Sant PRASAD, DEPARTMENT OF GEOGRAPHY DELHI SCHOOL OF ECONOMICS UNIVERSITY OF DELHI, India
B.w. PANDEY, DEPARTMENT OF GEOGRAPHY DELHI SCHOOL OF ECONOMICS UNIVERSITY OF DELHI, India
Urban heat island (UHI) is an anomaly where the urban area is significantly warmer than its surrounding areas due to anthropogenic activities. And for a past decade, the city of Varanasi has been facing the very same effect which is growing rapidly. In this study, the effects of UHI are analyzed by using Landsat 8 data of March and May 2018 for a case study of Varanasi City, India. An algorithm was applied to retrieve the land surface temperature (LST) distribution from the Landsat 8 TM data along with normalized difference vegetation index (NDVI) and the normalized difference build-up index (NDBI) calculations form Landsat 8 data. In addition, the correlation between LST, NDVI and NDBI were analyzed to explore the impact on green areas and the built-up areas of UHIs. As a result, the effects of UHI in Varanasi City are located mainly in sub-urban areas. Also the study shows that a negative correlation between LST and NDVI suggests that a green area can reduce the effect of UHI, while a positive correlation between LST and NDBI means that the built-up land can strengthen the effect of the UHI within the study area.The spatial patterns of LST shown have substantial variations across the Varanasi city. A higher LST is recorded in the southernmost parts of the city and along the sandbar parts of River Ganga, as well as in the centre west. We can conclude that the central parts of Varanasi city exhibit a strong UHI effect, likely caused by the dense built-up area and scarce green cover.
Mots clés : UHI|LST|NDVI|LULC|Varanasi City