Hydrogeology and ground Water Quality of the Aquifer of Guelma in North-East of Algeria

Guelma area is situated about sixty kilometres in south west of Annaba, in north -east of Algeria. It s an ancient basin. A basin, which belongs to multilayer system of two aquifer levels; an unconfined aquifer and another semi-deep one. Both the aquifer level covers a 120 km2 area of plio-quaternary covering. The geochemical study of unconfined aquifer accomplished during two campaigns (August 2006 and January 2007) has been performed by in situ measures and by analysing the major elements (anions and cations), fluorine and also nutrients elements in the laboratory. The results showed us that the ground waters are characterized by a salinity ranging from 0.40-1.42 g L-1, chlorides and sulphates ions concentration, which locally exceeded the international standards, show a rising gradient from South to north of the basin. Analysis of nutrients elements has shown that the water contents in fluorine, orthophosphates, ammonium and nitrites are generally below the standard of WHO where as nitrates present concentrations high, upstream and downstream, witnessing a contamination of the unconfined aquifer. At this level, water contents, relatively higher, can have as origin cultivated land leaching containing fertilizers, industrial rejects, as well as decomposition of organic matter.