ANALISIS INDEKS GEOMORFIK DALAM MENENTUKAN PENGARUH TEKTONIK PADA SUB DAERAH ALIRAN SUNGAI OYO KECAMATAN PLAYEN KABUPATEN GUNUNG KIDUL DAN KECAMATAN DLINGO KABUPATEN BANTUL DAERAH ISTIMEWA YOGYAKARTA

Abstract

Tectonics processes that form Southern Mountains marked on it landform. Landform is part of geomorphology which has values that can be used to analyse tectonic influenced in research area. The research area, namely sub Drainage basin Oyo is part of Dlingo District,Bantul Regency and Playen District, Gunungkidul Regency, located about + 30 kms Southeast of Yogyakarta. Physiographically, this area is a part of a Southern Mountains Zone especially Wonosari Platue Subzone. The study aims to understand tectonic influenced using geomorphic quantitative measurement that is geomorphic indices. Geomorphic indices is quantitative analysis method using to decide tectonics influenced by using geomorphic paramaters include elevation, stream length and total area. It based on hypsometric curve, drainage basin asymmetry dan stream-length gradient index (SL). Based on hypsometric curve analysis, research area have young stage in east and old stage in west. From drainage basin asymmetry calculate result AF value is 45,8 in west side of reserach area indicated asymmetry of drainage basin which show that riveron east side more lenght because of AF value is bigger and magnitude average T-indexs turn on 0,24 – 0,35 indicated that research area influenced by tectonics. Stream-length gradien index calculate result conture SL value turn on 20-150, anomaly conture SL value on less resistant rock, above 70, suggest that Oyo sub Watershed was strongly influenced by tectonics The evidences of tectonics influenced in research area can be seen from the result of geomorphic indices analysis as asymmetry drainage basin.