Performance of SRTM, PALSAR, and UAV DEMs in identifying landslides: Akchour, Morocco

The investigation of the Akchour landslide (AKL) demands precise examination on a local scale, which necessitates field surveys that are often hindered by the landslide's steep and extensive nature of the landslide (1100 m × 400 m, ΔZ of 300 m). Digital Elevation Models (DEMs) are among the key datasets used to achieve this objective. A comparative study between freely available DEMs such as Shuttel Radar Topography Mission (SRTM) (30 m × 30 m) and Phased Array type L-band Synthetic Aperture Radar (PALSAR) (12.5 m × 12.5 m), alongside those generated by unmanned aerial vehicles (UAVs) demonstrates their significant potential for both geomorphological and geomorphometric analysis. Indeed, scaling issues can lead to the oversight of crucial geological elements. Aerial photos at a 1/20000 scale, previously utilized for anaglyph, provide a broad overview but lack detailed information. To address this limitation, we employed the UAV to capture high-resolution aerial views (with a ground resolution of 17 cm). This approach enabled exploration of inaccessible areas, photogrammetry for orthophotos, and the generation of precise DEM supported geomorphological studies. The orthophoto allowed for detailed visual assessment, while the DEM facilitated geomorphological study. The dynamic behaviors within the landslide. Furthermore, the former irrigation network likely exacerbates the situation. Fractures delineating an unstable area are prominent along the main scarp suggesting the possibility of further sliding. This UAV-mapping revealed three distinct zones with varying based approach significantly enhances our understanding of the AKL, surpassing the limitations of traditional methods and providing critical insights into its morphology and potential risks.