A spatial model for the assessment of debris flow susceptibility along the Kodaikkanal-Palani traffic corridor

Debris flow is one of the most destructive water related mass movements that affects the development of mountain terrains. A reliable assessment of debris flow susceptibility requires adequate data, but in most developing countries like India, there is a dearth of such extensive scientific records. This study presents a novel approach for assessing debris flow using the analytical network process (ANP) in data insufficient regions. A stretch of hill road between Kumburvayal and Vadakaunchi along the Kodaikkanal-Palani Traffic Corridor (M171) was considered for this study. Five significant factors including the nature of slope forming materials, hydraulic conductivity, slope, vegetation, and drainage density were identified from intense field surveys and inspections in order to assess the susceptibility of the terrain to debris flow. This model endorsed the inter-dependencies between the selected factors. The resulting debris flow susceptibility map delineated regions highly prone to debris flow occurrences, which constituted nearly 23% of the selected road stretch.