Pollutants and suspended matters of a river can accumulate into the sedimentary column. Once deposited, they are submitted to autoconsolidation processes, ageing and burying, leading to an increase of their erosion resistance. Pollutant fluxes can be related to sedimentary fluxes, determined by threshold laws.
In this work, an erosion threshold model is suggested by introducing a cohesion force into the usual force balance. A model of cohesion is developed on the basis of interactions between argileous cohesive particles (clays), particularly the Van der Waals force, whose parameterization is ensured by means of granulometry and porosity.
Artificial erosion experiments were performed in a recirculating erosion flume with natural cored sediments where critical shear stress measurements were performed. Other analyses provided granulometry and porosity. The results obtained constitute a good database for the literature.
The model is then applied to the experimental conditions and gives good agreement with measurements. An example of the taking into account of autoconsolidation processes is finally suggested, before ending on a Mohr like diagram dedicated to soft cohesive sediment erosion.