The Lower Isère River between Grenoble and its confluence with the Rhône is heavily modified by numerous dams and flood protection dikes, which facilitate navigation. The high sediment flux in the Isère, one of the strongest among French rivers, creates challenges for the proper use of hydroelectric dams and for maintaining the navigability of the river (Poulier et al., 2019; Camenen et al., 2019). Given the significance of these sediment flows, Electricité de France (EDF) has been managing sediment transport in the Lower Isère through controlled flushing of the river’s infrastructure based on specific guidelines for several decades. However, after several years of unfavorable hydrological conditions preventing flushing, the Compagnie Nationale Rhône (CNR) has been forced to manage sediment through dredging.
As the main source of these issues, sand has been identified as the primary contributor to sediment deposition. Nevertheless, knowledge regarding the sand inputs from the watershed and the sand dynamics through the river’s infrastructures remains limited (Camenen et al., 2018). To better understand this issue, hydro-acoustic measurements are applied alongside turbidity probes (e.g., ISCO probes) at large scales, as well as in situ point measurements using sand transport samplers such as the Helley-Smith sampler and the P72 isokinetic suspension sampler or Delft bottles. These tools are used to validate new acoustic methods that provide continuous estimates of sand flux (Gray & Gartner, 2009). The applied methods largely rely on recent developments in acoustic techniques for the indirect measurement of sediment suspension (HADCP, UR RiverLy from INRAE; S. Moore, 2011; A. Vergne, 2017).

Thesis Objectives:

1. Development of In Situ Hydro-Acoustic Measurements: To improve the continuous monitoring of sand dynamics using advanced acoustic technologies.
2. Improvement of Sand Dynamics Quantification: To enhance the characterization and quantification of sand dynamics both upstream and downstream of the Lower Isère River, as well as at its confluence with the Rhône, extending to the Bourg-lès-Valence plant.