HYDROGEOCHEMICAL CHARACTER AND GROUNDWATER POTENTIAL IN TERNATE BASIN, NORTH MALUKU, INDONESIA

Abstract

Ternate Basin is located a small volcanic island in the archipelago of North Maluku, Indonesia. This island has very limited water resources and prone to seawater intrusion. This study aims to determine and analyze the distribution of hydrogeological interest points, determine patterns and directions of groundwater flow, and analyze hydrogeochemical quality and groundwater facies. Determination of the free aquifer zone was carried out by geoelectric measurements in 37 points, while the interpretation of confined aquifers was carried out in 17 drill log points. The quality of groundwater was analyzed in the study area, 126 samples were collected and analyzed. The piper diagram was adopted to identify groundwater facies. The determination of groundwater basin with a total recharge of 54,155 million m3/year. The saturated zone of groundwater flow reaches 1.237 million m3/day or 451.712 million m3/year. The quality of groundwater laboratory results indicates that the water from the two aquifer sources is suitable as a source of drinking water with moderate permeability and has met the quality standards. There were three groundwater facies in the study sites consisting of calcium magnesium bicarbonate (C4H4-Ca-MgO12), calcium magnesium chloride (CaCl2-MgCl2) and sodium potassium chloride (NaCL-KCL). Bicarbonate facies type in the groundwater basin indicated localized flow systems. This means the groundwater in the study site has a recharge area close to its groundwater source. Meanwhile, chloride facies type in the groundwater basin indicates a long process of flow pattern and allows the groundwater to interact with seawater or magmatic matters. These results can be used for policymakers to determine the appropriate and accurate location for groundwater exploitation for the public purposes. Determination of the location must be carried out by considering the flow, quantity, and quality of groundwater.