This study investigated groundwater suitability for irrigation in the Hennaya Irrigated region of Northwest Algeria. The research pursued two primary objectives: first, to establish the hydrochemical origin of the groundwater through comprehensive analyses including hydrochemical parameters, diagrams, and hierarchical clustering; and second, to assess its suitability for irrigation based on key criteria such as the Water Quality Index (WQI), Wilcox, and US Salinity diagrams. The analysis revealed a high level of groundwater suitability for irrigation, as indicated by various indices: Sodium Adsorption Ratio (SAR) values ranged from 1.69 to 2.55 (Excellent), Sodium Percentage (Na%) ranged from 24.22% to 36.98% (Good), and the Residual Sodium Carbonate (RSC) was negative, falling between −8.91 to −1.70 meq/L (Safe). Kelly’s Ratio (KR) ranged from 0.32 to 0.59 (Good), and the Permeability Index (PI) was between 62% and 99% (Moderate). Supported by the Analytic Hierarchy Process (AHP) and spatial analysis, the Water Quality Index (WQI) values ranged from 69.25 to 88.71, categorizing the groundwater in the study area as ‘Good’ quality. While suitable for irrigation, the groundwater showed slight salinity (EC 1247–2010 μS/cm) and alkalinity (pH 7.09–8.02), with elevated total dissolved solids (TDSs) ranging from 990 to 1930 mg/L, approaching the permissible limits for optimal agricultural use. The dominant ion concentrations (Ca²⁺ > Na⁺ > Mg²⁺ > K⁺; HCO₃⁻ > Cl⁻ > SO₄²⁻ > NO₃⁻) indicate a mixed hydrochemical facies influenced by both water–rock interactions and evaporative processes. Although these findings are promising, they highlight the necessity for preventive measures. Ongoing proactive management and continuous monitoring are essential to ensure the long-term sustainability and protection of groundwater resources in the region.

In semi-arid regions, climate fluctuations and recurrent drought episodes strongly affect both the quantity and quality of surface water stored in reservoirs. In this context, the Beni Bahdel Dam, located in western Algeria and constituting an important source of irrigation water, is increasingly...

Three-step graphic showing the ASM1 calibration workflow for the Ain Elhoutz wastewater plant: routine effluent COD data are fractionated and four parameters are optimised at 18 °C, then the same parameters are validated at 22 °C without re-tuning. Mechanistic simulation of municipal activated sludge plants relies predominantly on Activated Sludge Model No. 1 (ASM1), yet routine application is hindered by over-parameterisation: calibrating the full kinetic set to dynamic plant data invites equifinality and loss of predictive power. This study develops a sensitivity-Driven ASM1 calibration workflow for a low-load plant in north-western Algeria, extending our earlier steady-state and dynamic simulation work in the region. ASM1 was implemented in GPS-X, and influent chemical oxygen demand (COD) was fractionated using the CEMAGREF protocol supplemented by a post-calibration mass-balance adjustment. Four parameters (XBH, μmax, H, YH, and KS), the subset repeatedly identified as dominant for effluent COD variance and practically identifiable in recent sensitivity and collinearity studies, were optimised against a targeted dynamic calibration window at 18 °C using the Nelder–Mead simplex algorithm and then tested on an independent seasonal dataset at 22 °C. Calibration achieved strong agreement (ℛ2 = 0.79), validation confirmed acceptable predictive performance (ℛ2 = 0.68) with no systematic bias, while the uncalibrated nitrogen variables showed a consistent over-prediction, quantified and attributed in Section 3. Requiring only routine COD data, the workflow provides a transferable, operator-grade template for dynamic ASM1 calibration at municipal plants with comparable monitoring programmes.