The multi-channel concept explored from Bonn to Biesbosch
L.J.A. Schulte (Bureau Stroming, HAN University of Applied Sciences)
J.S. Rijke (TU Delft - Urban Design, HAN University of Applied Sciences)
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Abstract
The hydro-morphology of the Rhine River has significantly altered due to engineering interventions since the 18th century. These interventions improved navigability and reduced the risk of ice dams. Especially in the Waal River, normalization led to channel bed incisions at a rate of 1–2 cm per year (Blom, 2016). This has resulted in a 1–2-meter degradation of the riverbed in the Waal since the 1950s (Blom, 2016). In the business-as-usual scenario, the riverbed is expected to incise by up to 1.5 meters in the next 50 years (Yila Arbós, 2024). The incision causes shipping bottlenecks, affects the stability of infrastructure and groynes, undermines freshwater intake points, and impacts the ecological quality of floodplains (Beekers et al., 2017). Therefore, action is needed.
In this paper, we explore the multi-channel concept that was developed by Bureau Stroming, WWF and ARK Rewilding to reduce erosion while improving natural quality without affecting navigability. Due to the bypasses the flow velocity in the summer bed decreases, reducing erosion (Figure 1). Exploratory calculations show that large-scale floodplain lowering could potentially reduce the necessary sediment supplementation volume to counter incision by 14–33% (Barneveld et al., 2019).