Analysis of Land Conservation Directives Based on Erosion Intensity in the Mangguliling Sub-watershed, Segeri Watershed

Abstract

The Segeri Watershed, particularly the Mangguliling Sub-watershed spanning Barru and Pangkajene Kepulauan Regencies in South Sulawesi, faces intense ecological pressure from land use change, agricultural expansion, tourism development, and illegal mining. This study assesses erosion hazard levels and develops targeted land conservation strategies through integrated biophysical and socio economic analyses. A spatial modeling approach was applied using the Soil and Water Assessment Tool (SWAT) with an 8 m DEM (DEMNAS), 2021 Sentinel-2 land cover data (validated at ≥85% accuracy), RePPProT soil maps, slope classes, and climate data from NASA POWER and local stations. Field surveys and community interviews provided complementary socio economic insights. SWAT simulations indicate an annual rainfall of 2,040 mm, potential evapotranspiration 2,298 mm, and actual evapotranspiration 1,006 mm, with subsurface Xlow emerging as the dominant hydrological pathway. Erosion hazard mapping shows that 42.6% of the area falls in the heavy category (III-B) and 29.6% in the very heavy category (IV-SB), with an average soil loss of 535 Mg/ha/year. Simulated sediment yield reaches a maximum of 611.49 Mg/ha/year in steep, grasslandcovered HRUs, indicating severe erosion hotspots. Most agricultural lands lie in high-risk zones, while community awareness of watershed conservation is limited and no integrated management program is in place. Conservation zoning, developed in accordance with Perdirjen P.8/PDASHL/SET/KUM.1/8/2018, identiXies four priority zones ranging from strict protection to controlled cultivation, supported by mechanical, vegetative, and micro-water management measures. The Xindings provide a scientiXically grounded, spatially explicit framework for sustainable watershed management, offering guidance for land-use planning and conservation policymaking, and fostering collaboration among local communities and stakeholders to safeguard the Mangguliling Sub-watershed ecological functions.