Drone Surveying For Landslide Risk Assessment: Dem Generation, Contour Extraction And Slope Analysis

Abstract

Landslides pose significant threats to infrastructure and human safety in mountainous regions, particularly in Sarawak, Malaysia, where steep topography and tropical climate conditions create favorable conditions for slope instability. This study presents a comprehensive landslide risk assessment for the Matang Wildlife Road area using advanced drone surveying techniques. The study employed a DJI Mavic Air 2S unmanned aerial vehicle to capture 69 high-resolution images, which were processed using Agisoft Metashape Professional software to generate detailed Digital Elevation Models (DEMs), orthomosaic imagery and topographic contour maps. The methodology followed a systematic six-phase approach encompassing site reconnaissance, pre-flight planning, data acquisition, photogrammetric processing and terrain analysis. Three cross-sectional profiles were analyzed using Global Mapper software, revealing an average slope angle of 21o and average slope height of 12.00 meters. Application of the Slope Priority Ranking System (SPRS) yielded a hazard score of 79% which categorizing the slopes as "Very High" hazard rating, indicating significant potential for slope instability requiring immediate remedial measures. The study demonstrates that UAV-based photogrammetry provides a cost-effective and accurate alternative to traditional surveying methods, offering enhanced spatial resolution and comprehensive coverage for slope stability assessment. The findings contribute valuable scientific data to support improved disaster management strategies, enhance early warning capabilities and inform better planning decisions for landslide-prone infrastructure in challenging topographic environments. This study also underscores the critical need for prompt remedial measures and continued monitoring of high-hazard slopes to mitigate potential risks to infrastructure and public safety.