 Erosion in the reservoir , induced by rising water , causes frequent major landslides that have led to noticeable disturbance in the reservoir surface , including two incidents in May 2009 when somewhere between 20 @,@ 000 and 50 @,@ 000 cubic metres ( 26 @,@ 000 and 65 @,@ 000 cu yd ) of material plunged into the flooded Wuxia Gorge of the Wu River . Also , in the first four months of 2010 , there were 97 significant landslides . 
