Land use efficiency of functional urban areas: Global pattern and evolution of development trajectories

TLDR

Last‑generation spatial data modelling integrating Earth Observation, population, economic and other spatially explicit data provides unprecedented detail and international comparability for assessing the sustainability of global urbanisation, and Functional Urban Areas (FUAs)—the economic influence zones of cities—serve as key units for analysing land consumption relevant to spatial planning and policy. The study assesses the Sustainable Development Goals land‑use‑efficiency indicator globally for the first time at the level of Functional Urban Areas. Using statistical modelling, the authors defined each FUA as a city plus its commuting zone, then applied the boundaries of over 9,000 FUAs to estimate land‑use efficiency from 1990 to 2015 by combining population and built‑up area data from the Global Human Settlement Layer. From 1990 to 2015, FUAs in low‑income Global South countries experienced population growth outpacing land consumption, yet across most regions more than half of FUAs improved land‑use efficiency between 2000 and 2015 relative to 1990‑2000, while urban expansion within FUAs has reduced settlement compactness and no systematic advantage in land‑use efficiency is seen inside versus.

Abstract

The application of last-generation spatial data modelling, integrating Earth Observation, population, economic and other spatially explicit data, enables insights into the sustainability of the global urbanisation processes with unprecedented detail, consistency, and international comparability. In this study, the land use efficiency indicator, as developed in the Sustainable Development Goals, is assessed globally for the first time at the level of Functional Urban Areas (FUAs). Each FUA includes the city and its commuting zone as inferred from statistical modelling of available spatial data. FUAs represent the economic area of influence of each urban centre. Hence, the analysis of land consumption within their boundary has significance in the fields of spatial planning and policy analyses as well as many other research areas. We utilize the boundaries of more than 9,000 FUAs to estimate the land use efficiency between 1990 and 2015, by using population and built-up area data extracted from the Global Human Settlement Layer. This analysis shows how, in the observed period, FUAs in low-income countries of the Global South evolved with rates of population growth surpassing the ones of land consumption. However, in almost all regions of the globe, more than half of the FUAs improved their land use efficiency in recent years (2000-2015) with respect to the previous decade (1990-2000). Our study concludes that the spatial expansion of urban areas within FUA boundaries is reducing compactness of settlements, and that settlements located within FUAs do not display higher land use efficiency than those outside FUAs.