Author(s): Cuichao Pang, Jing Tao, Xiaohui Wu, Wei Gong, Fangfang Wang
Linked Author(s): Cuichao PANG
Keywords: Shallow lake, eutrophication, diversion, period of replacing water body
Abstract: Lake Yinghu located in Changjiang delta area is a planned manmade urban shallow lake. To maintain the water quality of lake, there are two main measures, one is establishing a perfect aquatic ecological system to purify and maintain the water quality of lake, and another is replacing lake water body with clear water. Lake Yinghu closely connects to surrounding river net, and has good condition of water diversion. Controlling the connection condition between lake and surrounding river net to regulate the period of replacing water body of Lake Yinghu is an important factor influencing effectiveness of improving the water environment of Lake Yinghu. The numerical models, MIKE11 and Delft3D, were used to investigate the effectiveness of two schemes of controlling connectivity (connection entrance complete opening scheme and connection entrance gating scheme) in regulating the period of replacing water body of Lake Yinghu. The numerical results show that in the complete opening scheme case the water replacing period is about 12 days in the condition of long term average tidal level, 18 days in the condition of low tidal level with the probability of once in 20 years, and 14 days in the condition of high tidal level with the probability of once in the 20 years. Therefore, the risk of occurrence of Cyanobacteria bloom is large according to the criteria that the Cyanobacteria bloom would occur if the water replacing period exceeds 15~18 days in the summer (temperature > 25�C). In gating scheme case, six operation alternatives were simulated. The results show that the water replacing period of the gate operation alternative (three gates are diverting water, two gates are discharging water) is 14~15 days regardless of tidal condition. This indicates that the risk of occurrence of Cyanobacteria bloom is small in the Lake Yinghu. Besides, gating scheme could also protect lake from water pollution accidents occurred in the surrounding river net
Year: 2017