Exploring the Variation Trend of Urban Expansion, Land Surface Temperature, and Ecological Quality and Their Interrelationships in Guangzhou, China, from 1987 to 2019

Jianhui Xu,Yi Zhao,Yong Li,Caige Sun,Kaiwen Zhong,Xulong Liu,Hanbin Liang,Ji Yang

doi:10.3390/rs13051019

Abstract

This study explored the model of urban impervious surface (IS) density, land surface temperature (LST), and comprehensive ecological evaluation index (CEEI) from urban centers to suburbs. The interrelationships between these parameters in Guangzhou from 1987 to 2019 were analyzed using time-series Landsat-5 TM (Thematic Mapper), Landsat-8 OLI (Operational Land Imager), and TIRS (Thermal Infrared Sensor) images. The urban IS densities were calculated in concentric rings using time-series IS fractions, which were used to construct an inverse S-shaped urban IS density function to depict changes in urban form and the spatio-temporal dynamics of urban expansion from the urban center to the suburbs. The results indicated that Guangzhou experienced expansive urban growth, with the patterns of urban spatial structure changing from a single-center to a multi-center structure over the past 32 years. Next, the normalized LST and CEEI in each concentric ring were calculated, and their variation trends from the urban center to the suburbs were modeled using linear and nonlinear functions, respectively. The results showed that the normalized LST had a gradual decreasing trend from the urban center to the suburbs, while the CEEI showed a significant increasing trend. During the 32-year rapid urban development, the normalized LST difference between the urban center and suburbs increased gradually with time, and the CEEI significantly decreased. This indicated that rapid urbanization significantly expanded the impervious surface areas in Guangzhou, leading to an increase in the LST difference between urban centers and suburbs and a deterioration in ecological quality. Finally, the potential interrelationships among urban IS density, normalized LST, and CEEI were also explored using different models. This study revealed that rapid urbanization has produced geographical convergence between several ISs, which may increase the risk of the urban heat island effect and degradation of ecological quality.

Highlights

To determine the spatiotemporal characteristics of ecological quality evolution under the pressure of urbanization in the Guangdong–Hong Kong–Macau Greater Bay Area (GBA), following the research of Xu [31] and Xu et al [32], a comprehensive ecological evaluation index (CEEI) was developed to detect changes in the urban ecological quality of an entire region by integrating VC, VHI, NDBSI, LSM, and land surface temperature (LST) [33]; the results showed that the proposed CEEI may yield effective results in the GBA
We explored the influence of rapid urban expansion on LST and ecological quality from urban centers to suburbs from 1987 to 2019
The urban impervious surface (IS) density curves and their corresponding parameters illustrate the general trend of urban IS density variation from the urban center to the suburbs

Summary

Introduction

As a benefit of China’s reform and opening-up policy in 1978, the Chinese national economy has developed rapidly, and the urbanization rate has increased dramatically [1,2]. Urban land use and landscape patterns have changed significantly [3,4,5]. A large proportion of natural land areas have been converted to impervious surface (IS) areas, which has led to the substantial expansion of IS areas and a dramatic decrease in the amount of natural land, including forests, farmland, soil, wetlands, grasslands, and rivers. The resulting expansion and aggregation of ISs are likely to aggravate

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