Construction land expansion and influencing factors of typical river valley cities in Northeast China: Taking Jilin City as an example

Jilin City is a typical river valley city in Northeast China.In this paper,the authors studied the spatial and temporal expansion characteristics of the built-up areas in Jilin City from 1990 to 2020 using the analysis of expansion speed and strength,fractal dimension,barycenter coordinate transfer index and sector analysis.The ultimate-goal is to analyze the driving and restrictive factors that affect the spatial expansion of river valley cities.The results indicate that(1)the expansion speed of urban land in Jilin City has been re-latively slow in the past 30 years,while only slightly faster in 2010–2020;(2)in the spatial dimension,Jilin City mainly expanded to the south,then to the west,and extensive expansion has resulted in complex mor-phology with little stability and compactness;(3)the expansion is affected by multiple factors,of which the positive factor is industrial development,while the restrictive factors include natural factors,population loss,etc.This study provides a case for the formulation of land use policies and land space planning in river valley cities.

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.

Application of Multi-agent Models to Urban Expansion in Medium and Small Cities: A Case Study in Fuyang City,Zhejiang Province,China

In this study,three-phase satellite images were used to define rules for the allocation of time and space in construction land resources based on a complex adaptive system and game theory.The decision behavior and rules of government agent,enterprise agent and resident agent in construction land growth were explored.A distinctive and dynamic simulation model of construction land growth was built,which integrated multi-agent,GIS technology and RS data and described the interaction among influencing agents.Taking Fuyang City in the Changjiang River Delta as an example,an assessment process for the remote sensing data in construction land and scenario planning was constructed.Repast and ArcGIS were used as simulation platforms.A simulation of the spatial pattern in land-use planning and the setting of scenario planning were conducted by using the incomplete active game,which was based on different natural,social and economic levels.Through this model,a simulation of urban planning space and decision-making for Fuyang City was created.Relevant non-structured problems arising from urban planning management could be identified,and the process and logic of urban planning spatial decision-making could thus be improved.Cel1-by-cel1 comparison showed that the simulation accuracy was over 72%.This model has great potential for use by government and town planners in decision support and technique support in the policy-making process.

Characterizing urban expansion of Korla City and its spatial-temporal patterns using remote sensing and GIS methods

Cities provide spatial contexts for populations and economic activities. Determining the spatial-temporal patterns of urban expansion is of particular significance for regional sustainable development. To achieve a better understanding of the spatial-temporal patterns of urban expansion of Korla City, we explore the urban expansion characteristics of Korla City over the period 1995-2015 by employing Landsat TM/ETM＋ images of 1995, 2000, 2005, 2010, and 2015. Urban land use types were classified using the supervised classification method in ENVI 4.5. Urban expansion indices, such as expansion area, expansion proportion, expansion speed, expansion intensity, compactness, and fractal dimension, were calculated. The spatial-temporal patterns and evolution process of the urban expansion （e.g., urban gravity center and its direction of movement） were then quantitatively analyzed. The results indicated that, over the past 25 years, the area and proportion of urban land increased substantially with an average annual growth rate of 15.18%. Farmland and unused land were lost greatly due to the urban expansion. This result might be attributable to the rapid population growth and the dramatic economic development in this area. The city extended to the southeast, and the urban gravity center shifted to the southeast as well by about 2118 m. The degree of urban compactness tended to decrease and the fractal dimension index tended to increase, indicating that the spatial pattern of Korla City was becoming loose, complex, and unstable. This study could provide a scientific reference for the studies on urban expansion of oasis cities in arid land.

