Assessment of groundwater quality of Pratapgarh district in India for suitability of drinking purpose using water quality index (WQI) and GIS technique

An attempt has been made to develop a water quality index (WQI) model in geographic information system (GIS) environment, using 12 groundwater quality parameters (pH, TDS, F⁻, Cl⁻, NO₃ ⁻, SO₄ ²⁻ HCO₃ ⁻, Ca²⁺, Mg²⁺, Na⁺, K⁺, and TH) at 55 different locations of the Pratapgarh district. The analytical results show alkaline nature of the groundwater resources of the Pratapgarh district. HCO₃ ⁻ and Cl⁻ are the dominant anions, while cation chemistry is dominated by Mg²⁺ and Na⁺. The computed WQI values in the groundwater range from 52 to 345 (avg. 115) and indicate that the groundwater quality varied from good to unsuitable for drinking. High WQI has been found at sites 3, 4, 7, 10, 20, 40, 41, and 50 primarily due to high TDS, F⁻, Cl⁻, NO₃ ⁻, SO₄ ²⁻, Mg²⁺, Na⁺, and TH. Western and eastern parts of the Pratapgarh district show low TDS along the Ganga and Gomti Rivers, respectively, due to aquifer recharging. Groundwaters of more than one-third area are not suitable for drinking. Analysis of the data reveals that rock weathering and agricultural activities govern the groundwater chemistry of the study area.