Sand Transport Studies with Radioactive Tracers

Experimental results show that radioactive tracer techniques provide a feasible means for applying Lagrangian techniques to the observation of sediment transport processes in natural rivers and laboratory flumes. The transport of bed-material particles can be described as a sequence of alternating steps and rest periods of random length and duration. The assumption of exponentially and identically distributed incremental step lengths and rest periods leads to a longitudinal concentration-distribution function that agrees with experimental results obtained in the North Loup River, Nebr., and in a laboratory flume. Bed-material discharge can be computed from a continuity equation in which the velocity is defined by the rate of movement of the mean position of a group of tracer particles, and the area is defined as the average cross-sectional area of the bed through which the tracer particles are distributed.