ABSTRACT
The present paper describes an innovative concept of controlled bank erosion to regenerate alluvial dynamics, sediment replenishment and transport, and ultimately improve habitats conditions for aquatic ecosystems and biodiversity in the Old Rhine river. The concept was optimized for a pilot site using an undistorted physical model (geometric scale 1/40). Physical model testing covered a large number of configurations (including removal of bank riprap, and modifications of existing groynes), and gave assessment of bank erosion rates and extension risk for a large number of hydrological scenarios, including safety scenarios for exceptional floods. The proposed concept (riprap, groynes modifications) was implemented on O3 pilot site in spring 2013. First morphological and ecological responses to a recent flood that occurred in June 2013 have shown promising results, and promote duplication of such a concept erosion test on other additional pre-selected bank sites along the Old Rhine. A comprehensive monitoring program, covering both morphology and ecology aspects, is under progress to confirm relevance and performance of such a restoration plan, before duplication to other additional sites.
