Hydrodynamics process of soil erosion and sediment yield by runoff on Loess Slope

Based on a series of the runoff scouring experiments on slopes with their gradient ranging from 3° to 30°,the runoff energy consumption and the sediment yield is analyzed.The results show that the average flow velocity increases with the flow discharge and the slope gradient in an exponential form,and the slope gradient has greater effect on velocity than discharge.On the slope of 3°~21°,the average runoff consumption increases with slope,and decreases with slope when the slope gradient is over the critical gradient (21°~24°).The similar trends exist in the relation between the average sediment transport rate and slope.On the slope of 3°~21°,the average sediment transport rate increases with slope,and decreases with slope when the slope gradient is over the critical gradient (21°~24°).The average sediment transport rate increases with the increase of the runoff discharge,which has greater effect on the sediment yield than slope.Further the analysis indicates that there is a linear relation between the sediment transport ratio of the unit runoff width and the energy consumption of the unit runoff width.The critical energy consumption of the unit width increases with slope,while the soil erodibility decreases with the increase of slop e,whose value varies from 10.369 to 30.366,and the average value is 14.61 in the experiment across all slope.