ABSTRACT
Formative hydraulic conditions for mesoscale bed configurations have been studied by many researchers. A wide range of methods has been used, which include linear bed instability analyses (e.g. Fredsøe 1976, Parker 1976, Kuroki & Kishi 1982) and dimensional analyses based on field data (e.g. Muramoto & Fujita 1978). Results of those studies showed that the widthdepth ratio plays an important role in determining formative hydraulic conditions for mesoscale bed configurations.As the width-depth ratio increases, the bed configuration changes in the order of No bar,Alternate bars, and Multiple row bars.Although the applicability of these studies to hydraulic conditions for generation of bed configurations and to conditions for cases in which dry bed regions like islands are not generated in the channel is clear, the applicability to the fully developed bed geometry in dynamic equilibrium state and to conditions that dry bed regions are generated in the channel remains unclear. Furthermore, with natural rivers, water and sediment supply conditions are unsteady while vegetation grows. Therefore, applicability of the previous studies to natural rivers is also unclear.
