Spatiotemporal Patterns Of Urban Expansion Research Articles

Monitoring Urban Expansion (2000–2020) in Yangtze River Delta Using Time-Series Nighttime Light Data and MODIS NDVI

The Yangtze River Delta Urban Agglomeration (YRDUA), which is located in the convergence zone of “The Belt and Road Initiative”, is one of the regions with the best urbanization foundations in China. Referring to the four five-year plans (China’s national economic plan), this study aimed to investigate the spatiotemporal patterns of urban expansion in the YRDUA from 2000 to 2020. To conduct a long-term analysis of urbanization, an extended time series (2000–2020) of a nighttime light (NTL) dataset was built from the multi-temporal Defense Meteorological Satellite Program’s Operational Linescan System (DMSP-OLS) data (2000–2013), and Suomi National Polar-Orbiting Partnership Visible Infrared Imaging Radiometer Suite (NPP-VIIRS) data (2014–2020); data from these sources are crucial to understanding the urbanization processes in the region in order for more effective decision making to take place. The support vector machine (SVM) method was used to extract urban clusters from the extended time-series NTL data and MODIS NDVI products. The evolution of the urban expansion intensity was detected at city scales, and the inequality of urban growth was demonstrated using the Lorenz curve and Gini coefficient. Finally, a quantitative relationship between urban NTL intensity and socio-economic data was built to explore the main factors that control urban intensity. The results indicated that the urban extents extracted from time-series NTL data were consistent with those extracted from Landsat data, with an average overall accuracy (OA) of 89%. A relatively fast urbanization pace was observed during the 10th five-year plan (from 2000 to 2005), which then declined slightly in the 11th five-year plan (from 2006 to 2010). By the 12th and 13th five-year plan (from 2011 to 2020), urban clusters in all cities tended to grow steadily. Urban expansion has presented a radial pattern around the main cities, with sprawl inequality across cities. The results further revealed that the primary factors controlling NTL brightness were gross domestic product (GDP), total fixed asset investment, tertiary industry, gross industrial output, urban area, and urban permanent residents in city clusters, but the same driving factors had a different contribution order on the NTL intensity across cities. This study provides significant insight for further urbanization study to be conducted in the YRDUA region, which is crucial for sustainable urban development in the region.

Spatiotemporal patterns of urban expansion and trade-offs and synergies among ecosystem services in urban agglomerations of China

Urbanization is advancing rapidly across the globe, and urban agglomeration (UA) has become an important by-product of urbanization expansion. The rapid development of UAs has profound impacts on land use and directly affects various regional ecosystem services (ES). Understanding these impacts in UAs with developed economies and fragile ecosystems can help decision-makers formulate ecological protection and land use planning policies. Here, we selected 13 UAs in eastern, central, and western China and analyzed the characteristics of spatiotemporal changes in built-up land and the trade-off and synergy between ES in UAs from 2000 to 2020. We found that the built-up land increased rapidly to the outer edge of a city in the form of edge expansion, which was more prominent in UAs at national and regional scales. Carbon storage, biodiversity conservation, habitat quality, soil and water conservation, and water conservation tended to decrease, but the nutrition delivery ratio and food supply tended to increase. Various ES presented a negative synergistic relationship. The difference in ES in UAs was closely related to the level of urbanization and geographical location. Our findings demonstrate the trade-off and synergy of ES in UAs at different levels and can be used to sustain ES and develop high-quality UAs.

Monitoring Long-Term Spatiotemporal Dynamics of Urban Expansion Using Multisource Remote Sensing Images and Historical Maps: A Case Study of Hangzhou, China

