The role of local land-use on the urban heat island effect of Tel Aviv as assessed from satellite remote sensing

Climate change in cities has received much focus in the past few decades. Heat stress in urban areas has an adverse effect on human health and is expected to worsen in the future due to the global warming. Vegetation has been shown to mitigate this effect, but introducing ‘green’ areas into the metropolitan space is a challenging task. We assessed the thermal load in terms of surface temperature in Tel Aviv, the biggest metropolitan area of Israel. The thermal effect of four different urban land uses was estimated. Specifically, we compared the cooling effect of residential areas with high vegetation cover (referred here as ‘green’ residential) to that of small to medium size (2–40 ha) public parks. To this end, we used satellite data of land surface temperature (LST) and the Normalized Difference Vegetation Index (NDVI), as a surrogate for vegetation cover. High-temporal data were combined with high spatial resolutions data to produce 10-year average LST and NDVI maps at high spatial resolution over Tel Aviv. As expected, industrial areas had the highest LST due to lowest ratio of vegetation to free space area (1%), while ‘green’ areas displayed the lowest LST. Green residential and small-medium public parks had comparable thermal loads, with green residential having slightly lower LST (by 0.5 °C). In general, small-medium public parks displayed higher LST than expected. Inefficient use of free spaces for vegetation, i.e., relatively low vegetation cover to free space ratio, was probably the main cause for this. Public parks had a higher local cooling effect, but a less continuous one on the proximate surrounding (30–90 m from the park), probably due to their relative location in the urban fabric. Our results suggest that ‘greening’ areas within the private urban space should be encouraged at the expense of building new small-medium parks in metropolitan areas that lack the sufficient free space for larger parks. The outcome of this study may have key implications for urban planners seeking to mitigate urban heat island effects under the limitation of existing dense urban layout.     

Land use and land cover change in Greater Dhaka, Bangladesh: Using remote sensing to promote sustainable urbanization

This study evaluates land use/cover changes and urban expansion in Greater Dhaka, Bangladesh, between 1975 and 2003 using satellite images and socio-economic data. Spatial and temporal dynamics of land use/cover changes were quantified using three Landsat images, a supervised classification algorithm and the post-classification change detection technique in GIS. Accuracy of the Landsat-derived land use/cover maps ranged from 85 to 90%. The analysis revealed that substantial growth of built-up areas in Greater Dhaka over the study period resulted significant decrease in the area of water bodies, cultivated land, vegetation and wetlands. Urban land expansion has been largely driven by elevation, population growth and economic development. Rapid urban expansion through infilling of low-lying areas and clearing of vegetation resulted in a wide range of environmental impacts, including habitat quality. As reliable and current data are lacking for Bangladesh, the land use maps produced in this study will contribute to both the development of sustainable urban land use planning decisions and also for forecasting possible future changes in growth patterns.     

Classifying and mapping the urban transition in Vietnam

The urban transition almost always involves wrenching social adjustment as small agricultural communities are forced to adjust rapidly to industrial ways of life. Large-scale in-migration of young people, usually from poor regions, creates enormous demand and expectations for community and social services. One immediate problem planners face in approaching this challenge is how to define, differentiate, and map what is rural, urban, and transitional (i.e., peri-urban). This project established an urban classification for Vietnam by using national census and remote sensing data to identify and map the smallest administrative units for which data are collected as rural, peri-urban, urban, or urban core. We used both natural and human factors in the quantitative model: income from agriculture, land under agriculture and forests, houses with modern sanitation, and the Normalized Difference Vegetation Index. Model results suggest that in 2006, 71% of Vietnam's 10,891 communes were rural, 18% peri-urban, 3% urban, and 4% urban core. Of the communes our model classified as peri-urban, 61% were classified by the Vietnamese government as rural. More than 7% of Vietnam's land area can be classified as peri-urban and approximately 13% of its population (more than 11 million people) lives in peri-urban areas. We identified and mapped three types of peri-urban places: communes in the periphery of large towns and cities; communes along highways; and communes associated with provincial administration or home to industrial, energy, or natural resources projects (e.g., mining). We validated this classification based on ground observations, analyses of multi-temporal night-time lights data, and an examination of road networks. The model provides a method for rapidly assessing the rural–urban nature of places to assist planners in identifying rural areas undergoing rapid change with accompanying needs for investments in building, sanitation, road infrastructure, and government institutions.     

