Seasonal Groundwater Quality Assessment in Lathiyani, Himachal Pradesh (India)

Groundwater is the primary source of drinking and domestic water in the Lathiyani region of Una district, Himachal Pradesh (India). The quality of water is substantially impacted by seasonally varying human activities, rainfall and groundwater recharge. The objective of this study was to assess the quality of groundwater for drinking purposes in the study area. This study is distinguished by its seasonal assessment of groundwater quality, which is substantiated by correlation analysis and estimating a Groundwater Quality Index (GWQI). A total of 96 groundwater samples were collected from six wells during the summer, monsoon, and winter seasons during 2023-2024. The GWQI and correlation heat maps were generated for the major physico-chemical parameters such as pH, electrical conductivity (EC), turbidity, total dissolved solids (TDS), dissolved oxygen (DO), calcium (Ca²+), magnesium (Mg²+), chloride (Cl⁻), nitrate (NO3⁻), and phosphate (PO4³⁻). The results indicated a discernible seasonal variation in the groundwater quality parameters. The monsoon season was characterized by the highest turbidity (2.1-7.5 NTU) and DO (6.2-8.6 mg L⁻1), while the pH of the water varied from 6.8 to 8.2. In summer, elevated EC (410-860 µS cm⁻1), TDS (280-590 mg L⁻1), Ca²⁺ (38-92 mg L⁻1), Mg²⁺ (22-61 mg L⁻1), Cl⁻ (24-86 mg L⁻1), NO3⁻ (4.5-19.2 mg L⁻1), and PO4³⁻ (0.12-0.35 mg L⁻1) were observed, suggesting evaporative enrichment. The GWQI values, ranging from 48.6 in winter to 112.4 in summer, indicated very poor to excellent groundwater quality. The Spearman rank correlation-based assessment of seasonal hydrochemical relationships revealed a persistent and robust EC-TDS association (r = 1.00, p< 0.01), which suggested that dominant mineral dissolution processes of groundwater are vital in the area. However, the absence of significant EC-Cl⁻ and NO3⁻-PO4³⁻ correlations suggested that multi-ionic regulation and variable nutrient mobility across seasons occurred. Overall, the groundwater was found suitable during the winter, moderately stressed during the rainy season, and deteriorated during the summer, highlighting the necessity of season-specific groundwater management.