Spatio-Temporal Analysis of Urban Expansion in Awka and its Environs, Nigeria Using Sentinel-2 Satellite Imagery and Google Earth Engine (2021 to 2026)

DR, ADEBOBOYE JAMES ADEYEMI, Adaobi Melvina Olisa AMO , CHINEDU ERNEST ANADEBE, EVAWERE OKPUGWO, ODO KINGSLEY OFORBUIKE, SYLVESTER EKWEALOR

Abstract
Rapid urbanization in secondary administrative and educational hubs across sub-Saharan Africa presents significant challenges for regional planning, infrastructure development, and sustainable resource allocation. This study evaluates the spatio-temporal dynamics of urban expansion in Awka and its environs Anambra State, Nigeria, between 2021 and 2026 using cloud-based remote sensing infrastructure. By leveraging Google Earth Engine (GEE) and multi-temporal Sentinel-2 Surface Reflectance imagery, the Normalized Difference Built-up Index (NDBI) was computed across dry-season composites to isolate concrete and structural surfaces from surrounding vegetation and bare soil.
The findings reveal an intensive peri-urban transformation of the landscape: the built-up area surged from a baseline of 239.87 hectares in 2021 to 2,752.91 hectares by 2026. This represents a net urban expansion of 2,513.04 hectares, translating to an extraordinary percentage growth rate of 1,047.67% over the five-year period, supported by a model validation accuracy of 98.50% and a Kappa coefficient of 0.98. Spatial clustering of new development was predominantly observed along the Okpuno, Ifite and Awka-Enugu expressway corridors, driven largely by educational expansion and demographic influx. The results demonstrate the efficacy of cloud-native geospatial computing for monitoring rapid urban sprawl, providing essential empirical metrics to guide master plan enforcement, real estate investment modeling, and municipal infrastructural planning.