| Author: | Yu, Peiheng |
| Title: | Capturing open space fragmentation in high–density cities : towards sustainable open space planning |
| Advisors: | Yung, Hiu Kwan Esther (BRE) Chan, Hon Wan Edwin (BRE) Wong, Man Sing Charles (LSGI) |
| Degree: | Ph.D. |
| Year: | 2024 |
| Subject: | Open spaces Public spaces Space (Architecture) -- Psychological aspects City planning -- Social aspects Urbanization Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Building and Real Estate |
| Pages: | xxiii, 243 pages : color illustrations |
| Language: | English |
| Abstract: | The fragmentation of urban open spaces is a significant and complex phenomenon that arises from the self–organisation within the dynamics of contemporary landscapes. This process is largely influenced by anthropogenic interference, which transforms the urban open space system from simple to complicated. In other words, open space evolves from a homogeneous, integral and contiguous structure to one that is uneven, separated and interrupted mosaic structure. Therefore, urban studies have been focusing on assessing the fragmentation of open spaces and developing sustainable strategies for high–density cities. Nevertheless, there is insufficient documentation of the numerous scenarios that make up different forms of fragmentation as well as the intricate characteristics of open space fragmentation. This lack of comprehensive documentation could potentially result in the implementation of inapplicable control regulations and the emergence of controversial results. Moreover, the multifaceted nature of urbanisation and the complication of its heterogeneous impact on the fragmentation of open spaces has been largely overlooked. Whether open space fragmentation has made existing spatial inequality worse is still unknown. In light of these issues, this research attempts to address these problems by outlining an approach for describing the patterns, forms and scenarios of open space fragmentation. It also seeks to investigate open space fragmentation and spatial equity issues in towns at various phases of high–density urbanisation growth. The results of this study, which are given the data from Hong Kong’s built–up area, as a representative case with fragmentation issues, could serve as a broadly applicable reference. A set of metrics was put forth in order to achieve the main aim and capture the intricate interactions among different forms of fragmentation. Principal components analysis has verified the validity of these indicators for their broad use in open space fragmentation studies. The relationship between forms of open space fragmentation and urbanisation has been further investigated using the factor and interaction modules of the geographical detector model. The characteristics of open space fragmentation forms in both old towns and new towns have been elucidated by landscape pattern analysis and principal components analysis. The Theil index and spatial matching have been used to illustrate spatial horizontal equity and vertical equity on the basis of social economic status and demographic characteristics. First, this research illustrates that there are two types of open space fragmentation forms: morphological (use, internal, extensive and shape) and connectional (location) fragmentation, which encompass nine different scenarios. The Kowloon region has the highest fragmentation record (0.259), followed by Hong Kong Island and the New Territories regions (0.237 and 0.187), indicating spatial variation in open space fragmentation. The average open space fragmentation value of the old towns is 0.250, a significant amount higher than the new towns’ 0.187 value. Compared to new towns, old towns have more than one type of intricate scenario. Secondly, this research suggests that land urbanisation, represented by the proportion of construction land in total land, has the highest explanatory power for spatial differentiation in open space fragmentation, followed by social and population urbanisation factors. Moreover, the bivariate and nonlinear enhancement interactions are the relational interrelations of open space fragmentation drivers. The most significant bivariate enhancement interaction for use fragmentation form and the largest nonlinear enhancement interaction for internal fragmentation form are found in social urbanisation and land urbanisation. Open space fragmentation is a result of adaptation to elements related to population, land and social urbanisation; such self–organisation phenomenon has been further highlighted throughout history. Thirdly, the statistics show that the mean values of use fragmentation, internal fragmentation, extensive fragmentation and location fragmentation, in addition to shape fragmentation, are all higher in old towns than in the new towns. Furthermore, internal fragmentation form, deeply rooted in horizontal inequalities, manifests more prominently in old towns in comparison with new towns. This distinction underscores a greater degree of spatial horizontal inequality within the former. Specifically, certain vulnerable demographics including children, the elderly, low education groups, immigrant groups and unemployed groups are disproportionately affected by spatial vertical inequalities in these old towns. Unlike their counterparts in newer towns, these groups face heightened challenges due to their reliance on open spaces. Overall, this research introduces an innovative framework for ascertaining the measurements, forms and scenarios of open space fragmentation. Through this framework, a comprehensive analysis and deeper understanding of open space fragmentation's detrimental impacts are achieved, enhancing open space strategies for management in high–density cities. The methodology enables the identification and quantification of various forms and scenarios of open space fragmentation, regarded as instrumental in selecting precise indicators and developing tailored mitigation strategies. There is evidence that the old towns have more complicated and diverse scenarios and a higher degree of open space fragmentation than the new towns. Adding to this contribution, by utilising spatial horizontal and vertical equity lenses, this work further advances the bounds of open space fragmentation. This research emphasises the crucial role that urban self–organisation processes play in highlighting how children, the elderly, low–education groups, immigrant groups, and unemployed groups are disadvantaged by the fragmented open spaces that are a part of the built environment. This research also takes into account the intricate links among the numerous fragmentation forms and scenarios, offering a holistic and precise reference for realistic application. In contrast to related prior research that required a large amount of resources, labour and time to scale up, this approach solely relies on data that is available to the public. Open space is extremely fragmented in numerous regions of the world. The methodological flow of open space fragmentation is workable, reproducible and adaptable for assessing open space fragmentation in other similar high–density cities worldwide that share comparable political or socioeconomic characteristics with Hong Kong. These findings contribute to the knowledge base concerning how urbanisation affects open space fragmentation and provide insightful recommendations for enhancing open space management practices. Most importantly, this proposed framework could be used to investigate the location of open space fragmentation and to evaluate the efficacy of pertinent planning and land use policies aimed at addressing inequalities. The knowledge gathered from this study provides a crucial reference for informing open space planning both domestically and internationally. |
| Rights: | All rights reserved |
| Access: | open access |
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