Impacts of Urban Expansion on the Urban Thermal Environment:A Case Study of Changchun,China

Urbanization,especially urban land expansion,has a profound influence on the urban thermal environment.Cities in Northeast China face remarkably uneven development and environmental issues,and thus it is necessary to strengthen the diagnosis of thermal environmental pressure brought by urbanization.In this study,multi remote sensing imageries and statistical approaches,involving piecewise linear regression(PLR),were used to explore urban expansion and its effects on the thermal environment of Changchun City in Jilin Province,China.Results show that Changchun experienced rapid urban expansion from 2000 to 2020,with urban built-up areas increasing from 171.77 to 525.14 km².The area of the city’s urban heat island(UHI)increased dramatically,during both day and night.Using PLR,a positive linear correlation of built-up density with land surface temperature(LST)was detected,with critical breakpoints of 70%-80%during the daytime and 40%-50%at nighttime.Above the thresholds,the magnitude of LST in response to built-up density significantly increased with intensifying urbanization,especially for nighttime LST.An analysis of the relative frequency distributions(RFDs)of LST reveals that rapid urbanization resulted in a significant increase of mean LST in newly urbanized areas,but had weak effects on daytime LST change in existing urban area.Urban expansion also contributed to a constant decrease of spatial heterogeneity of LST in existing urban area,especially at daytime.However,in newly urbanized areas,the spatial heterogeneity of LST was decreased during the daytime but increased at nighttime due to urbanization.     

Relationship Between Urban Road Traffic Characteristics and Road Grade Based on a Time Series Clustering Model: A Case Study in Nanjing,China

With the increasing number of vehicles in large- and medium-sized cities challenges in urban traffic management, control, and road planning are being faced. Taxi GPS trajectory data is a novel data source that can be used to study the potential dynamic traffic characteristics of urban roads, and thus identify locations that show a notable lack of road planning. Considering that road traffic characteristics on their own are insufficient for a comprehensive understanding of urban traffic, we develop a road traffic characteristic time series clustering model to analyze the relationship between urban road traffic characteristics and road grade based on existing taxi trajectory data. We select the main urban area of Nanjing as our study area and use the taxi trajectory data of a single month for evaluating our method. The experiments show that the clustering model exhibit good performance and can be successfully used for road traffic characteristic classification. Moreover, we analyze the correlation between traffic characteristics and road grade to identify road segments with planning designs that do not match the actual traffic demands.     

Directional Analysis of Urban Expansion Based on Sub-pixel and Regional Scale: A Case Study of Main Districts in Guangzhou,China

Multi-scale data have had a wide-ranging level of performance in the area of urban change monitoring. Herein we investigate the correlation between the impervious surface fraction(ISF) and the Defense Meteorological Satellite Program/Operational Linescan System(DMSP/OLS) nighttime stable light(NTL) data with respect to the urban expansion in the main districts of Guangzhou. Landsat 5 Thematic Mapper and Landsat 8 Operational Land Image(OLI) data from 1988 to 2015 were used to extract the ISF using the linear spectral mixture analysis model and normal difference build-up index at the sub-pixel scale. DMSP/OLS NTL data from 1992 to 2013 were calibrated to illustrate the urban nighttime light conditions at the regional scale. Urban expansion directions were identified by statistics and kernel density analysis for the ISF study area at the sub-pixel scale. In addition, the correlation between the ISF and DMSP/OLS NTL data were illustrated by linear regression analysis. Furthermore, Profile Graph in ArcGIS was employed to illustrate the urban expansion from the differences in correlation in different directions. The conclusions are as follows: 1) The impervious surface(IS)in the study area has expanded to the northeast and the east, starting with the old urban zones, and the high-density IS area has increased by321.14 km^2. 2) The linear regression analysis reveals a positive correlation between the ISF and the DMSP/OLS NTL data. The multi-scale data changes are consistent with the actual urban planning of Guangzhou. 3) The DMSP/OLS NTL data overestimate the urban extent because of its saturation and blooming effects, causing its correlation with ISF to decrease. The pattern of urban expansion influences the saturation and blooming effects of the DMSP/OLS NTL data.     

