Spatially Heterogeneous Response of Carbon Storage to Land Use Changes in Pearl River Delta Urban Agglomeration, China

Carbon storage of terrestrial ecosystems plays a vital role in advancing carbon neutrality. Better understanding of how land use changes affect carbon storage in urban agglomeration will provide valuable guidance for policymakers in developing effective regional conservation policies. Taking the Pearl River Delta Urban Agglomeration(PRDUA) in China as an example, we examined the heterogeneous response of carbon storage to land use changes in 1990–2018 from a combined view of administrative units and physical entities. The results indicate that the primary change in land use was due to the expansion of construction land(5897.16 km2). The carbon storage in PRDUA decreased from 767.34 Tg C in 1990 to 725.42 Tg C in 2018 with a spatial pattern of high wings and the low middle. The carbon storage loss was largely attributed to construction land expansion(55.74%), followed by forest degradation(54.81%). Changes in carbon storage showed significant divergences in different sized cities and hierarchical boundaries. The coefficients of geographically weighted regression(GWR) reveal that the alteration in carbon storage in Guangzhou City was more responsive to changes in construction land(-0.11) compared to other cities, while that in Shenzhen was mainly affected by the dynamics of forest land(8.32). The change in carbon storage was primarily influenced by the conversion of farmland within urban extent(5.05) and the degradation of forest land in rural areas(5.82). Carbon storage changes were less sensitive to the expansion of construction land in the urban center, urban built-up area, and ex-urban built-up area, with the corresponding GWR coefficients of 0.19, 0.04, and 0.02. This study necessitates the differentiated protection strategies of carbon storage in urban agglomerations.

Influence Mechanism of New-type Urbanization on Urban Land Use Efficiency in the Yangtze River Delta, China

Rapid urbanization in China has led to inefficient use of urban land and spatial structure disorder,attracting attention from academia and society.Taking the Yangtze River Delta,China as an example,this study constructed an index evaluation system that quantitatively analyses the impact of new-type urbanization(NTU)on urban land use efficiency(ULUE)from 2000 to 2020 using a panel data vector autoregressive model.The results show that NTU in the Yangtze River Delta promotes ULUE improvement.However,the promotion of NTU to ULUE is limited,and the level of urban economic development also plays a role in promoting the change of ULUE.Moreover,the study further analyzed the results of urbanization decomposition and found that population urbanization(PU),economic urbanization(EU),spatial urbanization(SU),and social urbanization(SCU)can explain changes in ULUE in the Yangtze River Delta to a certain extent.In terms of variance decomposition,PU contributed the most to ULUE,followed by EU,SU,and SCU.Some necessary measures should be taken to coordinate the development of different types of urbanization,improve the sustainable utilization level of land resources,and provide a reference for high-quality development in the Yangtze River Delta.

Impacts of Weather Conditions Modified by Urban Expansion on Surface Ozone: Comparison between the Pearl River Delta and Yangtze River Delta Regions

In this paper, the online weather research and forecasting and chemistry （WRF-Chem） model is used to explore the impacts of urban expansion on regional weather conditions and its implication on surface ozone concentrations over the Pearl River Delta（PRD） and Yangtze River Delta（YRD） regions. Two scenarios of urban maps are used in the WRF-Chem to represent the early 1990s （pre-urbanization） and the current urban distribution in the PRD and the YRD. Month-long simulation results using the above land-use scenarios for March 2001 show that urbanization increases both the day- and night-time 2-m temperatures by about 0.6℃and 1.4℃, respectively. Daytime reduction in the wind speed by about 3.0 m s-1 is larger than that for the nighttime （0.5 to 2 m s-1）. The daytime increase in the PBL height （〉 200 m） is also larger than the nighttime （50-100 m）. The meteorological conditions modified by urbanization lead to detectable ozone-concentration changes in the PRD and the YRD. Urbanization increases the nighttime surface-ozone concentrations by about 4.7%-8.5% and by about 2.9%-4.2% for the daytime. In addition to modifying individual meteorological variables, urbanization also enhances the convergence zones, especially in the PRD. More importantly, urbanization has different effects on the surface ozone for the PRD and the YRD, presumably due to their urbanization characteristics and geographical locations. Even though the PRD has a smaller increase in the surface temperature than the YRD, it has （a） weaker surface wind speed, （b） smaller increase in PBL heights, and （c） stronger convergence zones. The latter three factors outweighed the temperature increase and resulted in a larger ozone enhancement in the PRD than the YRD.

