Landslide hazard analysis of Liyuan Town based on effective rainfall threshold

This paper takes Liyuan Town of Hunan Province as an example, and used the weight of evidence model and the grey relational degree model to calculate separately the weights of the five factors of slope, formation lithology, shape of slope, land use type and human engineering activity in secondary states and in first states. After defining the landslide susceptibility index of the whole region by combining two models, the susceptibility zoning based on the slope unit is completed. According to the geotechnical geological type of the rock and soil in the study area (clastic rocks, carbonate nip clastic rocks, carbonate rocks and loose rock soils), the effective rainfall threshold curves (I-D curve) under different landslides occurrence probability are determined by grouping. The time probability of landslides in different rock and soil types under 3-day duration and effective intensity of 22.4mm/d is studied. Finally, the landslide hazard zoning map of Liyuan Town based on effective rainfall threshold is obtained through. combining time probability and susceptibility results. The results show that the high-susceptible areas and extremely high-susceptible areas account for 25% of the total study area and distributed mainly along the river. The extremely high-hazard areas account for 14% of the total study area and are mainly distributed in the north of the river.