Recognition And Spatial Heterogeneity Of Urban Villages In The Guangdong-Hong Kong-Macao Greater Bay Area Integrating Remote Sensing And Social Sensing

The high intensity of urbanisation has caused the GBA(Guangdong,Hong Kong and Macao Greater Bay Area)to face an shortage of land resources.As an important national strategic area,the GBA requires comprehensive improvement in the quality of urbanisation and urban regeneration in accordance with local conditions.As a world-class urban agglomeration,the GBA faces one of the urban problems caused by the rapid urbanisation-urban villages.Urban villages are disconnected from city development and suffer from poor livability,including overcrowding,lack of infrastructure and security risks.Urban regeneration projects of urban villages can help to revitalise the stock of land resources.In this context,the construction of an effective method for recognizing urban villages and the analysis of their spatial heterogeneity can provide theoretical references for urban regeneration research.With the development of remote sensing technology and information communication technology,a large amount of multi-source spatial data has laid a solid data foundation for urban regeneration research.From the perspective of remote sensing and social sensing,this study carries out a detailed research of urban villages at the urban agglomeration level in the following three aspects.(1)Model construction of urban villages.In this study,the model of “urban village” is constructed for the "urban" and "village" aspects.In particular,dur to the inconsistency of administrative and physical boundaries of Chinese cities,the "urban" area is defined as the physical boundary of cities.Secondly,the “village” landscape of urban villages in the study area is classified into two categories: the middle-& highrise urban villages,and the low-rise urban villages,based on the standard landscape types of local climate zone.In addition,remote sensing data and social sensing data were constructed into multi-source spatial features,and the correlation between the samples of urban villages and the features was analysed.(2)The hierarchical recognition method of urban villages integrating remote sensing and social sensing.This study proposes a hierarchical framework for the recognition of urban villages from the perspective of geographical scale effect.The framework combines the advantages of fusing the remote sensing features and social sensing features,combining large-scale neighbourhood information and small-scale local information.A case study in the Futian-Luohu central urban area of Shenzhen is conducted.The map of urban villages at a spatial resolution of 2 m is obtained,and the accuracy of the proposed method can reach an overall accuracy of 98.68% and a Kappa coefficient of 0.807.Moreover,the gain effects of fusing multi-source spatial features and using the hierarchical recognition framework on the spatial recognition of urban villages are verified.(3)Multi-scale spatial heterogeneity of urban village landscapes in the GBA.This study recognizes the landscapes of urban villages in the GBA and then analyzes their spatial heterogeneity at multi-scale.Specifically,the spatial patterns of urban villages in the GBA are analyzed at the city scale,street scale and landscape patch scale respectively.The results show that at the city scale,the more developed the economy is,the more urban village landscapes exist in the GBA;at the street scale the urban village landscape of the GBA show has a spatial structure of double agglomeration centre;at the landscape patch scale,the rank-size distributions of urban villages in most cities of the GBA are found to confirm Zipf’s law.Finally,this study tries to give sugguestions for urban regeration and planning research based on the discovered patterns.In conclusion,this study constructs a hierarchical framework for urban villages recognition that integrates remote sensing and social sensing,and explores the spatial heterogeneity of urban villages in the GBA at multiple scales,which helps urban planners understand the spatial patterns of urban villages and provides theoretical support for the formulation of urban regeneration policies in the GBA.