From Hazards to Settlement Planning in Nepal: Using Machine learning and GIS to assess impact of critical Flood and Landslide Overlays

Surrounded by active seismic zones and influenced by one of the most dynamic climatic systems on Earth in the Himalayas, Nepal faces increasing threats from cascading natural hazards. Despite frequent co-occurrence of floods and landslides, national-scale assessments that explicitly quantify their spatial interactions remain largely unexplored. This study presents the first machine learning and Geographic Information System (GIS) based approach to map country-wide cascading zone for Nepal. The model is built on topographic, climatic, environmental, and hydrological datasets, yielding strong predictive accuracy (Area Under Curve: 0.84 for floods and 0.85 for landslides). The results indicated that 19% of Nepal's total area, mostly in lowlands is medium to very highly susceptible to floods with threat to 900 thousand people and over 3.4 million infrastructures, and 40% is susceptible to medium to very high landslides susceptibility, which pose threats to 200 thousand individuals and 600 thousand infrastructures. A high-threshold interaction analysis (flood above 60% and landslide above 80%) produces novel four zones 81% low hazard zone area, 9% flood only zone, 5% landslide only zone, and 5% critical cascading hotspots. We further traced cascading landslides, and floods flow downstream to the nearest settlements. These critical zones cover approximately 7588 km ² with possibility to impact 88 km ² of built-up area (12% of total built-up area) and 1722 km ² of cropland. The results reveal that while valley regions show lower probabilities of co-occurring hazards, high mountain areas, especially around glacier lake, and steep slopes are prone to compound impact, highlighting potential downstream risk to settlements. These insights provide actionable guidance for sustainable human settlement plans, infrastructure planning, and land use management. Importantly, the study emphasizes that establishing resilient settlement requires us to consider all potential risk scenarios and mitigation strategies in future infrastructure projects to enhance resilience settlement.