This presentation examines the Cenomanian–Turonian Bahloul Formation in NE Algeria and NW Tunisia through integrated facies, stratigraphic, structural, and geochemical analysis. It highlights the role of synsedimentary tectonics and OAE2-related sea-level rise in controlling organic-matter distribution and source-rock development in the Algero-Tunisian Atlassic Basin.

L’aquifère de Hammam Bradaa se situe au Nord-Est de Guelma à l’Est algérien. Il fait partie du bassin versant de la Seybouse et plus précisément le sous bassin de la moyenne Seybouse qui couvre une superficie de 820 km2. Du point de vue géologique, les formations rencontrées sont en majeure partie carbonatées d’âge Crétacé, avec une couverture récente hétérogène (remplissage d’âge tertiaire). L’objectif est l’identification de la qualité des eaux par l’outil statistique pour ressortir les tendances et par conséquent les groupes chimiques qui caractérisent les eaux de la nappe profonde de Hammam Bradaa. Tout d’abord, l’estimation du coefficient de variation (CV%) indique que la majorité des mesures liées à chaque variable se rapprochent de la moyenne et ne montre pas une grande dispersion, contrairement aux mesures des nitrates qui présentent une grande dispersion autour de la moyenne, ceci peut être expliqué par l’utilisation sélective des engrais chimiques pour l’agriculture des terres exploitées. Par ailleurs, la corrélation simple (matrice de corrélation) et multiple (ACP et C.A.H), mettent en évidence des liens significatifs entre les ions issus de la dissolution des minéraux carbonatés (Mg et HCO3) ainsi que ceux résultants des minéraux évaporitiques (Na et Cl). La conductivité électrique n’indique pas une bonne corrélation avec les ions témoignant ainsi de la faible minéralisation des eaux étudiées. Nous remarquons la bonne concordance entre les résultats de l’analyse statistique et ceux de l’interprétation hydro chimique. 

This paper presents a gravimetric study aimed at analyzing the geological structure and hydrogeological potential of the Télidjene basin in eastern Algeria. The data used are based on the EGM2012 gravimetric model and have been corrected using the International Gravimetric Bureau (BGI). Bouguer anomalies were calculated using spherical harmonic coefficients and underwent topographic corrections. The upward continuation method was used to attenuate shortwavelength anomalies and separate regional and residual components. Spectral analysis allowed for determining the average depths of geological formations. The results obtained from the gravimetric processing provided valuable information on the geological structure and hydrogeological potential of the study area and enabled the creation of a structural map illustrating the fault system responsible for the structuring of the study area. This map serves as a highly useful document for guiding future hydrogeological research in the study area.

The landslide studied is located on RN 77 at PK 23+100 in the municipality of Texenna, 25 km southeast of the wilaya of Jijel. The faults observed in the study area are the result of the combination of several factors: the slope of the slope, the lithology of the soil and the strong pluviometry. The project studied consists in the design and analysis of the stability and reinforcement by backfill reinforced with geotextiles. A visual survey was carried out to clarify the probable causes of the impairments, followed by a geological and geotechnical reconnaissance campaign to determine the lithological nature and the physical and mechanical properties of the different formations that make up the soil. The study continued with a backfill reinforced with geotextiles. The analysis of stability and reinforcement was carried out using the finite element method and Plaxis 2D software. According to the results obtained, which give satisfactory values for the coefficient of safety for different combinations of loads, the choice of installing the geotextile wall at the foot of the road is a technical and economic solution aimed at ensuring stability and restoring the collapsed part of the roadway Keywords: Stability; Reinforced embankment; Coefficient of safety.

Located in northeast Algeria, the coastal aquifer of the Plain of the El-Nil River constitutes a significant source of groundwater. It contains many municipal and private wells used for several purposes, including agriculture irrigation and drinking water. This paper describes a review of potential anthropogenic sources of groundwater contamination over the Plain of the El-Nil River territory. Different potential sources are identified, including 1) cultivated fields, 2) old private sanitation systems, 3) seawater intrusion, 4) dumpsite, and 5) the contaminated rivers crossing the study area. The multi-sources of contamination in the coastal aquifer of the Plain of the El-Nil River could affect large sectors of the aquifer. However, the existing documentation of groundwater contamination of the Plain of the El-Nil River is still limited. Hence, a hydrogeochemical study, including the analyses of major chemical elements and certain stable isotopes, is proposed as the principal outcome of this site-review paper. If undertaken, this proposed study is expected to provide more accurate information on groundwater contamination and, subsequently, could help decision-makers to prepare a practical plan for protecting the local water resources.

Located in north-east Algerian, the coastal aquifer of Taleza constitutes a significant source of groundwater. It contains hundreds of private wells installed by the population for several purposes including drinking water. Recently, the groundwater has become quite saline; in order to investigate this issue, hydrochemical and isotopic groundwater characterization is carried out, including the analyses of major elements and water stable isotopes d2H-H2O and d18O-H2O. Results confirmed a saltwater intrusion, and interestingly, the intrusion mechanism appears to be more complex than a direct intrusion from the Mediterranean Sea. During the high-water period, saltwater intrusion may also originate from the two rivers bordering the aquifer, via upstream migration of seawater through the river mouths. The heavier ratios in d2H-H2O and d18O-H2O of surface water collected from the rivers suggest that the Mediterranean Sea water is mixing with rivers water. The present study shows that seawater may exert deleterious impacts on groundwater quality and greatly limit conditions for the sustainable groundwater management.