Abstract
Most of the shrinking cities experience an unbalanced deurbanization across different urban areas in cities. However, traditional ways of measuring urban shrinkage are focused on tracking population loss at the city level and are unable to capture the spatially heterogeneous shrinking patterns inside a city. Consequently, the spatial mechanism and patterns of urban shrinkage inside a city remain less understood, which is unhelpful for developing accommodation strategies for shrinkage. The smart city initiatives and practices have provided a rich pool of geospatial big data resources and technologies to tackle the complexity of urban systems. Given this context, we propose a new measure for the delineation of shrinking areas within cities by introducing a new concept of functional urban shrinkage, which aims to capture the mismatch between urban built-up areas and the areas where significantly intensive human activities take place. Taking advantage of a data fusion approach to integrating multi-source geospatial big data and survey data, a general analytical framework is developed to construct functional shrinkage measures. Specifically, Landsat-8 remote sensing images were used for extracting urban built-up areas by supervised neural network classifications and Geographic Information System tools, while cellular signaling data from China Unicom Inc. was used to depict human activity areas generated by spatial clustering methods. Combining geospatial big data with urban land-use functions obtained from land surveys and Points-Of-Interests data, the framework further enables the comparison between cities from dimensions characterized by indices of spatial and urban functional characteristics and the landscape fragmentation; thus, it has the capacity to facilitate an in-depth investigation of fundamental causes and internal mechanisms of urban shrinkage. With a case study of the Beijing-Tianjin-Hebei megaregion using data from various sources collected for the year of 2018, we demonstrate the validity of this approach and its potential generalizability for other spatial contexts in facilitating timely and better-informed planning decision support.
Highlights
The “urban shrinkage”, first put forward by [1] as an alternative paradigm of urbanization that is completely different from the traditional “urban growth”, has become an important topic in urban studies
With a case study of the Beijing-Tianjin-Hebei megaregion (BTH) using data from various sources collected for the year of 2018, we demonstrate the validity of this approach and its potential generalizability for other spatial contexts in facilitating timely and better-informed planning decision support
This study proposes a new concept, namely functional urban shrinkage, which is defined as the degree to which the two major aspects related to urban shrinkage, the human activity demand, and the supply of urban built-up areas and associated urban functions are mismatched geographically
Summary
The “urban shrinkage”, first put forward by [1] as an alternative paradigm of urbanization that is completely different from the traditional “urban growth”, has become an important topic in urban studies. Research on this phenomenon has been carried out in Germany [2], the United States [3], and other countries. As China has entered the new era of spatial planning [9], the traditional paradigm of growth-oriented planning is being replaced by a new paradigm that reinforces the coordination between various spatial systems and plans, posing new opportunities as well as challenges for the understanding of urban shrinkage
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