A WATER QUALITY INDEX APPROACH TO APPRAISE TEMPORAL VARIATION AND HEAVY METAL ACCUMULATION IN URBAN STORM WATER FLOW WITH SPECIAL EMPHASIS ON IRRIGATION UTILITY, CHANDIGARH, INDIA

The present work has been done to evaluate and classify the water quality of a storm water rivulet (N-Choe), flowing through the heavily urbanized areas of the city Chandigarh for irrigation purposes, by using the model of irrigation water quality index (IWQI) developed in Brazil by Meireles et al. (2010). N-Choe which drains the major parts of the city was chosen as the study area to understand the water quality index approach during pre monsoon and post monsoon periods, as water of the N choe receiving toxic effluents from the industrial and residential areas of the city is being utilized by the farmers of the adjacent villages to grow crops. The results showed that the value of IWQI ranged between 70-85 for both the seasons thus falls under the ‘Low restriction’ category for irrigation purposes. Water in this category should be used in the soils with light texture or moderate permeability and should be avoided in soils with high clay. The study area witnessed heavy textured soil indicating that this water which was used for irrigation purpose was potentially leading to the sodicity problem in the area under investigation. The metal concentration in the samples taken from the study area showed the trend of Fe>Ni>Mn>Cd thus showed a severe drop in the water quality. Sodium absorption ratio (SAR), Residual sodium carbonate (RSC), Percent Sodium (% Na), Permeability Index (PI), and Kelly’s Index (KI) was calculated for better understanding the suitability of water quality for irrigation purposes.