Alluvial aquifers of the Indo-Gangetic Plains (IGP) sustain nearly 900 million people, serving as essential groundwater resource for drinking, agriculture, and industrial needs. Effective management of these aquifers requires a thorough understanding of hydrochemistry and geochemical evolution, particularly in regions like Punjab, northwest India, where intensive farming and over-extraction have significantly impacted water quality. This study utilized 14 physicochemical parameters from 319 groundwater monitoring wells to evaluate spatial variability and governing hydrogeochemical processes in the Punjab region of India. Results identify varied hydrochemical facies, including Ca-Mg-HCO3, Na-K-HCO3, and Na-K-Cl-SO4 types. Silicate weathering emerged as a primary geochemical process, supported by cation exchange with limited evaporite dissolution. Geochemical modelling using PHREEQC indicates carbonate mineral supersaturation (e.g., calcite, dolomite) causes precipitation, while sulfate and chloride dissolution contribute to salinity. The Entropy-weighted Water Quality Index (EWQI) classified 5% of samples as “Excellent,” 28% as “Good,” and 31% as “Average,” while 14% were “Poor,” and 22% were “Extremely Poor,” requiring significant treatment for drinking. Southwestern districts were the most affected due to agricultural intensification and poor waste management. Source apportionment based on Principal Component Analysis (PCA) identifies anthropogenic activities i.e., NO3– likely from fertilizers and silicate weathering as key factors influencing groundwater chemistry. Sensitivity analysis highlights EC, TDS, SO42– and Cl– as critical parameters for water quality in the region. Tube wells (TW) have higher deterioration of water than hand pumps (HP) and dug wells (DW) due to localized geogenic factors. The study emphasises the importance of understanding spatial variations in the groundwater chemistry from specific water sources to effectively inform and guide water sustainability initiatives. Graphical Abstract The graphical abstract presents an integrated overview of the data-driven and geochemical methodology adopted to assess groundwater quality across Punjab, India. Aiming the dual influences of natural and anthropogenic stressors, the present study incorporates hydrochemical data from CGWB, analyzed using Entropy-weighted Water Quality Index (EWQI) and supported by geochemical modeling. The EWQI workflow comprises key steps, including data normalization, entropy-based weight determination according to parameter variability, and subsequent classification into defined water quality categories. Geochemical weathering processes, specifically silicate and carbonate dissolution are identified as major natural drivers influencing groundwater chemistry, particularly within the Quaternary alluvial plains, in addition to anthropogenic pressures. Principal Component Analysis (PCA) and sensitivity assessment highlight critical parameters (Cl–, SO42–, TDS, EC) contributing significantly to groundwater quality variability. The spatial visualization of contamination illustrates source-specific vulnerability across tube wells, hand pumps, and dug wells. The framework culminates in actionable policy recommendations aligned with Sustainable Development Goal 6 (SDG 6), aimed at guiding water management agencies, governmental bodies, and global stakeholders. This approach provides a scalable and adaptable methodology for groundwater quality management in regions facing intensive agricultural stress.

Hydrogeochemical Dynamics of Groundwater in the Punjab Region of the Indo-Gangetic Plains: An Entropy-Weighted and Geochemical Modeling Approach

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发表日期：

2025年6月4日

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Imran Khan,
Ajit Singh,
Yusuf Jamal

摘要

Alluvial aquifers of the Indo-Gangetic Plains (IGP) sustain nearly 900 million people, serving as essential groundwater resource for drinking, agriculture, and industrial needs. Effective management of these aquifers requires a thorough understanding of hydrochemistry and geochemical evolution, particularly in regions like Punjab, northwest India, where intensive farming and over-extraction have significantly impacted water quality. This study utilized 14 physicochemical parameters from 319 groundwater monitoring wells to evaluate spatial variability and governing hydrogeochemical processes in the Punjab region of India. Results identify varied hydrochemical facies, including Ca-Mg-HCO₃, Na-K-HCO₃, and Na-K-Cl-SO₄ types. Silicate weathering emerged as a primary geochemical process, supported by cation exchange with limited evaporite dissolution. Geochemical modelling using PHREEQC indicates carbonate mineral supersaturation (e.g., calcite, dolomite) causes precipitation, while sulfate and chloride dissolution contribute to salinity. The Entropy-weighted Water Quality Index (EWQI) classified 5% of samples as “Excellent,” 28% as “Good,” and 31% as “Average,” while 14% were “Poor,” and 22% were “Extremely Poor,” requiring significant treatment for drinking. Southwestern districts were the most affected due to agricultural intensification and poor waste management. Source apportionment based on Principal Component Analysis (PCA) identifies anthropogenic activities i.e., NO₃^– likely from fertilizers and silicate weathering as key factors influencing groundwater chemistry. Sensitivity analysis highlights EC, TDS, SO₄^2– and Cl^– as critical parameters for water quality in the region. Tube wells (TW) have higher deterioration of water than hand pumps (HP) and dug wells (DW) due to localized geogenic factors. The study emphasises the importance of understanding spatial variations in the groundwater chemistry from specific water sources to effectively inform and guide water sustainability initiatives.

Graphical Abstract

The graphical abstract presents an integrated overview of the data-driven and geochemical methodology adopted to assess groundwater quality across Punjab, India. Aiming the dual influences of natural and anthropogenic stressors, the present study incorporates hydrochemical data from CGWB, analyzed using Entropy-weighted Water Quality Index (EWQI) and supported by geochemical modeling. The EWQI workflow comprises key steps, including data normalization, entropy-based weight determination according to parameter variability, and subsequent classification into defined water quality categories. Geochemical weathering processes, specifically silicate and carbonate dissolution are identified as major natural drivers influencing groundwater chemistry, particularly within the Quaternary alluvial plains, in addition to anthropogenic pressures. Principal Component Analysis (PCA) and sensitivity assessment highlight critical parameters (Cl^–, SO₄^2–, TDS, EC) contributing significantly to groundwater quality variability. The spatial visualization of contamination illustrates source-specific vulnerability across tube wells, hand pumps, and dug wells. The framework culminates in actionable policy recommendations aligned with Sustainable Development Goal 6 (SDG 6), aimed at guiding water management agencies, governmental bodies, and global stakeholders. This approach provides a scalable and adaptable methodology for groundwater quality management in regions facing intensive agricultural stress.