Exploration of eco-environment and urbanization changes in coastal zones: A case study in China over the past 20 years

Abstract With the rapid development of urbanization and population migration, since the 20th century, the natural and eco-environment of coastal areas have been under tremendous pressure due to the strong interference of human response. To objectively evaluate the coastal eco-environment condition and explore the impact from the urbanization process, this paper, by integrating daytime remote sensing and nighttime remote sensing, carried out a quantitative assessment of the coastal zone of China in 2000–2019 based on Remote Sensing Ecological Index (RSEI) and Comprehensive Nighttime Light Index (CNLI) respectively. The results showed that: 1) the overall eco-environmental conditions in China's coastal zone have shown a trend of improvement, but regional differences still exist; 2) during the study period, the urbanization process of cities continued to advance, especially in seaside cities and prefecture-level cities in Jiangsu and Shandong, which were much higher than the average growth rate; 3) the Coupling Coordination Degree (CCD) between the urbanization and eco-environment in coastal cities is constantly increasing, but the main contribution of environmental improvement comes from non-urbanized areas, and the eco-environment pressure in urbanized areas is still not optimistic. As a large-scale, long-term series of eco-environment and urbanization process change analysis, this study can provide theoretical support for mesoscale development planning, eco-environment condition monitoring and environmental protection policies from decision-makers

Identifying China’s polycentric cities and evaluating the urban centre development level using Luojia-1A night-time light data

Studying the structure of polycentric cities can promote a better understanding of urban development and contribute to urban planning. In this study, we identified polycentric cities in China and evaluated the urban centre development level of polycentric cities from new data and method. We used Luojia-1A night-time light (NTL) data, combined with the concept of natural cities (NCs), to identify urban centres and thus identify polycentric cities in China. In addition, we used the urban centre development index (UCDI) to quantify the urban centre development level (UCDL) that represents the overall urban centre development level within a polycentric city. The polycentric cities in China are characterized by the spatial distribution pattern of a larger number in the east and fewer in the west. There are a large number of polycentric cities in eastern China, and the closer to the coastal areas, the more polycentric cities there are. The distribution of UCDL in China’s polycentric cities is characterized by significant spatial heterogeneity. UCDLs are generally smaller in polycentric cities in western China. In addition, polycentric cities in northeastern China have smaller UCDL. Polycentric cities with high UCDL are concentrated in the central and coastal regions of China

The Formation of Government-Oriented Creative Community and Its Driving Mechanisms: A Case Study of the 39° Space Art Creative Community in Foshan, China

With the arrival of the era of the creative economy, the “creative community„, a joint product of the regional/community revival movement and the localization of cultural and creative industries, has become a new goal of sustainable urban development. Creative communities can be government-oriented (top-down), or they can involve a sequence of autogenic developments (bottom-up) depending on the initial motivating force behind their formation. This paper provides a case study of the government-oriented Foshan 39° Space Art Creative Community (hereinafter, the 39° Community), though questionnaires, interviews, field observations, and other methods, to obtain a better understanding of how government-oriented creative communities formed. The paper discusses the mechanisms driving such communities in Chinese cities by constructing a driving mechanism model. The results show that policy decisions, under a special policy and industrial background jointly provided by the Foshan municipal government and the Nanhai District government together, is the initial impetus for the emergence of the 39° Community. The community has a concise and flexible organizational structure, creative community members, reasonable community function partitioning, a vibrant and innovative environment, and a variety of creative elements. Finally, the key to the sustainable development of the government-oriented creative community lies in the combined effect of endogenous and exogenous motivations that include a strong support from the local government, market demand, a favorable location, high-quality community services, and creative spirit. High-quality community service is a critical factor in the interaction between exogenous forces and endogenous factors because it can create bridges among governments, enterprises, employees, and the community

Detection of City Integration Processes in Rapidly Urbanizing Areas Based on Remote Sensing Imagery

Since China’s reform and development commenced, in the context of rapid urbanization and coordinated regional development, Chinese cities with a close geographic proximity and social ties have gradually formed an integrated city development model. As a new phenomenon in China’s urbanization process, existing research on China’s integrated cities mainly focuses on typical case studies, and most research has been limited to literature reviews and theoretical analyses. The growing application of remote sensing technology in urbanization research in recent years has provided new opportunities for the analysis of city integration. Therefore, based on multi-spectral Landsat-8 and nighttime light images (SNPP/VIIRS, Suomi National Polar-orbiting Platform/Visible Infrared Imaging Radiometer Suite), this paper selects four of the most representative integrated cities with different backgrounds in China to analyze the land-use conversion, plot light fluctuation, and light gravity center shift in the boundary zone between cities. The results show that (1) Guangfo has the highest level of integration and urban expansion is mainly concentrated in the south-central part of the boundary area; (2) Guanshen’s level of integration is second to Guangfo’s and is mainly concentrated in the west; (3) HuSu’s integration is still in the initial stage and its increase in light intensity lags behind the expansion of building land during the study period; (4) although the light intensity and building land area increased significantly during the study period in Xixian, the overall development level of Xixian still lagged behind coastal cities due to the restriction of its geographical location. Our application results expand the data sources for integrated city research and the obtained results can potentially support decision-making and planning in the process of urban development

