Groundwater is the principal source of potable and irrigation water for the rural and peri-urban communities of Vizianagaram Mandal in northern coastal Andhra Pradesh, yet rapid urban expansion, intensive cultivation, and inadequate sanitation are progressively altering its quality. A district-scale, season-resolved evaluation that integrates hydrochemical interpretation with geographic information system (GIS) mapping has so far been lacking for this khondalitic terrain. During the 2024 hydrological year, ninety groundwater samples were obtained from forty-five fixed wells distributed across nineteen villages, with each well sampled twice in the pre-monsoon (PRM, May–June 2024) and post-monsoon (POM, October–November 2024) periods. Thirteen physico-chemical variables (pH, EC, TDS, HCO3⁻, Cl⁻, SO4²⁻, F⁻, NO3⁻, Na⁺, K⁺, Ca²⁺, Mg²⁺ and total hardness) were analysed following APHA (2017) and BIS:10,500 (2012) procedures, and analytical reliability was verified through ionic balance error (IBE). Spatial maps were produced in ArcGIS 10.8 using inverse-distance-weighted (IDW) interpolation, and the data were further interrogated by Pearson correlation, principal component analysis (PCA), Piper, Gibbs and Wilcox plots, irrigation indices (SAR, RSC, Na%, MAR, Kelly’s ratio, permeability index) and a weighted-arithmetic Water Quality Index (WQI). Mean EC was 1401 µS cm⁻¹ (PRM) and 1306 µS cm⁻¹ (POM); mean TDS was 905 mg L⁻¹ (PRM) and 848 mg L⁻¹ (POM). Paired t-tests showed that EC, TDS, HCO3⁻, Cl⁻ and Na⁺ were significantly higher in PRM (p < 0.05), whereas F⁻ and NO3⁻ were significantly higher in POM (p < 0.05); the elevated pre-monsoon Cl⁻ reflects evapo concentration and reduced recharge during the dry season. The dominant hydrochemical facies was Na–Cl (≈ 73% PRM, 60% POM), pointing to ion-exchange and anthropogenic salinity overprinting carbonate weathering. PCA reduced thirteen variables to four components explaining 84% of variance, with PC1 (≈ 55%) representing salinity/mineralization. The WQI classified 88.9% of PRM samples and 88.9% of POM samples as Excellent or Good for drinking, while 11.1% were Poor in both seasons (Dharmapuri, Jonnavalasa, Korukonda, Malicherla, Sarika). For irrigation, 97.8% of samples were rated Excellent on SAR and Safe on RSC, although 60% fell in the Doubtful Wilcox category due to elevated sodium. Groundwater in Vizianagaram Mandal is largely potable but locally compromised by sodium-chloride enrichment of anthropogenic origin; the GIS-based hotspot maps and WQI provide a quantitative basis for targeted remediation, controlled extraction and managed aquifer recharge.

Spatiotemporal assessment of groundwater quality using GIS in Vizianagaram Mandal, Andhra Pradesh, India

期刊论文
出版模式：

开放获取
发表日期：

2026年7月28日

查看全文

K. Satyanarayananaidu,
P. J. Ratnakar

摘要

Groundwater is the principal source of potable and irrigation water for the rural and peri-urban communities of Vizianagaram Mandal in northern coastal Andhra Pradesh, yet rapid urban expansion, intensive cultivation, and inadequate sanitation are progressively altering its quality. A district-scale, season-resolved evaluation that integrates hydrochemical interpretation with geographic information system (GIS) mapping has so far been lacking for this khondalitic terrain. During the 2024 hydrological year, ninety groundwater samples were obtained from forty-five fixed wells distributed across nineteen villages, with each well sampled twice in the pre-monsoon (PRM, May–June 2024) and post-monsoon (POM, October–November 2024) periods. Thirteen physico-chemical variables (pH, EC, TDS, HCO₃⁻, Cl⁻, SO₄²⁻, F⁻, NO₃⁻, Na⁺, K⁺, Ca²⁺, Mg²⁺ and total hardness) were analysed following APHA (2017) and BIS:10,500 (2012) procedures, and analytical reliability was verified through ionic balance error (IBE). Spatial maps were produced in ArcGIS 10.8 using inverse-distance-weighted (IDW) interpolation, and the data were further interrogated by Pearson correlation, principal component analysis (PCA), Piper, Gibbs and Wilcox plots, irrigation indices (SAR, RSC, Na%, MAR, Kelly’s ratio, permeability index) and a weighted-arithmetic Water Quality Index (WQI). Mean EC was 1401 µS cm⁻¹ (PRM) and 1306 µS cm⁻¹ (POM); mean TDS was 905 mg L⁻¹ (PRM) and 848 mg L⁻¹ (POM). Paired t-tests showed that EC, TDS, HCO₃⁻, Cl⁻ and Na⁺ were significantly higher in PRM (p < 0.05), whereas F⁻ and NO₃⁻ were significantly higher in POM (p < 0.05); the elevated pre-monsoon Cl⁻ reflects evapo concentration and reduced recharge during the dry season. The dominant hydrochemical facies was Na–Cl (≈ 73% PRM, 60% POM), pointing to ion-exchange and anthropogenic salinity overprinting carbonate weathering. PCA reduced thirteen variables to four components explaining 84% of variance, with PC1 (≈ 55%) representing salinity/mineralization. The WQI classified 88.9% of PRM samples and 88.9% of POM samples as Excellent or Good for drinking, while 11.1% were Poor in both seasons (Dharmapuri, Jonnavalasa, Korukonda, Malicherla, Sarika). For irrigation, 97.8% of samples were rated Excellent on SAR and Safe on RSC, although 60% fell in the Doubtful Wilcox category due to elevated sodium. Groundwater in Vizianagaram Mandal is largely potable but locally compromised by sodium-chloride enrichment of anthropogenic origin; the GIS-based hotspot maps and WQI provide a quantitative basis for targeted remediation, controlled extraction and managed aquifer recharge.