Ground water quality after Tsunami in Coastal area of Kanyakumari, South Tamilnadu, India

Hydrochemistry of groundwater in Coastal Area of Kanyakumari to Colachel coastal belt after Tsunami, South TamilNadu, India was used to assess the quality of groundwater for determining its suitability for drinking and agricultural purposes. Physical and chemical parameters of groundwater such as electrical conductivity, pH, total dissolved solids (TDS), Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻HCO₃₋, CO₃²⁻, SO₄²⁻, NO₃⁻, F⁻, B⁻ and SiO₂ were determined. Concentrations of the chemical constituents in groundwater vary spatially and temporarily. Interpretation of analytical data shows that mixed Ca–Mg–Cl, Ca–Cl and Na–Cl are the dominant hydro chemical faces in the study area. Alkali earths (Ca²⁺, Mg²⁺) and strong acids (Cl⁻, SO₄²) are slightly dominating over alkalis (Na⁺, K⁺) and weak acids (HCO₃⁻,CO₃²⁻).

The abundance of the major ions is as follows: Na⁺>Ca²⁺>Mg²⁺>K⁺=Cl>HCO₃>SO₄²>NO₃>CO₃²⁻. Groundwater in the area is generally very good, pleasant, fresh to brackish, average to very low saline and low alkaline in nature and fit both for agriculture and drinking purposes. Permissible average Total Hardness and TDS in all places of the study area identify the suitability of groundwater for drinking and irrigation. In some areas due to high Total Hardness and TDS identified in ground water such areas require special care to provide adequate drainage and introduce alternative salt tolerance cropping. Based on the TDS value, the ground water in these areas is of bicarbonate/calcium chloride/sodium chloride type. Fluoride and boron are within the permissible limits for human consumption and crops as per the international standards. Nitrate concentration is slightly high in some areas. In the study area less ground water extraction keeps the water table high. The elevated topography, more rainfall and limited ground water extraction, keeps the Kanyakumari coastal belt free from sea water intrusion. The surface water resources have been fully utilized. The surface flow is more during monsoon periods. Surface water and rain water are widely used for irrigations. Surface water irrigation constitutes nearly 94% of major source of irrigation. Of the total net area irrigated only 6% is under well irrigation and hence there is no over extraction of ground water in the area. Quality of water is generally good through out the district except some places in the study area like Keelamanagudi,Thengampudur and Colachel and some pockets along the coastal belt. Comparing the results of water parameters before and after Tsunami there is not much change in the quality.