Spatial Structure of Urban Residents' Leisure Activities: A Case Study of Shenyang,China

The spatial characteristics of residents' leisure activities not only reflect their demand for urban leisure space but also affect the urban spatial layout. This study takes Shenyang, China as an example and analyzes the characteristics of residents' leisure activities through questionnaires. On this basis, it uses point of interest data and mobile phone signaling data to identify various types of residential and leisure functional relationships, and uses spatial analysis and community detection to assess the distance characteristics, flow patterns, and community structure of residents' leisure activities, so as to discuss the spatial structure of residents' leisure activities in Shenyang. The results showed that: 1) in addition to leisure at home, Shenyang residents mainly went to shopping malls, supermarkets,and parks for leisure activities, and the proportions of residents of the two types of leisure activities were approximately equal; 2) the average distances that residents traveled for shopping and park leisure were near in the middle and far in the periphery, and the travel costs of peripheral residents for centrally located leisure were higher than those for residents in central areas; 3) the flow patterns of the residential-shopping and residential-park functional relationships displayed clustering mode characteristics, and Shenyang presented a significant monocentric structure; and 4) residents' shopping activities were concentrated in the southern community, and walking in the park activities were concentrated in the western community. Residents' leisure activities were characterized by centripetal agglomeration,which was prone to problems such as traffic congestion and big city diseases. The spatial expansion process in the city was characterized by obvious directional inheritance and path dependence, and the construction of sub-cities is needed to improve the related service facilities.     

Evaluation of Three-dimensional Urban Expansion: A Case Study of Yangzhou City,Jiangsu Province,China

With rapid urban development in China in the last two decades, the three-dimensional(3D) characteristic has been the main feature of urban morphology. However, the vast majority of researches of urban growth have focused on the planar area(two-dimensional(2D)) expansion. Few studies have been conducted from a 3D perspective. In this paper, the 3D urban expansion of the Yangzhou City, Jiangsu Province, China from 2003 to 2012 was evaluated based on Geographical Information System(GIS) tools and high-resolution remote sensing images. Four indices, namely weighted average height of buildings, volume of buildings, 3D expansion intensity and 3D fractal dimension are used to quantify the 3D urban expansion. The weighted average height of buildings and the volume of buildings are used to illustrate the temporal change of the 3D urban morphology, while the other two indices are used to calculate the expansion intensity and the fractal dimension of the 3D urban morphology. The results show that the spatial distribution of the high-rise buildings in Yangzhou has significantly spread and the utilization of the 3D space of Yangzhou has become more efficient and intensive. The methods proposed in this paper laid a foundation for a wide range of study of 3D urban morphology changes.     

A Comparative Study of Methods for Delineating Sphere of Urban Influence: A Case Study on Central China

A number of urban and regional plans have been developed with the advancement of urbanization and regional integration, among which the delineation of sphere of urban influence and improvement of integration between the city and its hinterland have be- come vital important for guiding practices. In terms of delineating sphere of urban influence, existing studies have been focused on static study by using single year data or single method, resulting in a lack of time-series longitudinal analysis or comprehensive analysis based on multiple methods This study emphasizes on comparing two methods from both the theoretical and empirical perspective. Both gravity model and improwd field model are applied to the selected study area for measurements and comparison, to explore their strengths and weaknesses. A research framework for comprehensive analysis on delineating sphere of urban influence is proposed. In the end, the differences of deli：aeating methods are illustrated and the feasibility of comprehensive analysis is discussed. Recommendations are provided for selecting appropriate methods for delineating sphere of urban influence or developing regional hierarchy system plans and urban spatial structure schemes.     

Impact of Urban 3D Morphology on Particulate Matter 2.5(PM_(2.5)) Concentrations:Case Study of Beijing,China

Urban particulate matter 2.5(PM_2.5) pollution and public health are closely related, and concerns regarding PM_2.5 are widespread. Of the underlying factors, the urban morphology is the most manageable. Therefore, investigations of the impact of urban three-dimensional(3D) morphology on PM_2.5 concentration have important scientific significance. In this paper, 39 PM_2.5 monitoring sites of Beijing in China were selected with PM_2.5 automatic mo...     

Evaluation and Promotion of the Service Capacity of Urban Public Open Spaces Based on Improving Accessibility: A Case Study of Shenyang City,China

The service capacity of urban public open spaces is an important indicator of the justness and soundness of the allocation of public space resources, such as parks and green spaces, in the process of urban development. Improving the service capacity of urban public open spaces is conductive to healthy, sustainable urban development. In this study, taking Shengyang City, China as a case study,a Gaussian-based two-step floating catchment area method(2 SFCA) is used to calculate an accessibility in...     

