Path-Dependent Urban Expansion in Arid Cities: A Multi-Decadal Remote Sensing Analysis and ANN–CA–Markov Modelling of Saudi Arabian Cities (1984–2034)

Urbanisation in arid environments evolves through distinctive spatial processes shaped by abundant developable land, strong environmental constraints, and infrastructure-led planning. Despite the rapid growth of Saudi Arabia’s major cities, the long-term interplay between land-cover change, demographic dynamics, and future expansion pathways remains insufficiently understood. This study reviews a consistent four-decade record of urban growth (1984–2024) for Riyadh, Jeddah, Makkah, and Madinah and examines it through an integrated framework combining multi-sensor remote sensing, demographic indicators, landscape fragmentation metrics, and ANN–CA–Markov modelling. Across all four cities, urban expansion follows a shared three-phase trajectory: an initial phase of fragmented and discontinuous growth (1984–1994), a prolonged period of corridor-driven consolidation aligned with major infrastructure investments (1994–2014), and a recent shift toward outward suburban diffusion (2014–2024). While this temporal sequence is highly synchronised, its spatial expression differs markedly. Fragmentation metrics (Patch Density and Edge Density) identify the mid-2010s as a peak of morphological discontinuity, most pronounced in the basin-confined cities of Makkah and Madinah. Jeddah, constrained by its coastline, retains a predominantly linear growth form, whereas Riyadh expands multi-directionally across an unconstrained plateau. Coupling demographic change with land consumption shows that population growth alone cannot explain observed expansion patterns: Riyadh maintains relatively stable land-use efficiency, while Jeddah and Makkah experience phases of disproportionately land-intensive development. The ANN–CA–Markov simulations reproduce observed spatial patterns with high agreement (Kappa 0.61–0.85) and project continued path-dependent expansion to 2034, with future growth largely reinforcing established corridors rather than generating new development fronts. By explicitly linking multi-decadal reconstruction, demographic efficiency, spatial fragmentation, and predictive modelling, this study advances a path-dependent interpretation of arid-city urbanisation and provides a transferable framework for understanding and anticipating urban growth in rapidly transforming desert environments.