Abstract:

Soil erodibility (the K factor in the Universal Soil Loss Equation,USLE) is an important index to measure soil susceptibility to water erosion,and an essential parameter needed for soil erosion evaluation and soil erosion prediction.Based on the second soil survey data,we established a database of soil properties of the upper reaches of the Yangtze River.We used cubic spline interpolation to convert the soil texture,the EPIC model to calculate the soil species erodibility, and the areaweighted method to obtain the erodibility values of subclass.After linking the K value of every soil subclass to the soil map,we got the spatial distribution characteristics of soil erodibility.The results showed that the mean value of soil erodibility was 0239 0,and the study area with lower erodibility,moderate erodibility and higher erodibility accounts for the main part,occupied 2796%，3261 % and 2720%，respectively.Soil erodibility of the Hengduan Mountains,the YunnanGuizhou Plateau and the Three Gorges Reservoir area was significantly higher than Sichuan Basin.High erodibility soils mainly located in the upper Jialing River and the valleys of the HengDuan Mountains.The average value was 0239 0,the maximum value was 041 and the minimum value was 007. K value had a certain regularity with soil erosion intensity,elevation gradient and slope gradient