阿賀川における礫河原再生に向けた河道整備

抄録

In Agagawa River, nature restoration works were carried out to restore gravel riverside, which is commonly seen in local river environment, by natural processes. This paper reports on the restoration of gravel riverside and the reduced impacts to eroded outer curves of meander bend after the floods in July and September 2011.

In those sections where gravel riverside was restored, the relative water depth was increased to between 0.3 and 0.4 after river improvement works were implemented. According to a study by Fukuoka, in meandering compound channels, the maximum flow velocity occurs on inner curves when a relative water depth is between 0.3 and 0.5. It is understood that the maximum flow velocity occurred on fixed point bars where an inner curve of meander bend was excavated, inducing flood disturbance on the point bars.

In future river improvement works, gravel riverside is expected to be restored and maintained by natural processes with channel excavation works which reflect the results obtained in this report.