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International Journal of Research in Social Sciences
Year : 2016, Volume : 6, Issue : 5
First page : ( 614) Last page : ( 625)
Online ISSN : 2249-2496.

The Relationship between Land Surface Temperature and Land Use: A Remote Sensing Analysis of Colombo, Sri Lanka

Laranjeira M.M.*, Nianthi Rekha K.W.G**, Pinheiro Almeida C. de***

* Geographical Studies Center, University of Lisbon, Portugal

** Department of Geography, University of Minho, Portugal

** Department of Geography, University of Peradeniya, Sri Lanka

*** Department of Geography, University of Minho, Portugal

Online published on 28 July, 2016.

Abstract

Land Surface Temperature (LST) is an important factor in urban climate studies because it modulates both the energy balance and air temperatures of the urban canopy layer. It is now a well established fact that LST is closely related to spatial distribution of land use, and surface radiative and thermal properties. Therefore, urban areas with mixed land use types comprise a mosaic of warm, heat releasing surfaces, and cool, evaporative surfaces. The purpose of our research is to investigate the relationship between LST and land use/land cover (LULC) types in the urban area of Colombo, Sri Lanka. LST values were derived from a Landsat 7 ETM+ multispectral image acquired on March 14, 2001. Several indices were derived namely NDVI (Normalized Difference Vegetation Index), NDBI (Normalized Difference Built-up Index), NDWI (Normalized Difference Water Index), and NDBaI (Normalized Difference Bareness Index). These indices were used to classify distinct LULC types (vegetation, built-up areas, densely built-up areas, and moist surfaces). The correlations between LST, NDVI, NDBI, NDWI, and NDBaI indices were analysed, and the thermal signature of each LULC type was statistically established. The results show positive correlations between NDBI, NDBaI and LST, and negative correlations between NDVI, NDWI and LST. Densely built-up areas (NDBI>0.25) were found to have significantly higher LST values than vegetation areas (with a mean of 30.7oC and of 26.1oC, respectively). In fact, the spatial pattern of LST reveals major gradients between cooler green spaces and their warmer built-up surroundings. As a conclusion, this study stresses the importance of the presence of urban green parks (with large water surfaces) in the urban environment of Colombo, due to their cooling effect.

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Keywords

urban climate, thermal infrared remote sensing, spectral indices, spatial analysis.

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