Tono Regional Hydrogeological Study Project Annual Report 2002

Amano, Kenji  ; Iwatsuki, Teruki  ; Uehara, Daijiro; Sasaki, Keiichi; Takeuchi, Shinji; Nakama, Shigeo 

Tono Geoscience Center, Japan Nuclear Cycle Development Institute has been conducting a wide range of geoscientific research in order to build firm scientific and technological basis for the research and development of geological disposal. One of the ongoing geoscientific research programme is a Regional Hydrogeological Study (RHS) project in the Tono region, central Japan. The main goal of the RHS project is to develop and demonstrate the surface-based investigation methodologies to characterize geological environments on regional scale in Japan. The RHS project was initiated in 1992. To date, remote sensing, geological mapping, airborne and ground geophysical investigations have been carried out and thirteen deep boreholes have been also drilled and investigations include geophysical logging, hydraulic tests etc. using these boreholes have been done in the study area of the RHS project (c. 100 km). Groundwater chemistry and hydraulic head monitoring is under way in these boreholes. Important results that have been obtained from these investigations include various information concerning the heterogeneity of lithological, hydrogeological and geochemical parameters, and evolution of the groundwater geochemistry. During fiscal year 2002, as the research for regional scale, groundwater simulation was carried out, and the domain setting method of modeling in regional scale was shown and the domain of local scale in the RHS project area was determined. The setting method of modeling/simulation of the local scale domain and its boundary condition were shown. Lineament investigation and reflection seismic survey were carried out in the local scale domain. VSP survey and some investigations concerning groundwater flow and chemistry were conducted in DH-2 borehole. Long-term groundwater monitoring using the existing boreholes was continued. Improvement of the instruments of hydraulic test and groundwater sampling was also continued.