Are the Fouta Djallon Highlands Still the Water Tower of West Africa? - INRAE - Institut national de recherche pour l’agriculture, l’alimentation et l’environnement Access content directly
Journal Articles Water Year : 2020

Are the Fouta Djallon Highlands Still the Water Tower of West Africa?

1 PALOC - Patrimoines locaux, Environnement et Globalisation
2 LMI PATEO - Patrimoines et Territoires de l'eau
3 DGPRE - Direction de la Gestion et la Planification des Ressources en Eau
4 UASZ - Université Assane Seck de Ziguinchor [Sénégal]
5 UL - Université de Lorraine
6 UFHB - Université Félix Houphouët-Boigny
7 School of Public Administration and Development Economics, Doha Institute for Graduate Studies
8 Ecole polytechnique de Thiès
9 ESPACE - Études des Structures, des Processus d’Adaptation et des Changements de l’Espace
10 UniCA - Université Côte d'Azur
11 UMR G-EAU - Gestion de l'Eau, Acteurs, Usages
12 Pléiade - Centre de recherche pluridisciplinaire en Lettres, Langues, Sciences Humaines et des Sociétés
13 HSM - Hydrosciences Montpellier
14 Université Gamal Abdel Nasser de Conakry
15 IUHEG - Institut Universitaire des Hautes Etudes de Guinée
16 UMR LISAH - Laboratoire d'étude des Interactions Sol - Agrosystème - Hydrosystème
17 NBA Niger Basin Authority
18 Direction Nationale de l'Hydraulique [Guinée]
19 Leïdi - Girardel - Laboratoire Leïdi
20 IRD - Institut de Recherche pour le Développement
21 Independent Consultant
22 UCAD - Université Cheikh Anta Diop de Dakar [Sénégal]
23 Grdr Migrations, Citoyenneté, Développement
24 OMVS - Organisation Pour la Mise en Valeur du Bassin du Fleuve Sénégal
25 IRGM - Institut de Recherches Géologiques et Minières
26 OMVG - Organisation pour la Mise en Valeur du Bassin du Fleuve Gambie
27 UMR Eco&Sols - Ecologie fonctionnelle et biogéochimie des sols et des agro-écosystèmes
28 SENASOLS - Service National des Sols
29 IGE - Institut des Géosciences de l’Environnement
Andrew Ogilvie
Gil Mahe
Nadine Braquet

Abstract

A large share of surface water resources in Sahelian countries originates from Guinea's Fouta Djallon highlands, earning the area the name of "the water tower of West Africa". This paper aims to investigate the recent dynamics of the Fouta Djallon's hydrological functioning. The evolution of the runoff and depletion coefficients are analyzed as well as their correlations with the rainfall and vegetation cover. The latter is described at three different space scales and with different methods. Twenty-five years after the end of the 1968-1993 major drought, annual discharges continue to slowly increase, nearly reaching a long-term average, as natural reservoirs which emptied to sustain streamflows during the drought have been replenishing since the 1990s, explaining the slow increase in discharges. However, another important trend has been detected since the beginning of the drought, i.e., the increase in the depletion coefficient of most of the Fouta Djallon upper basins, as a consequence of the reduction in the soil water-holding capacity. After confirming the pertinence and significance of this increase and subsequent decrease in the depletion coefficient, this paper identifies the factors possibly linked with the basins' storage capacity trends. The densely populated areas of the summit plateau are also shown to be the ones where vegetation cover is not threatened and where ecological intensification of rural activities is ancient.
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hal-03082841 , version 1 (21-12-2020)

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Luc Descroix, Bakary Faty, Sylvie Paméla Manga, Ange Bouramanding Diedhiou, Laurent A. Lambert, et al.. Are the Fouta Djallon Highlands Still the Water Tower of West Africa?. Water, 2020, 12 (11), pp.2968. ⟨10.3390/w12112968⟩. ⟨hal-03082841⟩
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