Position: PhD position at Géosciences Rennes (France): Loire River geomorphology: from natural river toward a model
Employer: University of Rennes
Associated with the University of Rennes, OSUR is entrusted with a training mission in the field of Earth sciences, ecology and environment
OSUR facilitates and coordinates environmental research, working with 6 laboratories in this field in the scientific center of Rennes.
As a member of the French national network of Observatoires des sciences de l’Univers (Earth Science and Astronomy Observatories: CNRS-INSU), OSUR designs and oversees long-term observation of planetary and socioecological systems.
OSUR is made up of approximately 700 people organized in 6 divisions (see below). Fundamentally multidisciplinary, OSUR brings together nationally and internationally recognized ecologists, geologists, geographers and archeologists. In addition to research staff, OSUR employs approximately 250 other employees. Altogether, nearly 1000 researchers, teachers, doctoral students, postdoctoral researchers, technical engineers and administrative staff work under the umbrella of OSUR.
One of OSUR’s key research objectives is to understand human influence on the sustainability of socioecological systems..
Homepage: https://www.univ-rennes.fr/en
Location: Rennes, France
Sector: Academic
Relevant division: Geomorphology (GM)
Type: Full time
Level: Student / Graduate / Internship
Salary: 2300 € / Year
Preferred education: Master
Application deadline: 28 April 2023
Posted: 31 March 2023
Job description
Hypothesis et scientific questions
Since the 1960s, the geomorphological analysis of rivers in terms of physical control variables has been based on a planimetric vision (2D) for a lack of full bathymetric data of rivers. Consequently, it is still difficult today to predict the shape of rivers and their evolution in time and space. The recent acquisition of 3D data of river geometry, using topo-bathymetric lidars, allows a major qualitative step in the perception of their complexity. This thesis takes the opportunity to analyze 3D topo-bathymetric data, acquired on the Loire River (within the framework of the CIT Loire & Fleuves of the ARD IPAT2), with unprecedented resolution and spatial extent, to better understand the physical link between the dynamics of river forms and sediment transfer processes. The Loire River presents a great variety of channel forms, sedimentary bodies and associated granulometries, largely induced by contrasting hydrological regimes.
The main scientific question of the thesis is to understand what controls channel shape at the scale of a sandy-gravel river system based on this new 3D perception of rivers, which implies a paradigm shift to establish causal links between channel shape and sediment transfer processes. The 3D analysis will be coupled with numerical simulation of explanatory variables (water level, velocity, shear stress). This approach has never been applied to the entire shape and complexity of such a large river. One of the innovations is to consider the size, shape and orientation distributions of the grains to fit the transport laws of the models. This work will be carried out at various spatial scales, from the whole Loire River to specific sectors that reflect critical geological, anthropogenic or hydrological boundary conditions.
The thesis will rely on (1) the analysis of lidar’s 3D point clouds to characterize the 3D shapes of the Loire channels (Cloud Compare software or similar) as well as the granulometric distribution (G3Point software), and (2) the use of numerical models of erosion and sedimentation (RiverLab software). These numerical tools are developed by the DEMOD team at Geosciences Rennes. Such simulations will help to define in-situ field measurement to acquire new topographic and hydraulic data to constrain and/or validate the models.
Required skills
- Fluvial geomorphology / sediment transport/hydraulics
- Basics (or more) in programming language (Python, Matlab, …)
- Basics on sedimentology
- Appetence for field work
- Ability to work as part of a team
- scientific English (speaking and writing)
Upgraded skills during the thesis:
- Ability to carry out a scientific project (project management, scientific methodology, funding, communication);
- Working as part of a team;
- Knowledge of the research community
- Expertise in river geomorphology;
- Expertise in 3D analysis softwares;
- Expertise in hydro-geomorphology simulation;
- Skills in sedimentology.
Thesis context:
The PhD student will be located in the laboratories of Geosciences Rennes (team River, sediment transfer and extreme events – https://geosciences.univ-rennes.fr/rivieres-transfert-sedimentaire-et-evenements-extremes) and will be likely to spend some time in Tours in Polytech Tours & UMR CNRS CITERES. The thesis will concretize a collaboration between these two teams of complementary skills on data analysis and in-situ observations. He/she will be supervised by Alain Crave, François Guillocheau, Laure Guerit and Stéphane Rodrigues, members of the Geosciences Rennes and CITERES Tours University.
How to apply
The financing of this thesis corresponds to an Establishment Doctoral Contract (CDE). It will start at the beginning of October 2023 for 3 years according to the modalities of the doctoral school of Rennes EGAAL (https://ed-egaal.doctorat-bretagne.fr/fr/deroulement-du-doctorat). The selection of the candidates is done in two phases. A first phase of interviews with the thesis supervisors at the end of which (end of May) two candidates will be eligible to be auditioned by an EGAAL jury in June 2023. Candidates can now submit their application on the website: https://theses.doctorat-bretagneloire.fr/egaal/campagne-2023 and send a copy of their CV with a cover letter to the email addresses of the supervisors:
Alain Crave: alain.crave@univ-rennes1.fr
François Guillocheau: francois.guillocheau@univ-rennes1.fr
Laure Guerit: laure.guerit@univ-rennes1.fr
Stephane Rodrigues: srodrigues@univ-tours.fr