Impact of urban expansion on regional temperature change in the Yangtze River Delta

Based on non-radiance-calibrated DMSP/OLS nighttime light imagery from 1992 to 2003, urban land area statistical data, meteorological data and land surface temperature data retrieved by MODIS and NOAA/AVHRR data, the influence of urbanization on regional climatic trend cf temperature in the Yangtze River Delta （YRD） was analyzed. Conclusions are as follows： 1） There is a significant urbanization process from 1992 to 2003 in the YRD. Four city clusters of Nanjing-Zhenjiang-Yangzhou, Suzhou-Wuxi-Changzhou, Shanghai and Hangzhou Bay form a zigzag city belt. The increase rate of annual mean air temperature in city-belt is 0.28-0.44℃/10a from 1991 to 2005, which is far larger than that of non-city-belt. 2） The urban heat island （UHI） effect on regional mean air temperature in different seasons is summer〉autumn〉spring〉winter. 3） The UHI intensity and the urban total population logarithm are creditably correlated. 4） The UHI effect made the regional annual mean air temperature increased 0.072℃ from 1961 to 2005, of which 0.047℃ from 1991 to 2005, and the annual maximum air temperature increased 0.162℃, of which 0.083℃ from 1991 to 2005. All these indicating that the urban expansion in the YRD from 1991 to 2005 may be regarded as a serious climate signal.

Relationship Between Producer Services Developing Level and Urban Hierarchy——A Case Study of Zhujiang River Delta

As the Central Place Theory indicates, the centricity of a central city can influence the extension of its ser- vice. Since the service industry in the theory is mostly consumer services, it is worth studying the relationship between the producer services and the centricity of the city in the service society with producer services becoming a more im- portant part of the service industry. The paper takes the case of the Zhujiang (Pearl) River Delta (PRD), a developed region in China, to study the relationship between the developing level of producer services and the urban hierarchy. Based on the analysis about the spatial difference of the producer services in the nine cities of the PRD, and the divi- sion of the nine cities according to some economic indices, it is shown that there is a correlation between the develop- ing level of producer services and the urban hierarchy. Furthermore, two deductions about the future status of the pro- ducer services in the city and the location of the producer services in a large region can be made from this correlation between the developing level of producer services and the urban hierarchy.

Characterization of Air Pollution in Urban Areas of Yangtze River Delta,China

The hallmark of development in the Yangtze River Delta(YRD) of East China has been sprawling urbanization. However, air pollution is a significant problem in these urban areas. In this paper, we investigated and analyzed the air pollution index(API) in four cities(Shanghai, Nanjing, Hangzhou and Ningbo) in the YRD from 2001 to 2012. We attempted to empirically examine the relationship between meteorological factors and air quality in the urban areas of the YRD. According to the monitoring data, the API in Shanghai, Nanjing, Hangzhou slightly declined and that in Ningbo increased over the study period. We analyzed the inter-annual, seasonal, and monthly variations of API, from which we found that the air quality had different temporal changes in the four cities. It was indicated that air quality was poor in winter and spring and best in summer. Furthermore, different weather conditions affected air quality level. The wind direction was considered as an important and influential factor to air pollution, which has an impact on the accumulating or cleaning processes of pollutants. The air quality was influenced by the different wind directions that varied with seasons and cities.

Urbanization effect on precipitation over the Pearl River Delta based on CMORPH data

Based on the satellite data from the Climate Prediction Center morphing(CMORPH) at very high spatial and temporal resolution, the effects of urbanization on precipitation were assessed over the Pearl River Delta(PRD) metropolitan regions of China. CMORPH data well estimates the precipitation features over the PRD. Compared to the surrounding rural areas, the PRD urban areas experience fewer and shorter precipitation events with a lower precipitation frequency(ratio of rainy hours, about 3 days per year less); however, short-duration heavy rain events play a more significant role over the PRD urban areas. Afternoon precipitation is much more pronounced over the PRD urban areas than the surrounding rural areas, which is probably because of the increase in short-duration heavy rain over urban areas.

