Available Online: https://proceeding.researchsynergypress.com/index.php/cset/index RSF Conference Series: Engineering and Technology ISSN 2809-6843 (Online) | 2809-6878 (Print) Volume 1 Number 1 (2021): 01-08 Identification of the Aquifer Type to Determine the Location of Groundwater Drilling in Karangsari Village, Kulonprogo Regency, Special Region of Yogyakarta Purwanto 1 , Siti Hamidah 2 , Rina Sri Lestari 3 1 Department of Geological Engineering, Faculty of Mineral Teknologi, UPN Veteran Yogyakarta, Indonesia 2 Department of Agribisnis, Faculty of Agriculture, UPN Veteran Yogyakarta, Indonesia 3 Department of Agrotechnology, Faculty of Agriculture, UPN Veteran Yogyakarta, Indonesia Abstract Kulonprogo Regency is area that have an existing problem with clean water resource. This water resource distribution influed by the rock formation of this area and can be overcome with developing groundwater source. This research was conducted with the aim of determining the location of groundwater drilling that can meet the availability of clean water for the area. The method used is geoelectrical measurement using the Schlumberger method, by Vertical Electrical Sounding (VES) method. The best drilling point is at KP 05.3 with aquifer resistance value is 20.20 ohm-m at a dept of 53-70 m and 41.9 ohm-m at a dept of 90-115 m. The aquifer is composed of volcanic sandstone lithology. Each drilling point is measured by three geoelectric points, obtained an error rate of 10% and an accuracy of 90%. Keywords: Kulonprogo Regency, groundwater source, Schlumberger method, Vertical Electrical Sounding (VES) method, aquifer This is an open access article under the CC–BY-NC license INTRODUCTION Groundwater as one of the potential raw water resources has received a lot of attention in relation to meeting the needs of raw water domestic needs. Groundwater resources are naturally renewable, because groundwater is an important part of the hydrological cycle on earth. Groundwater is found in several types of geology and geological structures also stratigraphy. The most important are aquifers, which is namely rock formation that can store and drain water in sufficient quantities (Todd, 1980). One of the method that can be applied to determine the groundwater drilling location is the geoelectrical estimation method which can be correlated with the result of the analysis of existing drill data. The results obtained are in form of information about type, composition and thickness of the constituent materials, so that the groundwater drilling location can be de5ermined properly. This research will conduct geoelectrical measurement using the Vertical Electrical Sounding (VES) method at three different locations. LITERATURE REVIEW Kulonprogo is part of the southern part of the Central Java zone, so the Kulonprogo area is one of the most extensive plateaus known as the Jonggrangan Plato (Van Bemmelen, 1949). This area is an uplift area that forms a large dome. The dome is relatively rectangular with a length of about 32 km across from the north-south direction, while the width is about 20 km in the west-east direction. By Van Bemmelen, the dome was named Oblong Dome. The stratigraphic order of the Kulonprogo Mountains area can be divided into sedimentary rock groups and volcanic rock groups. According to Sujanto, Roskamil (1975) the Kulonprogo area is an elevation bounded by the highs and lows of Kebumen in the west and Yogyakarta in the east, which is based on the tectophysiographical division of the southern part of Central Java. The height of Kulonprogo is characterized by the number of ancient volcanoes that appear above paleogene rocks and are covered by carbonate and neogene marl rock. The stratigraphy of the Kulonprogo Mountains was reviewed based on the literature and research results that had been used as parameters according to Van Bemmelen (1949, p.598), Pringgoprawito et al. (1988), Suroso, et al. (1986) and according to several experts. The lithology that composes the research area is Tertiary deposits that make up the Kulonprogo Mountains. The naming of the lithological unit in the study area refers to its physiographic position, which refers to the Stratigraphy of the Kulonprogo Corresponding author: purwanto_geotek@upnyk.ac.id; shamidah81@yahoo.co.id; rinasrilestari@ymail.com DOI: 10.31098/cset.v1i1.331 Research Synergy Foundation