ABSTRACT
Most hydraulic engineering methods in rivers focus on bank enhancement for protecting the banks from erosion. By contrast, submerged river training structures function by effectively guiding eroding currents away from the banks and hence lowering shear stress in the bank area. Such installations known as “micro groins” and “meandering ramps”” are built of natural boulders. They operate from within the river bed, not from the banks. Accordingly, these designs are covered under the term Instream River Training (IRT). A further key feature is the generation of helicoidal secondary flows which have an effect on sediment transport as well as on velocity and shear stress distributions. As opposed to conventional groins, IRT structures protrude only marginally from the river bed (i.e. 0.15 m), yet they operate efficiently during floods. In this paper we present fundamentals as well as monitoring results of recently built IRT structures. The monitoring results are promising. In 2011 micro groins and meandering ramps were installed in the Taverna river, canton Freiburg, Switzerland. These submerged groins proved to successfully protect the outer banks from erosion during a 30 -year flood and to diversify bed morphology. The monitoring program for the Taverna river will be continued until 2017 to further investigate IRT structures.
