Abstract
This study in the department of Didiévi focuses on the
analysis of potential water aquifers and hydrochemical process knowledge of
these waters. The choice of this research theme has been guided by the desire
to know the hydrogeological potential of aquifers in the department. The
methodological approach is a combination of hydrochemical, hydrological and
hydrodynamic methods.
The hydrodynamic study was carried out using an approach that
takes into account the water balance, the relationship between the hydrodynamic
parameters (Q, Pt, Ns, EA, Qs and T) and the influence of these parameters on
the drilling productivity. The area of Didiévi receives on average
1024.89 mm of rainfall per year and the quantity of water may infiltrate to
refill the aquifers is 76.6 mm or 7.47% of the rainfall. The study of physical
and hydrodynamic parameters shows that the depths of drillholes varies from 45
to 90 m with an average of 69 m, the thickness of the regolith is between 2.7
and 31 m with an average of 11.9 m . Hydraulically active depths are between 60
and 80 m. The transmissivity values ??obtained by the method of Cooper-Jacob
downhill lie between 2,58.10-6 and 4,78.10-4
m2/s with an average of 4,07.10-5 m2/s. The
flow rates of wells range from 0.2 to 10 m3/h with an average of
2.45, the values ??of specific flow rates to vary between 5,4.10-6
and 5,63.10-4 m3/s with an average of
5,19.10-4 m2/s.
The study of the hydrochemical characteristics of this
groundwater shows on the Piper's and Schoeller-Berkaloff's diagram that the
majority of them are mainly HCO3- and Ca2+
water type. According to the calc-carbon system, there are three families of
water in the study area based on the saturation indices vis-à-vis
carbonates: the waters to flow very slow, slow-moving waters and fast moving
waters. The main mechanisms that govern the mineralization of the waters of the
Department are: the residence time of water in the rock aquifer, geothermal and
rainfall-leaching. Except some points such as that of N'dié who
sometimes presents abnormal contents in certain elements, the groundwater of
the Didiévi area is drinkable for human consumption in a general
manner.
Keywords: Hydrodynamics, groundwater
recharge, productivity, weathering, drilling depth, transmissivity, operating
speed, mineralization, hydrofacies, hydrochemistry, Didiévi.
Liste des
abréviations
ACP : Analyse en Composante Principale
CEDEAO : Communauté Economique Des Etats d'Afrique
de l'Ouest
DTH : Direction Territoriale de l'Hydraulique
IEB : Indice d'Échange de Base
INS : Institut National de la Statistique
NTU : Unité Nephelométrique de
Turbidité
OMS : Organisation Mondiale de la Santé
ONEP : Office National de l'Eau Potable
SODEXAM : Société de Développement
et d'Exploitation Aéronautique, Aéroportuaire et
Météorologique
| 
