Author(s): K. SUNDARA KUMAR | Dr. P. UDAYA BHASKAR | Dr. K. PADMAKUMARI
Journal: International Journal of Engineering Science and Technology
ISSN 0975-5462
Volume: 4;
Issue: 2;
Start page: 771;
Date: 2012;
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Keywords: Urban Heat Island | Land Surface Temperature | Land Use/Cover | NDVI
ABSTRACT
The urban air temperature is gradually rising in all cities in the world. One of the possible causes is the drastic reduction in the greenery area in cities. The distinguished climatic condition termed ‘Urban Heat Island’ (UHI) is developing in the rapidly urbanized cities. Vijayawada city of Andhrapradesh is experiencing rapidurbanization that has resulted in remarkable UHI. Understanding the distribution of Land Surface Temperature (LST) and its spatial variation will be helpful to decipher its mechanism and find out possible solution. This study tries to investigate and identify land use types which have the most influence to the increase of ambienttemperature in Vijayawada city. For the present study Landsat ETM+ images of 2001 was obtained from USGS for the study area. Using bands 1-5 and 7 of the pre-processed images the land use / cover pattern was mapped by supervised classification with the maximum likelihood classification algorithm of ERDAS imagine 9.1 software. Five classes considered for the study are Built-up land, Barren Land, Water bodies, Agricultural fields and Vegetation. Normalized Difference Vegetation Index (NDVI) image was developed. The digital number ofthermal infrared band is converted in to spectral radiance using the equation supplied by the Landsat user’s hand book. The effective at-sensor brightness temperature is obtained from the spectral radiance using Plank’s inverse function. The surface emissivity based on NDVI classes is used to retrieve the final LST. It was noted thatmaximum air temperature was observed in built up areas of the city and minimum temperatures are observed in areas where vegetation cover is more. Urban heat island phenomenon is evident from the LST images. NDVI is found to have negative correlation with LST. The study reveals that appropriate strategies are necessary for the sustainable management of the urban area.
Journal: International Journal of Engineering Science and Technology
ISSN 0975-5462
Volume: 4;
Issue: 2;
Start page: 771;
Date: 2012;
VIEW PDF
DOWNLOAD PDF Original pageKeywords: Urban Heat Island | Land Surface Temperature | Land Use/Cover | NDVI
ABSTRACT
The urban air temperature is gradually rising in all cities in the world. One of the possible causes is the drastic reduction in the greenery area in cities. The distinguished climatic condition termed ‘Urban Heat Island’ (UHI) is developing in the rapidly urbanized cities. Vijayawada city of Andhrapradesh is experiencing rapidurbanization that has resulted in remarkable UHI. Understanding the distribution of Land Surface Temperature (LST) and its spatial variation will be helpful to decipher its mechanism and find out possible solution. This study tries to investigate and identify land use types which have the most influence to the increase of ambienttemperature in Vijayawada city. For the present study Landsat ETM+ images of 2001 was obtained from USGS for the study area. Using bands 1-5 and 7 of the pre-processed images the land use / cover pattern was mapped by supervised classification with the maximum likelihood classification algorithm of ERDAS imagine 9.1 software. Five classes considered for the study are Built-up land, Barren Land, Water bodies, Agricultural fields and Vegetation. Normalized Difference Vegetation Index (NDVI) image was developed. The digital number ofthermal infrared band is converted in to spectral radiance using the equation supplied by the Landsat user’s hand book. The effective at-sensor brightness temperature is obtained from the spectral radiance using Plank’s inverse function. The surface emissivity based on NDVI classes is used to retrieve the final LST. It was noted thatmaximum air temperature was observed in built up areas of the city and minimum temperatures are observed in areas where vegetation cover is more. Urban heat island phenomenon is evident from the LST images. NDVI is found to have negative correlation with LST. The study reveals that appropriate strategies are necessary for the sustainable management of the urban area.
