Abstract
Because of the high denudation rates in Japan, the landform and geological characters will be largely changed in the geological time-scale. These changes are major controlling factors on the hydrogeology, and affect the hydrological and chemical conditions of the groundwater. Estimation of these effects on geological environments by the denudation is one of the important problems for the safety of geological disposal of HLW in Japan.
Development of the methodology to predict the long-term (104-5 year order) denudation rates is the first priority for solving this problem. Statistical analyses of the denudation rates and patterns in the geologic and geomorphic records are the basis for the prediction.
The relationship of uplift rates and denudation rates of the marine terraces was analyzed as a case study. Denudation rates were calculated from the volume of dissected valleys on the marine terraces by using a 50-m DEM. Time-dependency of the denudation rates was also examined from the geomorphologic data of terraces, hills and mountains in the various landform development stages.
Percentages of the denuded volume to a total uplifted volume of the land is 10-20 % in the first 125 kilo years since the emergence, come to several tens of % in next 100 ky and amount to 100 % in the equilibrium stage, ca. 0.5 to one million years after the emergence.