The Interannual Calibration and Global Nighttime Light Fluctuation Assessment Based on Pixel-Level Linear Regression Analysis

The Operational Linescan System (OLS) carried by the National Defense Meteorological Satellite Program (DMSP) can capture the weak visible radiation emitted from earth at night and produce a series of annual cloudless nighttime light (NTL) images, effectively supporting multi-scale, long-term human activities and urbanization process research. However, the interannual instability and sensor bias of NTL time series products greatly limit further studies of lighting data in time series with OLS. Several calibration models for OLS have been proposed to implement interannual corrections to improve the continuity and consistency of time series NTL products; however, due to the subjective factors intervention and insufficient automation in the calibration process, the interannual correction study of NTL time series images is still worth being developed further. Therefore, to avoid the involvement of subjective factors and to optimize the Pseudo-Invariant Features (PIF) identification, an interannual calibration model Pixel-based PIF (PBPIF) is proposed, which identifies PIF by pixel fluctuation characteristics. Results show that a PBPIF-based model can reduce subjective interference and improve the degree of automation during the NTL interannual calibration process. The calibration performance evaluation based on Total Sum of Lights (TSOL) and Sum of the Normalized Difference Index (SNDI) shows that compared to the traditional PIF-based (tPIF-based) and Ridgeline Sampling Regression based (RSR-based) models, the PBPIF-based one achieves better performance in reducing NTL interannual turbulence and minimizing the deviation between sensors. In addition, based on the corrected NTL time series products, pixel-level linear regression analysis is implemented to maximize the potential of the NTL resolution to produce global Light Intensity Change Coefficient (LICC). The results of global LICC can be widely applied to the detailed study of the characteristics of economic development and urbanization

The desaturation method of DMSP/OLS nighttime light data based on vector data: taking the rapidly urbanized China as an example

The saturation of night light data caused by sensor defects conceals the differences and details of light luminance in the urban area, which greatly limits the application of Nighttime Light (NTL) in the study of urbanization. Although some methods have been proposed to mitigate the saturation of NTL data, the research of desaturation is worth further advancing due to its shortcomings in highlighting light differences and spatial resolution. Therefore, we propose a new spectral index, the Vector Data Adjusted NTL Index (VDANTLI) after analyzing the influence of different auxiliary parameters on saturation elimination. Then, we select the three most developed urban agglomerations in China and make a series of qualitative and quantitative analysis. The results of various assessments confirm that VDANTLI can effectively alleviate NTL saturation and enhance urban lighting differences. Moreover, by dynamically adjusting the length of the grid and single-phase vector data modified time-series NTL data, we further achieve the resolution-series and time-series VDANTLI. Therefore, compared with previous desaturation models, the VDANTLI can be used as an effective indicator and even an indispensable basic data for urbanization research and socio-economic spatial analysis because of its unique advantages in spatial resolution and the capability in time-series native NTL desaturation

The coupling relationship between construction land expansion and high-temperature area expansion in China's three major urban agglomerations

With the development of urbanization in China, construction land (CL) expansion is obvious, and urban heat island (UHI) is becoming more and more serious. Many scholars have shown a strong interest in the study of UHI caused by land expansion, but less attention has been paid to the coupling relationship between CL expansion and high-temperature area (HTA) expansion during the process of urbanization. This study obtained the land surface temperature (LST) data of China's three major urban agglomerations (CTM-UAs) in 2000, 2005, 2010 and 2015. Then this paper used overall coupling model and spatial coupling model to reveal the coupling relationship between the CL expansion and HTA expansion of CTM-UAs in different periods. The results showed that: (1) From 2000 to 2015, the trend of CL expansion and HTA expansion in CTM-UAs was synchronous; (2) The distance between the CL barycentre and HTA barycentre in CTM-UAs was shrinking, the spatial overlap was constantly strengthening, and the overall coupling was constantly strengthening. And the highest value of the overall coupling was reached in 2015; (3) The number of grid units of very strong coupling and strong coupling increased with fluctuation in Beijing-Tianjin-Tangshan Urban Agglomeration (BTT), that in Yangtze River Delta Urban Agglomeration (YRD) was increasing, and that of Guangdong-Hong Kong-Macao Urban Agglomeration (GHM) has gone through the process of increasing to decrease