Hazard Assessment of Debris Flow in Jinsha River

Hazard assessment is a crucial measure for early warning, disaster prevention and mitigation in disaster-prone areas. The Jinsha River flows through the Jinsha River-Ailao Mountain suture zone, with complex tectonic background and frequent mountain disasters. Recently, it has gradually attracted the attention of academics due to the development and construction of hydropower projects. Hence, this paper takes the debris flow of the Jinsha River as the object, and combined with field investigation and GIS technology, 2551 debris flow of the main stream and key tributaries of the Jinsha River were acquired. In general, debris flow in the upper reaches of Jinsha River is not active, mainly low and medium frequency, whereas high-frequency debris flow is mainly distributed in the lower reaches, particularly in the Taoyuan to Qiaojia section. The hazard assessment of debris flow was carried out based on the characteristics of debris flow activities, and the zoning map was examined by the ROC test and spatial clustering analysis. The results show that: (1) the most favorable factors for the formation of debris flow are slopes between 15 ~ 35°, the most intensive earthquake distribution areas, and soft and hard alternating clastic rock groups; (2) The medium-high hazard debris flow in the Jinsha River accounts for 47.48 %, nearly half. (3) The high-hazard area of the Dongchuan-Qiaojia section has a high degree of aggregation, which is strongly coincident with the active fault, and the material source is abundant, basically controlled by the active fault. The hazard zoning map obtained in this study can provide a reference for avoiding debris flow risk and formulating disaster prevention and mitigation measures in the planning and construction of projects such as hydropower and traffic corridors.