Methane and carbon dioxide emissions from tropical reservoirs: Significance of downstream rivers

Frédéric Guérin (1) , Gwenaël Abril (1) , Sandrine Richard , Benoît Burban , Cécile Reynouard , Patrick Seyler (2) , Robert Delmas (3)

1 EPOC - Environnements et Paléoenvironnements OCéaniques
2 LMTG - Laboratoire des Mécanismes et Transfert en Géologie
3 Équipe Troposphère

Methane (CH4) and carbon dioxide (CO2) concentrations and water-air fluxes were measured in three tropical reservoirs and their respective rivers downstream of the dams. From reservoirs, CH4 and CO2 flux were in the range of 3 +/- 2 and 254 +/- 392 mmol.m-2.d-1, respectively. Rivers downstream of dams were significantly enriched in CH4 and CO2 originating from reservoir hypolimnions. From rivers, CH4 and CO2 flux were in the range of 60 +/- 38 and 859 +/- 400 mmol.m-2.d-1, respectively. Despite their relatively small surfaces, rivers downstream of dams accounted for a significant fraction (9-33% for CH4 and 7-25% for CO2) of the emissions across the reservoir surfaces classically taken into account for reservoirs. A significant fraction of CH4 appeared to degas at the vicinity of the dam (turbines and spillways), although it could not be quantified.

Domaines: Sciences de la Terre

Frédéric Guérin, Gwenaël Abril, Sandrine Richard, Benoît Burban, Cécile Reynouard, et al.. Methane and carbon dioxide emissions from tropical reservoirs: Significance of downstream rivers. Geophysical Research Letters, 2006, 33, pp.21407. ⟨10.1029/2006GL027929⟩. ⟨hal-00324596⟩