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.

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.

The present study aimed to contribute to the hydrogeological knowledge of a region in the department of Santander, Colombia, which suffers from drinking water supply problems. Groundwater is exploited in the region, but there is no detailed conceptual model available to help environmental authorities manage groundwater resources. To advance the conceptual model of the region an isotope study of monthly rainfall and its temporal and spatial response in the groundwater was made.