Research on Surface Debris Flow Sensitivity Evaluation Based on RS and GIS

Abstract

Sensitivity analysis about small watershed is an important way to objectively understand the development characteristics of debris flow ditches. With the support of Remote Sensing and Geographic Information System technologies, Dongchuan County with frequent debris flow development in Kunming, Yunnan Province, southwest China was selected as the research object, the Landsat image and Digital Elevation Model were used to interpret the small watersheds on both sides of the Xiaojiang River. By selecting four indicators of fault zone, slope, gully density and land use as the impact factors, the sensitivity coefficients were quantitatively calculated. The following research results were obtained: The distribution feature of debris flow small watersheds was that, the Dongchuan fault zone was the axis which small watersheds were symmetrically distributed on; the sensitivity of the Dongchuan fault zone was the highest in the buffer distance of 5-10 km, which was prone to debris flow disasters; the debris flow was most sensitive in the slope range of 40°-50°; the debris flow was most sensitive to the gully density of 0.6-0.9 km/km2 with broken surface; three types of land use such as bare land, water and construction land had high sensitivity coefficient and were easy to cause mountain disasters. According to the sensitivity coefficients of the above impact factors, the stacking method superposition analysis was carried out to obtain the sensitivity distribution of debris flow disasters in Dongchuan County. The medium sensitive area accounted for 53.84% of the total area, and the high sensitive area accounted for 27.02% of the total area. The medium sensitive area and the high sensitive area were the main areas where debris flow occurred. This study has certain reference significance for disaster prevention, soil and water conservation by quantitative calculation and comparison of debris flow disaster sensitivity.