Sustainable groundwater management through water quality index and geochemical insights in Valsad India

Groundwater quality assessment is crucial for sustainable water resource management and public health protection. This study evaluated the Water Quality Index (WQI) of groundwater in the southern part of Gujarat focusing on the Valsad District. Groundwater in this region occurs in porous, unconsolidated formations and fracture formations, both under groundwater table conditions and confined aquifers. Various parameters including Nitrate (NO₃¯), pH, Calcium (Ca²⁺), Electrical Conductivity (EC), Total Hardness (TH), Magnesium (Mg²⁺), Total Dissolved Solids (TDS), Potassium (K⁺), Sodium (Na⁺), Sulphate (SO₄^2-), Chloride (Cl¯), Bicarbonate (HCO₃¯), Silicate (SiO₄^4-), and Fluoride (F¯) were analyzed to assess groundwater quality. Results indicate that most of the parameters fell within acceptable permissible limits for drinking water, except for Muli and Nanaponda villages with the parameters Cl¯, EC, and TDS exceeding the permissible limit. The WQI analysis revealed that 31.25% of water samples from different villages were found in the excellent category (WQI < 25). About 68.75% of samples from 16 villages were classified as good quality category (WQI ∼ 25-50). Overall, the WQI ranged from 14.20 to 41.98, suggesting that groundwater in the Valsad district is suitable for drinking. The Piper diagram analysis of water samples collected from the field indicated unique geochemical compositions and good water. The diagram revealed that the Ca²⁺ was the predominant cation, followed by K⁺, Na⁺, and Mg²⁺. Among the anions, the HCO₃^- showed the highest concentrations, followed by SO₄^2-, NO₃^-, and Cl^-. This dominance pattern demonstrated that the weathering of minerals significantly influenced the groundwater. This study recommends remediation for areas with reduced water quality to address geogenic and anthropogenic contamination.