Abstract:

We tried, by this work, to contribute a share to study it the aquifers of the plain of Zana, and to evaluate the

risks of pollu

tion related to nitrogenized flow.

The plain of Zana belongs to the catchment area of the high plateaus constantinois and more precisely of under

area catchment Merdja Zana, which extends on a surface of approximately 369 Km².

The study of geology with

the data of geophysics highlights the existence of two formations.

First formation, of

Mio

-

Plio

-

Quaternary surface of age formed by levels of sand, gravel, water limestone and argillaceous

intercalations.

The second formation, it is carbonated and formed

primarily by limestones of the lower Cretaceous and

Jurassic superior of the southern unit sétifien and parautochtone aurésien.

The covering of surface reaches in certain

places the 150m thickness in particular in the medium of the plain and a low thicknes

s in the vicinity of the solid

masses.

As for the carbonated formations they have 350m thickness.

The geomorphology, shows that our basin is lengthened, it has an average altitude of 935m and it is

characterized by a moderate relief and of soft slope.

Th

e hydrographic network is fart to develop and of endoreic type

with a temporary flow.

The climatological study showed that the area of study has an arid semi climate with an overdrawn

hydrological assessment.

The outline hydrogeologic of the plain show

s that the trainings of the lower Cretaceous and the Jurassic

superior can offer very interesting aquiferous possibilities just as the surface formation, it presents considerable

aquiferous potentialities.

Piezometry shows a convergence towards the depress

ions of Merdja de Zana and Chott

Saboun, which represent natural discharge system of the tablecloth.

The hydrochimic study made it possible to allot the evaporitic origin to the elements Na

+

, Mg

++

, K

+

, Cl

-

,

SO4

--

, as for element HCO3

-

,

it results fr

om the carbonated formations

The two partners of analyses carried out show that water resulting from the aquifer surface and the karstic aquifer has

the same facies hydrochimic which of magnesian type is chlorinated and sulphated, which testifies to the

existence of a

probable interaction between the two aquifers.

.

Nitric pollution is not visible although the area is with agricultural vocation

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