Analysis of Urban Expansion and Driving Forces in Xuzhou City Based on Remote Sensing

Based on satellite remote sensing TM/ETM+ images of Xuzhou city,land use forms of the city in 1987,1994 and 2000 were extracted by using a neural network classification method. The expansion contribution rate and annual expansion intensity index of each administrative district have been calculated and the contribution rate matrices and spatial distribution maps of land use changes were obtained. Based on the above analysis,the characteristics of urban expansion from 1987 to 2000 have been explored. From 1987 to 1994,the expansion contribution rate of Quanshan dis-trict reached 46.80%,the highest in all administrative districts of Xuzhou city; Tongshan town was in a high-speed ex-pansion period; both Quanshan and Yunlong districts were experiencing fast-speed expansion periods while the entire city was expanding at a medium-speed with an annual expansion intensity index of 0.98; the city spread eastwards and southwards. From 1994 to 2000,the expansion contribution rate of Quanshan district reached 43.67%,the highest in Xuzhou; the entire city was in a medium-speed expansion period with an annual expansion intensity index of 1.04; the city has rapidly been extended towards the southeast. According to the contribution rate matrices of land use changes,urban expansion mainly usurps cropland and woodland. A quantitative analysis found that population growth,indus-trialization and economic development are the primary driving forces behind urban expansion.

Characteristics and Driving Forces of Spatial Expansion of Oasis Cities and Towns in Hexi Corridor, Gansu Province, China

This paper presents an integrated study of urban spatial expansion in the Hexi Corridor, Gansu Province, China based on TM, ETM remote sensing data in 1987, 1990, 1995, 2000, 2006 and 2011. The study explores the characteristics of urban spatial expansion and dynamic mechanism by using expansion speed index, expansion intensity index, compact index, fractal dimension, and extended flexibility index. We built the index system of influencing factors of urban spatial expansion by using the grey incidence model. The results showed that urban spatial expansion rate in the Hexi Corridor has been on the upward trend since 1987. Expansion intensity showed an obvious upward trend, however, the upward trend varied in different urban areas. In addition, the urban structure was loose relatively, but the urban compactness was more obvious. The urban spatial form tended to be simple, and the urban land use tended to become more intensive. Urban spatial expansion experienced several stages: padding internally, external expansion and padding internally. The main driving factors of urban spatial expansion are not the urban water resources and the oasis scale, but one or several factors such as economy, traffic, population, resource and national policy.

Hydrogel-supported poly(L-lactic acid) and polystyrene microsphere-based three-dimensional culture systems for in vitro cell expansion

The in vitro expansion of stem cells is important for their application in different life science fields such as cellular tissue and organ repair.An objective of this paper was to achieve static cell culture in vitro through peptide hydrogel-supported microspheres(MSs).The peptides,with their gel-forming properties,microstructures,and mechanical strengths characterized,were found to have good support for the MSs and to be injectable.The internal structures of poly(L-lactic acid)microspheres(PLLA-MSs)and polystyrene microspheres(PS-MSs)made in thelaboratory were observed and statistically analyzed in terms of particle size and pore size,following which the co-cultured MSs with cells were found to have good cell adhesion.In addition,three-dimensional(3D)culturing of cells was performed on the peptide and microcarrier composite scaffolds to measure cell viability and cell proliferation.The results showed that the peptides could be stimulated by the culture medium to self-assembly form a 3D fiber network structure.Under the peptide-Ms composite scaffold-based cell culture system,further enhancement of the cell culture effect was measured.The peptide-Ms composite scaffolds have great potential for the application in 3D cell culture and in vitro cellexpansion.

Urban spatial expansion and its impact on ecological service values of Chongqing City Proper in the last 30 years

Based on the remote sensing images of urban land use of Chongqing City Proper in the last 30years(from 1978 to 2011),The paper focuses on the impact of urban spatial expansion on urban ecosystem service.The charactereristics of urban spatial expansion pattern are expressed by Landscape Expansion Index and Index of Fractal Dimension.Taking advantage of calculation of these two indices,changes of the ecological service values in the main urban area of Chongqing caused by the variation of urban expansion patterns are evaluated and the interrelationship is analyzed.The main conclusions and results are as follows;in Chongqing City Proper,the ecological service value decreased rapidly from 1978 to 2011,especially in the period of 2002-2011.Urban spatial expansion pattern has exerted significant impact on urban ecosystem service value.Edge-expansion pattern broke into a great deal of urban enclaves and caused the disadvantage effect of the function of urban ecological system.At the same time,negative correlation existed between the indices of fractal dimension and the ecosystem service value.

