Effect of Green Spaces on Urban Heat Distribution in Bwari and Abuja Municipal Area Councils of the Federal Capital Territory of Nigeria

Abstract

Urban Heat Distribution (UHD) is considered as one of the major problems in the 21st century posed to human beings as a result of industrialization and urbanization, though they tend to improve our material lives and comfort in some ways. Urbanization has resulted in alterations in spatial patterns of urban land use/land cover change; leading to decreases in green spaces. It is necessary to assess the role of green spaces on heat distribution in fast growing cities like Abuja. Developed countries have invested huge resources in developing green spaces as part of the best practices in mitigating urban heat, purifying the air, among others. This study analyzed the effects of green spaces in urban heat distribution (UHD) in FCT, Abuja, Nigeria. The urban temperature was estimated from Landsat Operational Land Imager (OLI) 2015 imagery and in situ data. ArcGIS 10.3 was used to generate Normalized Difference Vegetation Index (NDVI) and thermal maps of the study area. Results from the analysis of the thermal band of the satellite images and the in situ data revealed that differences in vegetation distribution caused differences in temperature variation. The ratio of temperature between urban heat area and green space areas increased rapidly with increasing distances from the green space boundaries. A comparison of temperature of some selected green areas and non-green areas showed marked differences. The three arms zone, a non-green area had a temperature4.2°C higher than National Arboretum, a green area. Louga Road (non-green area) had a temperature 4.47°C higher than Lobito Crescent Park. Thus green areas had relatively lower temperatures than built up areas and bare sources. This shows the important role played by green spaces in mitigating urban heat in urban central areas. The study also utilized Effective Temperature (ET) in calculating the Human Thermal Comfort Index in the study area to further buttress the mitigating effects of green spaces on urban heat distribution.