Where is the peri-urban? a working definition and global typology

As the fastest expanding land use globally is the peri-urban, this raises new challenges and insights for urban research and policy. The peri-urban is very broadly, the area between urban and rural, or in the outer gravity field of urban areas: in more detail, there are many definitions, such as by population density, economic activity, travel patterns, urban infrastructure, land cover, or bio-regions. The present chapter starts with an overview and conceptual framework and then sets out the definitions developed by the Peri-cene project ([email protected]). Building on the international classifications of GHSL / OECD, this proposes a working definition for peri-urban areas: within the “functional urban area” (FUA), areas with population densities of 0–300 pp/km2, and outside the FUA, with 50–300 pp/km2. This definition then covers a very wide range of types: from the high-density desakotas (urban-rural combinations) of South East Asia to the extended sprawl and “edge cities” of the North American model. Secondly, we apply these definitions to a sample of 21 city regions, covering 10% of the global urban population. Extrapolating from the sample, total peri-urban land around the world could be in the order of 1.8 million km2 with a growth rate of 3% per annum. Thirdly, we set up a global typology that overlays macro-scale changes on peri-urban land use, population, social inequality, climate risk, vulnerabilities, and governance capacity. From this sample, distinct peri-urban types can be highlighted for further investigation. Fourth, we look at the internal structure of each city-region, via a series of analytic maps, charting by density bands the 25-year growth of peri-urban areas, with a typology of urban restructuring. The chapter concludes with a further research agenda on this very topical issue of the peri-urban.