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.

This paper studies aquifer's hydrodynamic behavior by combining a flow-simulation model with transmissivity optimization (cokriging) in order to provide an optimal management scheme for the groundwater aquifer. The use of a cokriging approach improves the transmissivity data which are insufficient for the database of the groundwater flow simulation model. The obtained results are then used to model the groundwater flow of the Tebessa-Morsott shallow aquifer, located in NE Algeria, under a steady and transient regime. The results of the model calibration for the steady-state (year 2010) show that the recharge by rainfall and leakage rate are similar compared to those calculated by the analytical approach, (84,354 m³/day for the recharge and 36,986 m³/day for pumped water flow rate). The results of the transient regime show the alluvial aquifer affected by large drawdowns reaching 40 m over 20 years (year 2030 scenario) due to increase in water exploitation from pumping wells to answer water needs of the Tebessa region.

This study investigates the multiple contamination sources of a coastal Mediterranean aquifer in northeastern Algeria that is bordered by two rivers and neighboring densely populated areas. Hydrogeochemical and isotopic groundwater characterization is carried out, including the analyses of major elements, water stable isotopes δ²H-H₂O and δ¹⁸O-H₂O, and stable isotopes of nitrate δ¹⁵N-NO₃ and δ₁₈O-NO₃, and then integrated into the history of land use over the study area. Groundwater nitrate concentrations ranging from 1.6 to 235 mg/L with a median value of 69 mg/L are evidence of the degradation of groundwater quality induced by anthropogenic sources. The combined of δ¹⁵N-NO₃ and δ₁₈O-NO₃ ratios showed that nitrate in groundwater is attributable to (i) the uncontrolled development of inadequate private sanitation systems over the study area, and (ii) the unsafe application of animal manure to fertilize crops. Very active saltwater intrusion is confirmed by several hydrogeochemical indicators. 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 δ²H-H₂O and δ¹⁸O-H₂O of surface water collected from the rivers suggest that water from the Mediterranean Sea is mixing with water in the rivers. Multi-source contamination not only contributes to complex chemical reactions within the aquifer, but also contributes, via the cumulative effect of the various sources, to affecting large parts of the study area. The present study may serve as a warning to the effect that historical land-use practices may exert seriously deleterious impacts on groundwater quality and greatly limit conditions for the sustainable management of Mediterranean coastal areas.

The groundwater quality of Tadjenanet- Chelghoum Laid Semi-arid region was assessed for irrigation suitability; where the intensity of salinization process depends on soil characteristics, water quality, irrigation practices and in particular the inefficiency of the drainage system. The drought of the last decade has created an agricultural deficit due to high evapotranspiration, influencing the water salinity. To achieve this assessment, thirty groundwater samples were collected at identical locations from deeper wells. The physicochemical parameters such as, pH, electrical conductivity (EC), total hardness (TH), Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO3⁻, SO4²⁻, Cl⁻ and NO3⁻ have been studied. Obtained results were measured and interpreted with different irrigation indexes like EC, sodium percentage (SP), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), permeability index (PI) and Kelly’s ratio (KR). These parameters combined allowed to conclude that the quality of groundwater was roughly suitable for irrigation.

The study of the water quality in the shallow aquifer of Tebessa-Morsott was carried out to perform a preliminary assessment of the hydrochemical quality of same groundwater samples and their suitability for irrigation uses. The high salinity coupled with groundwater level decline pose serious problems for current irrigation and domestic water supplies as well as for future exploitation. The statistical treatment of hydrochemical data by principal component analysis revealed two components related to salinity and pollution. The US salinity diagram illustrates that most of the groundwater samples fall in C3S1- C4S1 quality with high salinity hazard and low sodium hazard.