Influence of herbaceous plants on runoff hydraulic characteristics and sediment generation on terrene roads

Indoor rainfall simulation was employed to investigate the hydraulic characteristics of runoff, and runoff generation and sediment generation processes on terrene roads with different coverage degrees of herbaceous plants. The study indicated that on the roads the Froude numbers and Reynolds numbers of runoff fell into the category of supercritical flow of laminar flow. Their unit energies were consistent with the runoff velocity and water-carrying section, which were decreased with the increasing of the coverage degrees of herbaceous plants. The Manning roughness coefficients and the Darcy-weisbach friction coefficients increased as the coverage degrees increased. On the terrene roads with different coverage degrees, the amounts of runoff initially increased sharply and then stabilized with runoff-lasting time. Both the amounts of runoff and the runoff-lasting time were following an offset hyperbola, whereas the sediment yield rates initially increased and then declined. With the increasing of coverage degrees, the infiltration rates of water into the terrene roads gradually increased and the amounts of runoff, sediment yield rates and sediment concentration all gradually decreased. The study revealed that on terrene roads herbaceous plants could play a favorable role in soil and water conservation and provided a theoretical basis for understanding the relations between herbaceous plants and soil erosion.