Study of Urban Heat Island Trends to Aid in Urban Planning in Nakuru County-Kenya

Abstract

Urban Heat Island (UHI) is a phenomenon characterized by higher surface and atmospheric temperatures in urbanized areas as compared to the surrounding rural areas. This phenomenon is a consequence of increase in Land Surface Temperatures (LST) as a result of trapped heat energy on the surface. The objective of this study is establishing the trends in and relationship between LST and land use/land cover in Nakuru County as it seeks to achieve the ultimate goal to contain the UHI effect. Urban heat island inference was based on the generation of a time series set of Landsat imagery, with particular emphasis on the thermal band. Land use/land cover mapping was conducted using maximum likelihood classification techniques, and this, like the LST, is generated in a time series fashion from 1989 to 2015. Accuracy assessment was conducted in order to give confidence in the classification results. The accuracy of the development was assessed using observed temperature data as recorded by the ground stations at the Kenya Meteorological Department. This study employed Normalized NDVI and NDBI to investigate the variation land use/land cover. Results revealed that over the years, settlement has been on an upward trend in terms of area whereas forests have been decreasing due to deforestation. Also, the land surface temperatures have been increasing over the years. In order to qualify this, the correlation between LST and Land Use change was conducted and it indicated that changes to settlement/urban increased proportionately with Land Surface Temperature.