Hydrochemical characteristics and quality assessment of groundwater along the coastal tracts of Tamil Nadu and Puducherry, India

Abstract

Abstract Coastal areas provide the largest avenue for human settlement worldwide. Among the different sources of water, groundwater comes under the most exploited for domestic, agriculture as well as industrial purposes. The present study is aimed to evaluate the hydrochemical characteristics and quality of groundwater. A total of 132 groundwater samples were collected during post-monsoon and pre-monsoon seasons and analyzed for major and minor ions, and the results were used to evaluate water quality parameters like sodium absorption ratio, magnesium absorption ratio, soluble sodium percentage, permeability index and residual sodium carbonate to establish water quality for various utilities. Groundwater samples show acidic to alkaline nature; dominant cations reported were in the order of Na+ > Ca2+ > K+ > Mg2+ and dominant anions Cl− > HCO3 − > SO4 2−. The hardness of water ranges from soft to very hard. The major water types noted were CaHCO3, NaHCO3, CaCl2, mixed CaNaHCO3 and NaCl. Based on electrical conductivity, total dissolved solids and total hardness majority of the samples are appropriate for consumption and domestic utilities with few exceptions. Computed parameters reveal that a majority of the groundwater samples are suitable for agricultural purposes. The Gibbs plot reveals that interaction between rock and water is the major mechanism controlling groundwater chemistry in the study area. Multivariate statistical analyses such as correlation analysis and principal component analysis were carried out for better understanding and classification of water quality and factors which control the groundwater chemistry.

Keywords

• Coastal groundwater
• Agriculture
• Domestic
• Seawater intrusion
• Multivariate statistical analysis