Mechanism of Resurrection of Ancient Landslides within the Xiaonangou Watershed of Yan'an City
Northwest University, China

Yan'an, Shaanxi Province, is located in the middle reaches of the Yellow River, and its unique geomorphology and fragile ecological environment make landslide disasters frequent. Due to the shortage of land resources in the city, people are expanding urban space with a large number of development watersheds, inducing the resurrection of many ancient landslides. The resurrection of ancient landslides poses a threat to soil and water conservation, ecological environment, engineering construction, human and property safety, so it is extremely important to study the resurrection mechanism and propose green management measures. In this paper, we use geological survey, geological mapping and geotechnical investigation to obtain the ancient landslide boundary, stratigraphic lithology and watershed DEM. On this basis, we find that the moisture and soil shear strength in the ancient landslide body increase with depth, and there is a certain degree of decay law of soil shear strength near the sliding surface. Through the processing of remote sensing image data of vegetation in the study area and long-term subsidence and rainfall monitoring on site, it is found that rainfall affects the degree of vegetation cover, and different degrees of vegetation cover make the resurrection of paleolandslides different. Based on the resurrection factors of ancient landslides in the watershed and the results of indoor experiments, the author proposes the resurrection mechanism of ancient landslides in the watershed. This paper can provide an insight to deal with the resurrection of ancient landslides with a watershed as a starting point.