Impact of Reclamation in Coal Mining Subsidence Area on Urban Spatial Expansion of Huaibei City

Based on the GIS data platform,and taking the spatial analysis as the main means,this paper explored the impact of reclamation in coal mining subsidence area on urban spatial expansion of Huaibei City. The analysis took the time evolution of urban space development as the basis,took the sectors,circle rings and sub-district offices as the basic spatial units. From the aspects of urban expansion rate,expansion direction,function and construction intensity,it analyzed the impact of reclamation on the urban spatial expansion. In addition,it analyzed the correlation between the reclamation utilization of the subsidence area and the changes in spatial expansion. Finally,it summarized the characteristics of the impact.

The characteristics of oasis urban expansion and drive mechanism analysis:a case study on Ganzhou District in Hexi Corridor,China

Ganzhou District is an oasis city in the Zhangye Municipality of Gansu Province, China. Based on multi-temporal TM and ETM satellite remote sensing data in 1985, 1996, 2000, and 2012, and by using corrected figures of land use status over the same periods, the spatial area of Ganzhou District since 1985 was extracted with statistical methods, and urban spatial expansion was measured by quantitative research methods. The characteristics of spatial expansion of Ganzhou District were analyzed by urban expansion rate, expansion intensity index, compactness, fractal dimension, and the city center shift method. The results showed that the built-up area of Ganzhou District increased by 3.46 times during 1985-2012. The expansion in 1985 1996 was slow, during 1996 2000 it was rapid, and during 2000-2012 it was at a high speed. This city mainly expanded to the northeast and northwest. Government decision making had a decisive influence on urban expansion. Initially the expansion was uniform, but later the local tfansportation, economy, resources, population, and national policies factors had an obvious influence on urban expansion.

Spatial Differences of Coastal Urban Expansion in China from 1970s to 2013

As the ′economic engines′ of China,coastal cities have developed and expanded considerably since the 1970 s.In this study,information on the urban expansion process of Chinese coastal cities from the 1970 s to 2013 was retrieved.Through the analysis of stage characteristics,spatial expansion modes,influences on land use,centroid shifts,and spatial morphological evolutions,the spatial differences of coastal urban expansion were revealed.Results indicate that 1) the expansion stages of southern coastal cities are more complex than those of northern coastal cities,and the expansion ranges and speeds of the former are far higher than those of the latter;2) the spatial expansion of southern coastal cities mostly adopt a single mode,whereas northern coastal cities mostly adopt a mixed mode;3) significant spatial differences in the occupations of different land sources exist between the south and the north along the coastline;4) the centroid of coastal cities tends to migrate toward the coastline,and the centroid shift distances of southern coastal cities are clearly higher than those of northern coastal cities;and 5) the spatial morphology of southern coastal cities tends to be compact,whereas that of northern coastal cities tends to be loose.Policies have a powerful significance in terms of guiding urban expansion and its spatial differences in coastal cities.Urban expansion in coastal cities will encounter new opportunities and challenges under the guidance of new types of urbanization strategies.

Integrating Geotechnical Investigation with Hydrological Modeling for Mitigation of Expansive Soil Hazards in Tabuk City, Saudi Arabia

