On improvement of water quality of a reservoir by optimizing water exchange

Reservoirs provide important water resources for economic and social sustainable development. However, many shallow reservoirs are confronted with the problem of severe eutrophication. In this study, a method of optimizing the water exchange of reservoir was proposed to improve the water quality. The improvement was evaluated by the spatial and temporal eutrophic state of the reservoirs predicted by the water quality parameters, algal growth limitation factors and eutrophic state level. Three optimized schemes were designed, as an example, to improve the water exchange of Tianjin Erwangzhuang Reservoir. The results showed that the water quality of the reservoir is improved by the increase of water exchange. The best optimized design scheme for improving water quality was to open multiple gates and lift the amount of water in and out of the reservoir. The result indicated that the Trophic State Index was reduced from the range of 37.8 and 43.1 of the original scheme to that of 35.20 and 26.50 after about 160 day operations of the best optimized design scheme. (c) 2017 American Institute of Chemical Engineers