Driving Effect of Human Activity on the Environmental Change of the Sancha Lake

The water quality of the Sancha Lake has declined from Class III to Class IV and Class V due to increasing eutrophication, to which human activity has contributed considerably since it was built in 1977. This research examines changes in sedimentation rate and supply of mass accumulation of the Sancha Lake in recent decades through 210Pb and 137Cs dating and records of historical events in lacustrine sediments. This research also examines the process of change in the lake environment and identifies the driving effect of human activity on the evolutionary process of the lake environment by combining the analysis on the change characteristics of the sediments' grain size and C, N and P therein. The findings of the research show that human activities, especially cage culture, application of pesticides and chemical fertilizers, and development of tourism, are the main factors causing eutrophication and environmental change in the Sancha Lake.