Depositional processes of circular abandoned channels around the middle parts of the Kumano River, Southwest Japan

Nakanishi, Toshimichi*; Komatsu, Tetsuya  ; Ogata, Manabu ; Kawamura, Makoto; Yasue, Kenichi*

The formation process of terrace topography was investigated by observing and analyzing boring core samples collected in the middle reaches of the Kumano River. It was assumed that the older terrace topography was distributed higher than the current riverbed surface. However, since tributary debris flow deposits may be thickly distributed beneath the old gyre river valley, care must be taken when using the surface of the ground as an index of uplift and erosion.