PRELIMINARY-OBSERVATIONS OF SEDIMENT EROSION FROM A BOTTOM RESTING FLUME

A small portable flume was designed and constructed to measure in situ erosion velocities. Preliminary results from deployments in Lake Michigan, Lake Superior, and Lake Ontario show that the flume can produce and measure the velocities required to erode fine-grained material from the lake bottom. Shear stresses required for erosion (calculated from the measured velocities) varied from 0.03 to 1.34 dynes/cm2. As the flow velocity increases, erosion appears to occur as discrete episodes rather than continuously. Before flume results can be used to predict a sediment's resistance to erosion, both extensive measurements of sediment properties and comparisons of flume results to naturally-occurring erosion events are needed.