Experimental investigations of propagation characteristics and wave energy of dam-break waves on wet bed

Abstract

Understanding the characteristics of dam-break flows that move along a sloping wet bed is essential for timely flood warnings and risk mitigation. This study conducts laboratory experiments in a sizable flume, encompassing various upstream and downstream water depths and bed slopes. It examines the effects of the ratio between upstream and downstream water depths and the slope of the flume on the dam-break wave height and the velocity of the wavefront. The findings revealed that the average relative error between theoretical and experimental values initially decreases and increases as the slope rises. The dam-break waveform is characterized by introducing a global Froude number Frx and a local Froude number Frl, with critical values of Frx=1.225 and Frl=1.475. In addition, a model for predicting the dam-break wave height is developed by linearly fitting the values between dimensionless wave height and the local Froude number, and it is validated by comparison to experimental data. Based on experimental data and the Stoker equation, an attenuation function for the dam-break wave height at a downstream location is proposed for the undular wave. Finally, a theoretical analysis is conducted to predict the energy of the first dam-break wave.