Abstract
Formation of ripples and dunes on alluvial river bed is studied by river bed stability analysis, basing on two-dimensional shear flow equation and a Meyer-Peter and Wüller type bed load transport equation modified by the inclusion of the lag distance of bed load relative to local bed shear. Dominant dimensionless wave-numbers of sand wave are analyzed. The effect of sediment particle diameter and lag distance on the dominant wavenumbers is examined, and the difference between ripples and dunes, with respect to their cause of occurrence, is discussed.
