Roles of soil erodibility, rainfall erosivity and land use in affecting soil erosion at the basin scale

• Temporal and spatial patterns of soil erosion in Lushi basin are analyzed.
• Revised rainfall erosivity was calculated based on the runoff volume and peak rate.
• Roles of three factors: RQ, C and K on soil erosion are investigated.
• Considerable effect of soil erodibility factor is proved.

Evaluation of the factors affecting soil erosion is the foundation of erosion control. This study analyzed the temporal and spatial patterns of soil erosion, rainfall erosivity and land use change from 1980 to 2010. Also investigated the role of modified rainfall erosivity (RQ), land use (C), soil erodibility (K), on soil erosion in the Lushi Basin, using a multiple linear regression equation with the Soil Water Assessment Tool. The RQ spatial distribution is basically identical with rainfall. The forest and farmland from 1980 to 1995 and from 1995 to 2010 both increased. The erosion prone soil type with high K value distributes near the river. Soil erosion of whole basin had a decrease trend from 1982 to 1997, but increased in mid- and downstream regions by simulation. Through regression analysis, the considerable effect of K has been proved. Especially from July to October, the average effect of K is (1.4) larger than RQ (0.7). In the months with general rainfall amount, the average effect of RQ and K are 0.67 and 0.42 respectively. Although C factor in this basin has low sensitivity, the effect of land use on erosion cannot be ignored. These results confirm that soil erosion is driven principally by RQ and affected considerably by K, especially during the rainy season. In this basin, conservation of water and soil should both consider soil type pattern and land use adjustment on the regional scale.