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† Effect of changing land use scenario in Kolkata Metropolitan on the variation in volume of runoff using multi-temporal satellite images
Author : Bernadette John*, Subhasish Das and Rajib Das
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ABSTRACT
The city of Kolkata has happened to grow in an unplanned manner expanding towards the southern and the eastern part. The changing land use pattern of the city was studied using Landsat imageries, which were collected for the year 1987, 1997, 2007 and 2017. A study on the variation in runoff is ideal to understand the effect of urbanization on the environment. This paper attempts to study the effect of the changing land use scenario on the amount of runoff in Kolkata. The multi-temporal images were downloaded from USGS site and verified with topographical maps of scale 1:50,000 obtained from Survey of India. The runoff curve number is an empirical parameter used for predicting the direct runoff. The widely used NRCS-CN method was used to determine the runoff. Hydrology based mathematical expressions were used for direct conversion from Antecedent Moisture Condition I (dry) to Antecedent Moisture Condition III (wet). The runoff was estimated from the curve number which was determined from land use map of the area over time. It is seen that over the years there has been a considerable change in the land use pattern of the city. The built up area rose to as high as 75% in the year 2017, which in turn raised the volume of runoff from 798387 m3 in 1997 to 861197 m3 in 2017.
KEYWORD
Land use pattern, antecedent moisture content, curve number, runoff