Tracing and quantifying flows at interfaces
This axis seeks to understand and quantify the processes and flows across different interfaces of the water cycle. At the atmosphere-surface-subsurface interface, we are interested in the processes of evaporation, evapotranspiration and recharge, which are poorly understood, especially in arid and semi-arid environments.
Particular attention is paid to tropical and Mediterranean lake systems, in close collaboration with the laboratory's IRD projects and the "Climate" team.
The approaches used rely heavily on stable isotopes of water, through the study of kinetic fractionations associated with evaporative processes, and an effort will be made to develop tracing by the 17O-excess.
The groundwater-river, groundwater-lake/lagoon and groundwater-ocean interfaces, which are the site of crucial water exchanges and physicochemical and ecological processes, are addressed through a combination of geochemical approaches (δ 18O, δD, Radon and Radium isotopes, etc.), combined with modelling approaches.
The continent-ocean interface, and the physical sediment-water column interface, are also explored from the point of view of hydrodynamics and thus of sedimentary flows, hydro-saline exchanges, and other fluid flows such as methane.
The methodologies employed also rely on the interpretation of geochemical measurements (δ 18O, δD, 222Rn, 226Ra, ...), physical (temperature, conductivity, gravimetry, acoustics, water and sediment flux measurements) and geophysical (EM34, ERT) approaches combined with modelling of underground water circulation (e.g. studies of the sedimentary basin feeding the Fes-Meknes region in the Middle Atlas (Morocco) in relation to the evolution of the population and/or climate (project in collaboration with the Saïs basin water agency, the Moulay Ismail University of Meknes, INRAE Avignon and UAPV)
Several projects are being carried out with regional partners and the support of the water agency on the Rhône, the Camargue and on sea grass beds. The studies focus on chemical exchanges ("reactive filter"), the effects of irrigation and the evolution of the coastline and seabed. The monitoring of methane fluxes through the seabed is addressed in the Marmara Sea in the framework of the IR EMSO. Finally, the study (measurement and modelling) of the in situ evolution of the isotopic signal in 17O-excess, δ 18O and δD of water in the soil-plant-atmosphere continuum during transpiration is addressed in collaboration with team "Climate" (ANR HUMI-17).