基于Landsat卫星资料的苏州城市热岛效应遥感分析   总被引：6，自引：0，他引：6       下载免费PDF全文

朱焱  朱莲芳  徐永明  季嬿 《高原气象》2010,29(1):244-250

为了对苏州市快速城市化进程中的热岛效应进行研究,采用三个时期的Landsat/TM遥感影像资料来反映地表热辐射信息。基于CART决策树分类得到每个时期的土地覆盖分类图,然后通过单通道算法反演得到地表温度,并对2个时期的地表温度进行标准化分级处理,计算得到采取本文定义,1986,1995及2004年的热岛面积指数分别为4.87%,11.10%和37.87%。研究了城市化过程中城市热岛强度和空间分布变化,分析了土地覆盖变化对热岛效应的影响。结果表明,苏州市存在比较明显的城市热岛效应,并且在20多年中随着城市化过程热岛范围进一步扩展。  相似文献   

Changing urban governance in Ghana: the role of resistance practices and activism in Kumasi     

《Urban geography》2012,33(10):1568-1595

ABSTRACT

This article examines traders’ resistance practices in Kumasi, Ghana and their significance for changing urban governance in Africa. Conceptually, we introduce “activism” as a new variable into the present concept of urban governance as decentralization, entrepreneurialism and democratization (DED). From an empirical study in Kumasi, Ghana, findings reveal that activism by non-state actors does not only occur at the crucial earlier phases of the urban regeneration process, but extends into the subsequent phases, because urban governance is a continuous process. We demonstrate that activism and a multiplicity of resistance practices are embedded and significant dimensions of everyday urban governance in Africa. This paper argues that the additional dimension – activism – is necessary in rethinking urban governance in Ghana and Africa. This conceptualization views non-state actors not as resisters of urban governance but as activists whose resistance practices and innovations produce tangible and far-reaching changes in city governance. We learn that non-state actors do not rely on the state to control all aspects of urban governance but invent new practices to secure their socio-economic interests and provide them with leverage where they have to negotiate with or stand up to authorities. The study shows that successful change in urban governance is a function of the complementary and strategic adoption of contention, subversion and co-production. When the state perceives that the intervention of other key stakeholders legitimizes the grievances of non-state actors, it responds positively.  相似文献   

What makes a species synurbic?     

Robert A. Francis  Michael A. Chadwick 《Applied geography (Sevenoaks, England)》2012,32(2):514-521

The term ‘synurbic’ is sometimes used within the more recent urban ecology literature to refer to a species that colonises or is found within urban ecosystems, but this is too simplistic an interpretation. We consider that the term should be reserved for species populations that have higher densities in urban compared to rural areas, as a quantifiable measure of preferential urban association. This paper clarifies the terms ‘synurbic’ and ‘synurbization’ and considers some of the problems of defining ‘urban’, before detailing some of the positive responses exhibited by urban species that may lead to synurbic populations. It may be particularly important to determine whether responses drive directional selection leading to adaptation and genetic differentiation, or are within the range of expected phenotypic plasticity, and observed responses are discussed within this context. Further investigation of species response to urban environments, including the frequency and significance of adaptation, will be important for understanding the emergence of synurbic populations and their implications for urban biodiversity and management. We hope that the terms defined here will form the basis for comparative studies of urban species.  相似文献   

新亚欧大陆桥东端城市群空间结构规划构想   总被引：1，自引：0，他引：1  

孙峻岭  林炳耀  孙琳琳 《地理研究》2012,31(5):931-944

基于陆桥经济理论,着眼陆桥经济带东部崛起,分析了当前新亚欧大陆桥东端淮海城市群空间结构特点,指出当前陆桥经济发展带来的新的挑战和机遇。通过淮海城市群中心城市职能指数和经济联系强度的相互验证计算,进一步明确徐州作为本区域的中心性城市地位,提出了新亚欧大陆桥东端淮海城市群"一心五轴六组团"的总体空间规划构想,以及实施规划的三大措施,即建设具有强大辐射力的区域性特大中心城市、实施淮海城市群核心区一体化、推动淮海城市群规划上升为国家战略。  相似文献   

Soiling of limestone in an urban environment characterized by heavy vehicular exhaust emissions     

Nick Schiavon  Giuseppe Chiavari  Daniele Fabbri 《Environmental Geology》2004,46(3-4):448-455