Decumbent development: Urban sprawl in the Guwahati Metropolitan Area,India

Urban sprawl has become a global phenomenon as an outcome of growing population and rapid urbanization. Previous studies have addressed the rising incidence of uncontrollable urban development, particularly in peri-urban areas of cities, leading to chronic urban sprawl. The city of Guwahati, a million city in north east India, has expanded significantly in recent years. In this article, the links between population and growth of built-up areas were examined using geo-spatial techniques and remotely sensed datasets. The results indicate that the sprawl has accentuated in recent years. The intensity of land use remained uneven due to marked variations in the distribution of built-up areas, plausibly an outcome of unplanned urban growth. If current trends are anything to go by, future urban sprawl could pose serious threats to the vulnerable eco-sensitive and peri-urban areas of Guwahati. Secondary cities have unfortunately received scant attention in urban policy research, and Guwahati, epitomizes urban woes in a developing country.     

基于绿地生态机理的城市空间形态研究

通过研究城市大气污染自净化机制以及风与城市绿地间的相互作用机制,探索城市绿地生态机理.研究表明,城市绿地生态机理一方面是绿地植物对污染物的吸收净化,另一方面是绿地与城市环流共同作用稀释过滤城市大气污染物.进一步研究表明,基于绿地生态机理,绿带环绕的组团式形态是一种较为理想的城市空间形态,城市外围紧密布局城郊绿地,组团中心为"绿心",居住区环绕"绿心"布局.组团的规模应根据各城市的具体现状确定,绿带的宽度要适宜.该城市空间形态能协助实现城市空气污染自净化过程,保障城市生态环境.     

‘Locationally disadvantaged’: planning governmentalities and peri-urban agricultural futures

ABSTRACT

Peri-urban areas are the interface between urban and rural regions, with these regions traditionally acting as foodbowls for adjacent urban areas. This peri-urban agriculture provides a diverse suite of benefits to urban areas. Increasingly, however, peri-urban areas are being converted to residential uses, driven in part by higher land values secured for land converted for residential development. In Sydney, planning and development has tended to treat peri-urban areas as ‘suburbs in waiting’. Using a Foucauldian governmentality approach, this paper investigates the prevailing rationalities in metropolitan-level strategic planning documents—in particular A Plan for Growing Sydney and the Draft South West District Plan—and how these rationalities relate to peri-urban agriculture. Our analysis shows that the three overarching rationalities—the global city, the compact city and the sustainability agenda—frame the urbanisation of peri-urban agricultural lands as necessary and inevitable, and only integrate agriculture as part of the future of the city of Sydney when it can be rationalised within the ‘global city’ narrative. As a result, peri-urban areas are not considered to have unique planning needs, but are imagined as latent spaces that will enable Sydney to meet its housing and job targets through their future development.     

Exploring the future of rural–urban connections in sub-Saharan Africa: modelling urban expansion and its impact on food production in the Addis Ababa region

Abstract

The built-up area of Addis Ababa and its surrounding towns is expanding into the peri-urban region leading to high losses of farmland, directly influencing the food production for the urban population. This paper investigates the patterns of settlement growth in the region surrounding Addis Ababa and their impact on peri-urban agriculture using an urban spatial scenario design model. The effects of two population density scenarios are explored within the framework of a proposed master plan. The model output was used to estimate areas of different suitability levels that would be lost to the modelled settlement expansion. The settlement area in 2038 would represent 29% of the case study’s total area in the low-density scenario but only 19% in the high-density scenario. Compared to the low-density scenario, the high-density scenario would only require a third of the agricultural land transformed into settlement areas. Settlement development would contribute to higher losses of land suitable for cultivating important export products, high nutritional value and import-substituting products. The scenario approach can support sustainable regional planning for settlement expansion that conserves valuable farmland in the peri-urban area and contributes to building capacity for strategic planning of the city regions of sub-Saharan Africa.     

南京市热岛效应变化时空特征及其与土地利用变化的关系

利用遥感数据和气象统计数据分析自1985年以来南京市热岛效应变化的时空特征及其与土地利用变化的关系。结果表明:自1985年以来,南京市热岛效应强度和范围在增长。南京市的年均温逐年上升,与郊区六合县的温差呈上升趋势;南京市建成区内4级热岛效应面积增加了107.88km²。热岛效应增长在空间上存在差异,大厂>雨花台>市辖区>栖霞>浦口>江宁。南京市土地利用变化的结果使得热岛效应空间分布更广泛,城镇居民点及工矿用地利用强度变化最大的地方即城市热岛效应增加最多的地方,两者在空间上具有很好的吻合;而和城镇居民点及工矿用地的扩展规模没有很好的空间相关性。     

