Geospatial Assessment of Urban Heat Island in Port Harcourt L.G.A, Rivers State, Nigeria

Abstract

Urban development comes with its inherent challenges such as ecosystem alteration. Remote Sensing and GIS was used to assess the spatiotemporal variation of the surface urban heat intensity in Port Harcourt, Rivers State, from 1986 to 2018. The study period was chosen with specific objectives to examine land use land cover changes and assess the spatial and temporal extent of the land surface temperature(LST), determine a relationship between LULC and LST and examine the urban heat island (UHI) intensity using the Getis-Ord Hotspot Analysis. Landsat TM, ETM+ and OLI images of the study area (1986, 2003 and 2018) were implemented to carry out the study. The results of the land use and land cover analysis revealed that urbanised areas increased and covered 51% of the study area from 1986 to 2018. Vegetative cover reduced drastically between this time period, from 57% in 1986 to 30% in 2018, as forested regions made way for urban development to occur. Bare surfaces reduced in spatial extent over the study period, while water bodies within the study area increased. The results of the land surface temperature revealed that surface temperature increased consistently between 1986 and 2018, which was a direct consequence of the increasing urban areas. In 1986 the average temperature over the study area was estimated at 20.6°C in 1986 to 27.1°C in 2003, increasing to 33.2°C by 2018. The results showed that there is a relationship between urban land and land surface temperature indicated a strong relationship between the two variables, as surfaces with impervious materials were associated with the highest LST values. The number of hotspots within the study area were found to be increasing in number and intensity over the years, with the most concentrations of hot spots found in the northern and central parts of the study area.