Hydrogeological Modeling and Groundwater Flow Analyses of the Underground Research Laboratory Site Using the Various Conceptual Model

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

This study involves evaluation of uncertainty in hydrogeological modeling and groundwater flow analysis. Three-dimensional groundwater flow analisys in underground research laboratory site in Tono was carried out using three continuum models and one discontinuum model in the domain of 9km9km area. The acquired knowledge is as follows.The effect of variety of modeling method was evaluated under the condition that same analysis domain and same shape of Tsukiyoshi fault were assingned. The results indicated that the variation of travel pathway and travel length resulted from heterogeneity is sometimes larger than from the difference of models, depending on a place. Besides, since the difference between the models in travel time was larger than a travel pathway and travel length, it turns out that the uncertainty of effective porosity used for alculation of the actual flow velocity is large.Moreover, the existing data flow was reconstituted through a series of modeling and analysis of this work. The results indicated that it is necessary to continue reflecting the results of investigation and evaluation in data flow, since data flow varied with modeling concepts.