Abstract

To assess the ground water quality and its suitability for irrigation, a study was carried out during April and June 2010 in Parambikulam Aliyar Basin, Tamil Nadu. Ground water samples were collected from open wells, bore wells and dug cum bore wells in the Parambikulam Aliyar Basin and their quality parameters were assessed. pH values ranged from 6.6 to 8.6; electrical conductivity values were ranged from 0.29 to 6.80 dSm -1 and most of the samples were under medium salinity class (C 2 ) (48.57%). Calcium, magnesium, sodium and potassium content ranged from 0.40 to 13.36 m.e L -1 , 1.04 to 26.16 m.e L-1 , 0.80 to 25.48 m.e L -1 and 0.05 to 2.52 m.e L -1 respectively. Most of the samples were found to be magnesium dominating and magnesium exceeds the calcium content in most of the water samples both during April and June 2010. Magnesium toxicity will be exhibited in continuous use of water to crops. Carbonates, bicarbonates, chloride and sulphate concentration varied from 0.0 to 4.00 m.e L -1 , 0.80 to 12.80 m.e L -1 , 1.20 to 45.20 m.e L -1 and 0.02 to 7.97 m.e L -1 respectively. The sequence of cations were found in the order of Na + >Mg 2+ >Ca 2+ >K + and anions followed the sequence of Cl - > SO 4 2- >HCO 3 - >CO 3 2-. Total hardness in the study area varied from 6.26 to 140.66 m.e L -1 . Most of the samples were deficient of Ca and Mg category during both the seasons. RSC values varied from 33.12 to 8.56 meL -1 and most of the samples are coming under safe category (71.43% - 80.0 %). Residual sodium bicarbonates also come under safe category. SAR values ranged from 0.49 to 13.21 and all the samples were found to be low sodium category (S 1 ). There is no sodicity problem exist among the irrigation waters. In the present study, Permeability Index ranged from 26.49 to 101.59 and majority of the samples exhibited that there is no permeability hazard.

Keywords: Irrigation water quality, Parambikulam-Aliyar river basin, Tamil Nadu.