Estimating R-factor in Southwest China with Data of Daily Rainfall Amount

The rainfall was a key factor to soil erosion, and the rainfall erosivity (Rfactor) was a major parameter for predicting soil erosion model. Generally, Rfactor was estimated through the product which rainfall kinetic energy times the rainfall density during the most 30 min precipitation, such as EI30, EI10 or EI60with long term and continuous pluviograph data. In China, the most regions lack of these data, thus, this led to difficult to estimate Rfactor extensively. The parameters of model that estimating Rfactor with data of daily rainfall amount by Yu and Rosewell were determined according the actual condition of Southwestern China. The Rfactors were estimated in Nanning, Guiyang, Kunming, Chongqing and Chengdu, which were identical with EI10 or EI30. The method avoided the complex calculation for most rainfall density during one period of time in Rfactor estimated by usual method, and with high veracity. At the same time, the model can describe the spatial and seasonal distribution of rainfall of erosivity. So, the method can be used widely in Southwestern China. 