Assessment of Water Quality Index of Cauvery and Kapila Rivers and at their Confluence

Abstract

The water quality index (WQI) is an attempt to provide a mechanism for presenting a cumulatively derived, mathematical expression defining the level of water quality. WQI represents the level of water quality in the given water basin. WQI is a means to summarize large amounts of water quality data into simple terms (e.g., good, bad or moderate) for reporting to management and the public in a consistent manner and also allows for comparisons to be made between different aquatic bodies. WQI of Cauvery and Kapila rivers and at their confluence site was studied with the help of 21 Physico- chemical parameters obtained for two years from June 2009-May 2011. The study showed that Cauvery river is moderatly polluted with WQI of 59, whereas, water of Kapila and at confluence site was severely polluted with a WQI of 91 and 78 respectively. The first year and second year seasonal study revealed that all the three sampling sites were severely polluted during rainy season as the WQI ranged from 76-100. During winter and summer seasons Cauvery river and at confluence site showed moderate pollution as the WQI value ranged within 51-75, whereas, Kapila river water was severely polluted (WQI>76) in these seasons. The Monthly WQI values for the first year were highest in July 2009 in the entire sampling sites. The lowest WQI was found in February 2010 in Cauvery and Kapila rivers, whereas at the confluence site it was in January 2010. In the second year of study highest WQI in Cauvery river was found in June 2010, in Kapila and at confluence site it was in July 2010. The lowest WQI was recorded in December 2010 in Cauvery river, in Kapila and at confluence site it was in January 2011. These findings have been discussed in the light of recent literature published.