Effects of Erosive Single Rainfall on Surface Runoff Sediment Yield in Huyangshui in Northern Region of Guizhou Province

The relationship between sediment yield and erosive rainfall was studied based on the observed rainfall data of Huyangshui water and soil conservation monitoring stations in Zunyi from 2009 to 2012.The rainfall runoff erosion and sediment yield of small watershed in Huyangshui were analyzed using single rainfall erosivity, and the coverage of the optimal calculation model and multivariate nonlinear regression method with the data statistics of 4 runoff plots in the 28 times rainfall including rainfall, rainfall intensity, maximum 30 minutes rainfall intensity and time of rainfall erosion modulus.The results showed that the output of total runoff and sediment accounted for 64.05% and 62.62% respectively of the annual total from May to July in the basin.When rainfall erosivity was less than 20, the rainfall erosion modulus and rainfall erosivity was a positive correlation in power function, the rainfall erosion modulus and coverage was a negative correlation in quadratic function.When rainfall erosivity was more than 20, rainfall erosion modulus and the erosivity was positively in a function, the rainfall erosion modulus and coverage was negatively related to the power function relationship.The applicable formula among single rainfall erosivity, coverage and erosion modulus was established and verified through the binary nonlinear regression.