Applicability Index for Sand Transport Equations

Sediment transport relationships have been calibrated under a certain range of experimental conditions described here by three dimensionless parameters. For given stream-flow conditions, an applicability index is defined as the number of dimensionless parameters falling within the range of experimental values. An example involving four sediment transport equations applied to limited flow conditions illustrates the usefulness of the index. Good agreement between these four calculated rates of sediment transport is obtained when the index is high. At low values of the index, however, the discrepancies between the four equations can exceed several orders of magnitude. The Toffaleti method predicts very low transport rates for coarse sands. At larger flow depth, the equations of Toffaleti and of Ackers and White are sensitive to sediment size.