Influence of sediment concentration on deposition of silt and runoff hydraulics on grassland

In order to reveal the performance of grass strips on silt-laden flow with high sediment concentration, the experiments were carried out on different sediment concentration of 0-350 kg/m3 in grassplots on the slope of 3° and 9° and discharge of 20 and 60 L/min, and the deposition of sediment and hydraulic characteristics of runoff were analyzed. The results show that the sediment mass deposited on grassplots increase with the concentration. There is a positive relationship between the deposition rate and the sediment concentration at 3°, but a negative relationship at 9°. Under the experimental conditions, the discharge plays a negligible role in the total mass of sediment deposition, but slope significantly affects the sediment deposition. The flow velocities at downslope are greater than that at upslope, and the sediment concentration has a minor influence on the velocity. On the same slope and discharge, the Reynolds number of silt-laden flow decreases with the increase of sediment concentration. Runoff resistance coefficient (f) and Manning roughness (n) increase with sediment concentration at 3°, but there is no significant correlation between them at 9°. Therefore, sediment concentration should be considered in the estimation of hydrological processes in the region with severe soil erosion.