Effects of water diversion projects on water environment in Chaohu Lake

In recent years, more than 90% of lakes in China are facing different degrees of water pollution. As one of the five largest freshwater lakes in China, Chaohu Lake has a poor water environment where water blooms have frequently occurred. Water diversion is a main engineering method to promote the water exchange, shorten the water renewal cycle and improve environmental status, thus it is widely used in many lakes. Herein, this paper dynamically coupled PCLake aquatic ecosystem model and 3D finite volume FVCOM model to simulate the water environment response of Chaohu Lake under the non-diversion and different water diversion scheme conditions. The numerical results indicated that the optimal water diversion scheme is scheme A according to the water environment response results. When the water diversion volume is 3 × 10 9 m 3 /year, the nutrient reduction efficiency and inhibition efficiency of water blooms in Chaohu Lake is the highest; the environment degree in Chaohu Lake is further significantly improved for the most time of a year with the increasing amount of water diversion. Although the water diversion project plays significantly positive roles in improving the environment of Chaohu Lake, it still cannot completely prevent the outbreak of serious water blooms. • PCLake ecosystem model and FVCOM model is coupled and applied in Chaohu Lake. • Water environment changes with variable water diversion schemes and volumes. • Improved efficiency of water diversion is the highest when volume is 3 × 10 9 m 3 /year. • The environment degree is improved with the increasing water diversion volume.