Soil Erosion Assessment in the Red Soil Region of Southeast China Using an Integrated Index

A new method to calculate the integrated index of soil erosion (EI) for the Red Soil Region of Southeast China is proposed. The median of erosion rates for the extreme severe erosion grade was calculated by using the method of polynomial fitting curve and others based on the medians and the corresponding grades of soil erosion in the Classification Standard of Soil Erosion (SL190-96); then the weight values were calculated for each erosion grade. Based on EI values in 1986, 1996, and 2002, the evolution of soil erosion was studied in a total of 8 provinces and in a total of 476 counties of southeastern China. The results show that the overall EI value of the whole Red Soil Region of Southeast China decreased from 3.81 to 3.02 from 1986 to 2002, although EI values increased in 163 counties, decreased in 285 counties, and remained stable in 28 counties, which reflects a general alleviation of soil erosion. The EI values decreased in Jiangxi, Fujian, and Zhejiang provinces, but increased in Guangdong and Hunan provinces. The increases are mainly attributed to rapid social and economic development with insufficient attention to soil erosion.