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1.
Cropland is one of the essential elements of our ecological systems for producing agricultural products. In developing countries, urban expansion is a frequently appearing phenomena, which is a type of land cover land use (LCLU) change. This change can drastically alter the features on the land surface including croplands. It can lead to detrimental consequences which has considerable effects on the social-ecological systems when croplands are lost. Argentina is an extremely agricultural intense developing country, and Buenos Aires province is a top agricultural production site and has been urbanizing during the last 30 years. Thus studying and analyzing the metropolitan area of this province will contribute to our understanding of the relationship between urban expansion and its effect on croplands. So far, no research has used measurable quantitative methodologies on the Buenos Aires metropolitan region (BAMR) to reveal the relationship between urbanization and cropland. By using 30-meter resolution Landsat images of June 1985 and July 2015, this study finds urban land has expanded from 937.16?km2 to 1835.47?km2, and 30.28% of the new urban lands comes from existing croplands.  相似文献   

2.
China has experienced rapid and massive urban expansion in recent decades. To address the opportunities and challenges posed by urbanization, it is important to investigate this process. Although many studies have characterized China’s urbanization, mainly based on individual cities or urban agglomerations, few studies have compared the urban expansion patterns among cities of different regions and sizes at a national scale. Additionally, the source of the newly developed urban land has largely been ignored in previous research. To fill these gaps, we provide a comprehensive view of the growth patterns of 291 Chinese cities during 1990–2015, quantifying the rates, spatial forms, and corresponding landscape characteristics of the urban expansion. More importantly, we further investigate what their new urban land is converted from. Key findings include: (1) the annual expansion (AE) and annual growth rate (AGR) of all 291 cities were 1869.81?km2 and 4.81% during 1990–2015; (2) cropland and rural settlements were the predominant source, accounting for 65.22% and 17.49% of the new urban land during 1990–2015; (3) edge-expansion was the dominant growth form for most cities, followed by infilling and leapfrogging growth; and (4) the landscape characteristics of the occupied cropland differed across various cities.  相似文献   

3.
ABSTRACT

Urbanization in China is closely connected with ambient particulate matter 2.5 (PM2.5). However, the potential for altering PM2.5 through the urban landscape characteristics is uncertain. In this study, we analyzed the urban PM2.5 pollution situation for 2014–2016 and investigated the impact of landscape factors on urban PM2.5 in China at the city level. All the prefecture-level cities were stratified by urban population size into small (<500,000), medium (500,000–1,000,000), and large (>1,000,000), and the other second-level administrative cities were assigned as ‘other’ cities. The multivariate regression model including both urban landscape factors and social-economic variables explained 70.0%, 32.8%, 19.2%, and 12.4% of the arithmetic mean PM2.5 concentration (AMC-PM2.5) for the other, small, medium, and large cities, respectively. With regard to the configuration of land cover, agricultural activity is a major contributor of PM2.5 pollution, for which the explanatory power ranged from 7.6% (for the large cities) to 64% (for the other cities). In addition, grassland aggregation also has a limited but negative effect on urban PM2.5 pollution, despite the negligible effect on dry deposition. Overall, these findings likely reflect the interaction between urban air quality and urbanization, and will have implications for air quality control strategies.  相似文献   

4.
1973年—2013年经济特区城市空间扩展遥感监测   总被引：2，自引：0，他引：2  
选取1973年—2013年多源遥感影像为数据源,以深圳、厦门、海口为例,开展中国经济特区城市建城区的长时序、高频数空间扩展遥感监测。选取城市扩展速度、城市扩展对土地利用的影响、城市形态紧凑度和城市重心迁移作为指标,剖析经济特区城市扩展的时空特征,耦合自然要素与人为要素,对比分析深圳、厦门和海口在城市扩展过程中表现出来的异同,并探讨其原因。结果表明:(1)近40年来,经济特区城市扩展先后经历了一个缓慢平稳扩展阶段、两个加速扩展阶段和两个减速扩展阶段。深圳的扩展速度最快,其次是厦门,海口的扩展速度最慢;(2)耕地对经济特区城市扩展贡献最大,林地、水域、城乡工矿和居民用地、海域也是经济特区城市扩展的重要土地来源,草地和未利用土地的贡献最小;(3)经济特区城市的空间形态总体趋于松散,1973年—2004年城市紧凑度剧烈降低,2004年之后趋于平稳;(4)在政策与填海造地工程的共同影响下,经济特区城市重心有向海岸线方向迁移的趋势,深圳的迁移量最大,海口最小。  相似文献   

