Effect of Grass on Reducing Runoff and Sediment and its Critical Flow Shear Stress

Abstract

Reduction effects of grass on runoff and sediment yield and its mechanical mechanism of grass was studied under rainfall intensities of 45, 87 and 127mm/h with 20°slope gradient using simulated rainfall experiment. the results showed that average runoff rates ranged from 39.7 to 126.0 L/min for bare plots and 0.34 to 6.22 L/min for grass plots, and the runoff rates from grass plots were much less than from bare plots. Average sediment yields varied from 3636.7 to 9436.3 g/min for bare plots and from 26.7 to 581.5 g/min for grass plots. The critical flow shear stress of 2.85 N/m2 on grass slope and 0.861 N/m2 on bare slope were got under experiment condition. The sediment yield increased with the increase of flow shear stress. The experiment results are meaningful for quantifying runoff and sediment reduction and deepening soil erosion mechanical process also.