Hydrogeochemical Assessment and Irrigation Suitability of Groundwater in Banaskantha’s Vegetation Zone, India

Abstract

Groundwater serves as the principal supply of water for home and agricultural purposes  in the semi-arid Banaskantha district of Gujarat, India. This study provides a thorough hydrogeochemical analysis of 207 groundwater samples that were taken during the post-monsoon season in 2021 from the vegetation zone.  pH, EC, TDS, TH, Ca2+, Mg2+, Na+, K+, Cl-, SO₄²⁻, HCO₃⁻, CO₃²⁻, NO₃⁻, and F⁻ were among the physicochemical parameters that were examined and contrasted with BIS and WHO standards.  The majority of the samples have high salinity, excessive hardness, and high levels of carbonate and chloride, according to the results, making the water mostly unfit for human consumption.  Rock-water interactions, evaporation, and human inputs have modified the hydrochemical facies characterised by Piper and Durov diagrams, which show the dominance of Ca–Mg–Cl–SO₄ and Na–Cl types. In addition to the Irrigation Water Quality Index (IWQI), indices like SAR, MAR, KR, PI, PS, and RSC were used to assess irrigation suitability.  Irrigation use is restricted by high magnesium hazard and heightened potential salinity, even if SAR readings indicate low sodicity hazard.  Evaluation of irrigation water quality using IWQi values shows that only 1.45% of samples fall under the ‘no restriction’ category, while 18.84% have ‘low restriction.’ About 35.27% of samples are classified as ‘moderate restriction,’ and 39.61% as ‘high restriction,’ raising concerns about long-term soil and crop health. A further 4.83% fall into the ‘severe restriction’ class, indicating unsuitability for irrigation."  Critical salinity and alkalinity danger zones are highlighted by spatial distribution mapping using GIS.  To ensure stable agricultural output, the results underscore the crucial need for sustainable groundwater management and soil-water conservation techniques. These findings underscore the urgent need for sustainable groundwater management, soil–water conservation strategies, and policy interventions focused on regulating groundwater extraction, promoting efficient irrigation practices, and ensuring long-term water security in the region.