Sustainable Water Development and Suitability of Ground Water for Irrigation Purposes in a Small Coral Island of Minicoy, Union Territory of Lakshadweep, India

Abstract

Sustainable water development and suitability of ground water for Irrigation purposes in a small coral Island of Minicoy, Union Territory of Lakshadweep, India have been studied in detail. In the Island of Minicoy ground water occurs under phreatic condition and is seen as a thin lens floating over the saline water and coral sands and coral limestone form the principal aquifers. The depth to the water level in the Island varies from 0.62 to 1.75 mbgl and the depth of the wells varies from less than a meter to about 6 mgbl. The depth to the water table is highly influenced by the tides. The ground water in the Island is generally alkaline and EC varies from 592 to 2130 micromhos cm^-1 at 25 C. The ground water is generally alkaline and under Na⁺-SO₄^2- type and shallow meteoric percolation type. The factors affecting the quality are rainfall, tides, ground water recharge and draft, human and animal wastes, oil spills and fertilizers. The premonsoon groundwater samples of different areas are of Ca²⁺-HCO₃^-Type (Recharge type) and Na-HCO₃ Type (base exchange water type) and among cations Ca²⁺ and Na⁺ and anions HCO^- and Cl^- dominate the ionic concentration in groundwater. The groundwater of the area comes under Na⁺-SO₄^2- type and shallow meteoric percolation type. The hydrochemistry is mainly controlled by evaporation, partly influenced by water–rock interaction and aquifer material.