Shape of cities and built patterns in Burkina Faso: insights from advanced fractal analyses

Cities across Africa are expanding rapidly reshaping urban landscapes and transforming many rural areas into sprawling peri-urban zones and emerging cities. Accurate, data-driven analyses are needed to understand these dynamics and guide sustainable urban planning. This study examines the shape of built patterns in Burkina Faso using open-access fine-grained building footprint data. We first analyzed 60 cities with the fractal-based MorphoLim method to compute the inter-building distance threshold that marks the morphological limit of each city. We then compared cities using a series of morphological indices, among which fractal indices. Subsequently, we combined Geographically Weighted Fractal Analysis and a scale-invariance metric to create an original typology of local built patterns in Burkina Faso. Our findings reveal considerable morphological diversity among Burkinabe cities, in terms of inter-building distance thresholds, fractal dimensions, and fractal differences between the cities and their peripheries. The typology identifies eleven sub-classes of built patterns and shows that suburbanization remains largely limited to major cities such as Ouagadougou and Bobo-Dioulasso. Furthermore, it allows us to detect emerging urban areas that are not officially recorded. Finally, our study offers new insights into urban forms in West Africa and provides a replicable framework for morphological comparisons in data-scarce regions. • 60 cities of Burkina Faso are delineated morphologically with a fractal method. • The built fabric of 60 cities and their periphery is characterised using 9 indices. • Burkinabe built patterns are classified into four classes and 11 subclasses. • Suburbanization is limited to large cities, which are absorbing neighbouring towns. • Large, yet unrecognised, urban areas are emerging, particularly in the south.