Groundwater vulnerability assessment to pollution in Kasihan, Bantul Regency: A comparative method study (GOD, SINTACS and DRASTIC)

Groundwater vulnerability to pollution refers to the ease with which pollutants reach groundwater, in other words indicating the level of ease of an area to experience pollution. At present, the theme is one of the themes that attracts many researchers because pollution is more frequent in an area. The purpose of this study is to assess groundwater vulnerability in the study area for pollution using the GOD method and conduct a study of 3 groundwater vulnerability assessments, to determine the most appropriate assessment to be applied in the study area. The method used to determine groundwater vulnerability to pollution is GOD, which uses three parameters to assess the vulnerability of groundwater, namely aquifer type, rock type above aquifer and groundwater level. Furthermore, the results of the vulnerability assessment using the GOD method are compared with the vulnerability assessment according to the SINTACS and DRASTIC methods that have been carried out before in this area. The results showed that the variation of groundwater vulnerability index values in the study area according to the GOD method was from 0.35 to 0.63. Locations that are classified as medium vulnerability are generally located in the limestone Sentolo Formation, while locations that are classified as high vulnerability class are located in the volcanic rock of Yogyakarta Formation. Noting the results of determining groundwater vulnerability from the three methods, it can be said that the three methods are suitable for assessing groundwater vulnerability in the study area. However, looking at the distribution pattern of the level of pollution, the DRASTIC method can provide more detailed results related to the level of vulnerability.