Hydrogeochemical characterization and identification of a system of regional flow. Case study: the aquifer on the Gulf of Urabá, Colombia

Hydrogeochemistry is an essential tool for the verification of conceptual models, especially of groundwater flow models. This is even more relevant when dealing with complex hydrogeological models that have intercalating layers with different degrees of permeability, and regional flows contributing to the system. The hydrogeochemical characteristics of the Uraba-Colombia Aquifer and geological cross-sections were studied to establish possible processes that explain the groundwater flow evolution and the recharge zones. 4 flow lines were considered to show the groundwater evolution from Ca2+-HCO3 - facies and a TDS concentration of approximately 400 mg/L, trough Ca2+-Mg2+-HCO3 - and Na+ -Mg2+-HCO3 - facies, ending with Na+ -HCO3 - facies close to discharge area, with TDS=1,550 mg/L. Data on stable isotopes confirmed the groundwater flow directions. It is also clear that evolution orders correspond to the possible flow rates in areas with a homogeneous gradient, but with higher hydraulic conductivity conditions to the south and center, compared to the north.