Abstract
The river ecosystem is evaluated based on bar morphology, because bars provide numerous places of shelter to organisms. For the dual purposes of maintaining flood protection and proper environmental functioning of the river, we need to understand bar morphology in the low-flow channel. However, there is limited knowledge of the system that bars form and of the process of change in the compound channel. Accordingly, in this paper, field observation and numerical simulation are performed to clarify the characteristics of bar formation and change. Two research sites are established in the downstream reach of the Yada River. The sites are selected such that the width of the low-flow channel is representative at one research site, and this width is wider at the other site. The change in bar morphology at each site is investigated and we succeed in clarifying the characteristics of bar morphology.
