Spatial Clustering and distribution characteristics of large landslides in the Yalong River Basin, China

Abstract

The Yalong River Basin (YRB), situated on the eastern margin of the Tibetan Plateau, is characterized by high vertical erosion rates, rugged terrain, narrow gorges, and steep hill slopes, which host many large landslides. Analyze the distribution characteristics of landslides in this region is significant for understanding geomorphic evolution and assessing potential landslide risks. In the current study, a landslide database for the Yalong River was initially established based on remote sensing interpretation and field investigation. A total of 729 landslides were mapped, including 191 medium-scale and 538 large-scale landslides. According to the updated Varnes classification, 538 large landslides (73.8 %) were recognized and divided into four major types: slides (344 cases), flows (109 cases), topples (56 cases), and slope deformations (29 cases). The total area of these landslides was 886.2 km², and they were predominantly concentrated in the alpine canyon areas along the middle segment of the Yalong River. Based on integrated kernel density estimation and spatial autocorrelation, three landslide cluster zones (A, B, and C) were identified, with zone B showing the highest concentration of large landslides. Statistical results indicate that large landslides are concentrated in areas with elevations of 1500–3500 m, slopes of 20°–40°, topographic reliefs of 400–600 m, and dominant aspects being E, SE and SW. Active faults in the YRB play a crucial role in the formation and spatial distribution of landslides, showing a notable correlation with fault geometry, arrangement, and movement types.