Impacts of urban shrinkage on the built environment and its environmental sustainability: an analytical review

The proliferation of case studies of shrinking cities in recent years has stimulated intense debate on the impacts of urban shrinkage. However, assessing the impacts of urban shrinkage from a comprehensive perspective could be more present. Also, there is a lake of analytical review of historical studies about the impacts of urban shrinkage. The built environment has different characteristics under different urban development patterns involving infrastructure, services, and social, economic, and structural factors, which provides a best practice for exploring the impacts of urban shrinkage. This study synthesizes the literature surrounding urban shrinkage and built environment changes, identifying that urban shrinkage notably affects the different components of the built environment and gives rise to four related environmental and sustainability impacts involving urban landscapes and structures, ecological sustainability, socioeconomic vitality, and residents' perceptions. Furthermore, there are interactions between the environmental and sustainability impacts, involving trade-offs and synergies between residents' perceptions, ecological sustainability, and socioeconomic vitality. The study also summarized the mainstream methods for assessing the impacts of urban shrinkage and explored the effects of urban shrinkage management strategies on improving the built environment. Finally, a framework for future direction is presented for the final to integrate the theories of urban shrinkage, people and land relationship, and sustainable urban development to guide further exploration in the field. In summary, this study implies that restoring and upgrading the built environment can pave the way for a common goal for long-term sustainable development. The value of this study is to provide relevant researchers with the knowledge to understand the developing frontiers of urban shrinkage impacts on built environments.