Access to clean drinking water is vital for protecting public health and achieving global sustainability goals; therefore, systematic hydrogeochemical monitoring is essential, particularly in ecologically sensitive and rapidly urbanizing hilly terrains. This study evaluates groundwater quality dynamics and dominant hydrochemical drivers in Himalayan foothill aquifer systems, using Dehradun (Uttarakhand, India) as the study area. Forty groundwater samples were systematically collected across citywide north-south and east-west transects during the summer season and analyzed for 13 physicochemical parameters. Drinking water suitability was assessed using the Water Quality Index (WQI), while spatial variability was examined by Inverse Distance Weighting (IDW)-based geospatial interpolation. The hydrochemical composition exhibited cationic dominance following the order Ca2+ > Mg2+ > Na+ > K+, while the anion dominance followed HCO3– > Cl⁻ > SO42-> NO3-. Boxplots and bivariate plots asserted the dominance of Ca-Mg-HCO3 chemistry and ion sources linked to mineral dissolution. Piper diagrams confirmed the prevalence of Ca-Mg-HCO3 hydrochemical facies, while Gibbs diagrams indicated rock-water interaction and carbonate weathering as the primary governing processes. To elucidate the processes that dominate groundwater chemistry, multivariate statistical techniques were employed. Pearson correlation revealed strong ionic associations, while principal component analysis (PCA) separated geogenic mineralization from anthropogenic influences. Hierarchical cluster analysis (HCA) further grouped the parameters into three consistent clusters, reinforcing the patterns revealed by PCA. WQI values ranged widely, classifying 7.5% of sites as excellent, 25% as good, 15% as poor, 47.5% as very poor, and 5% as unsuitable. IDW-based spatial mapping identified distinct contaminant hotspots and zones of elevated WQI values across the study area. This study provides a robust, process-based baseline for groundwater quality assessment in urban-peri-urban Himalayan foothill aquifer systems. The findings offer valuable scientific insights to support sustainable groundwater management, urban planning, and policy formulation and serve as a transferable framework for similar underexplored and ecologically sensitive hilly aquifers. Graphical abstract

Deciphering groundwater quality dynamics and dominant hydrochemical drivers in Himalayan foothill aquifer systems

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发表日期：

2026年6月3日

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Diksha Dangwal,
Rahul Silori,
Balendu Shekher Giri

摘要

Access to clean drinking water is vital for protecting public health and achieving global sustainability goals; therefore, systematic hydrogeochemical monitoring is essential, particularly in ecologically sensitive and rapidly urbanizing hilly terrains. This study evaluates groundwater quality dynamics and dominant hydrochemical drivers in Himalayan foothill aquifer systems, using Dehradun (Uttarakhand, India) as the study area. Forty groundwater samples were systematically collected across citywide north-south and east-west transects during the summer season and analyzed for 13 physicochemical parameters. Drinking water suitability was assessed using the Water Quality Index (WQI), while spatial variability was examined by Inverse Distance Weighting (IDW)-based geospatial interpolation. The hydrochemical composition exhibited cationic dominance following the order Ca²⁺ > Mg²⁺ > Na⁺ > K⁺, while the anion dominance followed HCO₃^– > Cl⁻ > SO₄^2-> NO₃^-. Boxplots and bivariate plots asserted the dominance of Ca-Mg-HCO₃ chemistry and ion sources linked to mineral dissolution. Piper diagrams confirmed the prevalence of Ca-Mg-HCO₃ hydrochemical facies, while Gibbs diagrams indicated rock-water interaction and carbonate weathering as the primary governing processes. To elucidate the processes that dominate groundwater chemistry, multivariate statistical techniques were employed. Pearson correlation revealed strong ionic associations, while principal component analysis (PCA) separated geogenic mineralization from anthropogenic influences. Hierarchical cluster analysis (HCA) further grouped the parameters into three consistent clusters, reinforcing the patterns revealed by PCA. WQI values ranged widely, classifying 7.5% of sites as excellent, 25% as good, 15% as poor, 47.5% as very poor, and 5% as unsuitable. IDW-based spatial mapping identified distinct contaminant hotspots and zones of elevated WQI values across the study area. This study provides a robust, process-based baseline for groundwater quality assessment in urban-peri-urban Himalayan foothill aquifer systems. The findings offer valuable scientific insights to support sustainable groundwater management, urban planning, and policy formulation and serve as a transferable framework for similar underexplored and ecologically sensitive hilly aquifers.

Graphical abstract