Modeling Spatial Processes of Urban Growth in African Cities: A Case Study of Nairobi City

Africa's urban population growth has been especially rapid, averaging about 5% per year over the past two decades. As a result, many urban areas have experienced dramatic growth that is seriously outstripping the capacity of most cities to provide adequate services for their residents. Although population growth and urbanization rates in Africa have slowed recently due to a number of factors including HIV/AIDS, urban growth is still expected to double by 2030, leading to dramatic sprawl with serious environmental and social consequences. Using Nairobi as an example of a rapidly urbanizing African city, we studied the dynamics of land use and land cover change using satellite data and addressed the need for models and urban management tools that can guide sustainable urban planning policies. Cellular Automata, which integrate biophysical factors with dynamic spatial modeling, are used in this study. The model was calibrated and tested using time series of urbanized areas derived from land use/cover maps, produced from remotely sensed imagery, with future urban growth projected to 2030. Model assessment results showed high levels of accuracy, indicating that simulation findings were realistic, thereby confirming the effectiveness of the model. Results further showed that the model is a useful and effective tool to foresee the spatial consequences of planning policies in the context of many African cities. The forecast for Nairobi showed unsustainable sprawl.     

Provincializing urban appropriation: Agonistic transgression as a mode of actually existing appropriation in South African cities

Urban appropriation is a key dimension of both Lefebvre's widely hailed ‘Right to the City’ and Bayat's concept of ‘quiet encroachment’. For Lefebvre, appropriation is a (generally unrealized) claim by those who do not ‘have’ the city of a right to ‘take’ it. Bayat, in contrast, characterizes actually existing appropriation as motivated by everyday needs, not aimed at wider social change. While both theorizations may be useful, we argue that a third mode of appropriation is apparent in South African urban contexts. Actors often act in ways that could be characterized as appropriative, yet do not work to consolidate an abrogated appropriative right or durable permission. Nor are they adequately explained as apolitical or individualistic; the logic used to justify them similarly is based neither on rights nor needs. We label such appropriation ‘agonistically transgressive’. We argue that agonistically transgressive appropriations are particularly evident in post‐apartheid South Africa, in part because of changing urban conditions and consequent renegotiations of spatial regulation. Using examples of urban land appropriation for housing in South Africa, we briefly illustrate how thinking pluralistically about urban appropriation might help better understand its actually existing forms in—and beyond—the global South.     

Circulating planning ideas from the metropole to the colonies: understanding South Africa's segregated cities through policy mobilities

In the early part of the twentieth century, South African cities were segregated in accordance with British city planning concepts that embodied the belief that social order can be manipulated through the urban form. This paper surveys the history of South African planning practices to understand the spread of segregation policies and practices. Whereas scholars tend to agree that the apartheid city (post?1948) is a more highly organized and structured version of the colonial city (pre?1910), the literature lacks consensus on the development of the segregated city (1910?1948) within South Africa. How did concepts of segregation circulate and why was it implemented with such consistency? Accordingly, this paper employs concepts of policy mobilities to trace historical configurations in South Africa to international influences. The focus on the circuits of knowledge explains how concepts and designs transplanted from elsewhere helped create the form of South African cities today. Understanding the movement of planning ideas through policy mobilities furthers geographical understandings of historical circulation processes, the role of the local actors, and policy mobilities failure. This history of learning also challenges the assumption that South African cities are unique and in so doing opens the doors for knowledge sharing between postcolonial cities.     

Downgrading – An overlooked reality in African cities: Reflections from an indigenous neighborhood of Accra,Ghana

African cities contain a range of low-income ethnic and cultural enclaves that defy conventional ‘slum’ typecasts and intervention guidelines. Further, new forms of urbanization (e.g. gated communities and informal settlements) have received heavy emphasis in recent urban geographic research. Such research emphases have many unintended consequences; one of which is that traditional indigenous neighborhoods in the older city are glossed over. This paper focuses on urban downgrading in Korle Gonno, a prominent and established indigenous community in Accra, Ghana. Using mixed-method data (including surveys), the results illustrate that a traditional neighborhood encounters many of the same dimensions of urban poverty as the more famed slums in the city, yet it experiences different poverty trajectories. We argue that the prevailing slum profiling techniques fall short of capturing these trajectories; more nuanced approaches that capture continuity and discontinuity with past and present socioeconomic processes are necessary. Attention must be rebalanced toward understanding the deterioration of these neighborhoods if policymakers, planners and urban theorists are to obtain a comprehensive picture of poverty dynamics and appropriate interventions in African cities.     

