2010 Volume 16 Pages 95-100
In the Saigo River which is one of the sand bed rivers in Fukuoka Prefecture, different two areas of the cross- sectional profile were prepared. The riverbed in the one area was flat, a fairway was provided for another riverbed. We monitored the riverbed shape, the riverbed materials, and the vegetation in both areas, and grasped the effect of the fairway which had the possibility making the deposition speed of sediment decline.
As the result, the sediment deposition speed in the area where the fairway existed was slower than in the flat area and there was little sediment on the flood channel of the former. The cause of such a difference was that the amount of flown sand in the area where the fairway existed was more than in the flat area. Also, we supposed that the sand in the area where the fairway exists drifted in the low-flow channel mainly and the sand in the area on the flat riverbed drifted in both of the low-flow channel and the flood channel. This result clarified that the securing of a fairway is one of the ways of delaying the sediment deposition on the sand bed river, and will contribute to the cut of the administrative and maintenance expenses on the river.
