Local hydraulic jump effects on sediment deposition in open-channel flume experiments

Abstract

When a river channel is narrow, bifurcated, or intersected, or when extreme weather or geological disasters cause shed rock masses to occupy a river flood channel, local hydraulic jumps may develop in the channel. Natural disasters such as landslides, floods, and debris flows occur upstream, will result in large transport rate of large-sized gravel particles. Those particles may be blocked in hydraulic jump areas, causing river channel water depth to rise. In this study, the effect of local hydraulic jumps on the sediment deposition rate was investigated in flume experiments. The ratio of upstream and downstream Froude numbers, particle size, Sediment supply intensity, and flow discharge all affected the sediment deposition rate. With increases in the ratio of upstream and downstream Froude numbers, particle size, and sediment supply intensity, the sediment deposition rate increased. The sediment deposition rate decreased with an increase in flow discharge. Approach hydraulic conditions and particle properties jointly determined the sediment deposition rate in a hydraulic jump section, and an empirical formula was developed using those parameters to calculate the sediment deposition rate. Thus, to identify risks and prevent disasters in mountain rivers, local changes in hydraulic conditions and particle properties need to be jointly evaluated.