River dune dynamics in regulated rivers

The river bed of lowland rivers typically consists of river dunes. These dunes are the major source of roughness for the river flow and so, changes in their dimensions affects the roughness significantly. During floods these dunes grow in length and height. Numerical model studies and laboratory experiments have shown that for extreme discharges these dunes will wash out, i.e upper stage plain bed (USPB), decreasing the water level. In this study we investigate at which locations along the river Rhine, flattening of the dunes or USPB are most likely to occur, using the data-based relationship found by Naqshband et al. (2014a). The flood hydrodynamics is generated by WAQUA. Next, we will apply the steplength approach of van Duin et al (2017) to model this transitions on river scale and assess the water level reduction. Potentially, this USPB may lead to a self-regulation process in rivers decreasing water levels at the extreme discharges which may occur due to climate changes