The spatiotemporal patterns of urban expansion have attracted worldwide attention and have been generalized into several prevalent hypotheses, such as the diffusion–coalescence hypothesis and the three-growth-type hypothesis. Although many studies have examined the applicability of these hypotheses, long-term research and evidence are still lacking. This study incorporated a compiled dataset of multisource remote sensing images and historical maps covering nine snapshots of the urban built-up area from 1914 to 2018 to monitor the urban expansion process in Hangzhou, China. A fractal analysis of the area–radius relationship was employed for areal demarcation to explore the heterogenous patterns across different intra-city spatial extents. The results show that (1) Hangzhou has experienced a turbulent period of primitive urbanization in the pre-reform era and a consecutive period of market-oriented urbanization after the economic reform; (2) the urban expansion pattern characterized by landscape metrics demonstrates the existence of multiple alternations between diffusion and coalescence phases with peculiarities across different intra-city spatial extents; (3) the analysis of urban growth types documents a consistent predominance of edge-expansion with wax and wane between infilling and leapfrogging; and (4) institutional reform, industrial development, and administrative division adjustment are the main drivers of urban expansion in Hangzhou. Our findings suggest that effective planning policies need to be raised to curb urban sprawl. Differentiated planning strategies should be proposed to accommodate unique conditions in different urban subregions. The integrated-analysis approach based on multisource remote sensing images and historical maps establishes a feasible pathway for long-term urban research.

Quantifying urban expansion from 1985 to 2018 in large cities worldwide

The world has experienced widely distributed urbanization from local to global scales in the past decades. Urban expansion can bring multiple benefits for urban inhabitants, however it can also result in a series of environmental and ecological issues, such as carbon emission, air pollution, and biodiversity loss. Therefore, it is urgently required to conduct timely and quantitative monitoring of the dynamics of urban areas worldwide to support sustainable policy making for urban management and development, such as guiding rational urbanization in developing countries, uncovering inequality of global urbanization, and understanding the consistency of urbanization and population growth. However, we still lack high resolution information on the characteristics of global urban dynamics over the past decades. To fill this gap, we quantified spatiotemporal patterns of urban expansion from 1985 to 2018 in 501 large cities worldwide based on the 30 m fine resolution Global annual Artificial Impervious Area dataset. We then assessed the spatiotemporal patterns of urban expansion using the annual growth rate indicator. Our results showed that: (1) The total (mean) impervious surface area in these cities increased obviously from 50,778 (101.35) km2 in 1985 to 150,145 (299.69) km2 in 2018, i.e. the total (mean) impervious surface area tripled from 1985 to 2018. (2) cities in developed countries or high-income countries (e.g. North American and European cities) have a much higher impervious surface area than cities in developing countries or low-income countries (e.g. Asian and African cities). (3) cities in North America and Europe that are dominated by developed or high-income and upper-middle-income countries have lower annual growth rate of impervious surface than cities in Africa and Asia, which are dominated by low-income and lower-middle-income countries. In addition, cities in China and India experienced very high urban expansion rates during the past decades based on the annual growth rate indicator. The findings of this study could provide supporting information for land management and sustainable development for cities around the world.

Exploring the Patterns and Drivers of Urban Expansion in the Texas Triangle Megaregion

As the world becomes increasingly urbanized, it is vital for planners and policy-makers to understand the patterns of urban expansion and the underlying driving forces. This study examines the spatiotemporal patterns of urban expansion in the Texas Triangle megaregion and explores the drivers behind the expansion. The study used data from multiple sources, including land cover and imperviousness data from the National Land Cover Database (NLCD) 2001–2016, transportation data from the Texas Department of Transportation (TxDOT), and ancillary socio-demographic data from the U.S. Census Bureau. We conducted spatial cluster analysis and mixed-effect regression analysis. The results show that: (1) urban expansion in the Texas Triangle between 2001 and 2016 showed a decreasing trend, and 95% of the newly urbanized land was in metropolitan areas, especially at the periphery of the central cities; (2) urban expansion in non-metropolitan areas displayed a scattered pattern, comparing to the clustered form in metro areas; (3) the expansion process in the Texas Triangle exhibited a pattern of increased development compactness and intensity; and (4) population and economic growth played a definitive role in driving the urban expansion in the Texas Triangle while highway density also mattered. These results suggest a megaregion-wide emerging trend deviating from the sprawling development course known in Texas’ urban growth history. The changing trend can be attributed to the pro-sustainability initiatives taken by several anchor cities and metropolitan planning agencies in the Texas Triangle.

