Particle Size of River Sediments

The relationships between particle size of river sediments and the variation in stream discharge are studied. The results of a study carried out to determine the variation of both bed material and suspended sediment particle size for differing flow conditions is presented. A significant finding is presented which shows that the particle size of suspended and bed sediments remains relatively constant with variation in stream discharge. This condition was found from the analysis of results at four river sections on three rivers in Scotland and was also corroborated by results from research in the United States. Conclusions are presented which attempt to explain these findings in terms of the availability of material for transport by streams rather than on purely hydraulic considerations.