Résumé
The use of underground water reservoirs is increasing due to climate change and rising demographic pressure. Karstified carbonate formations play a major role, as they contain 25% of the world's water resources in over 50 countries. A good understanding of their hydrodynamics is crucial for achieving durable water management. Thanks to the recent technical developments in the field of muon tomography, new complementary information can be used to enhance standard geophysical tools. This chapter explains the interest of the Low Background Noise Underground Research Laboratory (LSBB) in Rustrel, France, in performing multi-technique observations aiming at elucidating the properties of the critical zone of a karst system and characterizing dynamically its fluid redistribution. Moreover, it provides a description of the methods used for the water monitoring at its facilities. Also, it explains the working principle of its in-house muon detection technology. Lastly, the results of the Buissonnière case study are presented, coupling muon measurements with state-of-the-art geophysical methods.