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Identification of Urban Canyons in the City of São Paulo from Landsat 8 Images

Cities in the last century have been suffering from the disorderly and unplanned growth of urban centers. Consequently, innumerable environmental problems started to plague these regions, one of them is the alteration of the surface temperature through the generation of heat islands and the urban canyons, caused by the alterations in the natural landscape. Based on OLI and TIRS images from the Landsat 8 satellite, a soil cover map was generated, an image of Surface Temperature (ST) and the NDBI index, which highlight built-up areas, verifying and identifying urban canyon regions of São Paulo. From the results of the correlation of low, medium, and high waterproofing areas generated by the soil cover map with the soil temperature images and the NDBI index, areas of medium waterproofing that had a (ST) similar to the areas of low waterproofing (28 to 31 °C). In this case, the areas of medium waterproofing should resemble the regions of high waterproofing (34 to 37 °C). Such regions have, as a main characteristic, a low index of trees and a greater number of constructions, which causes an increase in temperature (heat islands). In this case, it is observed that the regions of medium waterproofing are influenced by the height and spacing of the buildings, which generate wind corridors and shading of the surface, decreasing the temperature of the region and generating urban canyons. Thus, it is concluded that it is possible to identify regions of urban canyons through multispectral and thermal images. The methodology used allows a diagnosis of the islands of heat islands and urban canyons and to evaluate actions taken in these areas in order to mitigate the problems that such phenomena can cause, mainly related to the population’s climate and health.