Integrated Hydrochemical and Statistical Assessment of Groundwater Quality and Irrigation Suitability in the Semi‐Arid Hard‐Rock Aquifer of Madurai North Taluk, Tamil Nadu, India

Groundwater is the principal irrigation source in the semiarid hard‐rock aquifer of Madurai North Taluk, Tamil Nadu, India, where increasing agricultural demand and climatic variability have intensified pressure on groundwater resources. This study presents an integrated hydrochemical and statistical assessment of groundwater quality and irrigation suitability using long‐term monitoring data collected during the pre‐ and postmonsoon seasons from 2008 to 2022. Groundwater quality was evaluated using major hydrochemical parameters, irrigation water quality indices, United States Salinity Laboratory classification, groundwater‐level analysis, correlation analysis and normal distribution analysis. Groundwater chemistry was primarily controlled by rock–water interactions, with additional influences from evaporation and anthropogenic activities. USSL classification identified nine irrigation water classes, with only 13% of premonsoon samples suitable for unrestricted irrigation, while 45% belonged to the high‐salinity C3S1 class. Irrigation indices indicated that elevated salinity, magnesium hazard, potential salinity and permeability index constrain sustainable agricultural use. Groundwater levels declined markedly during 2013–2017 before partially recovering under variable recharge conditions. Correlation and normal distribution analyses revealed pronounced seasonal variability, with greater postmonsoon dispersion in electrical conductivity and sodium adsorption ratio. These findings highlight progressive groundwater deterioration and emphasize the need for artificial recharge, regulated abstraction, continuous monitoring and sustainable irrigation management.