5.
《The Cartographic journal》2013,50(3):233-241
Abstract

There have been numerous efforts over many years to map or delineate urban locations and features in the Kathmandu Valley of Nepal. This study acquired 27 land useland cover maps for the Valley or the urban portions of the Valley. Those maps vary greatly in their mapping parameters. The objectives of this study were to first conduct a cartographic comparison of the differences in the creation and content of the maps and then do an analysis of the urban changes in the Valley based upon the maps. The maps for the Valley have differed in their source materials, the amount of field work involved, scale and minimum mapping units, classifications used, definitions of classes and coordinate systems. Source materials have included various scales and formats of aerial photography and different satellite systems. The most difficult issue in comparing the maps is the varied classification systems and definitions. The same feature will be classified differently from map to map. This is particularly an issue for institutional features such as temples, palaces, educational facilities, open public space and governmental sites. Definitions of residential areas are also not consistent. Even with the differences in mapping parameters, considerable useful information can be obtained by comparing these maps. These include a simply documentation of the urban extent and the generally resulting loss in agricultural lands. There was an increase in urban extent from 22 to 83km2 between 1955 and 2000. Urban expansion has also changed from occurring on the upland river terraces or tars to the floodplains. Finally, while not directly documented in these maps, the tremendous pace of urban growth has resulted in multiple infrastructure and environmental challenges.  相似文献   

6.
以海上丝绸之路沿线的11个超大城市为例,基于长时间序列的Landsat MSS/TM/ETM+/OLI和HJ-1卫星CCD数据,利用基于面向对象的支持向量机SVM(Support Vector Machine)分类方法提取20世纪70年代到2015年的城市不透水层,并结合景观格局指数—最大斑块指数LPI(Largest Patch Index)、斑块密度PD(Patch Density)和欧几里得最邻近距离ENN(Euclidean Nearest Neighbor Distance)分析了超大城市的发展模式。研究结果表明:基于面向对象的SVM分类方法能够高效提取城市不透水层;平均总精度高于87.9%,平均Kappa系数高于0.87;过去40余年,各超大城市的面积扩张了4—13倍,中国和印度的超大城市扩张最快,广州、上海超过12倍;各城市以"中心—边缘"或"沿海—内陆"的方向扩张,表现为"扩散—聚集—再扩散"的扩张模式;总体来看,沿线的城市化进程仍处于上升期。本研究为建设"21世纪海上丝绸之路"提供了科学依据,对当地生态环境保护和新型城镇化建设具有重要意义。  相似文献   

7.
Urbanization effects on vegetation cover (VC) have been analyzed in many regions. However, little attention has been paid to Africa, which has undergone rapid urbanization in recent decades. In this study, MODIS land cover and enhanced vegetation index (EVI) data were used to examine urbanization effects on VC in 59 large cities in Africa during 2001–2017. The ΔEVI (urban EVI minus rural EVI) was used to represent urbanization effects on VC. Major findings include: (1) for 59 cities averaged, annual ΔEVI averaged from 2015 to 2017 was -0.116. Negative annual ΔEVI (i.e. urban EVI lower than rural) were observed in 56 of 59 cities. (2) For 59 cities averaged, urban area increased 17.9% from 2001 (262.8 km2) to 2016 (309.8 km2). (3) Annual ΔEVI decreased significantly (p<0.05) in 44 of 59 cities for the period 2001–2017, and annual average area of urbanization effects on VC increased significantly in 40 of 59 cities. For 59 cities averaged, the percentage of urban area with significant decreasing trends of annual ΔEVI was 60.0%. Spatially, cities near the Gulf of Guinea showed more significant decreasing ΔEVI than cities in other regions. In addition, the trends and spatial distributions of urbanization effects on VC differed little by seasons. These results suggested that urbanization and its effects on VC in Africa should arouse more attentions.  相似文献   

