Deformation Monitoring and Prediction of a Reservoir Landslide in Sichuan Province, China

Hydropower reservoirs change the local geo-environment greatly and often induce reservoir bank landslides. Hongyanzi landslide is a large rejuvenated ancient landslide in Pubugou Hydropower Station reservoir area in western China Sichuan Province. To study the deformation of the Hongyanzi landslide, we arranged multi-parameter monitoring using GPS, fixed borehole tilt-meter, osmometer, and crack-meter and collected continuous data of displacement and ground water table. The monitoring data, together with the reservoir water level data, show that the landslide deforms obviously during reservoir water level is falling, while it deforms little in the other period. Comprehensive analysis of the deformation and reservoir water level implies that the seepage force caused by water level difference between the inner and outer slope may be the key factor. Through regression analysis, the authors established a forecast model for landslide deformation based on ground water table and reservoir water level; thus concluded that reducing the falling velocity of reservoir water level may slow the landslide deformation down.