Indeks dan Tingkat Bahaya Erosi Kawasan Hutan Pendidikan Gunung Walat, Kabupaten Sukabumi

Abstract

Gunung Walat Education Forest (GWEF) is dominated by forest (Google Earth Image 2010). The river flowing within GWEF show less sediment load when the rainy days, that indicate the actual erosion of GWEF land is low. However, the physical conditions (soil and land morphology) of GWEF are dominated by the physical characteritics of land that potentially high erosion. Mapping of potential and actual erosion hazard in the region of GWEF are necessary and important for land use planning to reduce the negative impacts of land management of GWEF. The actual erosion is predicted by using indexes of USLE, i.e rainfall erosivity, soil erodibility, length and slope, land cover, and soil conservation measures indexes. Potential erosion is predicted also by using those indexes except the indexes of land cover and soil conservation measure. The results show that GWEF area is dominated by the very high potential erosion hazard index (92 %). The highest potential erosion is about 482,170.7 tons/ha/year (40,180.9 mm/year) and total potential erosion is 13,195,922 tons/year. Nevertheless, the actual erosion in GWEF area is mostly very low (59 %). The highest actual erosion is about 2,147.1 tons/ha/year (178.9 mm/year) and the total actual erosion is about 39,643 tons/year. Sediment Delivery Ratio in HPGW of sub watersheds is less than 0.2. Potential erosion in most areas of GWEF is very high, that indicate the most areas of GWEF is sensitive to erosion, but actual erosion of GWEF mostly is low. This phenomena is caused the area of GWEF is dominated by dense forest and forest floor. In the bare land, the actual erosion is very high. Based on these results, forested land should be maintained, especially in areas where potential erosion hazard index high until very high. In the areas where potential erosion hazard index is low – medium, forest land cover change is possible with consider the soil conservation measures.