Assessment of groundwater quality in Ghataprabha command area, Karnataka, India

The studies related to assessment of groundwater quality of Gokak, Mudhol Biligi and Bagalkot taluks of Ghataprabha command area, Belgaum District, Karnataka (India) were carried out during the pre-monsoon and post-monsoon seasons to evaluate its suitability for domestic and irrigation purpose. The samples were collected from 42 locations (including 25 open wells) during pre-monsoon (May, 2007) and post-monsoon (November, 2007) seasons. The samples were analyzed for pH, EC, TDS, carbonates, bicarbonates, alkalinity, chlorides, sulphates, hardness, calcium, magnesium, sodium, potassium, phosphates, nitrates, iron, manganese and fluorides. Based on the concentration of TDS, about 47 % of the samples were found within the permissible limits both for drinking and irrigation, 43% of the samples were useful only for irrigation and 10% of the samples were unfit for drinking and irrigation. Similarly during post-monsoon about 61% of the samples were within the permissible limits both for drinking and irrigation, 31% of the samples were useful only for irrigation and 8 % of the samples unfit for drinking and irrigation. Based on the irrigation water classification, it is understood that, the area falls under low to very high salinity zone for both seasons. The values of sodium absorption ratio indicate that all the samples fall under the category of low, medium and high sodium hazards. The Piper trilinear diagram shows that 60% fall under Na(2+)--K(2+)--HCO3- and Na(2+)-- K(2+)--Cl(-)--SO4(2-) types and rest 40% of the samples fall under Ca(2+)--Mg(2+)--HCO(3-) and Ca(2+)--Mg(2+)--Cl(-)--SO4(2) types. According to U.S.Salinity Laboratory Classification, water belongs to medium salinity to very high salinity and low sodium to high sodium water.