The inorganic and organic chemical composition of weathering sulphate patinas on the limestone walls of Emmanuel College, Cambridge, UK, have been analysed by FT-IR spectroscopy, pyrolysis gas-chromatography/mass spectrometry and scanning electron microscopy. The College location is characterized by heavy vehicular exhaust emissions including those from diesel powered public transport vehicles due to its proximity to the main Cambridge coach station. A complex mixture of gaseous and particulate air pollutants are found deposited in the weathering patinas including organic compounds (such as PAHs), which represent markers for present-day vehicular pollution. Slight differences in composition between patinas collected at different heights on the building facades with, in particular, more evidence for a biogenic overprint in samples collected at roof level as opposed to ground (street) level are found. Analytical results confirm how building stones in urban areas acted in the past and still do today as passive repositories for any kind of gaseous and particulate air pollutant present in the surrounding atmosphere; accordingly, weathering patinas are slowly changing their composition to accommodate new classes of present-day air pollutants.  相似文献   

Use and abuse of the urban groundwater resource: Implications for a new management strategy   总被引：3，自引：0，他引：3  

J.-O.?DrangertEmail author  A.?A.?Cronin 《Hydrogeology Journal》2004,12(1):94-102

Various human activities threaten the groundwater quality and resource under urban areas, and yet residents increasingly depend on it for their livelihood. The anticipated expansion of the worlds urban population from 3 to 6 billion in the coming 50 years does not only pose a large water management threat but also provides an opportunity to conserve groundwater in a better way than up to now. The authors argue for a new way to manage urban activities in order to conserve the precious groundwater resource. The focus is on the quality of the discharged water after use in households. Restrictions on what is added to water while using it, e.g. detergents, excreta, paint residues, oils, and pharmaceuticals, are important to simplify the treatment and reuse of used water. Avoiding mixing different wastewater flows has the same positive effect. If increased volumes of wastewater can be treated and reused, the demand on the groundwater resource is reduced, as also occurs with demand management measures. Reduced discharge of polluted water to the environment from households and utilities also conserves the quality of groundwater and reduces sophisticated treatment costs.

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Resumen La urbanización lleva a una demanda elevada y concentrada de agua de calidad adecuada, acompañada por el vertido de volúmenes análogamente mayores de aguas residuales. Los alimentos se importan a ciudades donde los microorganismos y nutrientes de los excrementos humanos son descargados a ríos, lagos y, también, aguas subterráneas. Más aún, gran número de los bienes de consumo son eliminados vía las tuberías de las cloacas. Las deudas medioambientales, es decir, el empobrecimiento de las condiciones medioambientales, que requerirán de aportaciones humanas y económicas para rehabilitarlas, son comunes a todas las ciudades, sobretodo en el Hemisferio Sur, donde, según la Valoración Global de Suministro de Agua y Saneamiento (OMS y UNICEF), la mayor parte de las aguas residuales urbanas no son tratadas (65% en Asia, 86% en Latinoamérica, 100% en África). La tarea pendiente consiste en proteger los recursos de aguas subterráneas para que estén disponibles de forma rápida para los habitantes urbanos también el futuro. En los próximos 50 años, se espera que la población urbana aumente de 3,000 a 6,000 millones de personas, según estimaciones de las Naciones Unidas, por lo que es imperativo dejar de contaminar las aguas subterráneas existentes bajo las nuevas áreas urbanas en construcción. En este artículo, se escudriña la calidad de las aguas subterráneas y su protección a la luz de los cambios recientemente introducidos en las políticas del agua, esto es, desde la gestión de los abastecimientos de agua a la gestión de la demanda y, eventualmente, hastaa la gestión de la reutilitzación.

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Résumé Lurbanisation conduit à une demande élevée et concentrée deau de qualité adéquate, accompagnée du rejet dimportants volumes correspondants deaux usées. La nourriture est importée dans les villes tandis que les micro-organismes et les nutriments provenant des excrétas humains sont rejetés dans les rivières, les lacs et aussi les eaux souterraines. De plus, une large gamme de biens de consommation est évacuée par les égouts. Les créances environnementales, cest-à-dire lappauvrissement des conditions environnementales qui demandera des apports humains et économiques pour la réhabilitation, sont habituelles dans toutes les villes, et pas seulement dans lhémisphère sud, comme cela est indiqué dans le rapport sur lalimentation en eau et la santé publique du monde (publié par lOMS et UNICEF), établissant que la plupart des eaux résiduaires des zones urbaines reste non traitée (65% en Asie, 86% en Amérique latine et 100% en Afrique). La tâche à réaliser pour lhomme est de protéger les ressources en eau souterraine en sorte quelle reste disponible pour les habitants des villes dans le futur. Dans les prochaines 50 années, il faut sattendre à ce que la population urbaine saccroisse de 3 à 6 milliards de personnes selon les estimations des Nations Unies; aussi il est impératif de ne pas continuer à polluer les eaux souterraines sous les nouvelles zones urbaines en cours de construction. Dans cet article, nous analyserons la qualité des eaux souterraines et leur protection à la lumière des récents changements de politique de leau, cest-à-dire de la gestion de lalimentation en eau jusquà une gestion de la demande et en abordant éventuellement la période de gestion du recyclage.