Are all cities with similar urban form or not? Redefining cities with ubiquitous points of interest and evaluating them with indicators at city and block levels in China

Urban forms reflect spatial structures of cities, which have been consciously and dramatically changing in China. Fast urbanisation may lead to similar urban forms due to similar habits and strategies of city planning. However, whether urban forms in China are identical or significantly different has not been empirically investigated. In this paper, urban forms are investigated based on two spatial units: city and block. The boundaries of natural cities in terms of the density of human settlements and activities are delineated with the concept of ‘redefined city’ using points of interests (POIs), and blocks are determined by road networks. Urban forms are characterised by city-block two-level spatial morphologies. Further, redefined cities are classified into four hierarchies to examine the effects of different city development stages on urban forms. The spatial morphology is explained by urbanisation variables to understand the effects. Results show that the urban forms are spatially clustered from the perspective of city-block two-level morphologies. Urban forms tend to be similar within the same hierarchies, but significantly varied among different hierarchies, which is closely related to the development stages. Additionally, the spatial dimensional indicators of urbanisation could explain 41% of the spatial morphology of redefined cities.     

Vertical differentiation in urban space: A case of Aizawl city

Cities are characterized by sociospatial differentiation. Intra‐urban inequality is found in cities across the world. Cities in the ‘peripheral south’ have been neglected in spite of their significant role in theoretical formulations and generalizations. The present paper attempts to argue that sociospatial differentiation is an inherent characteristic of cities, although the spatial form of inequality may vary depending on the specific culture and physical geography of the area. In the remote city of Aizawl in the eastern Himalayan region of India, multi‐storey buildings are cohabitated by higher and lower income classes ‐ the former were found at the top floors and the latter at the bottom floors. The vertical arrangement of income classes within a single building is seen as an adjustment strategy of the increasingly urbanized ‘tribal’ society in the hilly terrain of the city.     

"城市-景区"双驱动型乡村发展:路径选择及其动态演化过程

城市溢出和景区辐射是乡村发展的重要力量,已有研究对城市周边和景区附近区位下“城市-景区”双驱动乡村的发展路径探索较少。以北京市怀柔区慕田峪村、北沟村、田仙峪村和辛营村4个行政村共同组成的“长城国际文化村”为案例地,探索城市和景区双重优势驱动下的乡村发展路径选择及其动态演化过程。研究发现：① 城市、景区和乡村自身等多元力量共同驱动乡村发展,继而导致其发展路径呈现出非线性、多元化的演变特征;② “城市-景区”双驱动型乡村的发展路径可分为“景区主导-城市辅助”“城市-景区并重驱动”“城市主导-景区辅助”和“城市-景区双重弱驱动”4种类型;③ “城市-景区”双驱型乡村发展竞争性路径随着城乡、景乡间要素的差异化集聚引发了乡村产业结构变动及区域空间格局演化。     

广州小北路黑人聚居区社会空间分析

1978 年改革开放带来中国城市的快速转型。近年来, 针对经济转型背景下中国大城市 的社会空间研究很多, 但对在全球化影响下出现的跨国移民族裔聚居区的研究尚不多见。对 广州黑人聚居区展开研究, 以越秀区小北路为例, 探讨其社会空间特征与演进机制。研究采 用微观视角, 针对典型案例进行问卷调查和半结构式访谈。研究表明, 广州黑人聚居区与西 方同类族裔社会区存在诸多差异。小北路黑人聚居区因全球化下新的“自下而上”的跨国经 济联系而生, 因广州城市的商贸文化、宗教历史、贸易网络和地理气候条件而兴, 其跨国移 民多为来自西非地区的族裔散居者/ 漂泊者(Diaspora), 其人口构成异质多元, 且流动性强。 小北路的社会空间机制既包含被动隔离也包含主动聚居, 其经济形态已经开始向“族裔聚居 区经济”(ethnic enclave economy) 发展。     

