Hydrodynamics of Ebrié lagoon as revealed by a chemical and isotopic study

• Published in: Hydrobiologia 1992-01, Vol.245 (2), p.65-74
• Main Authors: GUIRAL, D, FERHI, A
• Format: Article
• Language: English
• Subjects: Brackish; Earth sciences; Earth, ocean, space; Exact sciences and technology; External geophysics; Freshwater; Geochemistry; Marine; Mineralogy; Physical and chemical properties of sea water; Physics of the oceans; Silicates; Water geochemistry
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1007/BF00764766

To determine the origin and the circulation of waters in the different areas of the Ebrie lagoon (Ivory Coast), ionic concentrations (potassium, chlorine) and isotopic measurements were performed. Sixty stations were sampled. Chemical and isotopic analyses were made 3 times during a hydrological cycle: in May 1986, at the end of the great dry season; in October 1986, during the maximum of rainfall; and in December 1987, after the Comoe river peak flow. From a hydrodynamical point of view, the results reported in this work indicate that the lagoon comprises 4 distinctive areas. The first is filled with freshwater all the year round and is characterized by an weak isotopic enrichment (these waters are of continental origin and annually renewed); the second corresponds to oligohaline waters highly enriched in oxygen-18 (waters essentially of continental origin and poorly renewed); the third area is made up of a mixture of waters of continental and oceanic origins. The latter groups can be separated into 2 subgroups: a group completely renewed by oceanic water during the dry season and another group totally renewed by freshwater during the rainy and flood seasons.