Hydrogeological Modeling and Groundwater Flow Analysis of the Underground Research Laboratory Site Using the Various Conceptual Model (Phase 2)

Ijiri, Yuji*; Ono, Makoto*; Sugihara, Yutaka*; Shimo, Michito*; Yamamoto, Hajime*; Fumimura, Kenichi*

In order to establish the most effective procedures for groundwater flow characterization in order to reduce the uncertainty this study, the identidication of essential uncertainty factors for the groundwater flow characterization has been attempted using various conceptual model. In this study, an integrated data flow on the groundwater flow simuration was developed for previously applied various conceptural models. The data flow consists of five steps in order: (1) field investigation, (2) raw / conditioned data, (3) interpretation / data set, (4) conceptualization / modeling / simulation, and (5) results / applications. These are uncertainties in each work and assumption in every step, and the uncertainties have an influence on the modeling methods and simulation resuls. Following the data flow, the uncertain factors affecting the groundwater flow simulation were extracted based on the simulation resuls. Investigation data, methods of investigation and modeling, and analysis technique were examined to solve the problems due to the uncertainties. Acquired information is summarized in the following. As for each work process in the data flow, the uncertainty factors that are considered to affect the results of simulations are extracted by two kinds of comparison methods as follows: (1) comparison of data flow among analysis cases for each conceptual model, and (2) comparison of data flow among conceptual models for each case. The uncertainty factors include hydrogeological mechanism of fault and effective porosity, and the likes. The development of each data flow for four modeling methods was additionally used to clarify the data interpretation technique, the modeling procedure, and the uncertainty factor in each data flow along with the data flow from investigation through evaluation. Extensive through information without bias is, therefore, reflected in groundwater flow analysis by defining the data flow. Establishment of data flow...