Stepwise hydrogeological modeling and groundwater flow simulation on site scale, Step 4

Onoe, Hironori ; Saegusa, Hiromitsu; Oyama, Takuya ; Endo, Yoshinobu*

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. To achieve this goal, a variety of investigations are being conducted using an iterative approach. In this study, hydrogeological modeling and groundwater flow analyses have been carried out using the data from surface-based investigation (Phase I) at the Step 4, in order to synthesize the investigation results, to evaluate the uncertainty of the groundwater flow system, and to specify items for Construction (Phase II). As a result of the study, it could be confirmed the uncertainty of groundwater flow system was decreased as stepwise investigation in Phase I. To characterize groundwater flow system, it could be understood that field investigation, hydrogeological modeling and groundwater flow simulation iteratively is most efficiently. Also, it could be learned techniques to decrease the uncertainty efficiently. The main items specified for Phase II investigation are summarized as follows: (1) Execution of monitor to understand change of groundwater flow system according to excavation of the shafts and research galleries; (2) Modification of hydrogeological model of Phase1.