Analysis of the urban surface thermal condition based on sky-view factor and vegetation cover

Abstract

The analysis of the surface thermal condition within the urban area of Akure City, Nigeria, has been investigated in this study. Surface heat flux, which is an expression of the thermal environment was estimated from Landsat 8 satellite image based on the Surface Energy Balance Algorithm for Land (SEBAL) model. The study applied the use of sky view factor and vegetation cover in identifying the variation of the surface heat flux and Land Surface Temperature (LST) within sixteen (16) different urban sites. The surface heat flux distribution at these sites differed distinctly in magnitude and intensity according to the sky-view and surface characteristics. The areas with the highest Sensible Heat flux (H) and Land Surface Temperature (LST) were notably the areas with higher sky-view factor and lower vegetation cover abundance. Two of the sites with the lowest intensities of H and LST had sky view factors of 0.82 and 0.42. However, the areas differed in the vegetation composition; one area was a park while the other was composed of a mixture of scattered trees and grasses. Correlation analysis revealed that over the city, surface features had more contribution to the variation of heat flux as well as LST compared to the sky-view factor. The information presented in this study is essential in sustainable urban planning and adequate response to urban thermal risks associated with the changing patterns of urban geometry and land use within the region.