Tracer Studies of Sediment Transport Processes

Particles of various diameters and specific gravities were coated with fluorescent dyes and used as tracers to study the transport and dispersion of sand-size particles for the flat-bed condition in the Rio Grande conveyance channel and for a dune-bed condition in the Atrisco Feeder Canal, NM. Particle velocities for the dune bed depended on size but were only weakly dependent on specific gravity. Particle velocities for the flat bed depended on size and specific gravity, and were several orders of magnitude greater than the particle velocities for the dune bed. Lateral mixing of the tracers from a point source was considerably greater for the dune bed than for the flat bed. Vertical mixing of the tracers for the flat bed was limited to the thin layer of material moving near the bed surface, with essentially no penetration into the bed. Vertical mixing for the dune bed occurred to a depth approximately equal to the heights of the dunes.