Urban morphogenesis of Bejaia (1833-1962): A GIS-based framework for architectural heritage planning

Evidence-informed architectural heritage planning requires a robust understanding of long-term urban morphogenesis. This paper reconstructs the spatial evolution of Bejaia (Bougie), Algeria, from 1833 to 1962 and tests how diachronic Geographic Information System (GIS)-based indicators can substantiate safeguarding priorities in Mediterranean coastal historic centres. A multi-source corpus of alignment plans, topographic and cadastral maps, port documents and administrative reports was critically assessed, georeferenced and vectorised to produce comparable urban-form states. A morphological geodatabase of built-up envelopes, street hierarchy, squares, facilities and boundaries supported measurements of land take, growth rates, block fragmentation and Gravelius compactness, with uncertainty addressed through source cross-checking. Results reveal three growth regimes: limited expansion up to 1890 (+11.4 ha; 0.20 ha/year), structured growth from 1890 to 1958 (+78.2 ha; 1.15 ha/year) and abrupt acceleration from 1958 to 1962 (+52.7 ha; 13.18 ha/year). Across phases, inherited boulevards, former defensive boundaries and the port-city interface emerge as active structures that organise urban continuity and guide phased conservation, regeneration and stitching interventions. The protocol is, in principle, transferable to comparable coastal and heritage cities with sufficient archival and cartographic coverage.