient density calculated by the ecological dynamics model. One of the constraint conditions is the minimum of the ecological water requirement; the other is the critical velocity above which the algal growth can be suppressed.Lastly, the muti-objective fuzzy program is used to resolve the ecological optimal dispatching model based on genetic algorithm. According to the coming water flow and the TP pollutant load, the paper computes the best peak-load dispatching mode in which the water quality of the reservoir can be improved and the power generation can be satisfied. Therefore, some useful suggestions will be provided for the Three Gorges Power Station when it works in peak-load mode.