城市地表温度对土地利用/覆被变化响应的遥感研究——以乌鲁木齐为例

 快速的城市化对城市环境产生显著的影响,基于遥感定量研究地表温度对土地利用/覆被变化（LUCC）的响应,来评估快速城市化对环境的影响,是一种快速、有效的途径。以干旱区典型绿洲型城市——乌鲁木齐为例,将遥感与地理信息系统相结合,利用1990年和2009年两期陆地卫星影像为基础数据进行土地利用/覆被分类,并基于单窗算法定量反演同期的地表温度,从而对快速城市化进程中的土地利用/覆被类型动态变化的空间特征及地表温度对快速城市化的响应情况进行了定量研究。结果显示,在近20 a间,乌鲁木齐城市迅速扩张,土地利用/覆被类型变化显著,城市建设用地增长率高达44.73%;同时城市的快速发展使地表温度提高了近6 ℃。研究表明,温度变化格局,尤其是增温区的空间分布与城市扩张的空间格局基本一致,说明地表温度对城市的土地利用/覆被变化产生了显著的响应。     

Common features and different trajectories of land cover changes in six Western Mediterranean urban regions

Land use and land cover change (LULCC) dynamics have been particularly strong in the Mediterranean region, due to its historical development and to agro-pedoclimatic conditions favorable to human settlement. This area has undergone in the 1950s and the 1980s intense urbanization processes that has followed different trajectories. Urban expansion commonly occurs at the expense of agricultural land, leading to the fragmentation of natural areas and conflicts over access to land resources. These dynamics mainly concern the fringe between urban and agricultural land, e.g. the peri-urban areas usually included within functional urban regions. Here, to identify common features of LULCC in Western Mediterranean urban regions, we investigated two main features: direct changes due to urbanization and indirect changes affecting non-artificial land uses. We compared LULCC dynamics in 6 case studies from the north and south of the Western Mediterranean region: the urban regions of Montpellier and Avignon (France), Pisa (Italy), Madrid (Spain), Meknes (Morocco), and Constantine (Algeria), using a 30-year multitemporal spatial analysis (1980–2010). Two series of Landsat TM images were acquired for each case study and land cover data were analyzed both for dynamics and for land patterns, using landscape and class metrics. We found no significant north-south differences in LULCC dynamics between the investigated Western Mediterranean urban regions. Differences are more pronounced between small–medium cities and large metropolitan areas in type of urban diffusion, which is more sprawled in small–medium cities and more compact in large metropolitan areas. Rather, differences occur in LULCC not directly affected by urbanization, since in Northern Mediterranean urban regions afforestation and abandonment of agricultural areas are prevalent and closer to the urban areas, whereas transformation of natural areas into agricultural ones occurs mainly in Southern Mediterranean urban regions at a similar distance from urban areas than it happens for afforested or abandoned areas. In attempting for the first time to assess LULCC in these Mediterranean urban regions, we provide a preliminary comprehensive analysis that can contribute to the active LULCC research in the Mediterranean basin and that can be easily applied to other Mediterranean urban regions.     

The impact of tree cover loss on land surface temperature: A case study of central Massachusetts using Landsat Thematic Mapper thermal data

Land surface temperature (LST) variability results from diversity in urban surface materials over space and time such that locations with impervious urban cover experience higher temperature and larger temperature variation compared to non-impervious cover. There is growing awareness that warmer temperatures in urban locations negatively impact city residents by increasing heat related death and energy usage during heat waves. However, little previous work investigates the linkages between urban tree cover loss events related to invasive species eradication and urban heat trends. This paper examines the variation in LST using Landsat-5 Thematic Mapper (TM) thermal imagery in Worcester County, Massachusetts where over 30,000 trees were removed since 2008 to eradicate the invasive Asian Longhorned Beetle (ALB), most of which existed in urban residential areas. Throughout the study area a 10% loss in tree canopy cover caused a 0.7 °C increase in LST whereas a 10% increase in sub-canopy impervious surface area exposed due to tree loss caused 1.66 °C increase in LST. The Burncoat and Greendale neighborhoods in northern Worcester experienced a combined 48% tree cover loss from 2008 to 2010 due to ALB eradication and an average relative LST increase of 2.4 °C (range 0.6–4.1 °C). Given that areas with an increase in exposed impervious surface produce greater temperature increases than areas of tree loss, future tree replanting efforts may focus on locations that reduce exposed impervious surfaces.     

