Risk assessment of debris flow along the northern line of the Sichuan-Tibet highway

Debris flow occurs frequently in mountainous areas due to the special geographical and geological environment, causing significant damage to linear infrastructure. However, a systematic assessment of debris flow risk to the national highway is limited by the lack of regional vulnerability data. Based on a detailed inventory of debris flow and highway structure characteristics, this study presents a comprehensive regional risk assessment framework on the northern line of the Sichuan-Tibet Highway in China. The proposed framework consists of three main procedures: (1) debris flow hazard analyses by the weight-of-evidence method, (2) analyses of physical vulnerability using 12 vulnerability indexes, and (3) risk calculation which considers the natural attributes of debris flow and the social characteristics of a linear highway. The predictive performance was evaluated through receiver operating characteristic (ROC) curves, and the validation results showed that areas under the ROC curves were 83.77%. The risk zoning map indicated that the high-risk areas were particularly distributed in Dege County and Daofu County, with a high disaster frequency and a low highway protection standard. The regional risk assessment framework supports decision-making for disaster prevention and highway rehabilitation in mountainous areas. We have constructed a regional risk assessment framework for the national highway in mountainous areas. Vulnerability indicators provide detailed information on the structural characteristics of the highway. Analysis of debris flow characteristics and causative factors about the northern line of the Sichuan-Tibet Highway.