Due to global climatic changes, flash floods are followed as a yearly disaster with high magnitude of influence. During the years 1981, 1988, 2010, 2012 and in January 2013, Tabuk city, northwest of Saudi Arabia suffered huge flash floods. These are major factors affecting on the swelling behavior of expansive Tabuk shale. The examined geotechnical properties of the surface and subsurface lithology of the sedimentary deposits distinguished Tabuk city into three zones. The expansive zone is spread in the middle and the non-expansive zones are distributed in the east and west of the city. The Watershed Modeling System (WMS) and Hydrologic Engineering Center (HEC-1) models were used to delineate and identify the drainage system and basin morphometry, where flash floods and accumulation of water might take place. Integration between geotechnical distribution maps of the expansion soil and surface hydrological data in terms of runoff maps was done. It has been identified the whereabouts the soils which have expansion characteristics and areas prone to flooding and surface runoff. They are helpful in defining the hazard zones map. Based on this map, it can be avoided constructions on the risk neighborhoods such as Al Qadsiyah, Al Maseif, Arrwdah, Al Nakhil and Al Rajhi. Also, it can suggest that the western side of Tabuk city is suitable for future urban extension. These results will help planners and citizens to create alternative development scenarios and determine their impact on the future urbanization patterns. Moreover, the direction of surface runoff flow or storm water discharge should be away from the expansion soil areas. Therefore, constructing dams on the outlet of the high-risk basins, south of Tabuk city is an important solution to control flash flood events, as well as increase groundwater recharge.

基于夜光数据的昆明市城市扩张格局演变分析

基于夜光数据采用POI&NPP综合指数提取建成区,然后进行建成区面积精度评定,从定性和定量两个角度进行城市扩张空间形态及格局演变分析。结果表明:1)POI融入夜光数据后,提高了提取的精度,提取边界与实际的分布范围更为接近。2)扩张速度和强度较快区域主要集中在呈贡区、嵩明县等,而较慢区域集中在北部的禄劝县、东川区、寻甸县等;嵩明县的动态变化率最高,中心城区的区域动态变化率较低,北部的寻甸县、东南部的宜良县、石林县动态变化率反而较高。3)昆明市整体上经济重心经度方向为向东偏移,纬度方向为向南偏移。

城市商业银行异地扩张与企业创新

基于城市商业银行异地扩张为准自然实验,通过手工整理的城市商业银行异地扩张及银企地理距离数据,并匹配1998—2013年中国工业企业数据库,使用双重差分和包括敏感性分析在内的多重稳健性检验,验证了城市商业银行异地扩张是否能促进企业创新。研究发现,城市商业银行异地扩张能够显著促进企业创新产出,并产生扩散效应,促进位于城市边界的企业创新。机制研究发现,城市商业银行异地扩张能够为企业提供更多信贷渠道并降低融资成本,但是也可能破坏当地原有的银企关系,加剧银行对成熟企业、大型企业和国有企业的信贷偏好。进一步研究发现,城市商业银行异地扩张通过促进金融科技发展,进而促进企业创新。

区域行政整合、市场扩张与企业高质量发展

打破地方保护和降低市场分割是加快统一大市场建设、推动高质量发展的内在要求。基于中国1998—2013年撤县设区改革,采用多时点双重差分法考察区域行政整合是否有利于企业发展质量提升及其作用机制。研究结果表明,区域行政整合对企业全要素生产率具有正向促进作用,有效提升了企业发展质量;机制检验表明,区域行政整合通过扩大企业市场规模和改善企业管理效率进而促进了企业发展质量提升;并且这种促进作用主要通过民营企业、非出口企业和小规模企业来实现;相较于县,县级市的整合效果更为明显;进一步研究证明,区域行政整合也有助于区域整体发展质量的改善。

近30a黄河流域中心城市空间扩展特征及启示

探究城市空间扩展特征,认识城镇用地开发效率,有助于科学践行城市开发边界和高质量发展政策。基于城市空间、人口和经济数据,采用扩展强度指数、差异指数和耦合协调度模型,分析1992—2020年黄河流域8个中心城市空间扩展数量和质量的时空特征及启示。结果表明:(1)中心城市平均扩展面积315 km~2,下游城市扩展规模大于中上游,济南市、郑州市、西安市和银川市扩展强度较高。(2)各市空间扩展与人口、经济耦合关系呈下游向中上游、中游向上下游递减的分布特征,平均值分别由1992年0.42、0.19提升至2020年0.89、0.81,扩展质量整体向好。(3)城市空间扩展分异是自然区位、经济发展、政策条件等多方面综合驱动的结果。(4)严格落实流域高质量发展政策,科学践行城市开发边界,协调优化城市用地扩展与人口、经济之间相互关系,合理规划城市发展,是黄河流域中心城市实现高质量发展的重要路径。

