Lokoja, the capital of Kogi State, Nigeria, situated at the confluence of the Niger and Benue Rivers, has experienced rapid urban expansion alongside heightened environmental risks, including flooding and ecosystem degradation. Using multi-temporal Landsat imagery (2000, 2010, 2020, 2024), Random Forest classification, and landscape metrics, this study analyses spatio-temporal patterns of urban growth and fragmentation in this underrepresented mid-sized African city. Urban land cover expanded from 6668 ha in 2000 to 15,985 ha in 2024 (net ~140% growth), following a non-linear trajectory of rapid expansion (2000–2010), partial consolidation (2010–2020), and renewed growth with intensified fragmentation (2020–2024). This growth caused severe ecological impacts: dense forest declined by 99.7% (from 373 ha to 1 ha), woodland by 73.9%, and core natural land cover by 23% to 13.8% of the landscape, below critical ecological thresholds. Edge density rose by 121%, exacerbating urban heat, runoff, and biodiversity loss, while apparent gains in grassland largely reflect secondary succession rather than recovery. This study recommends enforcing development restrictions below 10 m in elevation, with 100 m riparian buffers; restoring 500 ha of native corridors; mandating 20% urban tree canopy cover; and establishing community-based green space monitoring. The findings provide empirical insights into sustainability challenges facing mid-sized African cities and offer transferable strategies for ecologically sensitive urban planning.

Rapid peri-urban expansion in Ikorodu Local Government Area (LGA), Lagos State, Nigeria, has intensified local surface thermal conditions. Yet, the area lacks a dedicated, quantitatively grounded framework linking urban heat to green infrastructure (GI) planning. This study analyses spatio-temporal Surface Urban Heat Island (SUHI) dynamics in Ikorodu LGA across four epochs (1990, 2002, 2013, and 2025) using multi-temporal Landsat imagery (TM, ETM+, OLI/TIRS, OLI-2/TIRS-2) processed in Google Earth Engine, ArcGIS Pro, and Python, and translates the results into a spatially explicit GI priority framework. Built-up cover expanded from 8.31% to 46.26% of the LGA between 1990 and 2025, while vegetation declined from 78.39% to 37.27%; mean land surface temperature (LST) rose from 33.24 °C to 37.95 °C, and SUHI intensity from 2.98 °C to 5.86 °C. Random Forest land-cover classification achieved 96.8-99.5% overall accuracy across epochs. Interpretable machine learning (XGBoost regression with SHAP explanation) on a 468-cell fishnet grid explained 81-97% of spatial LST variance and revealed a shift in the dominant thermal driver, from NDBI (spectral built-up intensity) in 1990-2002 to BuiltupDensity (spatial built-up density) in 2013-2025, reaching a mean absolute SHAP value of 3.24 °C by 2025. Overlaying 2025 heat-exposure and vegetation-deficit classifications identified 18.45 km² (4.47% of the LGA) as priority zones for GI intervention, concentrated in the urban core. The findings provide a replicable, multi-decadal thermal baseline and an evidence-based, spatially targeted GI prioritization tool directly applicable to the Ikorodu Sub-Region Master Plan (2016-2036) and to comparable rapidly urbanizing West African peri-urban LGAs.