Forensic assessment of landslides induced by environmental changes in Sumedang, Indonesia, an important step for the future disaster prevention

Abstract

Landslide forensics assessment was conducted in Cimanggung, Sumedang with the aim of identifying the causes and processes of landslides to guide the critical step of future disaster prevention. The methodology includes investigations on geology, lithology, hydrology, land cover, land-use changes, and rainfall triggering the landslide. Unmanned Aerial Vehicles were used to investigate detailed spatial geomorphology for determining landslide development. The forensic assessment of the landslide that occurred in Cimanggung, Sumedang, on January 9, 2021, revealed the role of environmental changes. The conversion of open land to residential areas affects the water balance. The surface burden to the site on the hilltop by houses and toe-side cutting at the bottom of the slope has occurred. Changes in land conditions and hydrology, along with lithology thickness and variations, are essential aspects of the landslide incident. During the high rainfall rate, there is more water runoff, and the flow could be concentrated in a paleo channel formed by thicker unconsolidated sediments. The combination of these aspects destabilized the slope causing it to slide. Water management, particularly drainage improvement, should be established to prevent excessive runoff and centralized infiltration. Detailed hazard zonation, site delineation, and rainwater storage could be developed to avoid future landslides.