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 Printable version |
Geochemical and isotopic study of the shallow aquifer in the Kef region (North Western Tunisia) |
Science et changements planétaires / Sécheresse. Volume 21, Number 2, 121-30, avril-mai-juin 2010, Article de recherche
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 Résumé
Article gratuit
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Author(s) : Younes Hamed, Hamed Ben Dhia |
Summary : The salinity of groundwater in the Kef basin in north western Tunisia varies greatly. Electric conductivity (EC) thus varies extensively from one point to another and ranges from 1.7 to 15.2 mS.cm
-1. The highest EC values were registered in the irrigated areas, especially in the north-east and the south-west of the basin. The lowest EC values characterize the upstream zones in the vicinity of the wadis (non-perennial rivers). The Cl-Na and SO
4-Ca groundwater types are predominant. Groundwater mineralization increases along the low line, from 0.62 to 4.5 g/L, with an increasing of SO
4
2-, Ca
2+, Na
+ and Cl
- concentrations. Traces of evaporitic minerals were present in the matrix of the aquifers (halite, gypse/anhydrite) and represent the principal mineralogical control factors. The natural tracing of groundwater using stable and radioactive isotopes (
18O,
2H and
14C) makes it possible to characterize the recent water, resulting probably from actual recharge, and the relatively ancient water in relation with the ascending deep groundwater and/or with the water of the lower strata of the shallow water table. The confrontation of the geochemical and isotopic results indicates that the major mineralization processes are the evaporation and dissolution of the aquifer rocks, as well as the return flow of irrigation water. The recharge area of aquifers is near outcrops and shows an origin of the rainfall air masses from the Atlantic Ocean and Mediterranean Sea. |
Keywords : geochemistry, groundwater, hydrogeology, salinisation, Tunisia |
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