Modelling morphological effects of the Room for Living Rivers vision in 2DH

Ongoing bed degradation in the River Waal is causing negative impacts on a multitude of river functions. Recent studies show that this process will continue, leading up to 2 meters bed degradation by the end of the century. To mitigate this erosion, The World Wide Fund for Nature presented the ‘Room for Living Rivers’ vision consisting of a combination of floodplain lowering, side channel construction and removal of summer dikes. We assessed the proposed interventions on its efficacy in reducing erosion in the Midden-Waal using a 2DH morphological model. Results show that the interventions may reduce current erosion. In order to function optimally, the measures should be carried out over long trajectories, continuously extracting discharge from the main channel in order to be effective. As soon as the interventions stop, the increased transport capacity in the main channel will induce additional erosion to compensate for the reduced sediment influx from upstream.