Multi-Hazards Susceptibility Assessment for Landslides and Floods in Hunza-Nagar, Northern Pakistan

Abstract

The destructive potential of natural hazards has increased due to rapid urbanization and greater exposure, leading to significant loss of life, infrastructure damage, and environmental degradation. Floods and landslides, among the most prevalent geo-hazards, often occur simultaneously in vulnerable regions. This study focuses on the hazard component of disaster risk by developing a multi-hazard susceptibility map (MHSM) for the Hunza-Nagar region, prone to both floods and landslides. For landslide susceptibility, the Frequency Ratio (FR) model is employed, considering geo-environmental factors like elevation, slope, LULC, rainfall, lithology, and proximity to roads, rivers, and faults. A landslide inventory of 139 events is split into training (70%) and validation (30%) datasets, achieving an accuracy of 91.6%. For flood susceptibility, the Random Forest (RF) model is applied using ten explanatory factors. A 100-year return period flood simulation in HEC-RAS provides flood extents from which flood inventory is prepared, achieving an accuracy of 91.2%. The MHSM integrates FR-based landslide and RF-based flood susceptibility maps using a combined sum approach in GIS. The region is classified into four zones: No Hazard, Flood Hazard, Landslide Hazard, and Combined Hazard. The MHSM maintains high prediction accuracy and serves as a reliable tool for identifying multi-hazard zones. This map is essential for disaster management authorities and infrastructure planners, enabling targeted mitigation strategies to reduce hazard impacts and enhance regional resilience.