Hamma et al. (2025) Hydrogeochemical assessment of groundwater for agricultural suitability in the Ksour Mountains, Algeria

Identification

• Journal: Scientific Reports
• Year: 2025
• Date: 2025-10-17
• Authors: Bellal Hamma, Mohamed Faouzi Bekkouche, Foued Bouaicha, Khaled A. El-Nagdy, Ali Alzaed, Ayoub Barkat, Antonio Randazzo, Mekonnen Sileshi Andualem, Enas E. Hussein
• DOI: 10.1038/s41598-025-20352-8

Research Groups

• Environmental and Energy Systems Laboratory (LSEE), Ali Kafi University Center Tindouf, Tindouf, Algeria
• Geology and Environment Laboratory (LGE), Universite Constantine 1, Constantine, Algeria
• Department of Civil Engineering, College of Engineering, Taif University, Taif, Saudi Arabia
• Architectural Engineering Program - Civil Engineering Department, Faculty of Engineering, Taif University, Taif, Saudi Arabia
• Department of Landscape Protection and Environmental Geography, University of Debrecen, Debrecen, Hungary
• Laboratorio di Geochimica del Fluidi Istituto Nazionale di Geofisica e Vulcanologia (INGV), Roma, Italy
• Department of Civil Engineering, Faculty of Technology, Debre Markos University, Debre Markos, Ethiopia
• Water Management Research Institute, National Water Research Center, Shubra El-Kheima, Egypt

Short Summary

This study characterized the hydrogeochemical composition and evaluated the suitability of groundwater for agricultural irrigation in the arid Ain-Sefra region, Algeria, finding it generally suitable but requiring salinity control measures, particularly in downstream areas.

Objective

• To characterize the hydrogeochemical composition of groundwater in the Ain-Sefra region, Algeria, using classic hydrochemistry diagrams and statistical methods.
• To identify the dominant hydrochemical facies and geochemical processes (e.g., dissolution, ion exchange, evaporation) influencing groundwater quality.
• To evaluate the suitability of groundwater for agricultural irrigation using various water quality indices (SAR, %Na, RSC, MH, KR, PI).
• To map the spatial variation of groundwater suitability indicators for irrigation using Geographic Information Systems (GIS).

Study Configuration

• Spatial Scale: Ain-Sefra region, Ksour Mountains, south-western Algeria, spanning approximately 2700 km².
• Temporal Scale: Groundwater sampling campaign conducted in May 2022.

Methodology and Data

• Models used:
  • PHREEQC software for calculating mineral saturation indices.
  • OriginLab® software for Hierarchical Cluster Analysis (Q-mode and R-mode) using Ward’s agglomeration method and Euclidean distance/Pearson’s correlation coefficient.
  • Piper, Durov, and Stiff diagrams for water typology and hydrochemical facies assessment.
  • ArcGIS Desktop 10.8 for spatial analysis and mapping using the Inverse Distance Weighted (IDW) interpolation method.
  • Standard equations for calculating irrigation water quality indices: Sodium Absorption Ratio (SAR), Sodium Percentage (%Na), Residual Sodium Carbonate (RSC), Magnesium Hazard (MH), Kelly Ratio (KR), and Permeability Index (PI).
• Data sources:
  • 43 groundwater samples (boreholes, wells, springs) collected from Upper Jurassic (6 samples) and Lower Cretaceous (37 samples) aquifers.
  • On-site measurements of temperature, pH, and electrical conductivity (EC) using a HACH SL1000 multiparameter instrument.
  • Laboratory analysis (Algerian Water Authority (ADE) laboratory) for major ions (Ca²⁺, Mg²⁺, Na⁺, K⁺, Cl⁻, SO₄²⁻, HCO₃⁻, NO₃⁻) using volumetric, spectrophotometry, and flame photometer methods.
  • GPS device for recording water point coordinates.

Main Results

• Groundwater mineralization generally increases from upstream (western and southwestern parts) to downstream (eastern part) of the study area, indicating longer residence times and progressive mineral dissolution.
• Dominant hydrochemical facies identified by Piper diagram are Ca–Mg–SO₄–Cl (62.8%), followed by Ca–Cl (20.9%), Ca–Mg–HCO₃ (11.6%), and Na–Cl (4.7%).
• Hydrochemical processes include mineral dissolution (carbonates and evaporites), reverse ion exchange, and water mixing.
• Saturation index analysis shows groundwater is predominantly supersaturated with aragonite, calcite, dolomite, anhydrite, and gypsum, suggesting active precipitation or dissolution equilibrium. Conversely, it is undersaturated with halite, indicating ongoing dissolution.
• Cluster analysis (Q-mode) categorized samples into four groups based on electrical conductivity, ranging from low salinity (Group 1, 81.4% of samples) to very high salinity (Group 4, 2.32% of samples, represented by the Ain Ouarka thermal spring).
• R-mode cluster analysis grouped physicochemical parameters, reflecting influences from carbonate dissolution, evaporite weathering, salt leaching, and anthropogenic nitrate contamination.
• Evaluation of groundwater for irrigation using various indices revealed:
  • SAR: 98% of samples are excellent, 2% are good.
  • %Na: 28% excellent, 61% good, 9% permissible, and 2% doubtful.
  • RSC: All samples (100%) are good.
  • MH: 74% suitable, while 26% (primarily in the southern part) are unsuitable.
  • KR: 95% suitable, 5% unsuitable (concentrated in the Ain Ouarka region).
  • PI: All samples (100%) fall into Class II (good quality).
• USSL diagram classification indicates that 67.44% of samples have high salinity but low sodium content (C3S1), suitable for most soils under specific management, while 18.61% exhibit very high salinity (C4S1, C4S2, C4S4) posing potential alkalinity risks.
• Spatial distribution maps show the highest electrical conductivity and total dissolved solids in the eastern part, with lower concentrations in the western and southwestern regions.

Contributions

• Provides a comprehensive hydrogeochemical assessment of groundwater quality and its suitability for agricultural irrigation in the Ksour Mountains, a critical arid region in Algeria.
• Integrates multiple hydrochemical diagrams, advanced multivariate statistical methods (cluster analysis), and GIS techniques for a robust and spatially explicit evaluation of groundwater resources.
• Identifies the specific geochemical processes (mineral dissolution, ion exchange, evaporation, anthropogenic impacts) driving groundwater mineralization and quality evolution in the region.
• Offers practical recommendations for sustainable groundwater management, including controlling anthropogenic activities, continuous monitoring, and considering salinity variations for rational utilization.
• Highlights the importance of integrating remote sensing and GIS for understanding spatiotemporal changes in groundwater and suggests future research directions using advanced geostatistical methods and increased temporal sampling.

Funding

• Deanship of Graduate Studies and Scientific Research, Taif University.

Citation

@article{Hamma2025Hydrogeochemical,
  author = {Hamma, Bellal and Bekkouche, Mohamed Faouzi and Bouaicha, Foued and El-Nagdy, Khaled A. and Alzaed, Ali and Barkat, Ayoub and Randazzo, Antonio and Andualem, Mekonnen Sileshi and Hussein, Enas E.},
  title = {Hydrogeochemical assessment of groundwater for agricultural suitability in the Ksour Mountains, Algeria},
  journal = {Scientific Reports},
  year = {2025},
  doi = {10.1038/s41598-025-20352-8},
  url = {https://doi.org/10.1038/s41598-025-20352-8}
}