城乡融合背景下半城市化地区识别与演变研究——以苏州市为例

半城市化地区作为城乡景观混杂交错、城乡功能相互渗透的过渡性地域,推进这类地区的良性发展是促进城乡融合发展的关键。对半城市化地区空间范围的精确识别是对其实施精准管控的基础前提,对半城市化地区演变规律的科学把脉可为其未来的发展规划提供重要参考。然而,由于半城市化地区的复杂性、动态性和模糊性,目前对该类地区的精细尺度定量识别研究不多。基于此,论文综合考虑半城市化地区的复杂多维特征,在多源遥感数据支持下,建立了一种高精度的半城市化地区识别方法体系：① 构建了一套覆盖社会经济和空间格局2大维度的半城市化地区识别综合指标体系;② 运用空间网格化技术和线性加权建立了半城市化特征值的计算方法; ③ 结合滑动t检验与概率密度分析实现了半城市化特征临界值的确定。最后以苏州市为实例,运用建立好的方法体系,在1 km×1 km尺度下识别出了该市2010、2015和2018年的半城市化地区空间范围,并在此基础上进一步探讨了其时空演变规律,以期为苏州市以及其他地区未来的城市化进程提供参考。实证结果显示,苏州市的半城市化地区在空间上围绕中心城区不连续分布,在时间上总体呈现减少趋势,尤其是2015—2018年间下降幅度明显,表明苏州市城镇化发展趋于有序,乡村工业化与城市的无序蔓延有所放缓。     

基于多源数据和深度学习的城市边缘区判定

城市边缘区的定量分析及判定,对城市发展评价和规划,或是城市空间结构研究都具有重要意义。然而现有研究的边缘区判定指标选择过于单一,判定结果过于破碎,城市预设边界、水体及城市绿地对边缘区判定结果干扰大。针对上述问题,从自然、人口、社会经济的视角出发,以遥感影像、人口数据、POI大数据为数据基础,结合深度学习技术,构建基于多源数据和深度学习的城市边缘区判定方法,进行广州市城市边缘区判定及城市结构空间分布特征分析。结果表明：① 此方法能将城市划分为核心区-边缘区-外缘区,判定结果不会受到预设边界范围的影响,且消除了城市内部水体和城市绿地所造成的破碎化;② 城市边缘区与路网耦合良好;③ 广州市的城市核心区空间分布合理。综上所述,此方法能有效检测城市边缘地带,且结果符合实际情况,能为城市规划、政府决策提供参考。     

快速城市化过程中城市土地覆被的时空动态特征

1990~2005年间,是广州市经济快速发展和城市景观变化最大的时期,以同时段TM影像解译得到广州市的土地覆被类型图,从数量结构、空间信息及位置转移和景观等方面,分析了广州市土地覆被的动态特征.数量结构的研究结果显示:在快速城市化过程中广州市的耕地、林地等自然资源的利用程度在加大,自1995年起,这种变化的趋势开始减缓;土地覆被类型之间的信息与位置的转移变化频繁,并且表现出空间位置分异的特征.景观特征指数分析结果表明:广州市城市土地覆被向破碎化方向发展,城市建设用地呈扩展之势.     

快速城市化过程中城市土地覆被的时空动态特征

1990—2005年间，是广州市经济快速发展和城市景观变化最大的时期，以同时段TM影像解译得到广州市的土地覆被类型图，从数量结构、空间信息及位置转移和景观等方面，分析了广州市土地覆被的动态特征．数量结构的研究结果显示：在快速城市化过程中广州市的耕地、林地等自然资源的利用程度在加大，自1995年起，这种变化的趋势开始减缓；土地覆被类型之间的信息与位置的转移变化频繁，并且表现出空间位置分异的特征．景观特征指数分析结果表明：广州市城市土地覆被向破碎化方向发展，城市建设用地呈扩展之势．     

A basic assessment of residential plant diversity and its ecosystem services and disservices in Beijing,China

About 52% of the world's population now lives in urban areas, and 41% of urban land in developed countries is used for residential areas. The amount and quality of residential green space, an important element in urban residential infrastructure, is closely correlated to city dwellers' quality of life. The quality of green spaces is not only closely correlated to the ecosystem services they provide, but also to their disservices. In order to (i) examine how plant diversity and plant traits vary in different residential areas, (ii) determine the main socio-economic factors driving plant trait variations across different residential areas, and (iii) provide an overview on selected ecosystem services and disservices related to plant diversity, we investigated the flora and socio-economic properties of 83 residential areas in Beijing, China. We found a total of 369 plant species belonging to 99 families and 150 genera. With respect to plant traits, there were 90 annual species, 174 alien species, 169 pollen allergenic species, and 133 species with edible or pharmaceutical value. The number of perennial, alien, ornamental and edible plant species was largest in residential areas completed in the 1990s. The number of allergenic species was highest in residential areas completed prior to 1980. The Simpson, Shannon and Pielou indices for trees and shrubs were highest in areas completed in the 1990s, while those same indices for herbs were highest in residential areas completed prior to 1980. General Linear Model analyses revealed that richness increased with increasing housing price across all groups of species. Principal Component Analysis indicated that housing price and floor-area ratio are the variables that positively correlate with species richness for all groups of species.     

