Groundwater are commonly have good quality and become important source to fulfill human need for clean water. The good quality of groundwater is created naturally by the purification process during infiltration groundwater and percolation due to physical chemical process. The purification capability can be presented by groundwater vulnerability. This vulnerability varies on physical hydrogeological conditions where groundwater exists. Karst environment is one of the most vulnerable or easily polluted environment. Therefore, groundwater protection in this environment is important and the initial management strategy is to conduct mapping of the groundwater vulnerability on this karst area. This research is aimed to assess groundwater vulnerability of the karst environment in Semanu District, Gunung Kidul, Special Region of Yogyakarta. The method used in this study is EPIK. EPIK has four parameters that combine intrinsic and specific factors of groundwater vulnerability which are: 1. Epikarst condition (E), 2. Protection zone (P), 3. Infiltration Condition (I), and 4. Karst Network Development (K). Those factors are obtained by direct field observation and secondary data collection. Data evaluation was conducted by spatial analysis in the Geographic Information System (GIS). The result of this method shows that the research area has three zones of vulnerability with the following distribution: 14.2% high vulnerability, 41.7% moderate vulnerability, 44.1% low vulnerability. Areas with low vulnerability are proved by low concentration of nitrate which ranges from 0.3 to 8.3 mg/L.
