Along the way we often manage to make direct observations of natural phenomena. This work was supported by the U.S. Army Waterways Experiment Station. Large waves often generate sheet flow sediment transport, in which a thin, planar carpet of highly concentrated sand moves essentially horizontally over the seafloor. Occasionally, and quite importantly, an instability arises that disrupts the planar nature of the sheet, and the small perturbation in bed elevation is not smoothed by the intense sediment transport, but instead develops into a dune-like feature with a slipface. Development of dunes significantly modifies the bed roughness, in turn altering the gross flow field and thus sediment transport.
Similar processes occur in rivers and in slurries.
This work is supported by the Coastal Dynamics Program of the Office of Naval Research . Sedimentation in NC Piedmont Lakes Graduate student Walter Haven and I have surveyed sediments accumulated in Lake Wheeler and other lakes and ponds in the Swift Creek watershed. Lake Wheeler is immediately upstream of Lake Benson, which was a water supply for the City of Raleigh in the past, and is expected to again supply drinking water within a decade or so. We have also initiated a study of sedimentation in Lake Raleigh, a small lake on NCSU's Centennial Campus. Rainfall during Hurricane Fran broke the dam creating Lake Raleigh, and the newly-exposed sediments there are accessible without boats, though boots are pretty handy.