Erosion of Soft Cohesive Sediment Deposits

Abstract

Erosion behavior of soft cohesive sediment deposits has been investigated in laboratory experiments. Such deposits are representative of the top, active layer of estuarial beds. An experimental procedure involving layer by layer erosion under a range of bed shear stresses, τb, of successively increasing magnitude was utilized. Interpretation of the resulting concentrationtime data together with bed density profiles yielded a description of the variation of the bed shear strength, τs, with depth as well as an expression for the rate of surface erosion. In general, τs increased with depth and was also influenced by the type of sediment, bed consolidation period and salinity. The rate of erosion was found to vary exponentially with (τb-τs)1/2. In modeling estuarial bed erosion, it is essential to take these characteristics of τs and the rate of erosion into account.