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General disruption of climate and thus wind systems,
influence the availability of water resources in the world
and especially in tropical regions of Africa. Thus a study of
understanding of the aquifer system of the water in Abidjan
was undertaken.
The aim of this study is to create an actual conceptual
model of Abidjan Continental Terminal aquifer compared
with historical topographic data. So, recent collect of
topographic data, based on differential GPS levelling
method were done and compared with historical
topographic levels. At this effect, three conceptual models
were put out and only conceptual models made in East-
West and North-South directions coming from differential
GPS levelling data were validated. These conceptual models
show that the Continental Terminal aquifer is composed of
two mains beds n3 and n4 respectively made up of 90 m
thickness of gross sands and of fine sands of 80 m of
thickness. At the level of layer’s model, an average gap of 10
m is determined between the East-West model descended
from GPS data to the East-West model descended from
historical data. The n4 bed crops out in the Banco basin and
Fig.1: Carte lithologique de la zone saturée de
la nappe du Continental Terminal
saturée et de la zone non saturée montre que le Continental
Terminal est essentiellement constitué de sable grossier à 39% et
de sable moyen à 37% dans la zone saturée (fig.1). De même il est
principalement constitué de sable argileux à 35% et de sable fin à
25% dans la zone non saturée (fig.2)
Fig.2: Carte lithologique de la zone non saturée
de la nappe du Continental Terminal
Laboratoire Géosciences et Environnement - UFR Sciences et Gestion de l’Environnement - Université d’Abobo-Adjamé - 02 BP 801 Abidjan 02
La réalisation du modèle de couches révèle que le Continental
Terminal est composé de deux couches principales n3 (sable
grossier) et n4 (sable fin à moyen) d’épaisseur maximale
respective de 90 m et 80 m. Le Continental Terminal affleure dans
la vallée du banco, elle constitue donc une potentielle zone de
pollution de la nappe (fig.3). L’analyse de la coupe NS du
4ème Conférence Internationale AMMA-Toulouse, France -2 – 6 Juillet 2012 http://amma-conf2012.ipsl.fr/home/
exposes Abidjan’s ground water potentially to pollution in
this area. The ground water recharge evaluated to 324 mm
an-1 in 2006. Hydrodynamics parameters such us
transmissivity and permeability were reestimated and
respectively change from 2,77. 10-2 to 3,37. 10-1 m2 s-1 and
from 1,1. 10-3 to 1,2.10-2 m s-1. |
