GEOSPATIAL DIMENSIONS OF LAND COVER TRANSITIONS AND LAND SURFACE TEMPERATURE IN ABUJA CITY, NIGERIA
Keywords: Urban Heat Island, Land Surface Temperature, Land Cover, Thermal Comfort, Google Earth Engine
Abstract. Urbanization is often accompanied by succession of underlying land cover with impervious surfaces. Built intensification significantly alters the surface energy budget making cities warmer than their outlying suburbs, which signifies an ecological deterioration. Landsat imageries with scene covering Abuja city is processed using Google Earth Engine platform to estimate land cover and land surface temperature over the span of 30 years (1990–2020). Dimensions of land cover transitions were examined in-terms losses, gains, swaps, net-change and persistency. Thermal signature of each land cover type was estimated using land surface temperature. Urban thermal field variance index is computed from land surface temperature to evaluate the thermal conditions in the city. Results indicate that net-changes for built-up exhibited gains of 40% while agricultural land, bare-land and vegetation exhibited loss of 27%, 7% and 8% respectively. Built-up also showed the highest proportion of persistence (12%). Results shows that land surface temperature has increased by 2.01 °C from 1990 to 2020. Agricultural land, bare-land and built-up were found with the highest temperature. Lowest temperature was found in waterbody and vegetation. The ecological evaluation showed that 47% of the city is experiencing bad to worst thermal condition. These findings provide further information that can contribute towards an informed spatial planning in cities.