According to the investigations of Baozhusi Reservoir’s bank collapse and geological survey of typical bank collapse

the characteristics of bank collapse distribution are obtained.It is found that collapses mainly occur at ancient landslides.There exist three main kinds of collapse patterns: bank scour collapse

creep-crack deformation

sliding and tension-fracturing.The originating mechanism

developing process and the stability variation for each typical landslide at different water levers are analyzed.Stable slope angle after bank scour-collapse are analyzed statistically.Finally

conclusions are drawn that the geological structure and the layer lithology are the intrinsic factors of bank collapse

while dynamic water pressures caused by water lever decline are extrinsic factors.