Abstract
In the middle reaches of the Asahi River, gravel bars were disappeared and were mostly covered by vegetation on the bars in the recent years. At a sand bar of the Gion area which is one of the fairly vegetated bars, gravel bar restoration work was carried out by removal of vegetation and deposited sand in 2005. After that the gravel bar have been maintained there in several years, and aggradation of severely scoured riverbed at low-water channel was confirmed. Numerical simulation using a vegetation growth and disappearance model proves that the conducted gravel bar restoration work have an effect on an expansion of gravel bar and river bed aggradation at local scour area. Furthermore, an expansion of spawning area of ayu by gravel bar restoration was clarified quantitatively using PHABSIM assessment.
