A multidimensional morphological diagnosis of urban sprawl in the context of Melbourne’s Urban Growth Boundary

Urban sprawl remains an impediment to sustainable development, generating inefficient land-use, escalating infrastructure costs and environmental degradation. Urban Growth Boundaries (UGBs) are widely adopted to encourage compact growth, but their effectiveness depends not only on curbing outward expansion but also on the morphological qualities of development within the boundary. Existing evaluations often emphasise boundary compliance, overlooking internal urban morphology. This study develops a multidimensional, spatial-analytic framework to evaluate the performance of Melbourne’s UGB between 2000 and 2020. By integrating Shannon’s entropy, Local Indicators of Spatial Association (LISA), and landscape metrics, the analysis quantifies spatial dispersion, land-use homogeneity, and settlement patterns using Landsat imagery. The results show that sprawl persists despite containment, with relative entropy increasing from 0.84 to 0.88, edge expansion emerging as the dominant growth mode, and fringe local government areas characterised by dispersed, mono-functional, and poorly accessible development. In contrast, inner areas retained compact, mixed-use, and transit-accessible forms. The study introduces a three-tier morphological typology linking spatial forms to differentiated planning responses. By aligning measurable spatial outcomes with UGB objectives, the study demonstrates how integrated spatial metrics can serve as a diagnostic tool for assessing containment policy performance, detecting emerging sprawl trajectories, and supporting adaptive, spatially differentiated growth management strategies.