Assessing soil erosion risk in the Hilly-gullied area: A case study of Luoyugou watershed in Tianshui, Loess Plateau, North China

Nowadays using uncertainty inference to predict the risk of soil erosion is a new development tendency. This paper attempted to simulate the distribution of soil erosion risk in a small watershed named Luoyugou (Tianshui, North China) by an uncertainty inference model based on Subjective Bayes and GIS. The results indicated that: (1) Land cover and slope are the fundamental factors to control spatial pattern of soil erosion risk in Luoyugou watershed, and other factors, such as soil species, have less impact; (2) The areas which have the highest risky of soil erosion are those covered without plants, sloped closer to 30°-35° and distributed with Heilu soil which distributed in the slope region of upper and middle reaches. But the lowest-risky areas are always covered with more plants, slope of hillside less than 10° and with brown-soil in the right-shore watershed. (3) Practice proves that soil and water conservation measures and returning farmland to forest policy have positive significance to reduce soil erosion risk in study area.