Dynamics and Biogeochemistry of River Corridors and Wetlands (Proceedings of symposium S4 held during the Seventh IAHS Scientific Assembly at Foz do Iguaçu, Brazil, April 2005). IAHS Publ. 294, 2005, 183-190

1 Department of Earth Sciences, Faculty of Sciences, PO Box 812, University of Yaoundé I, Cameroon

2 LMTG, UMR 5563, 14 Av. Edouard Belin, F-31400 Toulouse, France

3 Indian Institute of Science, Department of Metallurgy, Bangalore 560012, India

Abstract The origin of water and fluxes of matter exported from the small experimental watershed of Mengong during a storm event was determined using a combination of hydrological and hydrochemical methods. For a given storm only 7% of rainfall flows at the outlet of the catchment. The flow rate of the spring does not change during floods and only represents 2% of the streamflow. The spacio-temporal evolution of physico-chemical parameters during a storm event indicates that about 96% of high flow water at the outlet comes from low ground. The chemical composition of water at the outlet is equally dominated by the component from the swampy zone. Low ground marshes play a very active role in the mobilization of dissolved elements and suspended particles through the process of storage and restitution. The principal mechanism of the liberation of water flux from swampy zones is the translatory flow.

Key words equatorial Africa; exfiltration; humid tropical forest; hydrogeochemistry; Mengong catchment; South Cameroon; storage; storm event; swampy area; translatory flow