RISK ASSESSMENT OF LANDSLIDE DISASTERS IN THE UPPER REACHES OF YAJIANG COUNTY, SICHUAN PROVINCE

Yajiang County, located in the middle reaches of Yalong River in western Sichuan Province, is dominated by the landform of middle mountain-alpine valley, with frequent geological disasters. The risk assessment of landslide disasters in the upper reaches of Yajiang County is carried out on the basis of overlay analysis of logistic regression (LR) and certainty factor (CF) to ensure people's life and property security. The results show that the landslides are prone to occur in the hard rock interbedded with soft rock zone, with an altitude of 2 500-3 000 m, relative height above river of 600-900 m, gradient of 30-45° and distance of 0-200 m from river system. The high and very high risk areas in the upper reaches of Yajiang County account for 46.75% of the total area, and 65.91% of the total landslide occurrences, indicating the dense distribution of landslides and high damage degree, which is consistent with the field survey results. The Xiala Town mostly belongs to very high and high risk area, Waduo Township mostly medium risk area, and Murong Township and Pubarong Township mostly low and very low risk area. The assessment results have high accuracy through verification of inspection points and ROC curve, and thus can serve as a reasonable plan basis for disaster prevention and mitigation, river development and utilization in the study area.