Improvement of the sizing methods of riverbank bioengineering following an empirical approach

Abstract

The choice of plant based engineering techniques used to protect the riverbanks generally depends on expert knowledge based on an empirical approach. In fact knowledge on dimensioning elements, especially concerning hydraulic stress, is still very fragmentary and the main obstacle to the development of plant-based engineering techniques used on riverbanks. To improve the methods an observation-based approach can be taken by gathering shear stress values which structures have withstood in the past. In this article we first gather values from the literature and then present new values based on hydraulic quantities characteristic of the morphodynamics of the minor river bed (considered at the river section level). The new values show new possibilities for some techniques which were underestimated until now. They also give more details about the evolution of the resistance of the vegetation [engeineering] structures over time. The limits of the approach and the indicative nature of the values obtained are then examined.