Evaluation of Water Quality for Irrigation Purpose in Sitanadi Basin, Udupi District, Karnataka

Abstract

Present study has been carried out with the objective to assess various factors controlling the groundwater quality with respect to irrigation, seasonal variations of groundwater quality for pre- and post-monsoon periods and to compare its suitability for irrigation use confirming to the latest water quality standards for irrigation. Sitanadi basin is located in the west coast of peninsular India, Udupi district of Karnataka. It extended between 13°20ʹ and 13°35ʹ N latitudes and 74°40ʹ and 75°10ʹ E longitude. The geographical area of basin is about 643.65 sq. km. A total of 56 open dug wells were inventoried for groundwater samples collection in Sitanadi basin. Two sets of groundwater samples were collected from the dug wells during pre-monsoon and post-monsoon seasons of 2013, 2014 and 2015. Immediately after sampling, pH, EC, and TDS are tested in the field by a portable pH and an EC meter. These samples are used for analysis of major cations (Mg²⁺, Na⁺, Ca²⁺, K⁺) and major anions (HCO₃^-, Cl^-, SO₄^2-, NO₃^2-). These parameters are used to derive irrigation quality of ground water such as SAR, %Na, Residual Sodium carbonate, Magnesium Hazards, Kellie’s ratio, CAI-I and CAI-II, Ca^2+/Mg²⁺ ratio, Soluble Sodium Percentage, Potential salinity and Exchangeable Sodium Percentage. The ground water is found to fit to use for irrigation purposes except in few locations with respect to very few parameters such as Kelliy’s Ratio and Soluble Sodium Percentage.

Keywords: Irrigation, water quality, classification