Bed-Material Transport and Bed Forms

Because the control of sediment transport is the rate that particles can be removed from the surface of the bed, the geometry of the bed must be a dominant factor in bed-material transport. Bed geometry can be classified by the amplitude of sand waves into three regions increasing amplitude, decreasing amplitude, and flat bed. Approximate limits between the regions was determined by analysis of sand-wave amplitude, of boundary-drag coefficient, and of sediment-transport rate. Limits between the three regions which define bed geometry are expressed in terms of the sediment number which is a form of Froude number. Close agreement of the limits of the three regions from the three independent analyses was interpreted as confirming the hypothesis that bed-material transport should be classified by bed-form geometry rather than as suspended load and bed load.