Why is determining peri-urban area boundaries critical for sustainable urban development?

In the age of climate change, for many cities around the globe seeking sustainable urban development is a key necessity. Nonetheless, many fail to develop effective policies when it comes to peri-urban growth, where these areas experience rapid land use transition, and become urbanized in a short period of time. Such transition poses a risk to sustainable urban development. This study provides evidence on the consequences of not clearly determining peri-urban area boundaries by placing a metropolitan region under the microscope. The study uses a remote sensing approach to determine peri-urban growth in the Brisbane Metropolitan Region, Australia. The changes that took place for a period of 30 years (1989–2019) are undertaken to map the level of peri-urbanization of the case study region, and the peri-urban area boundary is compared with the regional plan's growth boundaries. The study findings inform that: (a) There exists a significant contrast between the actual peri-urban area boundary and the boundary estimate upon which the regional plan bases its policies; (b) The lack of a clearly demarcated peri-urban area boundary caused the transition of significant size greenfield sites to urban uses, and; (c) Not clearly determining peri-urban area boundaries jeopardized achieving the region's sustainable development goals.