Data collection and predictive analysis of river denudation

Kawamura, Makoto; Jia, H.*; Koizumi, Yukiko*; Nishiyama, Nariaki  ; Umeda, Koji*

Using topographical analysis with GIS using 10 m DEM, we created 2 km river crossing lines on each side of the three rivers, Abegawa, Oigawa and Kumanogawa, starting from the estuary and going straight to the course of the river every 3 km. In addition, the geological information of the river transverse line was extracted. When the cross-sectional lines of the three rivers are displayed together, it can be seen that the river bed rises and the undulations increase as it goes upstream. A comparison of the cross-sectional shapes of the three rivers reveals similar trends, with peaks of undulations on both sides of the rivers in the middle to upper reaches located approximately 500-1,500 m from the center of the river. The relative height between bed and peak also tends to be around 200-600 m. The difference in elevation between the peaks on both sides of the river and the river bed increased in the upstream direction, that is, the depth of the valley to the river bed increased in the upstream direction. When the riverbed slope of the river longitudinal created from the riverbed elevation was taken, an inflection points where the slope trend rose from the upstream area was seen in all three rivers regardless of the geology and geological structure. Although the trend of elevation of the riverbed and increase in undulations from the relatively flat landform near the mouth of the river upstream is pseudo, it suggests a temporal process of landform formation due to uplift and denudation from the flat lowland. This will be information that contributes to verification of the validity of future predictions and performance evaluation models that incorporate topographical changes, such as topographical change simulations.