Appel à candidatures | Recherche, Emploi

PhD position: Hyperpycnal sediment-laden river plumes in lakes

Du 1 septembre 2023 au 31 août 2026

LEGI, Grenoble, France


Hyperpycnal sediment-laden river plumes in lakes: flow-sediment-bathymetry interactions

The focus is on the near-field flow dynamics and the flow-sediment-bathymetry interactions of hyperpycnal plumes, i.e., plumes induced by sediment-laden river inflows with a density higher than that of the receiving water body (lake, reservoir, ocean). The near-field hydro-sedimentary processes control the fate of
substances (e.g., sediments, nutrients, oxygen, contaminants) introduced by the river inflow, which is of critical importance in practical applications, e.g., water-quality modelling in lakes or sediment management in reservoirs. The current understanding of plume dynamics is limited to simple confined geometries, and
flow-sediment-bathymetry interactions are not well understood because of a lack of field and laboratory data. This project will address three research questions for a broad range of confined and unconfined geometries: (i) What are the characteristics and dominant control parameters of the flow processes? (ii)
What is the influence of sediment on these processes? (iii) What are the dominant flow-sediment-bathymetry interactions? This research project is based on laboratory experiments, field observations and numerical modelling. The experiments will be performed at the Coriolis Platform in Grenoble, which will be adapted for sediment-laden plumes. The implementation will be based on a preparatory experimental work ( Results of both field and laboratory investigations will be generalized by numerical experiments with the SedFoam model.

The candidate will be in charge of performing challenging physical experiments in the Coriolis Platform including measurements of flow and sediment concentration fields in the plunging flow, bed morphology evolution through optical techniques, in order to study the physical processes which govern flow-sediment-bathymetry interactions (Shi et al 2022, 10.1029/2022wr032633). Data analysis to evaluate turbulence and sediment fluxes and their characteristics, the feedback of the sediment laden plunging flow on the global
dynamics and the synoptic velocity field as well as diagnostic tools for turbulent mixing and transport will also be part of her/his tasks. Regular meetings with the consortium researchers within the ANR PRCI (HARP)
contract will permit comparisons of the experimental data with numerical/observational data (TUW,LEGI).
The PhD fellow may also participate to in situ-measurements and their analysis.

LOCATION AND PRACTICAL ASPECTS The successful applicant will be hosted at TU Wien and during the physical experiments at the laboratory LEGI (GRENOBLE France) within the team MEIGE and will work in close collaboration with K Blanckaert, ME Negretti and J Chauchat. The gross salary will be 2294 euros/months (for 14 months/year).

QUALIFICATION The PhD candidate will need to master several techniques, as Particle Image Velocimetry (PIV), Sediment concentration and transport measurements, image pre- and post-processing, data analysis and statistics. A solid background in fluid mechanics with special focus on river flows and sediment transport,
image processing, and theoretical/numerical tools is a prerequisite. Curiosity, autonomy and willingness to develop new skills are also necessary.