Landsat-Based Monitoring of the Heat Effects of Urbanization Directions and Types in Hangzhou City from 2000 to 2020

Rapid urbanization has produced serious heat effects worldwide. However, the literature lacks a detailed study on heat effects based on the directions and types of urban expansion. In this work, a typical city with an extremely hot summer climate, Hangzhou, was selected as a case study to determine the relationships between the urban heat-effect dynamics and spatiotemporal patterns of impervious surface expansion. Based on long-term Landsat imagery, this study characterized the spatiotemporal patterns of urban expansion and normalized surface temperatures in Hangzhou City from 2000 to 2020 using object-based backdating classification and a generalized single-channel algorithm with the help of a land-use transfer matrix, expansion index, and spatial centroids. Relevant policies, industries, and traffic networks were discussed to help explain urban expansion and thermal environment changes. The results demonstrated that in 2020, the area of impervious surfaces covered 1139.29 km2. The majority of the gains were in farmland, water, and forests, and the annual growth rate was 32.12 km2/year beginning in 2000. During the expansion of impervious surfaces, the city warmed at a slower rate, and more thermal contributions came from sub-urban areas. The southeast-oriented expansion of impervious surfaces was the key reason for the spatiotemporal dynamics of the urban heat effects. The dominant urban edge expansion intensified the local heat effects. This research provides a Landsat-based methodology for better understanding the heat effects of urban expansion.

Mapping dynamic peri-urban land use transitions across Canada using Landsat time series: Spatial and temporal trends and associations with socio-demographic factors

Transformations of agriculture and natural lands to urban use are dominant and well known effects of urbanization, but consistent and reliable methods to map regional-scale land transitions are limited. Herein, we develop a land use classification approach to assess spatiotemporal patterns of urban expansion and associated land use changes. We utilized a 33-year annual time series (1984–2016) of fractional land characteristics and cover data from Landsat satellite imagery to summarize multidecadal land use transitions on the pixel and census dissemination area level for 18 major Canadian cities. Across Canada, 41% of peri-urban areas analyzed experienced a transition, converting about 2,700 sq-km of natural and/or agriculture to an urban use. West coast peri-urban areas observed the greatest area conversion of natural to urban use (39%). In contrast, peri-urban areas of the Prairies (i.e. west-center stratum) experienced the greatest area transition from an agriculture to urban use (41%), while west- and east-center observed marked rates of natural to urban transitions (3.9 and 3.5% per annum per sq-km, respectively). Current high population densities were generally associated with historic losses of agriculture or natural use, while regional differences in correlations between land use trends and current levels of income, new residential construction, and single-detached housing highlight the potential influence of urban policies and historic socio-economic trajectories. The developed dynamic land use classification provides a reliable, transparent, and nationally consistent method to tabulate land use intensity across various spatiotemporal scales and may enhance interpretation of interdisciplinary studies involving social and community outcomes.

Exploring Annual Urban Expansions in the Guangdong-Hong Kong-Macau Greater Bay Area: Spatiotemporal Features and Driving Factors in 1986–2017

The Guangdong–Hong Kong–Macau Greater Bay Area (GBA) of China is one of the largest bay areas in the world. However, the spatiotemporal characteristics and driving mechanisms of urban expansions in this region are poorly understood. Here we used the annual remote sensing images, Geographic Information System (GIS) techniques, and geographical detector method to characterize the spatiotemporal patterns of urban expansion in the GBA and investigate their driving factors during 1986–2017 on regional and city scales. The results showed that: the GBA experienced an unprecedented urban expansion over the past 32 years. The total urban area expanded from 652.74 km2 to 8137.09 km2 from 1986 to 2017 (approximately 13 times). The annual growth rate during 1986–2017 was 8.20% and the annual growth rate from 1986 to 1990 was the highest (16.89%). Guangzhou, Foshan, Dongguan, and Shenzhen experienced the highest urban expansion rate, with the annual increase of urban areas in 51.51, 45.54, 36.76, and 23.26 km2 y−1, respectively, during 1986–2017. Gross Domestic Product (GDP), income, road length, and population were the most important driving factors of the urban expansions in the GBA. We also found the driving factors of the urban expansions varied with spatial and temporal scales, suggesting the general understanding from the regional level may not reveal detailed urban dynamics. Detailed urban management and planning policies should be made considering the spatial and internal heterogeneity. These findings can enhance the comprehensive understanding of this bay area and help policymakers to promote sustainable development in the future.

