Data collection and predictive analysis of river denudation (follow-up report)

Kawamura, Makoto*; Nishiyama, Nariaki  ; Jia, H.*; Ishikawa, Taiki*; Koizumi, Yukiko*

One of the challenges in the investigation and evaluation technology for the safety assessment of geological disposal of high-level radioactive waste is the quantitative evaluation of the changes and their impacts on future surface topography and underground geological environment caused by river incision due to uplift and denudation. Changes in the surface topography due to river incision will affect groundwater flow and will also require consideration of the location of the disposal site near the surface. Such studies require information on the cross-sectional shape of rivers, but there is little reference information available compared to the longitudinal sections of rivers, which are often the subject of research. Therefore, we have been collecting cross-sectional shape data, mainly of rivers, by performing topographical analysis using GIS with the 10m DEM. When comparing actual rivers, there was no significant difference in the relative height difference due to differences in the main geology of the riverbed, and a tendency was observed to depend on the uplift rate. When comparing the virtual and real rivers, although there is a difference in resolution between the virtual and real rivers, the data on peak relative height shows a tendency for it to increase with the uplift rate, which is not inconsistent with the trend of the real rivers. However, a tendency for the relative height to be smaller than that of the actual terrain was observed, and a gap was also confirmed between the virtual terrain and the actual terrain.