Effects of Reservoir Impounding on Key Ecological Factors in the Three Gorges Region

According to the analyzing of the monitoring data of key ecological factors, such as concentration of total phosphorus (TP), concentration of total nitrogen (TN), and algae cell density during 2002-2005 in the reservoir region, we can find that the number of algae species and the cell density are significant increase, nutrient concentration in Xiangxi Bay also has marked increasing tendency after impounding. It creates a necessary condition for the outbreaking of algal blooms in the tributary bay. Hydraulic structures locates in the tributaries upstream are suggested to be used to regulate and control water quality in the bays.