Mapping Enugu City′s Urban Heat Island

Abstract

The presence of a city has a major impact on its local environment in terms of the heat and water balance of the area. In particular, it has been widely observed that the centre of the urban area tends to be of the order of 4 to 6oC warmer than its rural surroundings (the urban heat island effect). This paper applied remote sensing data to map UHI phenomenon in Enugu urban. The selected area covered Enugu North; Enugu South; and Enugu East with a total area of 18704.25 hectares. The urban heat island was determined by using the land surface temperature (LST) information from thermal infrared band (Band 6) of landsat image with 120m pixel resolution. A subset of landsat TM acquired on October, 2008 that covered Enugu city was used in this study. Erdas imagine 8.5 was the main software for image classification of urban land cover in 2008, while GIS-Grid calculator functions were used to derive land surface temperature. This study demonstrates the spatial variation of land surface temperature (LST) within urban blocks with temperature above 37o Celsius. Urban impervious areas, highly populated areas, and areas with more anthropogenic activities were recognized to be areas with highest number of UHI- related pixels. The result revealed the effectiveness of remote sensing data application in analyzing UHI- land surface temperature relationship in Enugu.