Postdoctoral Research Associate in Geomorphology
Institut de Physique du Globe de Paris (IPGP)
The institut de physique du globe de Paris is a major institution for higher education and independent research, piloted by an executive board and a scientific council. The IPGP belongs to the new University of Paris and is affiliated with the French National Centre for Scientific Research (CNRS).
It brings together around 150 top-tier researchers recruited from around the world, 170 engineers and administrators and over a hundred PhD students from the world over that share the same passion for Earth and planetary sciences. The IPGP has numerous cooperation agreements with prestigious foreign institutions, making it possible to have ongoing scientific exchanges all across the world.
A world-renowned geosciences organisation, the IPGP studies the Earth and the planets from their core to their outermost fluid envelopes through observation, experimentation and modelling. Particular focus is placed on long-term observations, which are essential in the study of natural systems. The IPGP is in charge of certified observation services in volcanology, seismology, magnetism, gravimetry and erosion through its permanent observatories in Guadeloupe, Martinique and Reunion Island and in Chambon-la-Forêt in mainland France. The IPGP also equips and maintains two global geophysics networks that monitor variation in the magnetic field (INTERMAGNET network) and seismic activity (GEOSCOPE network) around the globe.
The IPGP hosts powerful computational resources and next-generation experimental facilities with top-tier technical support. Its flexible structure facilitates the emergence of research teams in the most promising fields.
The long-term objective is to provide new numerical methods for the quantitative analysis of vegetated dune fields. Dealing with such a complex system, the naive, brute force approach would be to set up a mathematical model that accounts for all the involved physical/biological mechanisms and their appropriate length scales. This type of modeling is unrealistic because of the number of parameters and the uncertainties about the underlying processes. Our strategy of model building is to work at an intermediate length scale of 1 meter with a coherent dune model, which can incorporate different physical/biological compartments and their subsequent sets of interaction. The ReSCAL dune model, a software package constructed on a modular basis for simulating systems in which multiple processes are combined, is particularly well-adapted for this purpose (Rozier et al., 2014).
We will start working on vegetation following the same methodology as for the analysis of different grain sizes (Gao et al., 2015). We will first introduce a new field into the structure associated with sedimentary cells to account for the role of plants on transport, erosion and deposition. Thus, immobile sedimentary cells will be either in a vegetated or non-vegetated substates. As for granular mixtures, these substates will have different threshold shear stress for motion inception and a different impact on deposition when the interact with other sedimentary cells. In addition, biological processes associated with seeding and vegetation growth can be easily incorporated into the 3D structure of the model. It takes the form of new transitions between the vegetated and the non-vegetated substates in order to account for changes in surface and subsurface properties. As a result, spatial heterogeneities associated with vegetation may dynamically evolve over time even without transport. Obviously, when considering transport, it will generate a new level of complexity in the model, which will have without any doubt a strong impact on both sand flux and dune morphodynamics. Specific attention will be given to the formation of blowout, an erosion pattern rarely observed on dunes in arid desert and common in coastal areas or in semi-arid environments.