基于最小累积阻力模型的土地利用功能分区研究——以广西贺州市为例

土地利用功能分区是国土空间开发保护与利用的重要前提。将最小累积阻力模型引入广西贺州市土地利用功能分区研究中,基于阻力约束视角开展建设用地、生态用地、农业用地扩张阻力评价,通过分析不同用地扩张的适宜性划分土地利用功能区。结果表明:(1)生态用地扩张阻力以各生态保护源为中心向四周扩张,农业用地扩张阻力由贺州市中部向四周递增,建设用地扩张阻力呈中部低、四周高的特点;(2)依据各类用地扩张的适宜性将贺州市划分为生态保护核心区、农业生产核心区、建设开发核心区、生态保护涵养区和生产生态拓展区,其空间分布与贺州市现状用地布局相符且契合相关规划的用途分区及管控要求。与传统适宜性评价相比,基于扩张阻力评价的适宜性分析综合考虑了各用地类型的垂直自然要素和水平扩张作用,为具体的土地利用功能分区提供了更为科学的依据;研究明确了各功能区的分布并提出对应的发展建议,能够为贺州市土地利用结构优化提供依据与指导。

基于遥感的郑州市主城区空间扩展和时空演变特征研究

为监测建成区时空演变过程,推进郑州市城市规划建设和高质量发展,选取6期Landsat影像,通过构建专家知识决策树对郑州市主城区在1990—2020年的空间扩展进行遥感监测和时空演变特征分析。结果表明:1990—2020年,郑州市主城区建成区面积增加了464.62 km^(2),城市扩展速度和强度均经历了先上升、后下降两个阶段,目前仍处于快速扩张时期;受功能新区规划建设的影响,郑州市往正东和东南方向扩展明显,城市发展重心主要集中于东部的金水区;研究时段内城市空间扩展弹性指数(5.75)远高于合理水平,意味着城市土地资源利用率不高。研究成果客观揭示了郑州市空间扩展规律,对优化国土空间格局和提升城市整体功能具有参考价值。

基于夜间灯光数据的重庆市主城区城市扩展分析

夜间灯光数据能够对城市夜间的照明特征进行成像,从而揭示人类活动的强度,且因其具有覆盖范围广、回访周期短等特点,逐渐成为监测城市扩展情况的可靠数据源。以重庆市主体规划范围内的主城中心城区为研究对象,利用DMSP/OLS和NPP/VIIRS夜间灯光数据,辅以MODIS NDVI数据和Landsat数据提取该区域内城市建成区的范围,研究城市建成区扩展的时空演变特征。结果表明,夜间灯光数据可以有效提取长时序的重庆市主城区城市建成区信息,重庆市主城区的城市建成区范围呈现由中心向四周扩展的趋势,重庆主城九区的城市建成区发展具有明显的空间分异性。

山地丘陵型城市空间扩展及形态演变研究——以绵阳市为例

为了解山地丘陵型城市的空间扩展及形态特征演变,以绵阳市为研究对象,基于1980-2020年的土地利用数据,通过城市空间扩展速度、强度指标、位置中心性指数和位置中心性聚集指数等对绵阳市城市空间扩展特征和形态演变趋势进行定量分析。结果表明:2020年绵阳市建设用地面积增加约为1980年的2.98倍,扩展速度和扩展强度不断增大;绵阳市在研究期内的不同时间段呈现出不同的扩展结构和聚集异质性;城市空间扩展遵循“内部填充-外部扩展”的规律进行,呈现出“集聚-分离”的演变特征。该研究结果有助于分析山地丘陵型城市空间扩展的时空规律,能为绵阳市未来土地利用规划提供一定依据。