Multi-source Data-driven Identification of Urban Functional Areas: A Case of Shenyang,China

Urban functional area(UFA) is a core scientific issue affecting urban sustainability. The current knowledge gap is mainly reflected in the lack of multi-scale quantitative interpretation methods from the perspective of human-land interaction. In this paper, based on multi-source big data include 250 m × 250 m resolution cell phone data, 1.81 × 105 Points of Interest(POI) data and administrative boundary data, we built a UFA identification method and demonstrated empirically in Shenyang City, Chi...     

基于RS与GIS的北京市热岛研究

基于普适性单通道算法,利用2005年5月6日的TM数据反演北京市区的实际地表温度。在此基础上,分析了北京市区的热环境特征、热岛分布的位置。运用GIS空间分析工具,分析了地表温度与地形特征和地表覆盖类型之间的关系。结果表明,北京市热岛分布具有环状和带状分布特征,高程较低处和坡度较小处更容易形成热岛中心,不同地表覆盖类型的热特征具有显著的差异。     

北京市TM图像城市扩张与热环境演变分析

北京城市规模的扩大,对城市环境的影响越来越显著。本文利用3期TM数据对北京市城市扩展、植被变化及其环境影响进行了分析。首先对图像进行辐射归一化,然后分别提取城市用地扩展信息和植被变化信息。并利用普适性单通道算法反演了地表温度,分析了热环境的变化。结果表明,城市扩展区和热状况加重区具有很好的对应性,而植被增加区则对应着热状况减轻区和热状况基本未变化区。城市扩展和热状况加重具有相似的规律,都是从市中心向外围呈辐射状蔓延,与北京市的环状城市结构相符合。     

基于Dyna-CLUE改进模型和SD模型耦合的山区城镇用地情景模拟研究——以岷江上游地区为例

山区城镇扩张受山区地形和山地灾害等因素限制,而常用的土地利用模型难以有效表达这一特征。本文通过对Dyna-CLUE（Dynamic Conversion of Land Use and its Effects Model）模型进行改进并结合系统动力学（System Dynamic,SD）模型,充分发挥这2个模型在微观土地分配,及宏观情景模拟上的优势,很好地表达了山区地形和山地灾害等因素对山区城镇扩张的限制作用,为山区城镇扩张情景模拟提供了一个有效的方法。以岷江上游地区为例,根据研究区历史统计数据构建山区城镇用地SD模型,模拟低速发展、惯性发展和高速发展3种不同发展情景下城镇用地的需求,结合Dyna-CLUE改进模型,预测了对应情景下2011-2030年的城镇用地范围,并探究其对其他土地利用类型的影响。结果表明,发展速度越快,城镇主体越快达到地理限制区域的上限,并开始沿山间平地向两端扩张。耕地受山区城镇扩张的影响要远远超出其他土地利用类型,离城镇越近受影响越大。随着城镇扩张的加剧,其对自然环境的影响也逐渐增大。模型模拟结果能为山区城镇用地规划、评估由城镇扩张造成的生态环境问题和制定相应的对策提供有效的技术支撑。     

Urban Economic Cluster Template and Its Dynamics of Beijing,China

Economic clusters have been a central focus of current urban and regional research, policies and practices. However, a meth- odology to identify and analyze policy-relevant economic cluster dynamics is still not well developed. Based on input-output （I-O） data of 1987, 1992, 1997, 2002 and 2007 of Beijing, this article presents an adapted principle component analysis for identifying the evolu- tion of local economic cluster patterns. This research addresses the changes of economic interaction of industries with complementary and common activities over time. The identified clusters provide an insight into the reality of economic development in a diversifying urban economy： the increasing importance of services and the growing interaction between service and manufacturing industries. Our method therefore provides the analysts with a better understanding of the emergence, disappearance and development of economic clus- ters citywide. The results could be used to assist monitoring urban economic development and designing more practical urban economic strategies.     

城市土地利用优化配置分析应用——以济南市为例

对城市土地资源进行优化配置,提高城市土地利用的集约程度,是当前城市土地利用研究领域中的热点问题。本文以济南市为研究区,通过构建系统动力学模型对济南市土地利用的数量结构进行预测,在此基础上,利用ArcGIS软件的二次开发语言编写程序,实现了济南市土地利用的空间优化配置,为济南市城市内部土地资源的合理开发与利用,提供决策参考。     

