Résumé: The scarcity of freshwater resources in the transboundary region of Sidi Fredj, located in the Souk Ahras province (northeastern Algeria), is exacerbated by the high salinity of groundwater, which exceeds 5 g/L. This elevated salinity is primarily attributed to the leaching of Triassic formations rich in gypsum and evaporites. To meet the growing demand for drinking water, two reverse osmosis desalination plants have been commissioned, supplied by boreholes AOB2 and AZ2. However, the brine discharges generated by these treatment units pose a potential threat to the receiving aquatic environments. This study aims to assess the impact of brine discharges on the water quality of two receiving streams: Oued Mellègue and Oued El Maleh. The adopted approach is based on a comparative monitoring of key physicochemical parameters, including temperature (T), hydrogen potential (pH), electrical conductivity (EC), total dissolved solids (TDS), and concentrations of sodium (Na+), chloride (Cl−), and sulphate (SO42−), both in the brine effluents and in the stream waters. A bimonthly monitoring campaign was conducted to evaluate the temporal variation of selected indicators (EC, Cl−, SO42−) upstream and downstream of the discharge points. The results reveal a significant increase in the mineralization of water in the receiving streams, directly linked to the brine effluents, specifically, Electrical Conductivity (EC), total dissolved solids (TDS), sodium (Na+) and chloride (Cl−), the results indicate that Electrical conductivity (EC) increases from 3500 to 6500 µS/cm upstream to values ranging between 3600 and 7100 µS/cm downstream, reflecting a rise in salinity attributable to brine discharges. Multivariate statistical analysis supports these findings and identifies sulphate as the primary contributor to the mineral load in the impacted waters. These results indicate a marked deterioration in surface water quality, with exceedances of Algerian water quality standards, suggesting a potential risk to local aquatic ecosystems. Further ecological investigations, including biological assessments, are needed to confirm this hypothesis.

Résumé: A new study for the Cretaceous–Paleogene Boundary (KPB) is proposed at Djebel Dyr (Tebessa, NE Algeria), based on biostratigraphic and geochemical evidence. Detailed investigations on the El Haria Formation mainly composed of marly to argillaceous lithologies reveal five KPB marker criteria. These are (1) mass extinction of all Maastrichtian planktic foraminifera, except Guembelitria cretacea; (2) evolution of the first tertiary species; (3) a KPB iron hydroxide (goethite) layer; (4) iridium (Ir) content anomaly; and (5) a sharp decrease in CaCO3 contents, down to ∼0%. Thanks to the high-resolution sampling and the evolution of the index species across this interval, we propose a new biozonation considred valid for low-to-middle latitudes, which includes four biozones: Plummerita hantkeninoides Zone, indicating the Late Maastrichtian; Guembelitria cretacea Zone (D1); Parvularugoglobigerina eugubina Zone (D2); and Parasubbotina pseudobulloides Zone (D3). The latter is subdivided into two subzones: the Eoglobigerina trivialis (D3a) and Subbotina triloculinoides (D3b), which specify the Lower Danian. Therefore, nine new planktic foraminifera species have evolved during this period. According to all this evidence, the Dyr section is considered one of the most complete sections clearly showing affinities with the Cretaceous–Paleogene Boundary (KPB) in a pelagic domain of the Tethys.

Résumé: Rapid climate change is amplifying the frequency and severity of global flooding events. These floods induce declines in agricultural areas, water bodies, barren lands, precipitating diminished crop productivity due to habitat loss and constrained water availability. Conversely, urban sprawl, notably within high-risk flood zones, exhibits substantial expansion. Projections anticipated approximately 5200 km2 of urban areas to confront heightened vulnerability to flash floods by 2030 and 2040, accentuating the exigency for immediate risk mitigation measures. This study scrutinizes the ramifications of flash floods on land use and land cover (LULC) dynamics over 20-years period within the Hodna watershed, situated in northern Algeria. The applied methodology integrates a random forest (RF) model for classification, complemented by a fused Cellular Automaton–Markov model to forecast future LULC trends for 2030 and 2040 based on the remote sensing data obtained from Landsat 5 and 8. The modeling results attained high prediction accuracy (Kno: 0.7857, Klocation: 0.8184, Kstandard: 0.7763), affirming the proposed methodology reliability. In addition, the study explored the employment of convolutional neural network (CNN) model coupled with Geographic Information Systems (GIS) for flood susceptibility and was delineated with 89% accuracy. The findings underscore significant susceptibility to flash floods, driven by hydrological and topographic factors, and explained through principal conditioning factors.

Résumé: This study evaluates the performance of machine learning (ML) algorithms in predicting the Irrigation Water Quality Index (IWQI) for irrigation in the Bouhamdane Basin, with XGBoost ML-2 emerging as the most accurate model (R2 = 0.93, root mean square error (RMSE) = 0.047). Other boosting-based methods like ADABoost ML-4 (R2 = 0.79, RMSE = 0.085) and CatBoost ML-2 (R2 = 0.87, RMSE = 0.065), as well as random forest (RF) ML-2 (R2 = 0.89, RMSE = 0.06), also demonstrate strong predictive capabilities, outperforming linear and support vector regression models. Additionally, voting ensemble models (R2 = 0.90, RMSE = 0.06) highlight the effectiveness of integrating multiple algorithms. The study also analyzes key water quality parameters, revealing variability in irrigation suitability, with some samples posing salinity and sodicity risks (sodium adsorption ratio (SAR) up to 24.509, IWQI as low as 16.86) and others being suitable (IWQI up to 53.80). Overall, the study underscores the significant role of advanced ML techniques in improving water quality assessment for irrigation, offering valuable insights for environmental monitoring and agricultural water management.

