GIS Study onVulnerability Assessment of Water Quality ina Part of Cauvery River

Cauvery River is one of the significant sources of water supply for domestic, agricultural and industrial usage in Tamil Nadu. Inspite of large scale utilization of the river water, poor water management has resulted in large scale degradation of the quality of water. Hence a detailed study has been attempted in the Cauvery River between the latitudes 11^°29' 35.1’ N & 10^°57' 24’ N and the longitudes 77^°42' 40.7’ E and 78^°14' 17.9’ E. Four major tributaries such as Bhavani River, Noyal River, Amaravathi River and Thirumanimuthar River confluence with the Cauvery River in the study region.

About fifty water samples were collected in the Cauvery River during February 2009 and the samples were analyzed for the physical and chemical parameters such as pH, Electrical Conductivity, Total Dissolved Solids, alkalinity, hardness, Ca ²⁺, Mg ²⁺, Na⁺, K ⁺, Cl ^{, SO₄2−, CO₃2−, HCO₃−NO₃−,and F −. The analytical results were compared with the Indian(BIS) and International (WHO) standards to assess the suitability of water for drinking and the extent of deterioration. Spatial variations of various surface water quality parameters were studied using the Geographical Information System(GIS). The study indicates that some of the samples of February 2009 exceed the permissible limit for drinking. The study further reveals that the variation of water quality with respect to space and time is not uniform. Agricultural runoff, sewage and industrial effluents are the probable sources for the variation of water quality in the study region. Key words: surface water pollution, Spatial variation, Industrial effluent.}