Tono regional hydrogeological study project. Annual report fiscal year 2001

Tono Geoscience Center, Japan Nuclear Cycle Development Institute has been conducting a wide range of geoscientific research in order to build a firm scientific and technological basis for the research and development of geological disposal. One of the major components of the ongoing geoscientific research programme is the Regional Hydrogeological Study (RHS) project in the Tono region, central Japan. The main goal of the RHS project is to develop and demonstrate surface-based investigation methodologies to characterize geological environments on a regional scale in Japan. The RHS project was initiated in 1992. To date, remote sensing, geological mapping, airborne and ground geophysical investigations, and measurements in eleven deep boreholes have been carried out in the study area (c. 100 km2). 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, and evolution of the groundwater geochemistry. During fiscal year 2001, hydraulic testing and groundwater sampling were conducted in borehole DH-13 which was drilled during fiscal year 2000. High density electrical resistivity measurements were conducted on a lineament. Groundwater monitoring was continued in the existing boreholes. As a part of evaluation of data uncertainties for modeling and simulation, study was started with the purpose of setting of modeling and simulation area around MIU constructionsite. Development of investigation instruments were also continued. (author)