Penelitian ini dilaksanakan di Tipologi Karst Gunung Sewu Kabupaten Gunungkidul. Tujuan dari penelitian ini adalah untuk (1) mengetahui berbagai bentukan erosi permukaan yang ada di daerah penelitian; (2) mengetahui nilai laju erosi permukaan yang terjadi di daerah penelitian. Metode penelitian yang digunakan adalah survei. Pada awal metode survei dilakukan interpretasi foto udara untuk memperoleh lokasi sebaran tipe-tipe karst yang berada di daerah penelitian. Selanjutnya hasil interpretasi tersebut diuji di lapangan berdasarkan lokasi yang telah dipilih sebelumnya. Sampel dalam penelitian ini diambil tiga bukit karst yang mewakili tipe karst labirin, tipe karst kerucut poligonal dan tipe karst kerucut residual di Karst Gunung Sewu Kabupaten Gunungkidul dengan penentuan jumlah bukit karst secara “purposive sampling” yaitu penentuan sampel berdasarkan pada tujuan. Penentuan berbagai bentukan erosi permukaan di daerah penelitian berdasarkan pengamatan di lapangan, pengukuran nilai laju erosi permukaan di lapangan digunakan rumus dari Stocking dan Murnaghan, sedangkan klasifikasi laju erosi permukaan menggunakan rumus dari Departemen Kehutanan. Hasil penelitian ini menunjukkan di Karst Gunung Sewu Kabupaten Gunungkidul bentukan erosi yang ada adalah plant root exposure, tree mound exposure, solution notches dan di daerah penelitian didominasi plant root exposure. Besarnya nilai laju erosi permukaan yang diamati, berkisar 7,8-81,0 ton/ha/tahun dengan rincian : (a) laju erosi permukaan di tipe karst kerucut poligonal berkisar dari 20,9-59,6 ton/ha/tahun; (b) laju erosi permukaan di tipe karst labirin berkisar dari 7,8-28,1 ton/ha/tahun dan (c) laju erosi permukaan di tipe karst kerucut residual berkisar dari 22,2-81,0 ton/ha/tahun. Berdasarkan hasil perhitungan agihan erosi permukaan tersebut menunjukkan erosi permukaan tipe karst labirin meliputi areal seluas 9726,2 hektar atau sekitar 12,16 % dari daerah penelitian; erosi permukaan tipe karst kerucut poligonal meliputi areal seluas 16220,8 hektar atau 20,37 % dari daerah penelitian dan erosi permukaan tipe karst kerucut residual meliputi areal seluas 20063,3 hektar atau 42,34 % dari daerah penelitian. Klasifikasi laju erosi permukaan menunjukkan laju erosi permukaan sangat berat dijumpai di tipe karst kerucut residual dan tipe karst kerucut poligonal, sedangkan laju erosi permukaan berat dijumpai di tipe karst labirin

The study was done in the Typology Karst of Gunungsewu, Gunungkidul regency. The objectives of this study were to (1) study of surface erosion features in the study area; (2) study of a rate of surface erosion in the area. The method used in this study was field survey. At the first step of this method was interpretation of the aerial photographich to gain location distributions of karst typology which were needed in this study. Then the result of the interpretation was tested in the field based on the locations which were selected previously. The samples in this study were taken from three karst hills which were representative for labyrinth karst type, polygonal cone karst type and residual cone karst type in the range of Typology Karst in Gunung Sewu, Gunungkidul regency. The number of observed hills was defined by “purposive sampling”; it is a sample determination which is based on the purpose of the study. In determining features of surface erosion, it based on field observations, in estimating the rate of surface erosion, this study used a formula of Stocking and Murnaghan, to classify of surface erosion, this study used a formula of Forestry Departement. The result of this study give features of observed erosion were dominated by plan/tree root exposure, tree mound exposure, solution notches and study give conclusion that the level of observed surface erosion was around 7,8-81,0 ton/ha/year; (a) labyrinth karst type was around 7,8-28,1 ton/ha/year; (b) polygonal cone karst type was around 20,9-59,6 ton/ha/year and (c) residual cone karst type was around 22,2-81,0 ton/ha/year. Based on the result of surface erosion calculation was shown an erosion level in polygonal cone karst type which covered an area of 16220,8 ha or about 20,37 % of the study area width. Then the level of surface erosion in residual cone karst type covered an area of 20063,30 ha or about 43,34 % of study area width. Furthermore, the level of surface erosion in labyrinth karst type covered an area of 9726,2 ha or about 20, 37 % study area. The clasification of the surface erosion shows polygonal cone karst and residual cone karst type on very severe erosion level, where as labyrinth karst type is on severe erosion level.

Kata Kunci : Erosi permukaan,Bentukan erosi permukaan,Surface Erosion and Surface Erosion Features