Landslide hazard spatial analysis and prediction using GIS in the Xiaojiang watershed, Yunnan, China

Abstract

The Xiaojiang watershed in Southwest China has high landslide hazard and has been given the title of “the Museum of Geohazards in China”. However, the available information on landslides in the Xiaojiang watershed is still limited. We constructed the essential spatial database of landslides using the GIS techniques. The quantitative relationships between landslides and factors affecting landslides are established by the Certainty Factor model (CF). The affecting factors such as lithology, structure, slope angle, slope aspect, elevation and off-fault distance are recognized. By applying CF value integration and landslide zonation, the most significant affecting factors are selected. The widespread landslide activities in the Xiaojiang watershed are caused and triggered by heavy rain. A promising approach to modeling the spatial distribution of rainfall-triggered landslide is combining the mechanistic infinite slope stability model with a hydrological model. A model modified from Stability INdex Mapping (SINMAP) is used to prepare the landslide susceptibility maps for different rainfall conditions. Information on these maps could be useful for explaining the known existing landslide, making emergency decisions and relieving the efforts on the avoidance and mitigation of future landslide hazards.