城市形态演化的粒子群智能随机元胞模型与应用——以上海市嘉定区为例

城市形态演化是一个非线性的复杂时空动态过程,认识、理解和模拟此变化过程,有助于探索城市扩展的机理。地理元胞自动机(CA)因其较强的复杂系统模拟和预测能力,越来越多地应用于城市形态的演变研究。CA"自下而上"的结构特性,与粒子群智能(PSO)由底层单元交互而呈现系统全局的自组织性,本质上是一致的。本研究将两者结合,以模拟结果和真实形态的差异最小化为基础,利用粒子群智能,以快速随机搜索的方式,获取CA参数的优化组合和模型结构,从而建立了一种粒子群智能地理元胞自动机模型(PSO-CA)。以上海市嘉定区为案例,通过较长时段的历史数据对PSO-CA模型进行校正,成功模拟了该区域1989-2006年的城市形态演化过程,并进行了2010年发展预测。与传统地理CA模型比较,PSO-CA模型模拟结果的精度更高。     

Measurement and Scenario Simulation of Effect of Urbanisation on Regional CO2 Emissions Based on UEC-SD Model:A Case Study in Liaoning Province,China

Based on the logical causal relationship and taking Liaoning Province, China, which is the Chinese traditional industrial base and is in the stage of accelerated urbanisation, as a case study, this study builds the ′Urbanisation-Energy Consumption-CO2 Emissions System Dynamics(UEC-SD)′ model using a system dynamics method. The UEC-SD model is applied to analyse the effect of the urbanisation process on the regional energy structure and CO2 emissions, followed by simulation of future production and living energy consumption structure as well as the evolutionary trend of CO2 emissions of three urbanisation scenarios(low speed, intermediate speed and high speed) under the assumed boundary conditions in urban and rural areas of Liaoning Province, China. The results show that the urbanisation process can alter production and the living energy consumption structure and thereby change regional CO2 emissions. An increase in the urbanisation rate in case area will lead to regional CO2 emissions rising in the short term, but when the urbanisation rate approaches 80%, CO2 emissions will reach a peak value and then decrease. Comparison of different urbanisation rates showed that production and living energy consumption exhibit different directions of change and rules in urban and rural areas. The effect of urbanisation on CO2 emissions and energy structure is not direct, and urbanisation can increase the differences in energy and CO2 emissions between urban and rural areas caused by the industrial structure, technical level and other factors.     

Spatial Characteristics and Influencing Factors of Urban Resilience from the Perspective of Daily Activity: A Case Study of Nanjing,China

Based on the connotation of urban resilience and the main contradictions of China’s urbanization, urban resilience is placed within the main daily activities contradictory scene of the urban man-land system to build a theoretical framework of urban activity resilience. Relying on geographic big data, this study identifies the spatial characteristics of activity resilience, reveals the impact of activity environment on activity resilience in Nanjing, and proposes countermeasures. The main conclus...     

Exploring Temporal Activity Patterns of Urban Areas Using Aggregated Network-driven Mobile Phone Data: A Case Study of Wuhu,China

The increasing availability of data in the urban context(e.g., mobile phone, smart card and social media data) allows us to study urban dynamics at much finer temporal resolutions(e.g., diurnal urban dynamics). Mobile phone data, for instance, are found to be a useful data source for extracting diurnal human mobility patterns and for understanding urban dynamics. While previous studies often use call detail record(CDR) data, this study deploys aggregated network-driven mobile phone data that may reveal human mobility patterns more comprehensively and can mitigate some of the privacy concerns raised by mobile phone data usage. We first propose an analytical framework for characterizing and classifying urban areas based on their temporal activity patterns extracted from mobile phone data. Specifically, urban areas' diurnal spatiotemporal signatures of human mobility patterns are obtained through longitudinal mobile phone data. Urban areas are then classified based on the obtained signatures. The classification provides insights into city planning and development. Using the proposed framework, a case study was implemented in the city of Wuhu, China to understand its urban dynamics. The empirical study suggests that human activities in the city of Wuhu are highly concentrated at the Traffic Analysis Zone(TAZ) level. This large portion of local activities suggests that development and planning strategies that are different from those used by metropolitan Chinese cities should be applied in the city of Wuhu. This article concludes with discussions on several common challenges associated with using network-driven mobile phone data, which should be addressed in future studies.     

Urban Expansion in Major Grain Producing Area from 1978 to 2017: A Case Study of Zhengzhou Metropolitan Area,China

The spatial form of urbanization in China has developed from single-core city expansion to a multi-center metropolitan area.However, little attention has been paid to the growth process of the emerging metropolitan area situated in major grain producing locations in the central China. Taking the Zhengzhou metropolitan area(ZZMA) as a case study, we developed an inverse S-shape model to characterize the spatial distribution of urban land density, and constructed an urban expansion core index, urb...