8.
Abstract

Urban integration is an increasingly popular phenomenon. It is important to characterize the dynamic processes of urban integration from the perspective of geography. However, previous studies mainly focussed on the overall characteristics of a single entity and failed to consider inter-city influences. Therefore, this study aims to systematically investigate this phenomenon. Firstly, spatial clustering technique and landscape metric were used to analyze the temporal change of spatial layout. Secondly, we built multiple ring buffers of city boundary to reveal the directional differences in urban expansion. Lastly, we compared the observed land use data with the results simulated by cellular automata model. These experiments have shown that the urban expansion characteristics during the urban integration process are rather different from those of a single city, and the above methodology can effectively characterize the urban integration phenomenon. The successful example of Guangzhou–Foshan integration could also provide practical experience for other similar attempts.  相似文献   

9.
Abstract

The outward expansion of cities in the United States has been a source of concern and policy debate for well over forty years. This sprawling urban landscape has been cited as a contributing factor behind the loss of open space, environmental damage and increased congestion. To better understand urban expansion, monitoring programs are required to facilitate the systematic observation of urban expansion, and to provide critical information in order to adjust urban development policies. Monitoring the urban landscape has been a major application focus of satellite remote sensing technologies. Yet, research has shown that the complexity of the urban landscape frustrates simple characterization of cumulative land cover processes such as sprawl. In this paper an approach to the remote detection and characterization of sprawl is introduced based on the use of Dempster‐Shafer Theory of Evidence. Functioning as a soft‐classification algorithm, Demptster‐Shafer Theory offers a unique solution to the mapping problem when evidence of class structure in underscored by uncertainty. Through the use of this technique it was possible to model uncertainty based on the concept of belief. This conceptualization was instrumental in deciphering the complexities of urban land cover arrangements and offered an alternative logic which enhanced delineation of subtle changes in land cover indicative of sprawl.  相似文献   

10.
The policy of the Chinese government concerning the horizontal expansion of the cultivated land through the reclamation of desert soils result in a total increase of 665. 985 km2 during the period 1987–1999 in North Shaanxi. This increase is less than the loss in arable land by urbanization. The accelerated rate of change in agricultural areas calls for more rapid surveys of urbanization and loss of arable land. Remote sensing has a number of advantages over ground-based methods for such surveys. The multi-scale concept of remote sensing data help us study the problem in four towns. Several maps were produced to analyze the situation of urban coverage in different times. The evaluation of the status, rate and risk of urbanization are based on an accepted average of urban increase as 2% of population growth per year.  相似文献   

11.
The policy of the Chinese government concerning the horizontal expansion of the cultivated land through the reclamation of desert soils result in a total increase of 665. 985 km^2 during the period 1987-1999 in North Shaanxi. This increase is less than the loss in arable land by urbanization. The accelerated rate of change in agricultural areas calls for more rapid surveys of urbanization and loss of arable land. Remote sensing has a number of advantages over ground-based methods for such surveys. The multi-scale concept of remote sensing data help us study the problem in four towns. Several maps were produced to analyze the situation of urban coverage in different times. The evaluation of the status, rate and risk of urbanization are based on an accepted average of urban increase as 2% of population growth per year.  相似文献   

12.
Abstract

A methodology is presented for estimating percent coverage of impervious surface (IS) and forest cover (FC) within Landsat thematic mapper (TM) pixels of urban areas. High-resolution multi-spectral images from Quickbird (QB) play a key role in the sub-pixel mapping process by providing information on the spatial distributions of ISs and FCs at 2.4 m ground sampling intervals. Thematic classifications, also derived from the Landsat imagery, have then been employed to define relationships between 30 m Landsat-derived greenness values and percent IS and FC. By also utilizing land cover/land use classification derived from Landsat and defining unique relationships for urban sub-classes (i.e. residential, commercial/industrial, open land), confusion between impervious and fallow agricultural lands has been overcome. Test results are presented for Ottawa-Gatineau, an urban area that encompasses many aspects typical of the North American urban landscape. Multiple QB scenes have been acquired for this urban centre, thereby allowing us to undertake an in-depth study of the error budgets associated with the fractional inference process.  相似文献   