Homeowners associations: Friend or foe to native desert avifauna? Conservation concerns and opportunities for research

The rapid urbanization experienced in arid environments worldwide has raised the issue of how wildlife adapt to such drastic landscape changes. Along the periphery of many desert cities are housing developments governed by homeowners associations. These homeowners associations often place strict restrictions on planted vegetation which may have implications for bird usage, particularly for those dependent on thorny vegetation. However despite the potential negative effects of such restrictions, such organizations may offer promise as a means of maintaining consistent landscape cover over a large urban area. Consideration of such organizations, through research and education can provide a means of pursuing conservation practice in difficult urban areas.     

Monitoring vegetation and land use quality along the rural-urban gradient in a Mediterranean region

This paper illustrates a methodology to quantify vegetation quality and its possible degradation in a large ‘shrinking’ Mediterranean city. Vegetation quality was estimated at three years (1960, 1990, 2006) in the Nuts-3 prefecture of Rome, central Italy (5355 km²) through the analysis of comparable land cover maps. The aims of this work are to assess how ‘compact growth’ and ‘sprawl’ impact on vegetation quality, and to monitor the territorial disparities observed in the vegetation quality as caused by urbanization and land use polarization. Built-up areas covered 3.3% and 12.9% of the investigated area in 1960 and 2006, respectively, with a dispersed to compact urban surface ratio passing from 1.2 to 1.9. Vegetation quality increased slightly during the investigated period with a diverging trend between urban and rural areas. As a consequence, territorial disparities in the same variable grew due to low-density urban diffusion in lowlands and depopulation with land abandonment and natural forestation in mountain areas.     

Policy-relevant indicators for mapping the vulnerability of urban populations to extreme heat events: A case study of Philadelphia

The recent global increase in extreme heat events linked to climate change is projected to continue. The additive effect of urban heat islands from impervious surfaces and urban heat emissions (e.g., from transportation and building cooling) exacerbates extreme heat events in urban areas, exposing dense populations to extreme heat with implications for human health. Ground- and satellite-based data on urban and suburban temperatures and vegetation over a historical period can help identify temporal and geospatial trends in heat exposure. A set of indicators has been developed to map the exposure, social sensitivity, and vulnerability of urban populations to heat wave health impacts. Guided by an Advisory Group of local planners in the pilot city of Philadelphia, localized trends of increasing urban extreme heat events using MODIS Land Surface Temperature (LST) data, confirmed with urban and non-urban temperature monitor data were identified. For the Philadelphia study area, the number of heat-event days in the urban setting has increased from approximately 4 days in 1980 to almost 12 days in 2013, while the non-urban setting has consistently experienced 5 days of heat events per year across the time period. Warmer micro-climates with limited vegetative cooling and elevated LSTs were also identified. The exposure indicator was combined with areas of high social sensitivity (e.g., low-income and elderly) to create a vulnerability indicator, showing significant overlap between highly exposed and highly sensitive populations. As a measure of the adaptive capacity of local governments to reduce the urban heat island, evidence of targeted vegetation increases or reduced localized temperatures linked to urban greening and cooling programs were sought, though none were of a scale to be identified by the 1 km satellite data utilized. The indicators have helped local decision makers to understand patterns of vulnerability, and may be used in the future to target adaptation actions and measure results (LST reduction or vegetation increase) from existing adaptation actions.     

Suburbanizing Sofia: Characteristics of Post-Socialist Peri-Urban Change

In this article, I discuss the nature of peri-urban growth in the Bulgarian capital of Sofia. I argue that since the end of socialism in 1989, Sofia's peri-urban growth has been driven primarily by affluent households relocating from the central city to its scenic southern outskirts in search of a higher quality of life. In this sense, the process exhibits the classic signs of Western-style suburbanization and is qualitatively different from the peri-urban development that occurred under socialism. Much of the new growth, however, has occurred within the borders of former villages and areas occupied by summer cottages (villas). These once-modest city environs now exhibit a peculiar blend of the new and the old and house two distinct social strata, affluent newcomers and poor long-time residents. I conclude with a discussion of the social consequences of recent peri-urban change and the response of the local planners.