Study on tectonic uplift and surface erosion within the scope of intermediate depth disposal

Abstract

  This paper reviews tectonic uplift and surface erosion within the scope of intermediate depth disposal in Japan. With regard to the endorheic area in the middle reach of rivers, sediment supply increases during glacial periods while the riverbed is eroded during interglacial periods. The erosion rate is almost equal to the uplift rate in the long term, if the same longitudinal river profile reappears in the same climate period beyond one glacial-interglacial cycle for about hundred thousand years in the area occurring crustal movement. However, the erosion rate is higher than uplift rate for interglacial periods. Therefore, for interglacial periods shorter than hundred thousand years which corresponds to the evaluation period of intermediate depth disposal, the maximum erosion depth of the riverbed may have a large impact on the disposal site. On the other hands, in the lower reach of rivers near the coast, the erosion rate is higher than uplift rate for glacial periods with lowering of the sea level and the base level of erosion. Therefore, the maximum erosion depth may have a significant impact on the disposal site for glacial periods shorter than hundred thousand years. For evaluating tectonic uplift based on the previous studies at disposal sites, it is important to examine the applicability of the data considering their timescale.