Bedload transport assessment on a physical model of a large river widening using ultrasonic Doppler velocity measurements

The 3rd correction of the Rhône River is the largest flood protection project in Switzerland so far. Covering a length of 162 km, it aims to protect some 100,000 people and prevent flood damages, which could raise up to 10 billion Swiss francs for major events. It also intends to revitalize the river and its surrounding area. A natural or revitalized river presents a dynamic morphology that can be assessed using bathymetric survey, bedload transport and hydrodynamic flow behavior. The present case study aims to investigate the behavior of the bedload transport for the future Rhône at the Verney widening using physical model. A valid bedload assessment requires distributed water depths and velocities. The used dataset consists of Lidar scans and recorded streamwise and crosswise velocity profiles. The analysis is performed at two selected cross sections based on the ultrasound Doppler velocity profile method. The velocity profiles allow assessing the local shear stress on the mobile river bed. The different velocity profiles are compared, and the results discussed.