HR: 0800h
AN: H31B-1289    [Abstracts]
TI: A Flume Study of Silt Deposition to a Starved Bed
AU: * Hamm, N T
EM: nathan.hamm@dartmouth.edu
AF: Department of Earth Sciences, HB 6105 Dartmouth College, Hanover, NH 03755 United States
AU: Dade, W B
EM: brian.dade@dartmouth.edu
AF: Department of Earth Sciences, HB 6105 Dartmouth College, Hanover, NH 03755 United States
AU: Renshaw, C E
EM: carl.renshaw@dartmouth.edu
AF: Department of Earth Sciences, HB 6105 Dartmouth College, Hanover, NH 03755 United States
AB: Characterization of fine-particle delivery and re-entrainment under a range of flow and bed boundary conditions is crucial to an understanding of river channel and seafloor processes, including controls on water turbidity, contaminant transport, and sediment accumulation at the bed. We report new data from flume experiments designed to quantify the temporal evolution of deposition and re-entrainment rates of well-sorted, non-cohesive, silt-sized particles from a starved bed underlying a turbulent, well-mixed flow. We find that, as the product of the particle Shields number and particle Reynolds number (each conventionally defined) approaches unity, effective settling speeds of individual particles become vanishingly small and fine-particle re-entrainment rates from the bed become relatively large. These results are consistent with the temporal evolution of near-bed concentration of suspended sediment predicted by a simple model which accommodates particle settling and re-entrainment. Our results provide a fundamental, background perspective for ongoing flume studies on the importance of granular bed roughness to suspension transport processes over natural beds.
DE: 1815 Erosion
DE: 1861 Sedimentation (4863)
DE: 1862 Sediment transport (4558)
SC: Hydrology [H]
MN: Fall Meeting 2005