Rapid urbanization in a mountainous landscape: patterns, drivers, and planning implications

Understanding patterns and drivers of urbanization is essential for urban sustainability, but such understanding is lacking for mountainous regions. This study had three objectives: (1) to quantify the spatiotemporal patterns of urban expansion in Chongqing, the largest mountainous metropolitan area in China, during 1990–2015; (2) to explore major drivers for the observed urbanization patterns; and (3) to identify the spatial signatures of Chongqing’s urbanization which differ from those of topographically flat urban regions for sustainable urban planning in mountainous regions. We used multiple metrics to characterize urbanization patterns and expansion modes. Pearson correlation analysis and Classification and Regression Trees (CART) were used to identify potential drivers. The built-up area of Chongqing increased five times during 1990–2015 with regional variations. Three growth modes—leapfrog, edge-expansion, and infilling, took place concurrently, but their relative dominance varied in time and space with leapfrog as the dominant mode in recent years. The major drivers of built-up area expansion changed from demography to economy, with topographic constraints attenuating over time. Compared to flat urban regions in China, the spatial signatures of Chongqing’s urbanization were characterized by greater dominance of leapfrog expansion mode with smaller and more regularly-shaped patches. The unique patterns and drivers of urban expansion in Chongqing provide new insights of urbanization in mountainous regions for sustainable urban planning. We have proposed a conceptual urban planning framework for mountainous cities based on landscape sustainability science, GeoDesign, and regional landscape characteristics.

Assessing 40 years of spatial dynamics and patterns in megacities along the Belt and Road region using satellite imagery

ABSTRACT The Belt and Road (B&R) region, a vital area with historical, economic, cultural and political significance, has undergone rapid urbanization in the past several decades, especially in the form of urban expansion. In this study, 20 megacities in the B&R region were selected to explore different spatiotemporal patterns of urban expansion. Object-oriented support vector machines (SVM), annual growth rate (AGR) models, and landscape metrics were employed to delineate the urban areas and characterize spatiotemporal characteristics and landscape patterns of these megacities during 1975–2015. All urban maps presented high overall accuracies (80.70%–95.90%) and overall Kappa coefficients (0.76–0.95). The study revealed that megacities in the B&R region have undergone different types of urban sprawl, mainly adopting a ‘concentric circle’ pattern in inland areas and a ‘sector’ pattern in coastal areas. Besides, six expansion modes were summarized according to the AGRs of individual megacities. Differences existed in megacities of the developing and developed countries and among five sub-regions. Moreover, ‘dispersion, gathering, and re-dispersion’ and ‘coalescence’ were two major landscape patterns of megacities in developing and developed countries. Results of this study can provide a scientific reference for urban planning and aid in sustainable development of local areas.

高原河谷城镇化对植被覆盖度的影响

以典型的高原河谷城市——西宁市为例，定量分析了2000-2015年研究区景观格局及植被覆盖度的时空演变，揭示了高原河谷地区的城镇建设对植被覆盖度的干扰过程及生态环境质量的影响。结果表明：（1）2000-2015年间，西宁市城镇面积增幅为25.99%，总体城镇化率为4.76%，各区县城镇化水平差异较大；（2）西宁市平均植被覆盖度呈增加趋势但不显著（P < 0.57）。植被覆盖度以中高和高植被覆盖度为主，空间上呈现东西低-南北高的分布特征，退耕（牧）还林（草）区的植被覆盖度显著增加（P < 0.01），说明生态恢复工程效果显著；（3）区县尺度上，城镇化速率与中高覆盖植被面积变化呈显著负相关（P < 0.01），区县内生态质量有所下降，城镇发展程度和区位条件的差异是影响中高覆盖度植被变化的主要因素；（4）格网尺度上，建成区及其周边区域的低覆盖植被面积呈显著增加趋势（P < 0.01），表明城镇内部区域生态质量有所改善。研究结果对保护和提高西宁市生态环境质量及合理推进城镇建设等方面具有重要意义。;This paper took a typical plateau river valley city - Xining City as an example and quantified the spatiotemporal patterns of urban expansion and vegetation cover from 2000 to 2015. We then analyzed the impact of urban construction on vegetation coverage and the quality of the ecological environment. The results showed that: (1) From 2000 to 2015, the area of build-up lands increased by 25.99%, whereas the urbanization rate was 4.76%. Meanwhile, the urbanization levels of different districts and counties varied widely; (2) There was a slight but insignificant increasing trend in vegetation coverage (P < 0.57). The city was dominated by Medium-High and High vegetation coverage, in which spatially distributed characteristics are east-west low and north-south high. The vegetation coverage in the area of returning farmland (grazing) to forest (grass) has increased significantly (P < 0.01), suggesting the restoration project achieved significant effects; (3) On the district or county scale, the urbanization change rate and the medium-high coverage vegetation change trend showed a significant negative correlation (P < 0.01). Different degree of urban development and location conditions are the main factors affected the medium-high coverage vegetation; (4) On the grid-scale, the area of low-cover vegetation in the built-up area and its surrounding areas showed a significant increase (P < 0.01), indicating that the quality of the ecological environment in urban areas has improved; The research results are of great significance for protecting and improving the quality of the ecological environment of Xining City and for rationally advancing urban construction.

