Assessing Landslide susceptibility and formulating adaptation strategies in the Konto Watershed, East Java, Indonesia

A landslide is defined as the displacement of masses of soil or rock constituting a slope, or a combination thereof, resulting from the destabilization of the slope composition. This study aims to develop an integrated approach to managing landslide hazards in the Konto Watershed by assessing susceptibility through spatial mapping and providing a detailed risk assessment to inform disaster mitigation, landslide management, and land use planning. The susceptibility formula incorporates eight observational parameters: max 3-day rain, slope, rock geology, fault presence, regolith depth, land use, road infrastructure presence, and population density. Each parameter is assigned a weight value, representing its respective weighting factor. Primary data on landslide potential is gathered through direct field observations in critical areas with slopes exceeding 40 %, while secondary data is sourced from Indonesian government agencies. The secondary data is then identified, mapped, and analyzed using spatial scoring analysis. The research findings indicate that landslide hazards in areas with high slope gradients and specific soil types, land use combined with elevated rainfall, are categorized as very low (1.16 %), low (6.64 %), medium (89.24 %), and high (3.06 %) of susceptibility from 235.22 km2 of watershed area. The regional function area converts 75.8 % of existing land use into 61.2 % protected zones, 32.2 % buffer zones, and 6.6 % cultivation zones, without altering 24.2 % of existing settlement and rice field areas. Landslide control efforts encompass four treatments: protected and buffer area preservation, mechanical treatment, and cultivation area management based on susceptibility levels. Long-term vegetative treatments are designed according to regional function and susceptibility levels.