Research note: Method for delineating urbanized areas based on mean land parcel area

The expansion of growing cities into neighboring areas, known as urban sprawl, is reflected in morphological changes to the land parcel pattern. This paper examines urban cadastral parcel patterns, assuming that population-driven land demand drives fragmentation, and that the degree of fragmentation is proportional to local population density. Adopting a radial analysis of cities, the study analyzes 21 urban systems across three continents to examine how mean land parcel area scales with distance from the city center. The results reveal that mean parcel area increases exponentially within urbanized areas before stabilizing in the surrounding non-urban zone, thereby providing a clear structural threshold for delineating the extent of urbanized land. The characteristic distance of this exponential regime scales with the square root of total city population, showing that the spatial extent of high-degree parcel fragmentation associated with urbanization increases systematically with city size. This result is consistent with radial-scaling findings for urban land use, but is derived here independently from cadastral parcel data. This analysis offers a new approach to understanding spatial urbanization and the morphological evolution of the land parcel pattern as cities expand, while highlighting cadastral data as a valuable source for studying the spatial urbanization.