Quantifying Spatiotemporal Patterns and Major Explanatory Factors of Urban Expansion in Miami Metropolitan Area During 1992–2016

Urban expansion is one of the most dramatic forms of land transformation in the world and it is one of the greatest challenges in achieving sustainable development in the 21st century. Previous studies analyzed urbanization patterns in areas with rapid urban expansion while urban areas with low to moderate expansion have been overlooked, especially in developed countries. In this study, we examined the spatiotemporal dynamics of urban expansion patterns in South Florida, United States (US) over the last 25 years (1992–2016) using Remote Sensing and GIS techniques. The main goal of this paper was to investigate the degree and spatiotemporal patterns of urban expansion at different administrative level in the study area and how spatiotemporal variance in different explanatory factors influence urban expansion in this region. More specifically, this research quantifies the rates, types, intensity, and landscape metrics of urban expansion in Miami-Fort Lauderdale-Palm Beach, Florida Metropolitan Statistical Area (Miami MSA) which is the 7th largest MSA and 4th largest urbanized area in the US using remote sensing (satellite imageries) data from National Land Cover Datasets (NLCD) and Coastal Change Analysis Program (C-CAP) at 30 m spatial resolution. We further investigated the urban growth patterns at the county and city areas that are located within this MSA to portray the local ‘picture’ of urban growth in this region. Urban expansion in this region can be divided into two time periods: pre-2001 and post-2001 where the former experienced rapid urban expansion and the later had comparatively slow urban expansion. Results suggest that infilling was the dominant type of urban expansion followed by edge-expansion and outlying. Results from landscape metrics represent that newly developed urban lands became more aggregated and simplified in form as the time progressed in the study region. Also, new urban lands were generated away from the east coast and historic cities which eventually created new urban cores. We also used correlation analysis and multiple linear stepwise regression to address major explanatory factors of spatiotemporal change in urban expansion during the study period. Although the influence of factors on urban expansion varied temporally, Population and Distance to Coast were the strongest variables followed by Distance to Roads and Median Income that influence overall urban expansion in the study area.

Directional multi-scale analysis and simulation of urban expansion in Auckland, New Zealand using logistic cellular automata

In characterising urban expansion, existing landscape indices lack consideration for directional changes. This limitation is overcome with the proposed directional perspective (urban expansion vector) in this study, which can identify both the urban expansion mode and local changes at the patch and sectorial levels, and reveal the varying importance of the same urbanisation factors at multi-scales. Landscape (expansion) indices (LEI) and directional characteristics of newly grown urban patches were derived / extracted from time-series (1975–2016) satellite images in the Auckland metropolitan area, based on which urban expansion was simulated using logistic regression cellular automata at both the global and sectorial levels. The results show that Auckland urban development was mostly compact with “organic” being the dominant mode of expansion throughout the last 40 years. Most urban development took place in the southeast (270° - 360°) and northwest (90° - 180°) sectors, within which urban expansion occurred mostly in places that had favourable transportation infrastructures and are close to the CBD. The influence of the nine factors of urbanisation studied varies with scale and sector. In general, accessibility (e.g., proximity to roads and the CBD) and amenity (e.g., distance to transportation and schools) are more important than physical variables (e.g., terrain) in affecting urban development. The localised sectorial simulation result is in a closer agreement with the observed urbanisation than the global, sectorless result. The directional perspective, in conjunction with the LEI and other landscape indices, can effectively characterise the spatiotemporal patterns of urban expansion. More importantly, it improves the simulation accuracy of urban expansion (e.g., simulation kappa rising from 0.024 to 0.161 in the northwest sector, and from 0.31 to 0.40 in the southeast sector) for a monocentric city whose urbanisation is strongly sectorial.

