Effects of Rock Fragments on Runoff and Soil Erosion

Soil commonly contains large numbers of rock fragments in surface layer.Rock fragments on the soil surface have effects on infiltration,thus affect runoff and soil erosion.In this study,simulated rainfall experiments have been conducted on soil tray with 1 m long and 0.5 m wide in the laboratory in order to evaluate the effects of rock fragment cover on runoff and soil erosion.3 rainfall intensities (30,67,92 mm/h) and 6 levels of cover of rock fragments (0,5%,10%,20%,40%,and 60%) were included.The experimental slope was 20°.The results reveal that rock fragment cover enhanced infiltration and reduced runoff.Runoff decreased linearly with rock fragment cover.Flow velocity decreased and resulted in reduced sediment yield.The exponential decay function can be found between flow velocity and sediment yield and rock fragment cover.Rainfall intensity had no effects on the relationships between runoff amount and rock fragment cover,and between soil erosion and rock fragment cover.These results may provide parameters for soil erosion assessment.