利根川下流部における河道改修の経緯とその効果

Abstract

In the Lower Tone River, channel dredging and widening have been conducted for the river improvement works to respond to the flood discharge increase. However, the discharge capacity of the current river channel is still not sufficient even for the present design flood. So, it is required to discuss about the method for the appropriate river improvement works in the Lower Tone River. But, the effects of the past river improvement works on changes in river bed elevation are not sufficiently investigated. We investigated the process of the river improvement works in the Lower Tone River and clarified how the river improvement works have effects on changes in the river bed elevation by investigating the changes of channel shape and longitudinal distributions of hydraulic quantities. The results demonstrated the sediment deposition disappeared and the large bed scouring occurred and disappeared by the effect of the channel dredging and widening in each area.