Hydrogeochemical characteristics of groundwater in Thoothapuzha River Basin, Kerala, South India

Abstract

The present study attempts the hydrochemical characterization of groundwater in the Thoothapuzha River basin, Kerala, south India. Total 54 groundwater samples have been collected from the study area in the post-monsoon (POM) and pre-monsoon (PRM) seasons. The hydrochemical characteristics such as pH, electrical conductivity (EC), total hardness, salinity, alkalinity, Na⁺, K⁺, Ca²⁺, Mg²⁺, SO₄³⁻, Fe, Cl⁻, NO₃⁻, and total dissolved solids (TDS) were determined to understand the groundwater characteristics. The analytical results were used to create graphical plots and scientific calculations to determine the association between chemical components and water quality. The major facies identified in the samples were Ca-HCO₃ and mixed Ca-Mg-Cl. Minimal illustrations have been observed in the mixed Ca-Na-HCO₃ and Ca-Cl, Na-Cl facies. According to Gibbs plots, the key processes regulating water chemistry are rock-water interactions and evaporation. The association among Ca²⁺, Mg²⁺, Na⁺, and K⁺ reveals the control of ion exchange in regulating their concentration in groundwater. In addition, silicate weathering makes a higher contribution than carbonate and evaporite dissolution. The correlation analysis also provides evidence of reverse ion exchange, silicate weathering and anthropogenic sources in controlling the water chemistry. The study concludes that a variety of processes, such as silicate weathering, ion exchanges, mineral dissolution, and anthropogenic traces, are the major factors regulating water chemistry.