13.
Urbanization is increasingly becoming a widespread phenomenon at all scales of development around the globe. Be it developing or developed nations, all are witnessing urbanization at very high pace. In order to study its impacts, various methodologies and techniques are being implemented to measure growth of urban extents over spatial and temporal domains. But urbanization being a very dynamic phenomenon has been facing ambiguities regarding methods to study its dynamism. This paper aims at quantifying urban expansion in Delhi, the capital city of India. The process has been studied using urban land cover pattern derived from Landsat TM/ETM satellite data for two decades (1998–2011). These maps show that built-up increased by 417 ha in first time period (1998–2003) and 6,633 ha during next period (2003–2011) of study. For quantification of metrics for urban expansion, the Urban Landscape Analysis Tool (ULAT) was employed. Land cover mapping was done with accuracy of 92.67 %, 93.3 % and 96 % respectively for years 1998, 2003 and 2011. Three major land covers classes mapped are; (i) built-up, (ii) water and (iii) other or non-built-up. The maps were then utilized to extract degree of urbanization based on spatial density of built-up area consisting of seven classes, (i) Urban built-up, (ii) Suburban built-up,(iii) Rural built-up, (iv) Urbanized open land, (v) Captured open land, (vi) Rural open land and (vii) Water. These classes were demarcated based on the urbanness of cells. Similarly urban footprint maps were generated. The two time maps were compared to qualitatively and quantitatively capture the dynamics of urban expansion in the city. Along with urbanized area and urban footprint maps, the new development areas during the study time periods were also identified. The new development areas consisted of three major categories of developments, (i) infill, (ii) extension and (iii) leapfrog.  相似文献   

14.
一种基于地理探测器的城镇扩展影响机理分析法   总被引：1，自引：0，他引：1  
城市化是全球范围内普遍存在的重要现象,尤其发展中国家和地区正经历着快速城市化的过程。快速城市化导致了城市地区的大规模扩张,从而加重了土地资源的压力,带来了一系列的环境和社会问题。定量分析城镇扩展的空间驱动力能更好地辅助城市规划与管理。本文提出了一种量化城镇扩展的指数——城镇扩展密度,并通过地理探测器方法分析了1990—2000年北京市城镇扩展的时空特征及形成机理。研究表明:北京市城镇扩展沿交通干线呈线性扩张,其城镇扩展受到社会经济和地理的共同影响和制约作用,城镇固定资产投资对城镇扩展影响力最大,区域条件次之。这些发现可以为城镇扩展模拟和预测提供更好的改进空间。  相似文献   

15.

Background  

The main task is to estimate the qualitative and quantitative contribution of urban territories and precisely of the process of urbanization to the Global Carbon Cycle (GCC). Note that, on the contrary to many investigations that have considered direct anthropogenic emission of CO2(urbanized territories produce ca. 96–98% of it), we are interested in more subtle, and up until the present time, weaker processes associated with the conversion of the surrounding natural ecosystems and landscapes into urban lands. Such conversion inevitably takes place when cities are sprawling and additional "natural" lands are becoming "urbanized".  相似文献   

16.
武汉城镇化与热岛效应的定量研究   总被引：1，自引：0，他引：1  
针对目前城市化进程加快对城市增温和城市热岛效应的促进作用尚不十分明确的问题,提出基于遥感技术的城镇化与热岛效应数量关系的构建。结果表明,1987-2013年间,武汉市中城镇化水平(50%~80%ISA)面积增加了14.5倍,高城镇化水平(80%~100%ISA)面积增加了2.8倍,城镇化范围沿着武汉市主城区和主要干道不断扩张;不透水面值与地表温度表现出明显正相关,不透水面值平均增加1%,可使地表温度增温0.06℃~0.19℃,城镇化水平对武汉城市热岛效应作用明显。研究结果为探讨城市热岛效应的缓解对策提供了基础,对合理规划和管理城市化意义重大。  相似文献   

