Fig. 2: Simulated flow conditions and observed erosion in the river reach with deep scours during the 2021 flood.
a, Simulated peak flow velocities and bounds of the area where 90% of the flow passes, revealing bottlenecks between km 35 and 39 (location indicated in Fig. 1c) due to uneven widening (Extended Data Fig. 2c). Scale bar, 1.3 km. b, Scour holes (red contours), bank erosion and floodplain deposits in the Common Meuse. Bed and bank scour appear to alternate (for example, along km 34.5–35.5, 36–37 and 38.5–39.2). Locations A–C refer to Fig. 3. Extended Data Figs. 4–6 provide erosion and deposition volumes and composition for the entire Dutch Meuse. c, Simulated maximum flow velocities and differences in the main channel, averaged over depth and 50 m of width, for the river geometries in 1995 and 2021, showing acceleration in the bottleneck section (km 35–39), and velocity reduction in widened sections (upstream km 34, at km 38.7 and downstream km 40). d, Bed levels (Z), erosion and water levels (H) at the peak discharge (Q) of 3.310 m3 s−1 in the reach of the Campine Horst. Levels relative to the Dutch reference level NAP. The deepest points (thalweg) in July 2021 are compared to the cross-section-averaged bed levels every 250 m in February 2021. Lithology with formations (F.) from Extended Data Fig. 2b. Despite the thin gravel layer at km 40–41, erosion is limited owing to reduced flow velocities in the widened section. D50, median grain diameter.
