Groundwater conservation of small volcanic Island and the dynamics of its freshwater and saltwater interfaces revealed from electrical resistivity data: A case study from ternate island

Coastal areas are generally the location of residential areas. The main problem in coastal areas is seawater infiltration due to uncontrolled over-exploitation of groundwater. We investigated an assessment to know the groundwater quality to control water use in the study area of Ternate Island. We conducted two approaches: imaging freshwater to saline water interface and assessing water quality. We measured Electrical Resistivity Tomography using Wenner-Schlumberger electrode configuration to image the interface between freshwater and seawater. Laboratory measurements on water samples supported this investigation. Water quality parameters measured are pH, temperature, dissolved oxygen (DO), total dissolved solution (TDS), turbidity, electrical conductivity, nitrate, and chloride contents. Research results show that the interface between freshwater and seawater remains constant, and the water quality in the coastal area lies within the acceptable limits of the national water standard.