LAUSR

Abstract For testing the potential and increased usage of a ground source heat pump system (GSHP), chemical and isotopic (D, 18O) compositions of 50 shallow groundwater and six river water samples in Joganji and Toyama alluvial fans, central Japan, were analyzed to examine their water quality and origins with the simulation of the fluid flow mode using a 3-D state flow (transient) model. Results showed that groundwater was mainly a mixture of the Joganji River water and precipitation and moved from east to west. The groundwater flow velocity was estimated at 4–10 m/day, and the residence time could reach 10 years. The saturation indices of scaling components (deposit on heat exchanger) such as Fe and CaCO3 were discussed for the safe use of the GSHP.