Abstract:

The shallow landslide is universal in loess plateau with no distribution law and no distortion evidence. There is no good method to forecast the frequent occurrence of shallow landslide, causing risk to the residence, traffic and river ecology. The assessment and prediction formula of shallow landslide under different rainfall was established by means of the infinite slope model combined with rainfall infiltration-strength reduction law and GIS technology. Then the build assessment model was used to predict the landslide occurrence at the effective rainfall of 30 mm, 50 mm, 100 mm and 200 mm in Xingfuchuan watershed, a first tributary of Yanhe River. In order to check  the applicability of the predict formula, it was compared with the popular assessment model of shallow landslide. The results are as follows: ①the instable and potentially instable shallow landslides are mainly distributed in both sides and source of the final class river, the stable and more stable region are mainly distributed in both sides of the first class river and highland surface; by comparing, the assessment results of SINMAP model are more consistent with the assessment results obtained by the predict formula built in this paper at the effective rainfall of 30 mm. ②according to the assessment results obtained by the predict formula built in this paper, the area of unstable region (safe factor，F_s<1) is gradually increased from 1.12% at the effective rainfall of 30 mm to 4.79% at the effective rainfall of 200 mm; on the contrary, and the stable region presents a decreasing trend. ③according to the distribution of shallow landslides had occurred, the proportion of the happened shallow landslides that located in the unstable region are significantly increased with the growth of effective rainfall, from 62% at the effective rainfall of 30 mm to 88% at the effective rainfall of 200 mm; and 64% of the happened shallow landslides are located in the unstable region according to the assessment result of SINMAP model. So the assessment model built in this paper is more accurate compared with the SINMAP model. Finally, advantages and disadvantages of the established prediction formula in shallow landslide assessment in loess plateau were discussed.

Key words: loess plateau, shallow landslides, prediction model, Xingfuchuan watershed