ANALISIS SPASIAL POTENSI KUANTITAS RELATIF AIR TANAH DI DAERAH ALIRAN SUNGAI GALEH DENGAN SISTEM INFORMASI GEOGRAFIS

Abstract

The research is conducted in the Galeh Watershed, which is a sub watershed of the upper course of Progo. The research aims to map the determinant factors of relative quantity potential of the groundwater by using Geographical Information System. The method of the research is survey by using sample of the zone of selected mapped potential factors. The mapping method is by plotting the secondary data and interpreting Citra Landsat visual. The method of analyzing data is spatial analysis by using GIS technology. The result of the research shows that the determinant factors of the relative quantity potential of the groundwater in the research setting have many varieties. The wide of the research setting is about 298.86 km2 or 29886 Ha. The kind of lava rock dominates with the wide of 129.6 km2 or 43.7%; the dominant ground type is Latosol in the wide of 171.22 km2 or 57.72%, the widest slope aslant is 0-3% in the spread out area of 135.49 km2 or 45.33%, while the widest area use is irrigation rice field, that is 127.92 km2 or 43.12%. The precision of the interpretation of the Citra Landsat for the slope aslant and the use of each area are 82.35% and 86.23%, meaning that the accurate of mapping can be accepted because it is more than 80.00%. The result of the spatial analysis using GIS shows that in the research setting, there are 116 area units, with the relative quantity potentials of groundwater: 2 (two) area units are included in the ‘low’ potential class (7.62 km2 or 2.54%); 71 area units are included in the ‘middle’ potential class (175.25 km2 or 58.64%); and 43 area units are included in the ‘high’ potential class (115.99 km2 or 38.82%). Keywords: Potential, Relative Quantity, Groundwater, GIS Spatial Analysis