Simon Mang’erere Onywere’s research while affiliated with Kenyatta University and other places

Purpose This paper aims to assess the current and future dynamics of land cover transitions and analyze the vegetation conditions in Abuja city since its establishment as the capital of Nigeria in 1991. Design/methodology/approach A random forest classifier embedded in the Google Earth Engine platform was used to classify Landsat imagery for the years 1990, 2001, 2014 and 2020. A post-classification comparison was used to detect the dynamics of land cover transitions. A hybrid simulation model that comprised cellular automata and Markovian was used to model the probable scenario of land cover changes for 2050. The trend of Normalized Difference Vegetation Index was examined using Mann–Kendall and Theil Sen’s from 2014 to 2022. Nighttime band data from the National Oceanic and Atmospheric Administration were obtained to analyze the trend of urbanization from 2014 to 2022. Findings The findings show that built-up areas increased by 40%, while vegetation, bare land and agricultural land decreased by 27%, 7% and 8%, respectively. Vegetation had the highest declining rate at 3.15% per annum. Built-up areas are expected to increase by 17.1% between 2020 and 2050 in contrast with other land cover. The proportion of areas with moderate vegetation improvement is estimated to be 15.10%, while the proportion of areas with no significant change was 38.10%. The overall proportion of degraded areas stands at 46.8% due to urbanization. Originality/value The findings provide a comprehensive insight into the dynamics of land cover transitions and vegetation variability induced by rapid urbanization in Abuja city, Nigeria. In addition, the findings provide valuable insights for policymakers and urban planners to develop a sustainable land use policy that promotes inclusivity, safety and resilience.

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.