This study used hydrodynamic and hydrogeochemical data to understand the salinization processes of the crystalline groundwater (GW) in Ceará, Brazil. Results demonstrate that GW is generally recent and recharged by meteoric waters mainly through localized infiltration. The study suggests that GW, originally bicarbonated, becomes progressively enriched in chloride due to the dissolution and leaching of salts that have precipitated in the unsaturated zone and pond sediments during dryer periods.

In order to better understand the hydrogeological functioning of the Mornag aquifer system (NE Tunisia), chemical and isotopic (18O, 2H) analyses of water are carried out. This work highlights the fact that the water of this aquifer system is highly modified by geochemical interactions: cationic exchange and precipitation/dissolution phenomena. The water of this aquifer system has been recently recharged by direct infiltration from the boundary and in the valley of wadis.

The isotopic characterization of rainwater in the semi-arid regions of Northeastern Brazil (NEB) was only addressed by a few studies. Moreover, the isotopic data available were mainly linked to the establishment of the Global Network of Isotopes in Precipitation, which was paralyzed in the 1990s despite the extensive use of these data to improve the global knowledge of hydrological processes. This study allowed to improve the characterization of the isotopic signal of precipitation in NEB.