Nous avons essayé, par ce travail, d’apporter une contribution à l’étudier les aquifères de la plaine de Zana, et d’évaluer les risques de la pollution liée au flux azoté.La plaine de Zana fait partie du bassin versant des hauts plateaux constantinois et plus précisément du sous bassin versant Merdja Zana, qui s’étend sur une superficie de 369 Km² environ.L’étude de la géologie en association avec les données de la géophysique met en évidence l’existence de deux formations. La première formation, de surface d’âge Mio-Plio-Quaternaire formée par desniveaux de sable, de gravier, de calcaire lacustre et des intercalations argileuses. La deuxième formation, elle est carbonatée et formée essentiellement par des calcaires du Crétacé inférieur et du Jurassique supérieur de l’ensemble sud sétifien et du parautochtone aurésien. Le recouvrement de surface atteint dans certainsendroits les 150m d’épaisseur notamment au milieu de la plaine et une faible épaisseur au voisinage des massifs. Quant aux formations carbonatées elles ont 350m d’épaisseur.La géomorphologie, montre que notre bassin est allongé, il a une altitude moyenne de 935m et il est caractérisé par un relief modéré et de pente douce.Le réseau hydrographique est pet développer et de type endoréique avec un écoulement temporaire.L’étude climatologique a montré que la région d’étude a un climat semi aride avec un bilan hydrologique déficitaire.L’aperçu hydrogéologique de la plaine montre que les formations du Crétacé inférieur et du Jurassique supérieur peuvent offrir des possibilités aquifères très intéressantes de même que la formation superficielle, elle présente des potentialités aquifères non négligeables. La piézométrie montre une convergence vers les dépressions de Merdja de Zana et le Chott Saboun, qui représentent des exutoires naturels dela nappe.L’étude hydrochimique a permis d’attribuer l’origine évaporitique aux éléments Na+, Mg++, K+, Cl-,SO4--, quant à l’élément HCO3-, il est issu des formations carbonatées. Les deux compagnes d’analyses effectuées montrent que les eaux issues del’aquifère superficiel et de l’aquifère karstique ont le même faciès hydrochimique qui est de type chloruré et sulfaté magnésien, ce qui témoigne de l’existence d’une interaction probable entre les deux aquifères
Accessibility of fresh water, the nature's gift wheels the foremost part of the world economy. The sufficient supplies of water are essential for agriculture, human intake, industry as well as regeneration. The Oued Righ region is located in Algeria's South-East, specifically in the NorthEast of the Sahara, on the Northern edge of the Grand Erg Oriental and the Southern border of the Aures massif. This area appears as a lower Sahara synclinal basin and is part of a broad North-South trending ditch. It is famous for its date palms, the development of the date culture in this region is attributed not only to the population’s efforts, but above all to the particular climatic conditions, the favorable soil characteristics and the existence of significant groundwater. The aim of this study is to understand the results obtained from using different approaches of water hydrodynamics in the Complex Terminal aquifer. The aquifer’s hydrodynamic characterization was carried out using hydrodynamic parameters and piezometry. As a result, the transmissivity and permeability obtained data using traditional Cooper-Jacob method showed that the flow capacities of the aquifer environment and the productivities of the structures are important in the studied zone where, the highest value of transmissivity equal 2.36× 102-m 2 /sis found in the central part of the study area in El-Meghair. The establishment of piezometric maps reveals a flow direction oriented toward the chott.
The relative scarcity of water resources in Algeria and their unequal distribution induce a rational use of available resources. The Zana-Gadaïne plain appears as an exemplary case study, where the difficulties posed by the problem of crop water needs versus the availability of water resources appear. This article, based on field surveys and in-situ measurements, aims to identify the pressure of irrigation on water resources and the optimization of their use in an agricultural area, where irrigated agriculture represents 85% of the water consumption of the Zana-Gadaïne plain. The piezometric study in correlation with hydrogeological data reveals that groundwater resources are limited, aggravated by wastage resulting in a consequent drawdown of 24 meters over 11 years. The analysis of interannual climate variability has enabled us to draw rainfall maps characteristic of the evolution of rainfall over the past decades where we observe a net deficit in precipitation. We calculated the evapotranspiration and the requirements in irrigation water for each crop in order to compare them with the available hydric resources and the establishment of irrigation schedules for the principal irrigated crops. The analysis of interannual climate variability has enabled us to draw rainfall maps characteristic of the evolution of rainfall over the past decades where we observe a net deficit in precipitation. We calculated the evapotranspiration and the requirements in irrigation water for each crop in order to compare them with the available hydric resources and the establishment of irrigation schedules for the principal irrigated crops.
Considering three sites under different climate conditions (arid, semi-arid, and subhumid), this study aims to use the vadose-zone water stable isotope profiles to estimate the groundwater recharge rate. High-resolution vertical subsurface soil sampling along the vadose zone of the investigated sites was conducted. The collected samples were analysed to determine their stable isotope ratios (δ2H and δ18O) that were used along with the piston displacement method to estimate recharge. Annual recharge rates of 0.2% (± 0.1%), 2.5%, and 18% of the total annual precipitation were obtained for the arid, semi-arid, and subhumid sites, respectively. Recharge rates at the semi-arid and subhumid sites are comparable to those previously estimated using water balance-based methods. The recharge rate at the arid site is lower than that previously estimated for that site using the water budget-based method, revealing difficulties in applying the piston displacement method under an arid regime.
Stratigraphic, sedimentological and magnetic study was performed on alluvial terraces, rich in archaeological tools, the region of OUM ALI, in north-eastern Algeria. The sedimentological points of view, the sediments are dominated by the sand fraction followed by the silt fraction; moderate concentrations of CaCO3 are the result of the dissolution of the surrounding limestone reliefs (Maastrichtian limestone). The morphoscopic observation of quartz grains with a dissecting microscope allows us to offer more or less significant changes, since they are often dull or sub-blunted. The results of the magnetic survey are consistent with those of the sedimentological study. The values of magnetic susceptibility are strong in the middle part of the stratigraphic section (just above the archaeological level) and decrease slightly at the top. Lower values are stored in the lower part. The dependence of frequency values of magnetic susceptibility (fd) are strong throughout the stratigraphic section and show the presence of a mixture of single-domain grain size (R), pseudo-single domain (PMD) and superparamagnetic (SP) (with a predominance of SP grains). The high concentration of SP grain size reveals the presence of significant soil formation during the implementation of the sediment