17.
以多时相Landsat MSS,TM和ETM卫星影像为数据源,利用遥感和GIS手段,提取宁波、台州2市5个时相（1979,1990,1995,2000和2005年）城市建设用地信息,分析了城市建设用地扩展的时间特征、形态特征、空间特征并通过其与人口、GDP因素的相关分析研究其扩展的动力机制。结果表明：①1979年以来,甬台地区城市建设用地总体扩展速度表现为先升后降,而城市建设用地总体扩展强度则表现为不断提高的趋势。②甬台地区城市建设用地的空间结构存在明显的分形特征,城市建设用地空间结构分维逐渐增大,城市建设用地空间复杂性增加,城市建设用地趋向不稳定。③甬台地区城市扩展与社会经济发展具有明显的相关性。  相似文献   

18.
There has been an increasing interest in mapping and monitoring urban land use/land cover using remote sensing techniques. However, there still exist quite a number of challenges in deriving urban extent and its expansion density from remote sensing data quantitatively. This study utilized Landsat TM/ETM+ remote sensing data to assess urban expansion and its thermal characteristics with a case study in the city of Changsha, China. We proposed a new approach for quantitatively determining built-up area, its expansion density and their respective relationship with land surface temperature (LST) patterns. An urban expansion metric was also developed using a moving window mechanism to identify urban built-up area and its expansion density based on selected threshold values. The study suggested that urban extent and its expansion density, as well as surface thermal characteristics and patterns could be identified through quantitatively derived remotely sensed indices and LST, which offer meaningful characteristics in quantifying urban expansion density and urban thermal pattern. Results from the case study demonstrated that: (1) the built-up area and urban expansion density have significantly increased in the city of Changsha from 1990 to 2001; and (2) the differences of urban expansion densities correspond to thermal effects, where a high percentage of imperviousness is usually associated with the area covered by high surface temperature.  相似文献   

19.
《测量评论》2013,45(49):116-129
Abstract

The Dominion of Canada, with an area approximating that of Europe, is the largest and most populous of the great self-governing Dominions of the British Empire. Through the British North America Act, 1st July 1867, the Union of Upper and Lower Canada, with Nova Scotia and New Brunswick, were united to form the Dominion, Upper and Lower Canada being designated as the provinces of Ontario and Quebec. An expansion was made possible on 19th November 1869 by the Deed of Surrender to the Crown of the Hudson's Bay Company's territorial, rights in the Northwest. On 12th May 1870 the Province of Manitoba was established, and on 15th July the Northwest Territories were transferred to the Dominion, and Manitoba was admitted into Confederation. Although the boundaries of Manitoba have since been enlarged and those of the Northwest Territories diminished through the creation in 1905 of the Provinces of Saskatchewan and Alberta, the control of the resources and public lands in the West remained under Dominion authority until the year 1930. By this brief statement we are enabled to understand the background of what has developed into the largest connected and systematic Public Lands Survey in any country, that of the Canadian Northwest; and this survey is unique in having been performed under one organization.  相似文献   

20.
Studies of urbanization and urban thermal environment are now attracting wide interests among scientists all over the world. This study investigated the influences of urbanization on urban thermal environment as well as the relationships of thermal characteristics to other biophysical variables in Guangzhou, China utilizing three dates of Landsat TM/ETM+ images acquired in 1990, 2000, and 2005, respectively. Vegetation abundances and percent impervious surfaces were derived by means of linear spectral mixture model, and a method for effectively enhancing impervious surface has been developed to accurately examine the urban enlargement. As a key parameter for studying urban thermal characteristics, the land surface temperature (LST) was also retrieved from thermal infrared band of each TM/ETM+ dataset. Based on these parameters, the urban expansion, urban heat island effect and the relationships of LSTs to other biophysical parameters were then analyzed. Results indicated that the area ratio of impervious surface in Guangzhou increased significantly, which grew from 20.56% in 1990, to 34.72% in 2000, and further to 41.12% in 2005, however, the intensity of urban heat island was not always enlarged in observed years. In addition, Geostatistical analyses showed that the mean-centre of the impervious surface was moving towards the northwest during 1990–2005. And correlation analyses revealed that, at the pixel-scale, the association of LSTs to other two variables (vegetation abundance and percent impervious surface) was not straightforward, while LSTs possessed a strong positive correlation with percent impervious surfaces and negative correlation with vegetation abundances at the regional-scale, respectively. This study provided an integrated research scheme and the findings can be very useful for urban ecosystem modeling.  相似文献   

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