Abstract
The present paper briefly illustrates several issues of flood disaster mitigation and environmental resources in rivers, focusing on sediment transportations and associated topographic changes caused by debris flows in steep areas as well as by bedload and suspended load in alluvial reaches. In addition, several methods and corresponding results are shown for analyzing these sediment problems. Finally, the author will review the mechanics employed in existing methods in order to suggest that a stiff wall has formed, and to suggest the possibility for a new start.
