TITLE:
Hydrochemical and Isotopic Study of Groundwater in the North Djeffara Aquifer, Gulf of Gabès, Southern Tunisia
AUTHORS:
Mohamed Fethi Ben Hamouda, Ahmed Mamou, Jelloul Bejaoui, Klaus Froehlich
KEYWORDS:
Salinization; Hydrochemistry; Isotopes; Groundwater Recharge; Tunisia
JOURNAL NAME:
International Journal of Geosciences,
Vol.4 No.8A,
October
11,
2013
ABSTRACT: The northern Djeffara
aquifer system is located in the southeast ofTunisiaand extends over an area of400 km2. This
multilayer system of aquifers is essentially recharged by infiltration of rain
and by groundwater of the Continental Inter-calaire aquifer, and occurs mainly at two levels
between 0 and180 mdepth
that belong to the Mio-Pliocene to form the aquifers. A combined hydrogeologic and
isotopic investigation using several chemical and isotopic tracers’, i.e., major ions, δ18O, δ2H and tritium, was carried out in order to determine the sources of water
recharge to the aquifer and the origin of salinity. The
results of geochemical and isotopic studies show that the groundwater in the south
of the study area represents a mixture of the Djeffara aquifer groundwater and
locally infiltrates modern recharge. In the northern part, the groundwater
which resembles that of the Sekhira aquifer originates from locally infiltrated
rain and runoff. The salinity of the groundwater is caused by dissolution of evaporate rocks (gypsum and
halite minerals) in the aquifer system. The stable
isotopes data do not support the hypothesis of mixing with seawater.