Use of Isotopic Techniques for the Assessment of Hydrological Processes in Wetlands (Cienaga Colombia)

The study ''Hydrochemical and Isotopic techniques for the assessment of hydrological processes in the wetlands of Bajo Cauca, Antioquia'', done by the University of Antioquia in the framework of a cooperative project with the International Atomic Energy Agency (IAEA) in accordance with the terms of the CRP 14031 of 2006, evaluated the dynamics of groundwater flow to and from the wetland Cienaga Colombia in the Antioquenan Lower Cauca using hydrochemical and isotopic techniques. Because Cienaga Colombia is a marsh that depends on groundwater, this paper's general objective is to propose and validate a hydrological model of surface water-groundwater interaction. The physical geography of the area corresponds to a smooth topography with both flat and sloping areas, slopes reaching a maximum of 7%, covering an area of approximately 84 Km2. The average temperature: 27 degrees Celsius. Average annual rainfall is 2800 mm. Since 2007, the University of Antioquia, in the framework of an agreement with the IAEA, has been operating a monitoring network of groundwater levels with monthly water level readings with accuracy to the centimeter; within the same system there is also a monitoring network of hydrochemical and isotopic variables, for which water samples are taken during the two hydrological scenarios (rainy and dry) that occur annually in the basin within a normal cycle. The network consists of 5 rainfall stations, 22 stations for groundwater and 6 for surface water. Hydrochemical variables analyzed include major and minor ions, and isotope parameters corresponding to 18O and 2H. The sampling was done following the protocols defined by certified laboratories and the IAEA.