Research Of Rainfall Erosion Nutrient Loss Dynamics And Control Measures On Loess Plateau

Soil and water loss is an important factor to hinder the development of sloping land in the Loess Plateau.Studying the effect of different slop rainfall erosion rule and different control measures on rainfall erosion by field simulated rainfall experiment in this paper. The results are of great significance to the sustainable utilization of water and soil resources in Loess Plateau.The main works and detailed results of this study are as following:(1)The existence of critical slope of 30° has an effect on rainfall runoff erosion.When the slope is ?30° the runoff erosion increases with the slope, and the slope is less than 30°,The runoff erosion decreases with the increase of slope. The sediment yield and nutrient wastage rate all have a positive correlation with unit discharge,and the relationship between unit discharge and sediment yield rate is described by linear function,the quadratic function can be used to describe the relationship between unit discharge and nutrient loss rate.There is a positive correlation between the parameters of the hydrodynamics and the slope. The unit discharge and the sediment yield rate are positively correlated with the reynolds Re and the froude number Fr, which is negatively correlated with the resistance coefficient f, unit discharge,sediment yield and Shear force ?, stream power W, unit stream power P were positively correlated.The soil erodibility index K1 and K3 were positively correlated with the slope and the soil erodibility index K2 was negatively correlated with the slope.(2)Attapulgite(ATP) make the degree of soil infiltration rate, soil water tolerance, soil non-saturated diffusion rate and soil unsaturated conductivity decreases,and make the soil water stable aggregates and large soil particle content increases.The infiltration rate S and the infiltration rate A in the Philip formula are reduced, the infiltration coefficient K in the Kostiakov formula decreases and the empirical index?increases.The retention water content ?r decreases, the saturated water content ?s increases, the reciprocal a of the intake air increases,and the shape coefficient n decreases in van Genuchten formula. The results show that the RMSE of the simulated and measured values is less than 0.1 when the saturated hydraulic conductivity and saturated saturated water content were simulated by fractal model.ATP increased the runoff, sediment yield, nutrient loss, and sediment yield and nutrient loss increased with the increase of runoff.(3)Under the influence of three kinds of rainfall intensities, the runoff of crushed stone in the topsoil is larger than that of gravel, and the sediment by covered the topsoil is larger than that of embedded in topsoil The nutrient loss by embedded the topsoil is larger than that of covered in topsoil when the rainfall intensity is 60mm/h and the result is just the opposite when the rainfall intensity is 90mm/h,120mm/h.The runoff increased with the increase of the coverage,and the sediment yield decreased with the increase of the coverage under the five coverage.The nutrient loss decreases with the increase of the coverage when the rain intensity is 60mm/h and its contrary to the previous results when the rainfall intensity is 90mm/h,120mm/h.The runoff and sediment yield were negatively correlated under the two crushed stone pattems.The runoff and nutrient loss were negatively correlated with rain intensity of 60 mm/h, and positive correlation with rainfall intensity of 90,120 mm/h.