Toward a sustainable urban expansion: A case study of Zhuhai, China

Literature on urban expansion has grown rapidly, yet researchers are still far from a full spectrum of comprehensive understanding. Debates about the spatiotemporal patterns of urban expansion have risen alongside a lack of a comprehensive framework engaging environmental dimension in analyzing urban expansion efficiency. Moreover, cross-boundary development as a significant driving force of border city expansion has long been neglected in previous studies. By applying remote sensing and Geographic Information System (GIS) methods to the case of Zhuhai, this study attempts to add empirical evidence for enriching the discussion on spatiotemporal patterns, urban expansion efficiency, and the driving forces of urban expansion. Indices including annual urban growth rate, urban expansion intensity index, local Moran's I, and landscape expansion index are adopted to measure urban expansion and its evolving patterns. A set of urban expansion efficiency indices under a three-dimensional framework is proposed and applied in empirical calculation. The impacts of cross-boundary development are considered in analyzing the mechanism behind. Zhuhai's urban expansion was modest and fluctuated across the study period from 1980 to 2015, evolving from a double-center city to a multi-center city. Edge expansion dominated nearly all the phases, while the fast expansion periods coincided with the proportional increase of outlying expansion. Mixed performance in the three dimensions of urban expansion efficiency and significant correlation between the economic and environmental dimensions were identified. Accessibility factors were found to be the primary factors of the urban expansion of Zhuhai, followed by natural environmental factors and socioeconomic factors. Among these factors, cross-boundary factor played a substantial role. Current findings may generate implications for policymakers and contribute to a more comprehensive understanding of urban expansion.

Spatiotemporal Patterns of Urban Land Use Change in Typical Cities in the Greater Mekong Subregion (GMS)

The Greater Mekong Subregion (GMS) has experienced rapid economic growth and urbanization. However, few studies have paid attention to urban land use dynamics, especially spatiotemporal patterns of urban expansion and land use change, in this region. This research aimed to conduct a comprehensive study of urban land use change in Xishuangbanna, Yangon, Vientiane, Phnom Penh, Bangkok, and Ho Chi Minh City, from 1990 to 2015. The analysis was based on land use maps derived from Landsat satellite products and employed urban expansion intensity, sector analysis, gradient-direction analysis, and landscape metrics. The results show Xishuangbanna, Yangon, Vientiane, Phnom Penh, Bangkok, and Ho Chi Minh City all experienced dramatic urban expansion and land use change since 1990, with urban expansion intensities of 15.01, 5.26, 9.15, 1.56, 11.88 and 11.91, respectively. The landscape metrics analysis indicated that urban areas were always aggregated and self-connected, while other land use types showed trends of disaggregation and fragmentation. In the process of urban expansion, paddy and natural land use types were commonly transformed to built up area. The results further reveal several common issues in urban land use, e.g. land fragmentation and loss of natural land use types. Finally, the discussion on the relationship between government policy and land use change for these cities shows land reform and attitude toward foreign direct investments played important roles in urban land use change in GMS.