中国旅游城市生态安全系统评估与类型划分研究 ——基于节点权重约束网络DEA模型

采用 DPSIR概念模型作为旅游生态安全系统的基本形态,引入网络 DEA模型测度系统运行效率,从“投入-产出”的研究视角探究旅游生态安全系统内部作用机理。采用结构方程模型对网络 DEA模型的结构及权重加以限制,构建具有节点权重约束的网络 DEA评价模型,对主要旅游城市生态安全系统实例进行实证研究。研究结果认为：将生态安全系统分为自然运行阶段、管理反馈阶段2阶段进行效率评价,加权综合得出各旅游城市生态安全系统的综合评价值,以此为依据将样本城市划分为按系统效率的评价结果将其分划为绿色发展型、稳步发展型、高效发展型、双向提升型和管理能力缺失型,针对各类型旅游城生态安全系统特点提出改善其生态安全系统状况的建议。     

中等城市人居环境空间分异研究——以丹东市为例

城市人居环境的空间分异已经成为城市学、社会学、地理学等学科研究的热点之一,我国对于城市空间分异的研究大多集中于大城市,很少涉及中等城市.实际上,在我国快速城市化进程中,人居环境空间分异并不仅仅存在于大城市,在广大中等城市中也已初见端倪.我们以中等城市--丹东市为例,通过调查走访获取数据,建立数学模型,使用MapInfo和Surfer作图软件进行数据分析和图像处理,探讨了丹东市人居环境空间分异的特点.研究结果表明:(1)丹东市作为典型的中等城市,其内部人居环境已经异化,显现出明显的空间分异趋势;(2)人居环境空间分异的总趋势是沿鸭绿江岸线向陆地呈扇形逐级递减;(3)扇形外围--西北部地区的人居环境空间分异打破逐级递减和平行扩散的规律,在局部形成小范围的次级核心点.     

沈阳都市圈的范围及城镇空间分布的分形研究

科学界定都市圈范围是研究都市圈的基础,采用2014年沈阳市及周边市县镇乡社会经济统计数据,采用断裂点和经济隶属度模型,界定沈阳都市圈范围。用经济隶属度指标划分城镇体系。用分形理论分析沈阳都市圈城镇的空间分布特征,结果为：集聚维数、容量维数、信息维数和关系维数分别为1.430 1、1.294 1、1.473 5和0.393 8,说明沈阳都市圈城镇空间向心性集聚分布较为显著,城镇空间分布的均衡性较好,城镇空间分布具有较强的相关性,形成了以沈阳市为中心呈凝聚态分布的都市圈城镇空间结构,城镇间联系较为紧密,相互作用较强。进而提出沈阳都市圈城镇空间分布优化的对策。     

Making of high‐tech Hyderabad: Mapping neoliberal networks and splintering effects

Over the past few decades, cities and city regions have become the core of the global economy. Regional governments are increasingly drafting city development policies and implementing them through various visioning documents with the aim of making cities more global, networked and competitive. Welfarist governments especially in the global South are becoming increasingly entrepreneurial, and in the process poor citizens are getting pushed to the margins, evicted from their land and relocated to city fringes. Hyderabad in India provides an interesting illustration of neoliberal development trends in which poor local farmers are forced off their land to make way for a ‘world‐class’ knowledge enclave, popularly known as Cyberabad. This paper examines the policies and processes by which the regional government has sought to brand Hyderabad as a world‐class information technology destination and to restructure and reimagine it as a key node in a network of ‘globally connected cities’ of the world. It also considers the making of Cyberabad in terms of splintering urbanism, which is often understood as a defining feature of contemporary neoliberal urban processes.     

Postrevolutionary land encroachments in Cairo: Rhizomatic urban space making and the line of flight from illegality

After the January 2011 revolution, new and unpermitted constructions on previously empty land went up across Cairo at striking speed. This paper explores a case of such land encroachments carried out by waste collectors in the neighbourhood of Manshiet Nasser in Cairo, Egypt. It begins with theoretical debates about the production of urban space, arguing that the de Certeauian paradigm, in which urban marginals poach or hijack others' spaces evanescently, fails to account for the way such encroachments produce permanent new spaces rhizomatically alongside the pre‐existing order. The paper then turns to a close examination of the events in Manshiet Nasser. Although in a broad view the actors are marginals living in the ‘informal’ city, the conditions enabling the encroachments were such that only the wealthiest and most powerful members of the ‘community’ benefitted. In a context of generalized ‘illegality’, the squatters rely on practical norms and de facto recognitions to obtain some degree of tenure security. Since these efforts rely on and play off legal norms even as the squatters violate them, the paper argues that property rights in this context should be understood not in classificatory terms based on the legal/illegal binary, but rather through a trajectory of ‘becoming‐legal’: a ‘line of flight’ that approaches legality asymptotically.     

