Author(s): Yimin Zhang; Jincheng Duan; Jianying Chao; Yuexiang Gao; Chuang Zhou; Yang Yang
Keywords: Pre-dam; Inflow Rivers; Eutrophication; Gehu Lake. Gehu Lake (31°29＇~31°42＇N; 119°44＇~119°53＇E) is located at the western part of the Taihu Lake Basin; Across Wujin District of Changzhou City and Yixing of Wuxi City. There are many neighboring rivers around this lake and more than 20 rivers flowing into the lake. The main rivers are Biandan River; Xiaxi River; Huangli River; Zhonggan River and Beigan River; Etc. Inflowing rivers and surrounding rural sewages will discharge into plenty of resident sewage; Livestock and poultry breeding sewage and factory substandard wastewater; Which makes N; P and CODMn severely overweight (Wu et al 2010). Recent water water quality monitoring results show that the pollution contribution of inflowing river is higher than other main pollution sources; Nitrogen and phosphorus accounts for about 80% of the total mass into the lake (Tao et al 2010). Therefore; To improve the water quality of the Gehu Lake; It’s very essential to regulate inflowing rivers. The methods of controlli
Abstract: According to the research conducted by the pre-dam system built on the outlet of Gehu Lake, which is the confluent of Xiaxi and Biandan River that are located in the northern part of Gehu Lake, we found that pre-dam system had significant effect on inflow rivers. In the stable period, inflow water quality was improved from Grade Ⅴ to Grade Ⅲ~Ⅳ, as well as the concentrations of TN and TP were also decreased from 1. 21~3. 09mg/L to 0. 62~1. 26mg/L and from 0. 05~0. 24mg/L to 0. 03~0. 09mg/L respectively, with 60% average removal rate. For algae, Chl-a concentration was decreased from 15. 10~126. 07mg/m3 to 14. 32~42. 95mg/m3, with the average removal rate of (67. 55±3. 06) % and the highest rate of 82. 83% . Besides, in the different areas of pre-dam system, storage buffer zone had obvious role on TN, TP and Chl-a, which is significantly different with other areas (P<0. 05). In the same area, for different water quality indicators, only ecological stability area had obvious effect on Chl-a, which was significantly different from the effect on TN and TP (P<0. 05)..