Almost thirteen months of construction and four years of “conceptualization” of the well (four meters in diameter), sinking twenty meters below the surface of the Beauce and this estate in the small town of Villamblainnear patay.
A “unique in the world” facility, we remembered this Tuesday, during the inauguration of the O-ZNS research platform, born from a close collaboration between the CNRS, the University of Orleans and the BRGM.
“It will be our eye on the Beauce water table, our observatory.”then explained in the morning in the sun the deputy director from the Orléans Institute of Earth Sciences (ISTO) and the project director, Mohamed Azaroual.
Water tables are extremely low in the Loiret
Mohamed Azaroual is deputy director of the Institut des sciences de la terre d’Orléans (ISTO) and director of the project.
The well “will allow us to monitor the quality of groundwater (chemical composition) and its evolution in relation to agricultural practices.“Inevitably we will find in it” what farmers spread on the fields, herbicides, pesticides, fertilizers. This will allow us to understand how the soil is fixed, degraded or allows the passage of inputs to the water table”.
And this, studying the behavior of the unsaturated zone of water, which is between zero and twenty meters below the surface, the size of the well, equipped with sensors at all depths and starting in all directions.
After 2003, the summer of 2022 was the hottest ever recorded in the Loiret
how long does it take for the water to go down
The well (built by the Bouygues company) is located in the unsaturated water zone, that is, between the surface of the field and the water table. Photo: David Criff
Our observatory, completes Mohamed Azaroual, “It will also allow groundwater monitoring for micropollutants, emerging pollutants and endocrine disruptors“, also of agriculture. All thanks to mini-probes, “horizontal and oblique” of the well, “to take samples of water and rocks and then analyze their chemical compositions”.
The sensors that are located throughout the circumference of the cavity “offer very decisive and spatialized data, which allows us to know how long it takes for the water, rain or irrigation, to reach the water table.”
We could go down on Tuesday, well, not quite. Photo: David Criff
Note that the purpose of the installation is not to establish the level of the water table (“which we know from elsewhere”), but rather measure the time it takes for the water to sink. If 30 mm fall, “we can accurately determine how much reaches the water table, is first retained by roots, or has evaporated into the atmosphere.”
A forty year lease
As for “global changes”, understanding human activity and climate change, “this will allow us to fully understand how it works” and the impacts that large surface shocks have on the water table.
Mohamed Azaroual adds “that by compiling a lot of information (on contaminants, infiltrations, etc.), we will be able to predict the future evolution of the Beauce aquifer”. The data entered in the software, “memory effect”, will thus make it possible to determine its status on the horizon of the next hundred years, “through different scenarios, including that of the IPCC (Intergovernmental Panel on Climate Change).”
Science teams working around technology see very well, which explains why the plot in which it is submerged is now leased to its owner for the next forty years. Time to see coming…