Analysis on energy dissipation by turbulence and turbulence prevention by sediments

The flood process is analyzed in totality and in time steps respectively. It was found that at each time step the hydrological elements of a flood process, such as sediment contents, turbulent velocity and resistance slope, vary in direct proportion with each other, which shows that energy dissipation by turbulence is dominant. While for the whole flood process the turbulence prevention by sediments appears to be a controlling factor due to the accumulative effect of intermittent slipping of sediments from flow. Comparing those flood processes with similar discharges in the long-term flood records, the phenomenon of sediments preventing turbulence is also found. The features is found to be in accordance with the results of steady flow in laboratory flume, i. e., for the flood with larger sediment contents in flood season, its weighted mean velocity is also larger but its weighted mean resistant slope is smaller. In this paper, both features of energy dissipation by turbulence and turbulence prevention by sediments are demonstrated by measured data in Yangtze River and Yellow River.