A planning framework to explore shortages and improvements of urban green space provision at the metropolitan scale using novel nSFCA proximity indices

Where and how much to expand or create new urban green spaces (UGSs) in a city, to fulfill the shortages of such spaces under population pressure, is a global problem that lacks research attention. This study creates new indices based on improved step floating catchment area methods that integrate factors related to transportation, residents, and green spaces in the real world. These are used to measure UGS provision by proximity and estimate UGS shortage under the city's population pressure and UGS development standards. We make specific proposals, including the quantity, location, and priority of expanding and building new UGSs, to improve proximity at the metropolitan scale. We take the metropolitan area of Shanghai, China as the study site, demonstrate its very limited UGS provision in terms of proximity, and show that shortages at the neighborhood level mainly come from residents being located out of UGS service radii; shortages at the city level and community level mainly arise because the green space areas provided for the residents within the service areas do not meet relative standards. Building new green spaces provides a neighborhood-level service that is small in area but large in number, and locating suitable spaces according to priority proposal results is the most important and efficient path for Shanghai to achieve its goal of having only a 500 m distance to the nearest UGS for residents. The extensions needed for most green spaces under-meet area standards in Shanghai were not very large in area. But extensions with large areas and high priority are mainly distributed in the central city area, which is already quite strained in available land. It might be difficult to expand all these green spaces, and instead it might be easier to locate other available land and make new building decisions according to our priority proposal results. With these detailed and specific measures, effectively and efficiently improving the UGS service can be obtained according to the demands of the residents of Shanghai.