Anju Maria Joseph, M. Suresh Gandhi* and Annmaria K. George

Department of Geology, University of Madras, Guindy campus,Chennai-600025(TN),India (*Corresponding Author, E-mail: msureshgandhi@gmail.com)

Abstract

The ecology of lakes is largely dependent on rivers. However, because research has frequently concentrated on rivers and lakes independently, the interconnectivity between them is poorly defined. During the present study, hydrochemical investigation of surface water from the Vembanad Lake and its primary inflows, Periyar, Muvattupuzha, Manimala, Meenachil, Pamba and Achenkovil were carried out. This study describes the quality and suitability of lake and river water for consumption and irrigation purposes. It also aids in determining the influence of six rivers over the Vembanad lake water quality. Total 80 samples were collected during pre-monsoon and post monsoon seasons.Various physico-chemical parameters such as Temperature, Turbidity, Total Dissolved Solids (TDS), Conductivity, pH, Alkalinity, Total Hardness, Calcium, Magnesium, Sodium, Potassium, Chloride, Bicarbonate and Sulphate were analysed. The chemical classification using Piper trilinear diagram reveals that sodium is the predominant cation in both seasons. The Water Quality Index value of the Vembanad Lake is found to be higher in the pre-monsoon season compared to the postmonsoon. Sodium hazard (Sodium Adsorption Ratio- SAR), Residual Sodium Carbonates (RSC), Sodium Percentage (Na%), Magnesium Hazard (MH), Kelly’s Ratio (KR) and Permeability Index (PI) are the parameters used to identify the irrigation water quality. Based on the irrigation water quality parameters it can be concluded that water from southern portion of the lake and six inflows are suitable for irrigation purpose. The U.S. Salinity diagram indicates that the northern portion of the lake occupies the high sodium hazard zone. The water quality of the southern portion of the Vembanad Lake is chiefly controlled by its primary freshwater in flows and the northern portion by the saline water from the Arabian Sea.

Keywords: Hydrogeochemistry, Water Quality, Sodium Adsorption Ratio,Vembanad Lake Kerala