Determination of Urbanization Impact on Rain Water Quality with the Help of Water Quality Index and Urbanization Index

Abstract

Rain water quality is a vital factor for deciding whether the water is drinkable or not. But increase in urbanization could degrade the quality of rain water. In the present study, rain water was collected from different sampling locations near and far from urban centers. The influences of urbanization were analyzed with the help of the relationship between water quality index (WQI) of the collected samples and urbanization index (UI) of the sampling location. The WQI was developed with the help of different water quality parameters and their standards. The index was developed as per the standards of drinking water prescribed by All India Public Health Engineering and with the help of “Water Classifier” software developed by Majumder (2008). The urbanization index for the present study was developed as a function of population density, change in population within sampling locations, and density of residential and commercial complexes areas within a radius of 5 km of the sampling locations. According to the results, the relationship between WQI and UI was inversely proportional in sampling locations of both South and North 24 Parganas, which are located in southern and northern outskirts of Kolkata but the slope of the relationship is more tilted in case of sampling points located in South 24 Parganas, than in case of the samples taken from North 24 Parganas. As most of the polluting commercial complexes (leather, textile) were situated in southern outskirts of Kolkata and huge number of residential complexes were present or in verge of completion in the region, there was a massive migration of population from different parts of Kolkata to South 24 Parganas, The service and IT sectors, the nonpolluting industries of Kolkata were concentrated in the northern outskirts. The justification of the relationship between WQI and UI in southern and northern outskirts of Kolkata can be attributed to the above fact. The present study, thus, concluded that there is an impact of urbanization on quality of rain water in Kolkata. The same study can be made in other metro cities of India to verify the veracity of the relationship. The present study was conducted with very few sampling locations but still the locations were situated in regions of different UI and WQI. The study can be repeated with more sampling locations within the city with samples, which have more diverse WQI and UI.