Geospatial Assessment of Debris-Flow Hazard in District Chitral, Pakistan Using Google Earth Engine

Abstract

Debris flows are among the most destructive geomorphic processes in mountainous regions, posing serious risks to lives, infrastructure, and ecosystems. The present study assesses debris flow susceptibility in the District Chitral Using Google Earth Engine with Geographic Information Systems (GIS). Nine conditioning factors slope, aspect, elevation, rainfall, NDWI, NDVI, land cover, distance from streams, and distance from roads, were selected based on their geomorphological significance and data availability. Each factor was assigned a weight through pairwise comparison matrices and consistency checks following the AHP framework. Results indicate that approximately 43.2% of the study area falls within the Moderate susceptibility class, while 6.34% and 4.9% of the area are categorized as High and Very High susceptibility zones, respectively. Areas with Very Low and Low susceptibility account for 16.5% and 28.9% of the district. Spatially, High to Very High hazard zones are concentrated in the northern and central parts of Chitral, characterized by steep slopes, high drainage density, sparse vegetation, unconsolidated Quaternary deposits, and elevated rainfall intensity. Validation using historical debris-flow inventories from 1976 to 2021 reveals that nearly 85% of recorded debris-flow events occurred within the High and Very High susceptibility zones, confirming the strong predictive capability of the proposed model. This study provides a scientifically and spatially explicit framework for debris flow risk assessment and mitigation planning in the District Chitral. The generated susceptibility map can aid policymakers, engineers, and local authorities in prioritizing vulnerable zones, developing early warning systems, and implementing sustainable land-use strategies to minimize future hazard impacts.