Abstract
The continuity of impermeable layers and groundwater chemistry are studied using geological and hydrological information in Gifu city to assess installation potential of groundwater heat pumps. For former study, an estimation of sedimentation environment by diatom fossils and a measurement of water level change by groundwater pumping-up are performed. Extracted diatom fossils are composed of the fresh water assemblage, and suggest that the formation with these fossils was sedimented at the back marsh and its continuity is not good. The measurement result of groundwater level change shows that two aquifers above and under the impermeable layer are connected hydrologically. The latter study revealed that the groundwater with low dissolved contents is widely spread in the urban area of Gifu city. Although the contents of free carbon dioxide are higher than the recommended value in most areas, approximate <10mg/L of free carbon dioxide is assumed to be possible to utilize of groundwater heat pumps based on the present utilization situation. The result of continuity of impermeable layers shows that the influences of groundwater pumping-up for heat pumps are not concentrated into one aquifer due to aquifer connection. Groundwater chemistry reveals that the groundwater can be directly used in the heat pumps due to their low resolved contents.
