Integrated Geophysical And Geochemical Studies Of Aquifers In Vaippar Coastal Area, Thoothukudi District, Southern Tamil Nadu, India.

Abstract

The study of coastal aquifer characteristics is very essential for SGD and seawater intrusion studies in the Vaippar river basin of southern Tamil Nadu, India. The Vaippar basin is mostly seaward side, a river environment, and also an estuary environment. Whenever there is substantial rainfall, a large volume of fresh water will be dumped into the ocean. The present studies consist of analyses of water discharge and seawater intrusion during the pre-monsoon and post-monsoon seasons. In this study, we have used the magneto telluric method to investigate the aquifer depth and lithology of the studied region. Water samples were taken at the Vaippar river basin, Kullathur, Pallakulam, and Keelavaippar areas. The coastal clay-rich alluvium coastal sand bar, shell limestone and gneissic rock depth were obtained by Resistivity data interpretation from the collected water samples. Physico-chemical parameters such as pH, Ec, TDS cation (Ca²⁺, Mg²⁺, Na⁺, K⁺), and anion (Cl^-, HCO^-₃, So₄^2-) values were used for quality analyses applying Aquachem software plots. The water types of HCO^-₃-Cl^--So₄^2-, Ca²⁺, and Mg²⁺-Cl^--HCO^-₃ combinations in our data from the river, estuary, and beach were compared in terms of understanding water quality. The Water quality assessment is useful for recommending water for drinking and agricultural purposes.

Keywords: Vaippar basin, Magneto telluric method, Aquachem, GIS, HFE-Diagram.