LAUSR

ABSTRACT Sheet erosion has been the major erosion process on steep grassland since the Grain-for-Green project was implemented in 1999 in the Loess Plateau with serious soil erosion in China. Quantifying sheet erosion rate on steep grassland could provide scientific support for effectively controlling soil erosion and rationally managing grassland. Simulated rainfall experiments were conducted on grassland plot with vegetation coverage of 40% under complete combination of rainfall intensities of 0.7, 1.0, 1.5, 2.0 and 2.5 mm min−1 and slope gradients of 7°, 10°, 15°, 20° and 25°. Results showed that sheet erosion rate, varying from 0.0048 to 0.0578 kg m−2 min−1, was well described by binary power function equation (SE = 0.0026 I 1.306 S 0.662) containing rainfall intensity and slope gradient with R2 = 0.940. The logarithmic equation of shear stress (SE = 0.084 + Ln (τ)) and the power function equation of stream power (SE = 1.141 ɷ 1.073) could be used to predict sheet erosion rate. Stream power (R2 = 0.903) was a better predictor of sheet erosion than shear stress (R2 = 0.882). The stream power was an excellent hydrodynamic parameter for predicting sheet erosion rate. The study results can reveal the mechanism of sheet erosion process.