UAV based assessment of landslide morphology and slope instability in Miraswadi, Western Ghats, India

Abstract

The Western Ghats of India are highly susceptible to rainfall-induced landslides owing to steep topography, deeply weathered basaltic terrain, and increasing anthropogenic disturbances. This study investigates landslide morphology and post-failure slope instability in Miraswadi habitation, Satara district, Western Ghats, India using Unmanned Aerial Vehicle (UAV) based remote sensing integrated with field observations and multi-temporal satellite analysis. A UAV survey acquired 283 georeferenced high-resolution images which were processed to generate an ortho mosaic, digital elevation model (DEM), contour dataset, and a dense point cloud of ~ 31 million points with mean ground sampling distance of 5.52 cm. Morphometric analysis revealed that the July 2021 landslide affected ~ 1.34 ha, while the associated debris spread extended over ~ 2.95 ha area. The landslide extended approximately 255 m from crown to toe, with widths ranging between 112 and 162 m and an estimated displaced volume between 42,050 and 46,076 m. Geomorphological evidence indicates that the event initiated as a debris slide and subsequently evolved into a channelized debris-flow along a pre-existing second-order drainage course. UAV imagery and field investigations identified several post-failure instability indicators, including tension cracks (up to 70–90 m long and 0.5 m wide), active slumping, ground settlement, and vegetation tilting, indicating ongoing slope deformation adjacent to the habitation. Multi-temporal land-use analysis (2011–2022) revealed expansion of settlement areas and modification of vegetation and agricultural land. The study highlights the utility of UAV-based surveys for rapid, high-resolution characterization of landslide morphology and ongoing instability, providing valuable information for local hazard mitigation and slope management.