Evaluating the urban heat island over the city of Tshwane Metropolitan Municipality using remote sensing techniques

Abstract: The world is currently experiencing unprecedented urban growth. The influx of people into urban areas from rural areas is motivated by both economic and social factors such as increased employment opportunities, as a result of industrialization, and the perceived higher standard of living that is often associated with access to better infrastructure. Urban Heat Island (UHI) is a phenomenon whereby urban areas experience higher temperature than the surrounding rural areas. The presence of UHI in urban areas has a negative impact not only on city dwellers, but also on the environment and economy. The development of UHI is often associated with patterns of land use and land cover in urban areas. Numerous methods exist that can be used to study UHI. Published literature suggests that Land Surface Temperature (LST), derived from satellite imagery, is a proven method that produces reliable results. The aim of this study is to evaluate the UHI in Tshwane Metropolitan Municipality by studying the relationship between land surface temperature, land cover, land cover indices and atmospheric temperature. The derived indices are Normalized Difference Vegetation Index (NDVI), Normalized Difference Built-up Index (NDBI) and the Normalized Difference Bareness Index (NDBaI). These indices were selected as they were representative of the land cover scheme used in the study. The study was conducted for the City of Tshwane Metropolitan Municipality between 2001 and 2014, and covered both warm months (spring and summer) and cold months (winter and autumn). The land surface temperature was derived from Landsat ETM+ high thermal band data, using the single channel method developed by Jimenez-Munoz et al. (2009). The City of Tshwane Metropolitan Municipality, being home to the administrative capital city of South Africa, provides for a unique urban structure in which the phenomenon can be studied. The uniqueness is a result of Apartheid urban planning policies, which promoted fragmentation of urban areas based on race. . These urban areas also expand at a rate comparable to international trends...M.Sc. (Geography