article · City and Environment Interactions
Rapid urban expansion and infrastructure projects in Addis Ababa between 1990 and 2025 have markedly altered the city's thermal landscape. Analysis of multi-temporal satellite imagery using machine learning shows that built-up surfaces expanded from 14.8 percent to 53.3 percent, largely overtaking agricultural land, while total vegetation dropped from 13.8 percent to 8.1 percent. During this 35-year span, the average land surface temperature rose by 5.06 degrees Celsius, causing severe ecological heat stress to affect 48.0 percent of the municipal territory. Urban heat island intensity climbed from 0.40 degrees Celsius to 1.31 degrees Celsius, warming faster than adjacent rural land. Although vegetation and elevation provide substantial cooling effects, targeted corridor greening interventions failed to offset the widespread heating generated by rapid impervious surface expansion across the wider metropolis.
Rapid city growth without sufficient green space leads to dangerous surface temperatures and ecological heat stress. This assessment shows that targeted green corridors alone cannot undo city-wide warming caused by expanding concrete and asphalt. The findings underscore the need for urban planners to integrate thermal comfort indices and mandatory minimum vegetation ratios into municipal master plans to protect expanding African cities from severe microclimate warming.
This applied research demonstrates a machine-learning methodology for municipal satellite monitoring. Urban planning authorities, civil engineering consultancies, and spatial analytics software providers could adapt these models into environmental decision-support tools. Such tools would help municipal governments evaluate the thermal impacts of major infrastructure projects and define minimum vegetation ratios before construction begins. The analytical workflow is tested and validated, but practical deployment would require integration into commercial or public planning software platforms.
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Rapid urbanization and infrastructure expansion are fundamentally reshaping land surface thermal dynamics in Sub-Saharan African metropolises, yet the combined microclimatic impacts of simultaneous urban greening and corridor redevelopment remain understudied. This study systematically evaluated the spatiotemporal thermal and biophysical changes in Addis Ababa, Ethiopia, driven by the Corridor Development Projects between 1990 and 2025. Utilizing multi-temporal Landsat satellite imagery, we employed Random Forest machine learning classification alongside the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Built-up Index (NDBI) to quantify land-use and land-cover (LULC) transformations, surface temperature variations, and ecological severity via the Urban Thermal Field Variance Index (UTFVI). Over the 35-year period, built-up areas expanded nearly fourfold from 14.8% to 53.3%, primarily encroaching upon agricultural lands, while net vegetation cover contracted from 13.8% to 8.1%. Consequently, mean Land Surface Temperature (LST) increased by 5.06 °C (from 29.43 °C to 34.49 °C), expanding severe ecological heat stress (UTFVI ≥ 0.02) to 48.0% of the municipal area, with Bole, Akaki-Kality, and Kirkos emerging as considerable vulnerability hotspots. Bivariate spatial correlations confirmed strong cooling effects driven by elevation (r = −0.60 to − 0.68) and vegetation (r = −0.57 to − 0.71), contrasting with intense surface heating from built-up density (r = 0.54 to 0.63). The surface urban heat island (SUHI) intensity for Addis Ababa increased consistently from 0.40 °C in 1990 to 1.31 °C in 2025, reflecting faster urban warming than rural areas and a strengthening SUHI effect at an estimated rate of 0.026 °C per year over the study period. These findings expose a vital socio-ecological trade-off: localized corridor greening alters microclimate structure but cannot fully counterbalance city-wide warming from impervious surface expansion. Integrating thermal comfort metrics and minimum vegetation cover ratios into spatial planning is essential for climate-resilient urban development.
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DOI: 10.1016/j.cacint.2026.100465
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