Spatio-dynamic Modeling of Land Cover Changes on the Prediction of Erosion Hazard in Sepaku Watershed as Nusantara Capital Buffer Zone

Abstract

Located in East Kalimantan on the island of Borneo, Nusantara Capital City (IKN) is a massive ongoing development designed to replace Jakarta as the nation’s new administrative capital, based on Law Number 3 of 2022, which later changed through Law Number 21 of 2023. The development of IKN has triggered extensive land cover change in the Sepaku Watershed, an ecological buffer zone. The conversion of vegetated areas into built-up land threatens to cause systemic environmental degradation, particularly through increased erosion levels (TBE). This study models spatial-temporal land cover change and predicts its impact on erosion potential within the watershed. A multitemporal remote sensing approach using Google Earth Engine (GEE) was employed to analyze land use transition matrices. Erosion rates were predicted using the Universal Soil Loss Equation (USLE) model, which incorporates rainfall erosivity (R), soil erodibility (K), slope length and steepness (LS), and the vegetation cover and conservation practice factor (CP). The results indicate that converting vegetated land into open areas and settlements significantly increases the CP factor, thereby directly intensifying surface runoff erosion. Areas with high TBE (>60 tons/ha/year) increased from 8,085 ha in 2018 to 9,974 ha in 2025, representing a 23.4% increase, with the highest vulnerability concentrated in the middle to upper reaches of the watershed. This predictive modeling provides a critical empirical basis for stakeholders to develop adaptive spatial plans (RTR KSN) and implement soil conservation measures to support ecosystem sustainability.