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Scalar Fluxes from Urban Street Canyons Part II: Model   总被引：1，自引：1，他引：0  

Ian?N.?HarmanEmail author  Janet?F.?Barlow  Stephen?E.?Belcher 《Boundary-Layer Meteorology》2004,113(3):387-410

A practical model is developed for the vertical flux of a scalar, such as heat, from an urban street canyon that accounts for variations of the flow and turbulence with canyon geometry. The model gives the magnitude and geometric dependence of the flux from each facet of the urban street canyon, and is shown to agree well with wind-tunnel measurements described in Part I. The geometric dependence of the flux from an urban street canyon is shown to be determined by two physical processes. Firstly, as the height-to-width ratio of the street canyon increases, so does the roughness length and displacement height of the surface. This increase leads to a reduction in the wind speed in the inertial sublayer above the street canyons. Since the speed of the circulations in the street are proportional to this inertial sublayer wind speed, the flux then reduces with the inertial sublayer wind speed. This process is dominant at low height-to-width ratios. Secondly, the character of the circulations within the street canyon also varies as the height-to-width ratio increases. The flow in the street is partitioned into a recirculation region and a ventilated region. When the street canyon has high height-to-width ratios the recirculation region occupies the whole street canyon and the wind speeds within the street are low. This tendency decreases the flux at high height-to-width ratios. These processes tend to reduce the flux density from the individual facets of the street canyon, when compared to the flux density from a horizontal surface of the same material. But the street canyon has an increased total surface area, which means that the total flux from the street canyon is larger than from a horizontal surface. The variations in scalar flux from an urban street canyon with geometry is over a factor of two, which means that the physical mechanisms responsible should be incorporated into energy balance models for urban areas.  相似文献   

Gravitational drainage systems in urban areas: case study (Galaţi town, Romania)     

Fl. Zamfirescu  I. Popa  Al. Danchiv 《Environmental Geology》2006,49(6):887-896

The water leakage in the urban areas causes a continuous rise in the water table, with harmful effects. An experimental drainage system, based on horizontal well technology, was designed and implemented in a populated area. Groundwater flow modeling was used to assess the hydrodynamic efficiency of the system through drain conductance parameter estimation.  相似文献   

Effect of upstream ponds on stream temperature   总被引：2，自引：0，他引：2  

J. Ham  L. Toran  J. Cruz 《Environmental Geology》2006,50(1):55-61

Many tributaries feeding streams are connected to ponds that heat up during summer months; however, the influence of these ponds on receiving stream temperature was not known. Stream temperature affects microfauna and fish habitats in aquatic ecosystems. Three tributaries with headwater ponds exposed to sunlight and one tributary unassociated with a large, upstream pond were selected for study within the Pennypack Creek watershed in the Philadelphia Metropolitan Area. Temperature loggers were installed in the pond (when applicable), associated tributary, and in the Pennypack Creek up and downstream of its confluence with the tributary. Although diurnal temperature fluctuations were apparent, the study showed no significant differences in temperature up and downstream of tributary discharge to Pennypack Creek. Pond water temperatures were up to 4°C warmer than the Pennypack Creek; however, temperatures downstream and upstream of the tributaries leading out of the ponds were within 1°C of each other.  相似文献   

Community and Nostalgia in Urban Revitalisation: a critique of urban village and creative class strategies as remedies for social ‘problems’     

Kendall Barnes  Nicholas Gill  Chris Gibson 《The Australian geographer》2006,37(3):335-354

We examine how normative constructions of ‘the creative city’ have entered into Australian planning discourses. Although welcoming a place-based approach, critical consideration is given to how the misappropriation of ‘place making’ in creative city revitalisation plans may enhance rather than address processes of social marginalisation. A Foucauldian framework is employed, exploring the notion of the social production of power through discourse. We draw on a case study of Wentworth Street, a key urban space in Port Kembla, the industrialised district of Wollongong, New South Wales. The study focuses on various ideas of a common place-making theme of the ‘urban village’ evoked by planners, the media and a targeted local resident group (here elderly Macedonians) for a street positioned in ‘crisis’ because of declining infrastructure, services and its association with crime, drugs and prostitution. The case study demonstrates that marginalisation and exclusions are products of creative city strategies and wider, more oppressive urban discourses. But we also demonstrate that despite becoming normative in the texts of planning policies, discourses of place and identity always remain multiple, negotiated, and contradictory.  相似文献