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Volume 40, Issue 4 (2025)
GeoRes 2025, 40(4): 319-327 |
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Received: 2025/10/22 | Accepted: 2025/12/11 | Published: 2025/12/17
Received: 2025/10/22 | Accepted: 2025/12/11 | Published: 2025/12/17
How to cite this article
Behzadi J. Salinity Line Determination in Groundwater in Guilan Province. GeoRes 2025; 40 (4) :319-327
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Authors
J. Behzadi *
Department of Water Engineering, Campus Lahijan (La.C.), Islamic Azad University, Lahijan, Iran
Abstract (290 Views)
Aims: The aim of this study was to determine the salinity line and delineate the boundary between the saline water of the Caspian Sea and the groundwater resources of Guilan Province by utilizing concentration-increasing elements and the empirical relationships of Herzberg and Warwich. Furthermore, the study sought to identify and zone the critical areas of saltwater intrusion in coastal aquifers, particularly in the eastern part of the province.
Methodology: This applied research examined hydrogeochemical data from 127 piezometric wells distributed across four basins in Guilan Province. Parameters including Total Dissolved Solids (TDS), Total Hardness (TH), sodium (Na), chloride (Cl), and sulfate (SO₄) were analyzed over a 20-year period (2002–2022). Zonation maps were generated using interpolation and kriging methods within a GIS environment. A composite map of the influencing elements was then produced and compared with the electrical conductivity (EC) map. The empirical relationships of Herzberg and Warwich were applied to determine the depth and extent of saltwater intrusion.
Findings: The largest critical area was associated with chloride, covering approximately 5,541.989 km². The highest concentrations of elements and groundwater salinity were observed in eastern Guilan, particularly in the Chamkhaleh–Chaf coastal zone. The composite elements map (with a critical area of approximately 2,035.44 km²) demonstrated a complete correspondence between the salinity line and the triangular region in the eastern part of the province. Salinity decreased progressively from the coastline toward the mountainous areas.
Conclusion: Saltwater intrusion is more severe in the coastal aquifers of eastern Guilan compared to other regions. The most significant factors influencing the advancement of salinity include Total Dissolved Solids (TDS), Total Hardness (TH), sodium, and sulfate.
Methodology: This applied research examined hydrogeochemical data from 127 piezometric wells distributed across four basins in Guilan Province. Parameters including Total Dissolved Solids (TDS), Total Hardness (TH), sodium (Na), chloride (Cl), and sulfate (SO₄) were analyzed over a 20-year period (2002–2022). Zonation maps were generated using interpolation and kriging methods within a GIS environment. A composite map of the influencing elements was then produced and compared with the electrical conductivity (EC) map. The empirical relationships of Herzberg and Warwich were applied to determine the depth and extent of saltwater intrusion.
Findings: The largest critical area was associated with chloride, covering approximately 5,541.989 km². The highest concentrations of elements and groundwater salinity were observed in eastern Guilan, particularly in the Chamkhaleh–Chaf coastal zone. The composite elements map (with a critical area of approximately 2,035.44 km²) demonstrated a complete correspondence between the salinity line and the triangular region in the eastern part of the province. Salinity decreased progressively from the coastline toward the mountainous areas.
Conclusion: Saltwater intrusion is more severe in the coastal aquifers of eastern Guilan compared to other regions. The most significant factors influencing the advancement of salinity include Total Dissolved Solids (TDS), Total Hardness (TH), sodium, and sulfate.