Characteristics and parameters of bank collapse in coarse-grained-material reservoirs based on back analysis and long sequence monitoring

Abstract

Bank collapse is a common geomorphological hazard following initial reservoir storage. The width of bank collapse is an important index to evaluate site safety and reservoir siltation. For a long time, studies have focused on the prediction of the bank collapse width (BCW), while back analysis and verification of the bank collapse after several years of storage have been limited. In this study, 18 coarse-grained-material reservoirs in China, which have been storing water for many years were investigated; particularly in the Longkaikou Reservoir, there are three typical sections for 5-year monitoring. The underwater topography and the stable slope angle were measured. Based on considerable data statistics, the parameters of the stable angle were suggested for underwater and for the fluctuation zone, and the evolutionary rule of BCW with time was analyzed. We discovered that the collapse of coarse-grained-material bank generally finished after 6–7 years of water storage and showed its collapse process. Finally, typical sections in the Zipingpu Reservoir were selected to verify the reliability of the coarse-grained-material parameters. The results show that the prediction accuracy regarding BCW is greatly improved using the suggested parameters and they provide a reliable basis for accurately predicting BCW.