Simulating Block-Level Urban Expansion for National Wide Cities

Ying Long,Kang Wu

doi:10.3390/su9060879

Abstract

Large-scale models are generally associated with large spatial modelling units, for example, counties or super grids (several to dozens of km2). Few applied urban models can achieve a large spatial coverage with irregular spatial units due to data availability and computation load. The framework of automatic identification and characterization of blocks developed by Liu and Long (2016) makes such an ideal model possible by establishing the existing urban blocks using road networks and points of interest for very large areas (e.g., a country or a continent). In this study, we develop a mega-vector-blocks cellular automata model (MVB-CA) to simulate urban expansion at the block level for 654 Chinese cities. The existing urban blocks in 2012 were used for initiating the MVB-CA and are generated using multi-levelled road networks and ubiquitous points of interest. We then simulate block-based urban expansion of all the cities from 2012 to 2017. The national spatial development strategies of China are discussed extensively by academia and policy makers, while the baseline scenario and other simulated urban expansion scenarios have been tested and compared horizontally. As one of the first block-based urban expansion models at a national scale, its academic contributions, practical applications, and potential biases are also discussed in this paper. The developed MVB-CA using general approaches is also applicable for other counties.

Highlights

This study develops a vector cellular automata model for simulating urban expansion at the block level for all Chinese cities
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Total urban land areas estimated by business-as-usual scenario (BAU) are 62,835 km2 in 2017, an increase of 38.5% compared to 45,361 km2 of urban land in 2012

Summary

Introduction

This study develops a vector cellular automata model for simulating urban expansion at the block level for all Chinese cities. By the end of 2012, urban land area in China had reached 45,361 km, an increase of 608.6% compared to 1983 Such an extraordinarily expansion of these cities has put a great pressure on natural resources and ecological environments [6]. Under such a social-economic background, Chinese urban expansion has attracted extensive attention internationally and locally. These efforts have aimed at identifying urban spatial morphology and growth boundaries [7,8], monitoring temporal-spatial process and pattern [9,10,11,12], detecting driving forces and mechanisms [13,14], simulating temporal-spatial process [15], analyzing future scenarios [15], and assessing ecological and environmental impacts [16]. Several studies explored simulation methods and analysed the impending scenarios generally based on a micro-level or a mid-level scale but failed to meet the needs of urban dynamic spatial modelling at large scales

Results

Discussion

Conclusion