Abstract

Rainfall-induced landslides pose a significantthreat to tropical mountain roads, where the interaction ofhydrological loading, geomorphic development, and soilweakening drives failure. This study presents an integratedhydro-geomorphic diagnosis of the July 2022 Callawa–Fatimalandslide in Davao City, Philippines, by combining field surveys,drone photogrammetry, historical satellite imagery, DigitalElevation Models (DEMs), rainfall records, and numerical slopestability modeling. Multi-temporal analysis revealed a tensilecrack along the ridge crest as early as 2015, while 5-m contourinterpretation highlighted topographic irregularities thatsignaled long-term geomorphic preconditioning. Hydrologicalassessment based on rainfall data revealed that several days ofantecedent wetting, from July 8 to 12, 2022, saturated the slopebefore the short-duration, high-intensity rainfall on July 13-14,2022, triggered the failure. Catchment modeling in QuantumGeographic Information System (QGIS): GeographicResources Analysis Support System (GRASS) moduleconfirmed concentrated flow paths converging toward thefailure zone. Limit-equilibrium simulations conducted in GEO5demonstrated that the slope was already marginally unstableunder dry-season conditions with Factor of Safety,FoS≈0.87–1.35, and transitioned to global instability underrainfall-induced pore-pressure loading with FoS ≈ 0.58–0.76.During the spatial exposure, QGIS deep-learning mapping,identified house location along the active scarps as directlyexposed and downstream community as indirectly at risk. Theintegrated framework offers a cost-effective and transferableapproach for diagnosing rainfall-induced slope failures andenhancing community resilience in tropical mountain regions.