Rouages: "If we continue like this, one day these aquifers will no longer be able to supply us with water."
Muriel Geeraert is a hydrogeology engineer at Géosciences Montpellier. In the Hérault and Eastern Pyrenees regions, she travels from borehole to borehole to collect valuable data that will enable the Porous Media Transfers department to better preserve water resources. She explains her work in the video series Rouages produced by the University of Montpellier. Action!
On this December morning, even the flamingos are shivering in the wind sweeping across the Prévost pond in Villeneuve-lès-Maguelone. We meet Muriel Geeraert on the narrow strip of land separating the lagoon from the sea, a few hundred meters as the crow flies from the cathedral. Wearing a thick coat, hat, and gloves, the hydrology engineer flashes a broad smile, clearly moved by the beauty of the site and the light that bathes it."It's very cold today, but what a joy it is to work here,"she tells us as she takes a chair and a folding table out of her utility vehicle, which will allow her to set up her equipment and, if the temperature warms up, have a snack behind the container placed there, the only barrier against the wind.
60 meters deep
While the term "drilling" conjures up images of a relatively imposing installation for novices, we are surprised by the bareness of the site until Muriel draws our attention to thin PVC pipes emerging from the ground. "There are eight wells in total, but this one allows me to collect all the data I need in the field. It goes down to 60 meters and is fully lined to allow the probe to pass through and take very accurate measurements , " she explains as she unfolds a winch about 2 meters high. So as not to miss any of her explanations, we decide to equip her with microphones; the on-camera interview will come later.
A few minutes later, with the winch in place just above the well, the engineer takes a slender metal cylinder out of a black plastic box: "This is the probe. I'm going to lower it into the underground reservoir to bring up a small amount of water. I'll measure its pH and conductivity on site and send the rest of the samples to the lab for more detailed analysis." Muriel Geeraert quickly explains the importance of these procedures, revealing the fragility of the ecosystem around us.
Saltwater intrusion
"The problem here is the intrusion of salt water into coastal freshwater reservoirs. In summer in particular, we draw a lot of water for campsites and golf courses. The more we draw from the aquifers, the more salt water from the sea tends to enter them," notes Muriel Geeraert. "If we continue like this, one day these aquifers will no longer be able to supply us with water. We are having a major impact on nature," laments the engineer, who initially trained in mechanical engineering and industrial automation and joined Geoscience in 2019 after the particle accelerator she was working on was shut down. "It's true that I've come a long way and I'm learning a little more about geosciences every day. It's such a vast field, I find it fascinating."
As part of the Geosciences department's "transfers in porous media" (Tmp) team, Muriel Geeraert closely examines the human impact on the Villeneuve-lès-Maguelone site, but that's not all. "Every month, I take readings at Pégairolles-de-l'Escalette, just above Lodève, another very beautiful site where we are studying the effects of landslides in more detail. I also go to Barcarès and Canet-en-Roussillon, and the last site is in Majorca, but we don't go there very often anymore."It's a beautiful panorama of the region for this native Parisian who dreamed of coming to live in the South and appreciates above all the diversity of its activities, sites, and climate.
Practical work
When she is not in the field, Muriel Geeraert spends her days in the laboratory. "The equipment needs to be maintained and recalibrated. All the data also has to be processed, some of which is added to databases that are open to the general public." Every year, she also takes part in practical hydrogeology workshops where students can learn about fieldwork directly on site. "I run this workshop with Emmanuelle Petelet. We take water samples and have the students analyze them. It's a really fun practical workshop and it's also an aspect of my job that I really enjoy!" Except when a snake decides to join the party...