Quantifying spatio-temporal patterns of urban expansion in Beijing during 1985–2013 with rural-urban development transformation

Rural-urban development transformation has entered a crucial period with the development of urbanization, informatization, industrialization and agricultural modernization. Quantifying spatio-temporal patterns of urban expansion is essential to monitor and assess the process of urbanization and offer a theoretical basis for rural restructuring and landscape dynamics. In this paper, we used the remotely sensed land use data to quantify and research spatio-temporal patterns of urban expansion from 1985 to 2013 in Beijing, China. This study integrated methods of statistical analysis (i.e., calculation of time series landscape matrices and urban expansion index) and the gravity-center model to study the landscape configuration, the holistic change of urban land in area, size, expansion speed and movement direction, respectively. Meanwhile, GIS-based buffer analysis was also applied to study the spatial mode of urban expansion in Beijing. Results demonstrated that (1) Beijing has experienced magnificent urban sprawl in the last 28 years. The combination of time series landscape matrices exhibited a typical spatial configuration of urban sprawling in Beijing: leapfrog development of new urban nuclei formation in areas which were non-adjacent to existing urban centers with obvious fragmentation, as well as expansion of existing urban areas resulting in contiguous urban entities in each time interval; (2) The gravity center of urban land continued moving northeastward, except during the time intervals of 1995–2000 and 2010–2013 when it moved southward; (3) The northern fan-shaped suburb was the most active area of urban expansion before 2005, and urban later had a concentrated expansion toward the southern inverted-triangle-shaped area; and (4) Urban sprawl presented denotative features along the motorways, while urban also expanded in the form of a big pancake.

A comparative study of spatiotemporal patterns of urban expansion in six major cities of the Yangtze River Delta from 1980 to 2015

ABSTRACTIntroduction: China has been experiencing dramatic urbanization in parallel with its economic boom over the past three to four decades. The Yangtze River Delta (YRD), as the most important engine in the Chinese economy, has pioneered in the rapid urbanization road of China since the late 1970s. We quantified and compared the spatiotemporal patterns of urban expansion in six major cities in the YRD urban agglomeration between 1980 and 2015. Outcomes: We found that Shanghai, Nanjing, Hangzhou, Wuxi, Suzhou and Ningbo expanded by an annual rate of 5.4%, 5.9%, 9.6%, 7.4%, 6.3% and 8.1% from 1980 to 2015, suggesting larger cities generally possess lower growth rates. Spatiotemporal patterns of urban expansion are defined by multiple forces including physical conditions and urban planning and policy. The urbanization processes in Shanghai, Nanjing and Hangzhou generally conformed with the diffusion-coalescence theory as the number of patches (NP) and patch density (PD) of urbanized land peaked and the proportion of leapfrogging urban growth type began to decrease around 2005, which separating their urbanization processes into diffusion phase before and coalescence phase after. In contrast, Suzhou, Wuxi and Ningbo is either in the diffusion or in the transition phase from diffusion to coalescence, not showing temporal dynamics of diffusion-coalescence phase across the study period, which might be related to the fact that the urban areas in these three cities were more dispersive in space than that of other cities. Conclusions: These spatially explicit findings are the fundamental cornerstone to understand the characteristics, drivers and consequences of urban expansion in the urban agglomerations, and then detect the feasibility of general urbanization theories and further advance in-depth theoretical understanding to support a sustainable urban future.

The impact of urban expansion on the regional environment in Myanmar: a case study of two capital cities

This study examines the spatio-temporal patterns of urban expansion for Yangon and Nay Pyi Taw, the former and new national capitals of Myanmar, and its impact on the regional environment between 2000 and 2013. The objective is to examine different driving forces of urban expansion for Yangon and Nay Pyi Taw, and their environmental consequences during Myanmar’s transitional economy. Classified time-series Landsat images are used to evaluate urban expansion processes. Environmental parameters being evaluated in this study include five sets of remotely sensed MODIS land products that are land surface temperature (LST), percent tree cover (PTC), evapotranspiration (ET), terrestrial ecosystem net primary productivity (NPP), and aerosol optical depth (AOD). A time-series trend analysis technique is used to examine the environmental consequences. The built-up areas in Nay Pyi Taw and Yangon exhibit exponential and polynomial increase, respectively. A 1% increase of built-up area could potentially cause an increase of daytime LST of 0.7 °C, a PTC loss of 2.3%, a decrease in NPP of 34.3 kg/m2, and an ET decrease of 42.2 mm for Yangon. Similarly, for Nay Pyi Taw, a 1% increase in built-up area could potentially cause a daytime LST increase of 0.3 °C, a nighttime LST increase of 0.06 °C, a PTC loss of 2.5%, a decrease in NPP of 15.1 kg/m2, and a decrease of 19.2 mm ET. No significant change was observed for AOD for either city. Both cities have experienced extensive urban expansion but with different spatial and temporal characteristics, and their effects on the regional environment are different. Urban expansion of Nay Pyi Taw mainly was government-induced municipal infrastructure development. Yangon’s expansion is mainly caused by population pressure and migration from rural areas. The urban expansion in Yangon was mainly due to reconstruction and renovation, as well as infill development during the study period.

