Field Measurements of the Erosion of Cohesive Sediments

Abstract

Predictive modeling of estuarial fine sediment transport requires a description of the erosional properties of cohesive sediment beds. Available descriptions are commonly based upon flume experiments run on uniform beds. Field data pertaining to the erosion process are rather scarce. A field experiment was undertaken at Mare Island Strait near Vallejo, California, to address the issue of surface erosion of a cohesive sediment bed. Suspended sediment concentration and water velocity data were collected in the bottom boundary layer of this muddy estuary. As a result, the critical shear stress of erosion initiation was found to be 1.44 dynes/cm 2 and the erosion rate coefficient was found to be 6.25 X 10 -4 mg/cm 2 -sec. These values compare favorably with results obtained in recent flume experiments.