The Distribution Rule and Genetic Analysis of Debris Flow in Longmenshan Fault Zone, Sichuan Province

Abstract

As a large-scale destructive geological disaster activity, debris flow has caused a large number of economic losses and casualties over the years. It is of certain practical significance to analyze the distribution characteristics and causes of debris flow. In order to explore the temporal and spatial distribution law of debris flow provenance, this paper selects the multi-phase remote sensing images of Sichuan Province from 1985 to 2020 for man-machine interactive interpretation, obtains the debris flow surface vector data for 58 times and 124 gullies, evaluates the interpretation results, selects six typical watersheds, and analyzes the distribution difference of debris flow and its relationship with terrain, vegetation cover, earthquake Relationship between human activity factors. The results show that debris flow disaster has obvious temporal and spatial characteristics, which is easy to occur in rainy season. At the same time, debris flow disaster is easy to occur in the main streams of Tuojiang River, Qingyi River and Minjiang River and Dadu River Basin. In addition, there are significant regional differences in the scale and morphology of debris flow gullies in various watersheds along the Longmenshan fault zone. The high-risk areas of debris flow disasters are mainly concentrated in the main streams of Tuojiang River, Qingyi River and Minjiang River and Dadu river basins, which are large in scale and long in length. The study area is more likely to breed large-scale debris flow when the altitude is 2500-5500 m, the slope is 15°-40°, and the elevation difference is 1800-4000 m. For different regional zones, the relationship between debris flow and vegetation coverage varies greatly. There is an obvious relationship between debris flow and vegetation coverage in Western Sichuan Plateau and eastern basin, while the occurrence of debris flow in rapid change zone is almost irrelevant to vegetation coverage. Therefore, we should pay attention to the Countermeasures of disaster prevention and reduction in rainy season and debris flow prone areas, increase vegetation planting and anchor soil. At the same time, we should focus on the rational planning of human activities and reduce unnecessary mining.