Bearing of Morphometry and Morphotectonics on the Demarcation of Landslide Susceptible Zones in Lesser Himalaya along National Highway 58 between Rudraprayag and Devprayag Localities, Uttarakhand, India

ABSTRACT This study delineates landslide-prone zones along National Highway (NH 58), specifically between Rudraprayag and Devprayag in the Lesser Himalaya, to support hazard mitigation and infrastructure development efforts. The research highlights the importance of analysing morphometric and morphotectonic parameters to identify areas at higher risk of landslides due to tectonic activity. Key morphometric parameters were calculated for the Alaknanda River valley, such as the viscous flow index, displacement index, flowage index, classification index, dilation index, and tenuity index. These indices provide valuable insights into slope instability and material movement, contributing to a comprehensive landslide risk assessment. In addition, morphotectonic parameters, including the sinuosity index, valley floor width-to-height ratio, and mountain front sinuosity index, are evaluated to understand the relationship between tectonic activity and landslide morphology. Using ASTER-DEM data and historical earthquake records, we identify tectonically active zones along NH 58 in the Alaknanda River valley, marking high-risk areas with red circular patches. The morphotectonic parameter value of the Alaknanda River indicates that twenty two segments are tectonically active, and four are highly active. These findings offer critical guidance for understanding slope dynamics and improving landslide risk management along NH 58.