Groundwater Quality Assessment and Irrigation Suitability for Agricultural Use in Charnockite–Migmatite Terrains of Southern India

Abstract

Groundwater is a vital source for human life to survive and fulfil the needs for both drinking and irrigation purposes in the Alamarathupatti region of Dindigul district, Tamil Nadu, India. This research aims to evaluate the groundwater suitability for drinking and irrigation with 20 groundwater samples collected around the study region and analysed the physicochemical parameters using standard methods. pH, TDS, EC, TH, Ca²⁺, Mg²⁺, Na⁺, K⁺, Cl^-, HCO₃^-, and SO₄^2- exceeding permissible limits. Spatial distribution was mapped using Inverse Distance Weighting (IDW). The Piper interpretation indicates that the water type is Ca²⁺-Mg²⁺-Cl^--SO₄^2-, indicating ion exchange and anthropogenic influence. Gibbs suggests rock dominance is the primary factor affecting groundwater chemistry. In Irrigation suitability, Wilcox's interpretation indicates that most samples fall in the Good to Permissible category. The GWQI indicates that 95% samples fall in poor water, suggesting groundwater is generally unsuitable for direct consumption without treatment and 5 % in Good category. Correlation analysis revealed strong relationships among EC, TDS, hardness, and major ions, indicating rock–water interaction and ionic enrichment in the groundwater system. Principal component analysis explicates 55.34% total variance and the major component is PC 1, explaining 30.90% indicates rock-water interaction and anthropogenic activities.