Effect of Different Aggregate Size on Sediment Concentration and Hydraulic Parameters in Overland Flow

Abstract

Abstract This study is about the impact of the rainfall on different aggregate size by using the rainfall simulator. The objectives of this study are to estimate the runoff, sediment concentration production, hydraulic parameters on different aggregate size and to investigate the relationship between sediment concentration and different hydraulic parameters. The hydraulic parameters including flow velocity, flow depth, shear stress and stream power. The different aggregate size, D0.6mm and D1.18mm, were set up under the rainfall simulator on a flat surface and slope angle 20°. The rainfall simulator was adjusted to the rainfall intensity 10 Lmin−1. The average rainfall intensity was a constant variable for this experiment. The runoff flow was collected at several intervals (30, 60, 90 and 120 min) for 2 hours. Then, the hydraulic parameters, runoff discharge and sediment concentration were measured. As the result, the average of sediment concentration increased as the slope also increased, from 335.667 to 1365.333 gm−3 and 173.767 to 555.333 gm−3 for aggregate size D0.6mm and Du8mm, respectively. The measured of sediment concentration was higher as the flow depth and shear stress was decreased. On the other hand, flow velocity and unit stream power were increased when directly relate between the sediment concentrations. In general, the precision of the hydraulic parameters in anticipating sediment concentration was: flow velocity > stream power > shear stress > unit stream power > flow depth.