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AUVERWATCH project: an associated thesis

As part of the AUVERWATCH project, a long-term monitoring network for Auvergne water bodies, a study is being carried out by Jordan Labbe on the vulnerability and reactivity of alluvial hydrosystems in the face of global changes, using the example of the Allier River and its accompanying water table.

The Allier is a tributary of the Loire running through the Massif Central; it flows from south to north for 425 km. Accompanied by an alluvial water table from the beginning of the Limagne plateau, this hydrosystem is a strategic asset for the production of drinking, industrial and agricultural water. This resource is therefore the source of conflicts of use, making it vulnerable from the point of view of both quality and quantity, a phenomenon accentuated by increasingly long and intense periods of low water.
This thesis proposes to better characterise this vulnerability at different scales: watershed, alluvial groundwater and alluvium.

Jordan Labbe started his thesis in 2020 at the Chrono-environnement laboratory (CNRS-Université de Franche-Comté) under the direction of Hélène Celle, professor of hydrogeology (Chrono-environnement) and Gilles Mailhot, CNRS research director, (Clermont-Ferrand Chemistry Institute).

Programming probes to monitor groundwater levels during test pumping
©Celle

The first stage of the study is to carry out a hydrological assessment of the resource in order to better understand how the processes that allow the supply of this hydrosystem but also the various associated withdrawals evolve and to see if this situation is viable, stable over the long term, from a quantitative point of view. In a second phase, a digital model of the alluvial water table is being built on the Val d’Allier catchment area (south-east of Clermont), a strategic zone that supplies drinking water to 80% of Clermont Auvergne Métropole (145,000 inhabitants). The last part of this work consists of better characterising the heterogeneity of the alluvial environments, which is sometimes very important (alternation of sand/pebbles/clays, more or less fine/coarse) and which directly influences the underground flow speeds and also the transport of potential contaminants. For this purpose, the Port-Douvot experimental site, southwest of Besançon, was equipped in 2019 with fibre optics (FO), a material sensitive to external temperature variations. The idea is to use temperature as a passive sensor of flows. By injecting heat into the FO, it is possible to trace the underground flow velocities, which are directly dependent on the heterogeneity of the medium.

The aim of this study is to gain a better understanding of the sustainability of alluvial hydrosystems in terms of quantity and quality, using various tools (hydrological balance, numerical modelling, experiments with fibre optics, etc.) at different scales, taking into account climate change and current socio-economic developments. As this work is closely followed by the managers, the results obtained will enable them to improve the current operation of this hydrosystem and, in the long term, to better anticipate future crisis periods.

Contact : Jordan Labbe (jordan.labbe at etu.uca.fr)
Duration: 2020-2023
Financers: Loire-Bretagne Water Agency & I-SITE CAP20-25

For more information on the AUVERWATCH project

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