Modeling geomorphic changes in sedimentary rock areas; A Case study in the Boso peninsula area, Central Japan

Hanatani, Ikuo; Munakata, Masahiro ; Kimura, Hideo; Sanga, Tomoji*

Evaluation of the radionuclide migration toward the human environment associated with groundwater flow is an issue of importance in safety assessment of geological disposal. We constructed models depicting the influences of geomorphological evolution on long-term groundwater flow. This was done by reconstructing the processes of river deepening with historical simulation of the profiles of four rivers in the Boso Peninsula. The study resulted in the sum of erosion during the past 125,000 years which is the equivalent of one glacial to interglacial cycle. The profiles of four rivers during the last glacial age to the present were successfully reconstructed using similar parameters. It was found that the profiles were sculpted in accordance with the uplifting rates with very little influence of initial topography owing to the relatively soft and easily dissected characteristics of the geological units.