Geochemical and hydraulic analysis of groundwater for heat utilization around Sakuragaike in Nanto City, Toyama Prefecture, Japan

Oxygen isotopes, major and minor chemical compositions of 23 groundwater and 5 river water samples from the southern part of Nanto City were analyzed. From these results, the possibility of groundwater heat utilization was discussed. The water temperatures fluctuated between summer and winter. The groundwater in this area nearby Sho River is strongly influenced by river water infiltration and most groundwater in other areas is considered to be derived from precipitation. The Ca2+, HCO3−, and SiO2 concentrations increase due to reactions with rocks during water flow from the surrounding mountains to the alluvial fan areas. In some areas, Fe scale (goethite) is assumed to be precipitated from groundwater in heat exchangers and water pipes. Based on these results, an area around Sakuragaike potentially suitable for utilization of groundwater heat was selected for study.