Geohazard vulnerability assessment of Rawal lake watershed using remote sensing and geological indicators: Implications for risk management in Himalayan urban ecosystems

The Himalayan region's Rawal Lake watershed faces escalating geohazard risks from landslides, flash floods, and anthropogenic pressures exacerbated by climate change. This study presents a novel integrated multi-method approach combining Sentinel-2 spectral analysis, geological structural mapping, advanced image processing, and topographic analysis for comprehensive geohazard assessment. Spectral indices analysis revealed critical thresholds: NDVI values below 0.3 indicating vegetation degradation in 23 % of steep slopes (>30°), NDWI variations highlighting 12 flash flood-prone drainage pathways, and NDMI fluctuations identifying moisture-sensitive zones covering 15.7 km2. Advanced image processing (PCA, MNF) and directional lineament analysis identified 127 structural features across four orientations, with 68 % trending NS and NWSE, directly controlling watershed geomorphology. Land use classification (91 % accuracy, Kappa: 0.88) revealed 31 % urban encroachment into high-risk zones, while DEM analysis (481–877 m elevation) and slope mapping (0°–42.14°) identified 15 % of the watershed as landslide-susceptible terrain. Strong correlations between moisture indices (NDWI-NDMI: r = 0.78) established their utility as proxies for slope failure prediction, with 12 high-priority monitoring zones identified where geological vulnerability intersects with urban expansion. The framework successfully delineated 8 conservation priority areas and 15 high-risk zones, providing quantitative indicators for adaptive land-use policies and establishing a replicable model for disaster risk reduction in climate-sensitive Himalayan watersheds. © 2025 Elsevier Ltd.