ABSTRACT
The morphodynamics of fluvial fine sediments are especially influenced by stabilization processes due to the presence of biota. Biofilms, consisting of algae and/or bacteria and their secreted extracellular polymeric substances, glue single sediment grains together to form larger aggregates to impact the resistance towards erosion. Even though it is now well accepted, that adhesion forces (in combination with floc-size and -density) play a dominant role in this process, only little experimental data can be found in literature. Consequently, current mechanical models could not be validated so far. Therefore, a promising method was modified to approximate the surface adhesion forces and applied in long term experiments on biostabilization. The results suggest that the development of surface adhesion can be subdivided into three phases: Phase I is characterized by no or very low adhesion and lasts approximately two weeks. Consequently, in this phase no or very little biostabilization effect is measured in erosional studies. In the second phase adhesion increases drastically and can be correlated to the increasing stability of the sediments due to a growing biofilm. In the third phase, no such correlation is found, which may be ascribed to the heterogeneous nature of the matured biofilm.