Résumé: Accurate estimation of the hydrodynamic parameters of aquifers is extremely important for the operation and proper management of aquifer systems. Transmissivity is one of them, and is strongly correlated to the flows that can be taken from an aquifer. The multivariate classification by the method of potentials or dynamic clouds method was applied to the values of transmissivity, specific yield and hydraulic conductivity, determined on 82 wells capture the aquifer system of Annaba-Bouteldja. It allowed the discrimination of three multivariate subpopulations instead of two selected a priori. The geographical distribution of the wells forming each of these classes allows us to draw the following conclusions: - The field is not completely stationary, but a local stationarity can be tolerated; - Each of the multivariate classes is associated with a geological facies of the aquifer system. The results of the transmissivity mapping of the deep aquifer system show that the transmissivity semi-variogram can be well represented by a spherical model. The field data obtained by pumping test, allowed to make transmissivity maps from the surfer software using kriging for interpolation. The results show clear indications of the spatial distribution of transmissivity values of this aquifer over the entire study area. Furthermore, the spatial variability of these transmissivities, expressed by the variogram, can be explained by the tectonic structure deduced from the seismic data. It allows the definition of hydrogeological compartments, represented by the two grabens Ben Ahmed and Ben M'hidi, with different hydrodynamic behaviors delimited by faults.

Résumé: The current study was conducted to classify the quality of groundwater in wetlands. This research was carried out to evaluate the groundwater quality of wells in the surrounding area according to the Irrigation Water Quality Index (IWQI) to verify its suitability for agricultural purposes. The IWQI was developed in 2010 by Meireles; it was calculated based on the water quality parameters: EC, Na+1, Mg+2, Ca+2, Cl–1, and HCO3- of 37 monitoring wells. The results of the IWQI show that the water quality declined significantly in July, with the majority of wells 76% within the severe restriction category (SR), which means that it’s suitable only for irrigation of crops with high salt tolerance, and 14% of wells falling within the High Restriction category (HR). The lake’s discharge decreases during the dry season, and most of the water quality classified as a severe restriction (SR), this indicates that the groundwater is influenced by the saline waters of Lake Fetzara, which are already loaded with chemical elements due to evaporation. As a result, the study of groundwater suitability for irrigation revealed that these waters are generally acceptable for irrigation of salt-tolerant crops on well-drained soils but require a prior control of salinity evolution.

Résumé: A comparative assessment of water quality for drinking purposes was conducted in Ain Larbi area using the Weighted Arithmetic Water Quality Index (WA-WQI). The origin of minerals is assessed by a saturation index approach and the Gibbs diagram. Also, mineral correlation process and ion exchange mechanism are detected by the Principal Component Analysis (PCA). The PCA results indicate that the groundwater quality in the Ain Larbi study area primarily results from weathering and geochemical alteration of rock. The saturation index and Gibbs diagram support these findings. The WA-WQI was calculated for each station based on physicochemical parameters. During the wet season, three out of five classes of WQI were observed in the present study, including excellent (25%), good (70%), and poor (5%). In the dry season, the classes excellent (25%), good (30%), and poor (45%) were represented. The present situation demonstrates how hydrogeological regimes and water–rock interactions affect groundwater ion concentrations. Our results contribute to identifying drinking water requirements in the Ain Larbi region, promoting sustainable water management.

Résumé: This article presents an approach to the assessment of the environmental impact of a dam construction for agricultural use in the Boutheldja region. This region’s environment is rich in natural resources and forms a part of the El Kala National Park (P.N.E.K). It was designated a wetland of international importance under the Ramsar convention by UNESCO in 1983 and later declared a biosphere reserve in 1990. It is among the most significant aquatic areas in this region (contains about 40% of surface water resources). The physical characteristics of the watershed support the construction of the dam, although there could be a number of unfavorable effects: upstream – including soil erosion and reservoir sedimentation, reduced storage capacity, lower water quality and loss of productivity of flooded area; downstream – removal of silt from downstream flows, loss of fertilising functions, changes in water quality, changes in productivity, reduction in natural floods, loss of access to resources and ecological disturbance. Such processes will have an impact on an ecosystem so fragile. Although Boukhroufa dam provides significant benefits to the city, such as controlling stream regime, preventing floods, and supplying agricultural water from stored water, it also has significant negative effects on the surrounding watershed ecosystem.

Résumé: The current study was conducted to classify the quality of groundwater in wetlands. This research was carried out to evaluate the groundwater quality of wells in the surrounding area according to the Irrigation Water Quality Index (IWQI) to verify its suitability for agricultural purposes. The IWQI was developed in 2010 by Meireles; it was calculated based on the water quality parameters: EC, Na, Mg, Ca, Cl, and HCO3 of 37 monitoring wells. The results of the IWQI show that the water quality declined significantly in July, with the majority of wells 76% within the severe restriction category (SR), which means that it’s suitable only for irrigation of crops with high salt tolerance, and 14% of wells falling within the High Restriction category (HR). The lake’s discharge decreases during the dry season, and most of the water quality classified as a severe restriction (SR), this indicates that the groundwater is influenced by the saline waters of Lake Fetzara, which are already loaded with chemical elements due to evaporation. As a result, the study of groundwater suitability for irrigation revealed that these waters are generally acceptable for irrigation of salt-tolerant crops on well-drained soils but require a prior control of salinity evolution.