Demographic Structure and Center-Periphery Gradient in Greater Sfax: A Spatial Analysis

Greater Sfax has experienced strong urban expansion and population growth in recent decades, with differences between the center and the periphery in population, age structure and built-up area. This study examines these differences across the 44 administrative sectors of Greater Sfax. Demographic data come from the National Institute of Statistics for 2024, while built-up data come from GHSL 2018. The analysis considers population density, age structure, dependency ratio, distance to the center and share of built-up area. Thematic mapping, Spearman correlation and K-means classification were used. The results show that the share of under-15s increases from 19.61% within 5 km of the center to 24.05% beyond 15 km. Pooled population density decreases from 4604 to 123 inhabitants/km², while the pooled built-up share decreases from 34.77% to 2.66%. Population density and built-up share are strongly correlated (ρ = 0.806). However, the gradient is not regular: the dependency ratio does not follow the same trend, and local exceptions appear. K-means classification distinguishes four types. Central sectors are generally denser and more built-up, while peripheral sectors are younger and less dense. Distance to the center is important, but it does not explain all the differences in Greater Sfax.