Hydrochemical records on long-term changes of deep groundwater system, Japan

Iwatsuki, Teruki; Mizuno, Takashi; Hama, Katsuhiro; Kunimaru, Takanori

Proceedings of 36th International Association of Hydrogeologists Congress 2008 (IAH 2008) (CD-ROM), 9 Pages, 2008/10

This study aims to develop the methodology for the evaluation of long-term stability of groundwater systems. To this aim, crystal morphology, chemical and isotopic property of carbonate minerals are examined to estimate the past hydrogeological condition in different groundwater systems in the crystalline rock at Tono area and sedimentary rock at Horonobe area, Japan. The results show that detail analysis of multilayered mineralization associated with groundwater flow paths provides available information to evaluate long-term palaeohydrogeological changes of groundwater system in crystalline rock. On the other hand, it is inconclusive regarding the feasibility of such method for sedimentary rock.

Hydrogeological characterization for estimation of hydraulic responses due to construction of the Mizunami Underground Research Laboratory

Saegusa, Hiromitsu; Shimo, Michito*; Kumamoto, So*; Onoe, Hironori; Takeuchi, Ryuji; Takeuchi, Shinji; Oyama, Takuya

Proceedings of 36th International Association of Hydrogeologists Congress 2008 (IAH 2008) (CD-ROM), 10 Pages, 2008/10

One of the main goals of the Mizunami Underground Research Laboratory project is to establish comprehensive techniques for investigation, analysis, and assessment of the deep geological environment. Hydrogeological investigations using a stepwise manner have been carried out to obtain information on important properties. Hydrogeological modeling and groundwater flow simulations, which is for estimations of volume of inflow into underground tunnels and impact of construction of underground facilities on water table and hydraulic pressure, have been carried out by synthesizing these investigation results. From the study, the uncertainty of the hydrogeological model was evaluated and the main issues for further investigations were identified. Also, hydrogeological modeling and groundwater flow simulation using the data of hydraulic responses due to shaft sinking have been carried out in order to test/revise the models constructed in Phase I. These results are introduced in this paper.

Study for evaluation of the influence of long-term climate change on deep groundwater flow conditions; Integration of paleo-climatology and hydrogeology

Yasue, Kenichi; Saegusa, Hiromitsu; Onoe, Hironori; Takeuchi, Ryuji; Niizato, Tadafumi

Proceedings of 36th International Association of Hydrogeologists Congress 2008 (IAH 2008) (CD-ROM), 7 Pages, 2008/10

In this study, groundwater flow simulations on climatic changes suggest the importance to obtain the data for estimation of changes of the recharge rate. Therefore, this study indicates one of estimation methods of the recharge rate in the future. In addition, we surveyed existing information on an evapotranspiration of one of surface hydrological conditions. Relationship between the mean annual temperature and the evapotranspiration suggests that the evapotranspiration is estimated by the temperature. As for the paleo-climate in the study area, central Japan, the temperature of past glacial periods suggests that the information on surface hydraulic conditions of the present northernmost part of Japan is useful for the estimation of recharge rates in glacial periods of the study area.

GEOMASS; The Application to characterizations of groundwater flow in the Mizunami Underground Research Laboratory project in Tono area

Oyama, Takuya; Saegusa, Hiromitsu; Onoe, Hironori; Guimer, J.*; White, M. J.*; Robinson, P.*

Proceedings of 36th International Association of Hydrogeologists Congress 2008 (IAH 2008) (CD-ROM), 10 Pages, 2008/10