A Comparative Study of Urban Expansion in Beijing, Tianjin and Tangshan from the 1970s to 2013

Although the mapping of spatiotemporal patterns of urban expansion has been widely studied, relatively little attention has been paid to detailed comparative studies on spatiotemporal patterns of urban growth at the regional level over a relatively longer timeframe. This paper was based on multi-sensor remote sensing image data and employs several landscape metrics and the centroid shift model to conduct a multi-angle quantitative analysis on urban expansion in Beijing, Tianjin and Tangshan (Jing-Jin-Tang) in the period from 1970–2013. In addition, the impact analysis of urban growth on land use was adopted in this research. The results showed that Beijing, Tianjin and Tangshan all experienced rapid urbanization, with an average annual urban growth rate of 7.28%, 3.9%, and 0.97%, respectively. Beijing has especially presented a single choropleth map pattern, whereas Tianjin and Tangshan have presented a double surface network pattern in orientation analysis. Furthermore, urban expansion in Beijing was mainly concentrated in Ring 4 to Ring 6 in the northwest and southeast directions, whereas the major expansion was observed in the southeast in Tianjin, primarily affected by dramatic development of Binhai New Area and Tianjin South Railway Station. Naturally, the urban expansion in Tangshan was significantly influenced by the expansion of Beijing and was primarily southwestward. The hot-zones of urbanization were observed within the ranges of 7–25 km, 6–18 km, and 0–15 km, accounting for 93.49%, 89.44% and 72.44% of the total expansion area in Beijing, Tianjin and Tangshan, respectively. The majority of the newly developed urban land was converted from cultivated land and integrated from other built-up land over the past four decades. Of all new urban land in the Beijing, Tianjin and Tangshan, more than 50% was converted from cultivated land, and there was a general tendency for smaller cities to have higher percentages of converted land, accounting for 50.84%, 51.19%, and 51.58%, respectively. The study revealed significant details of the temporal and spatial distributions of urban expansion in Beijing, Tianjin and Tangshan and provided scientific support for the collaborative development of the Beijing, Tianjin and Hebei (Jing-Jin-Ji) regions.

How Did Urban Land Expand in China between 1992 and 2015? A Multi-Scale Landscape Analysis.

Effective and timely quantification of the spatiotemporal pattern of urban expansion in China is important for the assessment of its environmental effects. However, the dynamics of the most recent urban expansions in China since 2012 have not yet been adequately explained due to a lack of current information. In this paper, our objective was to quantify spatiotemporal patterns of urban expansion in China between 1992 and 2015. First, we extracted information on urban expansion in China between 1992 and 2015 by integrating nighttime light data, vegetation index data, and land surface temperature data. Then we analyzed the spatiotemporal patterns of urban expansion at the national and regional scales, as well as at that of urban agglomerations. We found that China experienced a rapid and large-scale process of urban expansion between 1992 and 2015, with urban land increasing from 1.22 × 104 km2 to 7.29 × 104 km2, increasing in size nearly fivefold and with an average annual growth rate of 8.10%, almost 2.5 times as rapid as the global average. We also found that urban land in China expanded mainly by occupying 3.31 × 104 km2 of cropland, which comprised 54.67% of the total area of expanded urban land. Among the three modes of growth—infilling, edge expansion, and leapfrog—edge expansion was the main cause of cropland loss. Cropland loss resulting from edge expansion of urban land totalled 2.51 × 104 km2, accounting for over 75% of total cropland loss. We suggest that effective future management with respect to edge expansion of urban land is needed to protect cropland in China.