Hydraulic characteristics of sheet flow with slope runoff regulation

In order to clarify the process of runoff movement under the complex surface conditions and the effect of flow and surface conditions on hydraulics parameters, the authors studied the hydraulic properties of shallow flow with different runoff by use of the field scouring experiments in the standard plots in this study. Thereinto, regulating measurers included the treatments of fish-scale pit, alfalfa grass, straw mulch and control, and hydraulic properties included flow velocity, flow depth, flow regimes and the resistance coefficient. The results indicated that the mean flow velocity and depth were mainly controlled by the slope runoff discharge, and there was also a power function relationship among mean velocity, depth and discharge. The slope flow regime was directly influenced by surface conditions and flow discharge. For the naked slope plot (control) and fish-scale pit plot, flow regimes were laminar flow and subcritical flow under the lesser discharge, and transitional flow under the discharge of 3.0 m3/h. For alfalfa grass plot and straw mulch plot, flow regimes were laminar flow and subcritical flow. The resistance coefficient on complex slope consists of granule resistance, configuration resistance and wave resistance and it was mainly influenced by the surface conditions. In a word, the capability of resisting soil erosion and sediment movement was stronger than the control whatever on grass and straw mulch slope or on the slope with fish-scale pits. At the same time, the measured slope had a function of slower runoff velocity and higher flow resistance.