Quantitative Estimation of the Velocity of Urbanization in China Using Nighttime Luminosity Data

Ting Ma,Zhan Yin,Chenghu Zhou,Baolin Li,Susan Haynie

doi:10.3390/rs8020094

Abstract

Rapid urbanization with sizeable enhancements of urban population and built-up land in China creates challenging planning and management issues due to the complexity of both the urban development and the socioeconomic drivers of environmental change. Improved understanding of spatio-temporal characteristics of urbanization processes are increasingly important for investigating urban expansion and environmental responses to corresponding socioeconomic and landscape dynamics. In this study, we present an artificial luminosity-derived index of the velocity of urbanization, defined as the ratio of temporal trend and spatial gradient of mean annual stable nighttime brightness, to estimate the pace of urbanization and consequent changes in land cover in China for the period of 2000–2010. Using the Defense Meteorological Satellite Program–derived time series of nighttime light data and corresponding satellite-based land cover maps, our results show that the geometric mean velocity of urban dispersal at the country level was 0.21 km·yr−1 across 88.58 × 103 km2 urbanizing areas, in which ~23% of areas originally made of natural and cultivated lands were converted to artificial surfaces between 2000 and 2010. The speed of urbanization varies among urban agglomerations and cities with different development stages and urban forms. Particularly, the Yangtze River Delta conurbation shows the fastest (0.39 km·yr−1) and most extensive (16.12 × 103 km2) urban growth in China over the 10-year period. Moreover, if the current velocity holds, our estimates suggest that an additional 13.29 × 103 km2 in land area will be converted to human-built features while high density socioeconomic activities across the current urbanizing regions and urbanized areas will greatly increase from 52.44 × 103 km2 in 2010 to 62.73 × 103 km2 in China’s mainland during the next several decades. Our findings may provide potential insights into the pace of urbanization in China, its impacts on land changes, and accompanying alterations in environment and ecosystems in a spatially and temporally explicit manner.

Highlights

As the nation’s economy continues to grow, China is experiencing a historically unprecedented scale and pace of urbanization
Continuous observations of anthropogenic nighttime light signals, which are closely correlated with population and socioeconomic dynamics in urban areas, provide timely and spatially explicit with population and socioeconomic dynamics in urban areas, provide timely and spatially explicit metrics of urbanization processes
Based upon a time series of satellite-derived nocturnal luminosity data, we developed a new index of the velocity of urbanization through calculating the pixel-level data, we developed a new index of the velocity of urbanization through calculating the pixel-level ratio of temporal gradients and spatial gradients of nighttime brightness to investigate the spatial ratio of temporal gradients and spatial gradients of nighttime brightness to investigate the spatial growth of urban activities in China from 2000 to 2010

Summary

Introduction

As the nation’s economy continues to grow, China is experiencing a historically unprecedented scale and pace of urbanization. Rapid urbanization usually leads to incremental changes and shifts in environmental systems resulting from the rising demands of infrastructure construction, material production, appropriation and consumption due to escalated human social and economic activities [4]. In the context of sustainable development and political decision-making, improved understanding of the pace of urbanization across geographical ranges is of crucial importance for spatially tracking urban growth, land change, environmental shift and ecological responses to the propagation of urban-related activities (i.e., population, socioeconomic status, buildings and infrastructures) [5,6,7]

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