Descroix Luc, Sané Y., Thior M., Manga S. P., Ba B. D., Mingou J., Mendy V., Coly S., Dieye A., Badiane A., Senghore M. J., Diedhiou A. B., Sow D., Bouaita Yasmin, Soumaré S., Diop A., Faty B., Sow B. A., Machu Eric, Montoroi Jean-Pierre, Andrieu J., Vandervaere J. P. (2020). Inverse estuaries in West Africa : evidence of the rainfall recovery ?. In :
Descroix Luc (ed.), Mahé Gil (ed.), Laraque Alain (ed.), Ribolzi Olivier (ed.), Lacombe G. (ed.). Multiscale impacts of anthropogenic and climate changes on tropical and mediterranean hydrology. Water, 12 (3), art. 647 [26 p.].
Titre du document
Inverse estuaries in West Africa : evidence of the rainfall recovery ?
Année de publication
2020
Auteurs
Descroix Luc, Sané Y., Thior M., Manga S. P., Ba B. D., Mingou J., Mendy V., Coly S., Dieye A., Badiane A., Senghore M. J., Diedhiou A. B., Sow D., Bouaita Yasmin, Soumaré S., Diop A., Faty B., Sow B. A., Machu Eric, Montoroi Jean-Pierre, Andrieu J., Vandervaere J. P.
In
Descroix Luc (ed.), Mahé Gil (ed.), Laraque Alain (ed.), Ribolzi Olivier (ed.), Lacombe G. (ed.), Multiscale impacts of anthropogenic and climate changes on tropical and mediterranean hydrology
Source
Water, 2020,
12 (3), art. 647 [26 p.]
In West Africa, as in many other estuaries, enormous volumes of marine water are entering the continent. Fresh water discharge is very low, and it is commonly strongly linked to rainfall level. Some of these estuaries are inverse estuaries. During the Great Sahelian Drought (1968-1993), their hyperhaline feature was exacerbated. This paper aims to describe the evolution of the two main West African inverse estuaries, those of the Saloum River and the Casamance River, since the end of the drought. Water salinity measurements were carried out over three to five years according to the sites in order to document this evolution and to compare data with the historical ones collected during the long dry period at the end of 20th century. The results show that in both estuaries, the mean water salinity values have markedly decreased since the end of the drought. However, the Saloum estuary remains a totally inverse estuary, while for the Casamance River, the estuarine turbidity maximum (ETM) is the location of the salinity maximum, and it moves according to the seasons from a location 1-10 km downwards from the upstream estuary entry, during the dry season, to a location 40-70 km downwards from this point, during the rainy season. These observations fit with the functioning of the mangrove, the West African mangrove being among the few in the world that are markedly increasing since the beginning of the 1990s and the end of the dry period, as mangrove growth is favored by the relative salinity reduction. Finally, one of the inverse estuary behavior factors is the low fresh water incoming from the continent. The small area of the Casamance and Saloum basins (20,150 and 26,500 km(2) respectively) is to be compared with the basins of their two main neighbor basins, the Gambia River and the Senegal River, which provide significant fresh water discharge to their estuary.
Plan de classement
Limnologie physique / Océanographie physique [032]
;
Hydrologie [062]
;
Etudes, transformation, conservation du milieu naturel [082]
Description Géographique
GAMBIE ; SENEGAL
Localisation
Fonds IRD [F A010085542]
Identifiant IRD
fdi:010079085
