Numerical analysis of landslide-generated impulse waves affected by the reservoir geometry

Impulse waves generated by landslides are a potential major hazard for the operation of hydropower reservoirs, as they pose a serious threat to the dam, to residents and to properties along the shoreline. A number of experimental studies have been conducted based on generalized models to predict the wave characteristics, but using the results from these models to predict landslide-generated impulse waves may result in significant errors due to wave reflection caused by changes in the reservoir width. To investigate the effects of reservoir geometry on the characteristics of landslide-generated waves during propagation, 14 numerical experiments were performed using Tsunami Squares. The real-sized numerical models were based on statistical data from the Yangtze River and a generalized cross section of the Gongjiafang landslide located in the Three Gorges Reservoir, China. Two types of generalized reservoir geometries were investigated – namely with converging and diverging reservoir widths. It is shown that the wave amplitudes decrease with increasing reservoir width, while wave heights and troughs have a complicated dependence on changes in reservoir width. Compared to the amplitudes of the leading waves, the wavelengths and start-up time of wave amplitudes were more affected in the converging reservoir models by variations in the reservoir width.