The importance of underground water resources is undisputed. However, there is still a paucity of studies on such reservoirs. As a result, estimates of the size of global reservoirs are not consensual and can range from 1 to 60 million km3 (Gleeson et al., 2016; Richey et al., 2015). However, these reservoirs certainly represent more than 90% of the total freshwater available to living organisms. The lack of information on this fundamental element for life on Earth is evident in the scientific literature (Bierkens et al., 2015; Clark et al., 2015; Gleeson et al., 2021; Lall et al., 2020; Sood and Smakhtin, 2015).