Revisiting and Rethinking Regional Urbanization in Changjiang River Delta,China

China is entering a critical and accelerating phase of urbanization.As one of the most urbanized regions in China,the Changjiang(Yangtze)River Delta has experienced dramatic urbanization and urban transformation.However,in the recent years,many changes have taken place in this region and there is limited attention to the regional urbanization path evolution,its problems and the way to solve these problems.Therefore,we should revisit the urbanization process in the Changjiang River Delta again.In this paper,we revisited urbanization paths of the Changjiang River Delta by data analysis,influence factors of urbanization by the Gray Relational Analysis,and major challenges to urbanization of the Changjiang River Delta by theoretical considerations.We found that the urbanization of the Changjiang River Delta had experienced several stages of large-scale spatial and urban system restructuring.Within the Changjiang River Delta,Shanghai,Zhejiang and Jiangshu had experienced different urbanization path with local characteristics.But with their development model gradually converging,their urbanization model is also converging.We also found that the major influence factors affecting the Changjiang River Delta urbanization were dynamic change and urbanization was driven by different key factors in different socio-economic development stages.Meanwhile,the Changjiang River Delta urbanization is facing many problems such as existing institutional arrangements,including the hukou(household registration)system and others which can not meet the needs of current socioeconomic development and urbanization.Therefore,it is imperative to promote institutional innovation and adopt a new urbanization development strategy for the sake of the orderly and sustainable urbanization development in the Changjiang River Delta.

Assessment of Urban Sprawl on Agricultural Soil of Northern Nile Delta of Egypt Using RS and GIS

Urban sprawl is threatening the limited highly fertile land in the Nile delta of Egypt. Landsat TM satellite images of 1984, 1992 and ETM+ of 2006 have been used to study the impact of urban sprawl on agricultural land of the Northern Nile delta, Egypt. Visual interpretation using on screen digitizing and change detection techniques were applied for monitoring the urban sprawl. Combining the land capability map and the urban thematic layer using GIS made it possible to point out the risk of urban expansion on the expense of the highly capable soil class. The results show that a total expansion of urban area amounted to 689.20 km2(6.3% of total area) during the study period 1984–2006. The urban expansion during the 1984–2006 was on the expense of the most fertile soils where, the high capable soils(Class I) lost 247.14 km2(2.26 % of total area) and the moderate capable soils lost 32.73 km2(0.3% of total area), while the low capable soils lost only 57.39 km2(0.53% of total area). The urban encroachment over the non capable soils was very limited during the study period 1984–1992, where 7.33 km2 only was lost. The pattern of urban sprawl has been changed during the 1992 to 2006 whereas much larger area(50.64 km2) of the non capable soils was converted to urban. It can be concluded that the urban sprawl is one of the dominant degradation process on the land of Nile Delta.

Tows Matrix Analysis on Developing Urban Agriculture in the Pearl River Delta Area

Based on the introduction of the profile of Pearl River Delta area, the strengths, weaknesses, opportunities and threats of developing urban agricultural in Pearl River Delta area are analyzed by using the SWOT analysis. The strengths are analyzed from three aspects, covering natural resources, geographic advantages and technological advantages; the weaknesses are analyzed from the terms of land resources, labor cost, industrial scale and quality of personnel involved; opportunities are analyzed from the aspects of potential clients, favorable policies and markets; the threats are analyzed from two aspects, including concept factor and income gap between urban and rural areas. on the basis of the above analyses, the countermeasures and suggestions on the development of urban agriculture in the Pearl River Delta area are put forward.

Evolution of Living Space in Traditional Villages in the Pearl River Delta under the Influence of Urbanization:A Case Study of Xiaozhou Village in Guangzhou City

Traditional villages in the Pearl River Delta are known as "Lingnan water village".Urbanization affects the style of traditional villages in three ways.It also presents a positive side under the background of new urbanization.The living space of Xiaozhou Village has the unique characteristics of Lingnan water village.At the same time,it is obviously affected by urbanization.Industrialization and commercialization continue to promote the villagers to dismantle the old and build new ones until it becomes a village in the city.The evolution of the traditional living space is reflected in three aspects:being nibbled away or even disappeared,destroying the traditional style,function disappearance or transformation.In the later stage of urbanization,some living spaces have been repaired and updated.

Influence of International Trade on the Urbanization in the Pearl River Delta

The Pearl River Delta is a typical representative of China s coastal economic belt and one of the most active regions for international trade.It has important reference value for the urbanization of other coastal economic regions in China to study the impact of international trade on the urbanization of the Pearl River Delta.This paper constructs the theoretical model of the three factors of export trade,import trade and industrial scale affecting the urbanization of the Pearl River Delta.It is empirically found that the international trade has positive effects on the total effect of urbanization in which export trade and import intermediate product trade have a positive effect on urbanization,and import trade and export intermediate product trade have a negative effect on urbanization.

