Prediksi Laju Erosi Potensial dan Batas Toleransi dalam Menentukan Tingkat Bahaya Erosi di Sub Das Rembangan, Kabupaten Jember

Abstract

Soil erosion is one of the main environmental problems that threatens land productivity and watershed sustainability, particularly in upland agricultural areas with intensive cultivation. This study aims to (1) estimate the actual soil erosion rate using the Revised Universal Soil Loss Equation (RUSLE), (2) determine the allowable soil loss (Edp), and (3) assess the erosion hazard level (TBE) in the Rembangan Sub-watershed, Jember Regency. Field surveys, soil sampling, laboratory analysis, and spatial modeling using GIS were conducted to obtain the RUSLE parameters, including rainfall erosivity (R), soil erodibility (K), slope length and steepness (LS), vegetation cover (C), and conservation practices (P). The actual soil erosion rate in the Rembangan Sub-watershed ranges from 1,5 to 837 ton/ha/year. Areas classified as very low to low erosion cover 1,607.26 ha (61.16%), while moderate erosion occupies 408.98 ha (15.56%), and high to very high erosion covers 613.10 ha (23.31%), mainly in steep areas with sparse vegetation and poor conservation practices. The allowable soil loss (Edp) ranges from 14.01 to 40.07 ton/ha/year, influenced mainly by effective soil depth and the soil depth factor (Fk = 1), indicating low deterioration of soil physical and chemical properties. Erosion hazard levels (TBE), calculated as the ratio of A to Edp, vary between 0.08 and 61.37. A total of 1,009.78 ha (38.38%) had erosion rates below Edp, whereas 1,619.53 ha (61.62%) exceeded Edp, indicating moderate to severe erosion hazards. These findings highlight the importance of appropriate conservation measures such as terracing, vegetative cover improvement, and controlled land management to reduce erosion and support sustainable watershed management in the Rembangan Sub-watershed