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Sediment transport in wave-dominated environments is of great interest for dredged material placement, contaminated sediments, habitat protection, and other issues. The shear stress at the sediment-water interface during a wave event is an important parameter in determining erosion and transport for both experimental and model simulation applications. Sandia National Laboratories has developed a laboratory and field device called the sediment erosion actuated by wave oscillations and linear flow (SEAWOLF) flume in which high-resolution, particle-image velocimetry (PIV) has been applied to investigate turbulent flow shear stresses for a variety of flow conditions. The results of the PIV analysis for a wave cycle demonstrate a fully developed turbulent flow, relaminarization, and an explosive transition back to turbulence. In many cases, the results of the flume tests did not show good agreement with previously reported computational fluid dynamic results and existing theories, such as Blasius, for ...

An adjustable shear stress straight flume commonly used to measure cohesive sediment erosion rates has been modified to include downstream bed load traps. The new flume can be used not only to measure erosion rates, but also to analyze and quantify the modes of transport for this complex problem. The new device was used to study transport modes of quartz particles ranging in size from 19 to 1,250 μm . As expected, the traps captured the coarse material (bed load) and the fine material bypassed the traps (suspended load). Transport properties of natural sediments from three locations were also studied. Fine sediments with little or no sand eroded as aggregates which maintained their integrity in the flume channel while moving as bed load into the traps. Natural sediments that included high percentage of sand also eroded as aggregates. However, these aggregates quickly disaggregated. Sand moved as bed load and fell into the traps while fine particles moved predominately in suspension.

Soil and sediments play an important role in water management and water quality. Issues such as water turbidity, associated contaminants, reservoir sedimentation, undesirable erosion and scour, and aquatic habitat are all linked to sediment properties and behaviors. In situ analysis is necessary to develop an understanding of the erosion and transport of sediments. Sandia National Laboratories has recently patented the Adjustable Shear Stress Erosion and Transport (ASSET) Flume that quantifies in situ erosion of a sediment core with depth while affording simultaneous examination of transport modes (bedload versus suspended load) of the eroded material. Core erosion rates and ratios of bedload to suspended load transport of quartz sediments were studied with the ASSET Flume. The erosion and transport of a fine-grained natural cohesive sediment were also observed. Experiments using quartz sands revealed that the ratio of suspended load to bedload sediment transport is a function of grain diameter and shear ...

Experiments have been done in order to determine the effects of particle size and bulk density on the erosion of quartz particles. Average particle sizes ranged from 5 to 1,350 μm, while bulk densities ranged from approximately 1.65 to 1.95 g/cm³. For the larger particles, the sediments behaved in a noncohesive manner, i.e., they consolidated rapidly and the surface eroded particle by particle. For the smaller particles, the sediments behaved in a cohesive manner, i.e., they consolidated relatively slowly and the surface eroded in chunks. Erosion rates were a very strong decreasing function of density for the finer particles and were essentially independent of density for the larger particles. For a particular bulk density and shear stress and as the particle size increased, the erosion rate increased rapidly for the smaller particles, reached a maximum, and then decreased rapidly for the larger particles. Critical stresses for erosion were strongly dependent on particle size and, for the smaller particles, were also strongly dependent on bulk density.