Mapping of Groundwater Vulnerability Index in the Alluvial Plain of Semarang City Using the Susceptibility Index Method

One of the negative impacts of settlements and urbanization is the decline in groundwater quality. In maintaining the sustainability of groundwater for a long period of time, a special study is needed, which can be done by examining groundwater vulnerability. The alluvial plain of Semarang City currently faces environmental problems such as degradation of groundwater quality which is the negative impact of the settlement, The purpose of this study was to examine groundwater vulnerability in the alluvial plain area of Semarang City. The Susceptibility Index method is using a spatial analysis tool based on rating and weighting value of some parameters, i.e. Depth of groundwater, recharge, aquifer media, slope, and land use. The result of this research reveals that about 41.3% area is covered under the high vulnerable zone, 50.3% area under moderately vulnerable zone and 8.4% area under the low vulnerable zone. 7 sub districts namely Tugu, Semarang Barat, Semarang Utara, Semarang Timur, Gayamsari, Pedurungan and Genuk, most of which are in the high vulnerability zone. Whereas the Ngaliyan, Semarang Selatan, Semarang Tengah, Candisari, and Gajah Mungkur, which are mostly in the low to moderate vulnerability zones