Urban Development and Water Management in the Yangtze River Delta

Throughout the history of the world, the development of the cities are related to the large water systems and the ocean. Where the river is abundant, the trade and regional centres could be formed. However, along with the prosperity of the water-cities, massive urban construction and environmental issues are enormous challenges in human process. A “scientific” urban planning, “Sponge City”, “Resilient City”, regional and urban culture and characteristics get more and more attention. The theme of “water and city” is clearly of great historical value and practical significance for the new resilient urban and water management strategies. The paper will summarize characteristics of geographical, historical, socio-cultural and political realms in metropolitan deltas and the historical governance as well as the recent developments in the Yangtze River Delta. It will introduce urban development and water management in four water cities: the canal and the city-Yangzhou, the river and the city-Nanjing, the lake and the city-Suzhou and the sea and the city-Shanghai. And then it will analyze the inner motivation of the interaction between water and cities in Yangtze River Delta. Furthermore, learning from successful historical experiences, the paper will provide suggestions for future sustainable urban development.

Analysis on Ecological Footprint of the Urban Agglomeration in Pearl River Delta

[Objective] The research aimed to calculate and analyze ecological footprint of the urban agglomeration in Pearl River Delta in 2009. [Method] 9 cities in Pearl River Delta as research zone, by using calculation model of the ecological footprint, ecological footprint and security of the urban agglomeration in Pearl River Delta were calculated. Current situation and sustainable development condition of the ecological environment in Pearl River Delta were conducted quantitative analysis. [Result] Except construction land and woodland, other 4 kinds of lands were all in ecological deficit states in Pearl River Delta. Especially arable land and fossil fuel land had obvious ecological deficit. [Conclusion] Biological resource consumption level and energy consumption level in Pearl River Delta were higher. We ought to take a variety of measures to reduce ecological deficit, making development manner turn toward sustainable direction.

Mapping Urban Networks through Inter-Firm Linkages: The Case of Listed Companies in Yangtze River Delta, China

Recently, literature on urban network research from the perspective of ?rm networks has been increasing. This research mainly used data from the headquarters and branches of all 2581 listed manufacturing companies in the Yangtze River Delta from 1990 to 2017, and studied the urban network through an interlocking network model that quantifies the links between enterprises. The results showed that the spatial distribution of listed manufacturing industries in the Yangtze River Delta was relatively concentrated, and cities such as Shanghai, Nanjing, and Hangzhou were hot spots for the spatial distribution of listed manufacturing industries. However, Fuyang, Suqian, Chizhou, Lishui and other network edge cities were less distributed in manufacturing. The urban network of the Yangtze River Delta has significant hierarchical characteristics. The urban network of the Yangtze River Delta presents a multi-center network development mode with Shanghai as the center and Nanjing, Hangzhou, and Hefei as the sub-centers. Moreover, we found that the development of inter-city connections in the Yangtze River Delta was driven by network mechanisms of priority attachment and path dependence. The radiating capacity and agglomeration capacity of cities in the Yangtze River Delta have a strong polarization characteristic. The core cities such as Shanghai, Nanjing, Hangzhou, and Hefei have much higher network radiation capabilities than network aggregation capabilities. However, other non-core cities and network edge cities have weak network radiation capabilities, and mainly accept network radiation from core cities. It enriches the research of urban networks based on real inter-?rm connections, and provides ideas for the wider regional study and the combination of econometric techniques and social network analysis.

The Effect of Urban Agglomeration Expansion on PM_(2.5) Concentrations: Evidence from a Quasi-natural Experiment

This study constructs a quasi-natural experiment based on the expansion of the Yangtze River Delta urban agglomeration(YRDUA) of China in 2010 to investigate the impact and inner mechanism of urban agglomeration expansion on fine particulate matter(PM_(2.5)) concentrations through propensity scores in difference-in-differences models(PSM-DID) using panel data from 286 prefecturelevel cities in China from 2003 to 2016. The results show that 1) urban agglomeration expansion contributes to an overall decrease in PM_(2.5)concentration, which is mainly achieved from the original cities. For the new cities, on the other hand, the expansion significantly increases the local PM_(2.5)concentration. 2) In the long term, the significant influence of urban agglomeration expansion on PM_(2.5)concentration lasts for three years and gradually decreases. A series of robustness tests confirm the applicability of the PSM-DID model.3) Cities with weaker government regulation, a better educated population and higher per capita income present stronger PM_(2.5)reduction effects. 4) Urban agglomeration expansion affects the PM_(2.5)concentration mainly through industrial transfer and population migration, which cause a decrease in the PM_(2.5)concentration in the original cities and an increase in the PM_(2.5)concentration in the new cities.Corresponding policy suggestions are proposed based on the conclusions.

