Spatial Distribution of Debris Flow-prone Catchments in Hengduan Mountainous Area in Southwestern China

Abstract

Hengduan mountainous area in Southwestern China is highly susceptible to debris flow hazards. In order to investigate the spatial distribution of 7181 debris flow-prone catchments, the area has been classified into six natural geographical sub-regions based on its climatic, geological, and geomorphic types. The spatial analysis reveals that their spatial distribution exhibits a significant difference in the six sub-regions. The sub-regions with East Asian monsoon climate have a higher density of the catchments than other sub-regions with Tibetan cold climate. The highest density is 286 catchments per 10,000 km2, seven times of the lowest sub-region. The climatic factor is more important than the other factors. The histogram of the catchments with average annual rainfall shows that the regions with the annual rainfall of 800–1050 mm are more prone to debris flows.