1999年大雨によって女鳥羽川河床に発達した深掘れ地形と砕屑物収支

概要

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A deep channel was developed in the Metoba River during strong rainfall in September 11-12, 1999. Riverbed was strongly eroded along the eastern side of Shinshu University, truncating from Akebono Bridge toward the upstream for over 200 meters. The resulted channel was straight, several meters wide, over one meter deep, having flat bottom and vertical walls, and it extends for over several hundred meters. The riverbed, not subjected to truncation, remains as the terraces on both side of the channel. Since the river flows through the most urbanized area of Matsumoto City, the channel have been reconstructed and its morphology is strongly controlled artificially, lower part in particular. The river is rejuvenated by the lowering of river mouth, because the bottom in river mouth area was excavated about two meters by the reconstruction of multiterraces. Stream power is the function of its water discharge and slope, so that the power of Metoba River have been increased due to the lowering of river mouth; moreover, the sediment transport system in the river has been intermitted by many dams for tens of years. The river has already reached erosive condition potentially, once the discharge increased by heavy rain the damage appears obviously.
信州大学の論文