An Overall Urban System: Integrating Central Place Theory and Urban Network Idea in the Greater Pearl River Delta of China

Following a half century of popularity, central place theory experienced 20 years of neglect when the new urban system theory of network modeling gained attention at the beginning of the 1990s. However, central place theory remains valid, and it seems there has been a reemergence with it. Using the Greater Pearl River Delta (Greater PRD) as an experimental study region, this paper intends to present an empirical study that validates central place theory and shows that it can be integrated into an overall regional urban system. The study uses the compound Central Place Importance (CPI) to evaluate whether there is a hierarchy among the urban centers within the study area. The results indicate the existence of a hierarchy. Furthermore, empirical observation finds distinct complementarity relationships, rank-size distributions, and co-operative actions between the different cities, thus substantiating the claim that central place theory can be incorporated into an overall regional urban system. Besides, the presence of the densely distributed modern infrastructure system also appears to constitute a dimension of the overall urban system. There need further theoretical and empirical studies in order to support this proposition.

KNOWLEDGE DISCOVERY OF REMOTELY SENSED DATA FROM ECOLOGICAL VIEW——A Case Study of Urban Spatial-temporal Relationship in the Pearl River Delta

From the ecological viewpoint this paper discusses the urban spatial-temporal relationship. We take regional towns and cities as a complex man-land system of urban eco-community. This complex man-land system comprises two elements of ' man' and ' land' . Here, ' man' means organization with self-determined consciousness, and ' land' means the physical environment (niche) that ' man' depends on. The complex man-land system has three basic components. They are individual, population and community. Therefore there are six types of spatial relationship for the complex man-land system. They are individual, population,community,man-man, land-land and man-land spatial relationships. Taking the Pearl(Zhujiang) River Delta as a case study, the authors found some evidence of the urban spatial relationship from the remote sensing data. Firstly, the concentration and diffusion of the cities spatial relationship was found in the remote sensing imagery. Most of the cities concentrate in the core area of the Pearl River Delta, but the diffusion situation is also significant. Secondly, the growth behavior and succession behavior of the urban spatial relationship was found in the remote sensing images comparison with different temporal data. Thirdly, the inheritance, break, or meeting emergency behavior was observed from the remote sensing data. Fourthly, the authors found many cases of symbiosis and competition in the remote sensing data of the Pearl River Delta. Fifthly, the autoeciousness, stranglehold and invasion behavior of the urban spatial relationship was discovered from the remote sensing data.

Evaluation of Coordinated Development of Urbanization and Ecological Environment in the Efficient Ecological Economic Zone of the Yellow River Delta

Based on the statistical data of urbanization development level and ecological environment in the Yellow River Delta during 2009-2014,a comprehensive index system for the coordinated development of urbanization and ecological environment was established to evaluate the coordinated development level. The results showed that the coordinated development level of urbanization and ecological environment in the Yellow River Delta was generally high during 2009-2014. The development level of urbanization was higher than that of ecological environment on the whole,that is,the development of ecological environment lagged behind. The development of urbanization in the region was relatively slow during 2009-2011 but rapid during 2012-2014. The development level of ecological environment was relatively stable and always increased.

Measurement of Digital Economy Development Level in Yangtze River Delta and Its Influence on Ecological Efficiency

Based on the panel data of 41 cities in the Yangtze River Delta from 2007 to 2018,this paper empirically tests the impact of digital economy development on urban ecological efficiency in the Yangtze River Delta.The results show that the development level of digital economy in Yangtze River Delta urban agglomeration is fluctuating and rising;the development of digital economy has a significant positive role in promoting the improvement of urban ecological efficiency;there is significant regional heterogeneity in the promotion of ecological efficiency by digital economy,especially in central cities.