Experimental study on the motion characteristics of turbidity currents in a non-uniform sloped flume

Turbidity currents frequently occur in rivers, reservoirs, and estuaries, where they exhibit distinctive hydrodynamic and sediment transport characteristics. In the current study, the motion characteristics of turbidity currents in a non-uniform sloped flume are systematically investigated, focusing on the effects of inflow discharge, sediment concentration, ambient water depth, and bed slope, as well as the variations in motion characteristics at the slope transition. The experimental results show that the plunge point shifts downstream with increasing inflow discharge or bed slope and shifts upstream with increasing sediment concentration or ambient water depth. For low-sediment-concentration turbidity currents, the Froude number (Fr) at the plunge point remains relatively stable at approximately 0.78. For medium-sediment-concentration turbidity currents, the plunge point Fr is jointly influenced by inflow discharge, sediment concentration, ambient water depth, and bed slope. For high-sediment-concentration turbidity currents, the plunge point F r is primarily governed by the inflow sediment concentration. The head velocity of the turbidity current increases with increasing inflow discharge and sediment concentration but is not significantly influenced by ambient water depth. The head thickness of the turbidity current increases with increasing ambient water depth and inflow discharge but decreases with increasing sediment concentration and is most strongly influenced by ambient water depth. At the slope–horizontal transition of the flume, intensified mixing leads to a decrease in head velocity and a pronounced increase in head thickness. Empirical formulas are developed for turbidity current head motion, and the contributions of key factors to head travel distance and head thickness are quantified using a data-driven approach. The main significance of the current study is to provide a clearer understanding of the motion characteristics of turbidity currents under different influencing factors. The results can serve as an initial reference for river regulation and reservoir sediment flushing.