03-02: New ways of measuring urban extent
Definition matters. Metropolitan areas and agglomeration economies in a large developing country
1World Bank, United States of America; 2Erasmus University Rotterdam
A variety of approaches to delineate metropolitan areas have been developed. Systematic comparisons of these approaches in terms of the urban landscape that they generate are however few. Our paper aims to fill this gap. We focus on Indonesia, and make use of the availability of data on commuting flows, remotely-sensed nighttime lights, and spatially fine-grained population, to construct metropolitan areas using the different approaches that have been developed in the literature. We find that the maps and characteristics of Indonesia’s urban landscape vary substantially depending on the approach used. Moreover, combining information on the metro areas generated by the different approaches with detailed micro-data from Indonesia’s national labor force survey, we show that the estimated size of the agglomeration wage premium depends nontrivially on the approach used to define metropolitan areas.
Densification vs. expansion: recent findings for a global sample of cities
New York University, United States of America
When the populations of cities grow, they can be accommodated within the existing footprints of cities or in newly-built expansion areas. Urban planners, have called for the densification of existing footprints, but there has been little data to measure the extent to which densification has been effective. Using a new dataset, a global stratified sample of 200 cities of 4,231 cities that had 100,000 people or more ind 2010, we explore the share of the populations added to cities between 1990 and 2015 that were accommodated in areas built before 1990, and compare it with the share accommodated in expansion areas built between 1990 and 2015. We also explore the extent to which the built-up areas in pre-1990 footprints increased in density, and the extent t to which vacant areas within pre-1990 footprints were built upon. We then seek to explain why some cities densified while others expanded.
Accurately monitoring urbanization at global scale – the world settlement footprint
1German Aerospace Center - DLR, Germany; 2Google Inc., USA
Reliably monitoring global urbanization is of key importance to properly estimate the distribution of the continually expanding population, along with its effects on the use of resources, transport, socioeconomic development, human health, etc. To this purpose, in order to accurately outline the actual settlement extent globally we generated the World Settlement Footprint (WSF) 2015 , i.e. a 10m resolution binary mask derived by jointly exploiting multitemporal optical and radar satellite imagery, which outperforms all other existing similar layers. Furthermore, to characterize the urbanization occurred in the last three decades, we are currently generating the WSF Evolution, i.e. a novel dataset aimed at outlining the growth of settlement extent globally at 30m spatial resolution and high temporal resolution (i.e., 5-year or even finer) from 1985 to 2015. The WSF Evolution will be released in 2019 and is expected to become a revolutionary product in support to a variety of end users.
Characterizing and managing urban expansion for higher equity, productivity, and environmental quality in the global south
1World Resources Institute, WRI, United States of America; 2Yale University, , United States of America
This paper examines how urban expansion can be managed in a way that achieves more equitable access to core urban services for the under-served, while bringing wider economic and environmental benefits to cities. It presents new remote sensing analysis of the growth in urban built up area over a decade in 499 cities with population greater than one million and develops new metrics to measure changes in their outward and upward growth. The analysis highlights regional trends in urban expansion, differences in urban structure within and between cities, and combines this information with urban population and economic growth projections. The paper then discusses some driving forces for outward expansion, highlighting key equity challenges of the phenomenon in cities of the global South. We argue that while some urban land expansion is inevitable with increasing urbanization, the pace, scale, and nature of this expansion can be managed through some proven strategies.