生态景观与城市形态整合研究

早在19世纪末生态思想就开始用于指导城市空间结构的研究,如今景观生态学关于格局与过程的生物空间理论,已成为城市自然景观组织和生态景观建设的主要理论支撑。本文探讨了生态景观的含义及建设途径,以南京为例运用景观生态学原理研究城市形态可持续格局,分析高密度开发条件下城市自然或近自然景观与人工建筑环境整合方法,并提出了在大都市区、主城区、街区三个不同尺度上由表及里、由内而外的生态景观与城市形态整合模式：绿楔与星形放射状城市相嵌、绿径网络与街区路网纹理相伴、须状绿色延伸与邻里环境相融。为城市景观生态重建和城市化地区生态安全格局构建提供参照。     

中国大城市外国人聚居区的形成机制——基于北上广的比较研究

在3个典型的外国人聚居区——北京望京韩国人聚居区、上海古北日本人聚居区、广州小北非洲人聚居区的实证研究基础上,探讨不同移民群体的城市选择偏好,以及移民群体和城市之间的互动关系。研究发现,在京韩国人以企业、商贸、教育指向型居多,在沪日本人以企业指向型为主,在穗非洲人以贸易指向型为主,这一特征说明北上广不同的城市职能差异;北上广的外国人聚居区均形成于相似的宏观制度环境,生产活动的全球性重组、国家间关系、国家制度和外国人管理政策等因素共同影响了外国人聚居区在大城市的兴起,但由于不同的城市软硬件环境与在华外国人的身份属性互动影响,也形成了各具特色的外国人聚居区,概括为耦合型（北京望京）、特区型（上海古北）和族裔型（广州小北）。中国城市的国际化已进入引资（资本国际化）和引人（人口国际化）并进的新阶段,应当进一步重视对大城市外国人聚居区的治理及服务的引导、规范,发挥其示范带动作用,推动中国对外开放深度高质量发展。     

A crack in the facade? Situating Singapore in global flows of electronic waste

Singapore is alleged to be a key node in global flows of e‐waste prohibited under the Basel Convention. We combine a close reading of the Convention and related documents with findings from nonparticipant observation of and interviews with Singapore‐based traders of discarded electronics. The case offers both important conceptual and empirical findings for future studies of territory in market‐making activity. Conceptually, our research suggests that it may be analytically useful in such studies to conceptualize territory without presupposing that it is generated as a result of separate domains or logics such as ‘the political’ or ‘the economic’. Empirically, we find that the regulatory framework of the Convention, combined with the action of traders based in Singapore, generates a territorialization of the city‐state such that it operates as a crack in the regulatory edifice of the Convention, even as Singapore lawfully fulfils its obligations to it. Moreover, allegations premised on the role of Singapore as a facilitator of global e‐waste dumping misrepresent its crucial role as a conduit of electronic equipment for the significant reuse markets elsewhere in Southeast Asia and beyond. The case indicates that the allegations against Singapore hinge on the city‐state being territorialized as a ‘developing country’.     

大城市低收入邻里社会贫困的测度差异与成因

社会贫困是对居民的社会保障和福利的享有情况、社会参与和融合等生活状况的测度。利用中国3 大典型地域、6 个代表城市、3 类邻里的1809 份个体问卷调查数据, 本文选取13 个相关指标, 判定个体是否处于社会贫困状态, 利用回归模型探究其影响因素, 并分析社会贫困现象在不同邻里、不同城市集聚的分异特征。研究发现, 6 个城市间的社会贫困集聚程度顺序为东部、中部和西部;3 大类邻里中, 社会贫困在城中村表现最为明显, 内城居住区次之, 企业配套居住区最低。中国城市居民是否处于社会贫困状态是体制(户口类型) 和家庭(教育程度、年龄等) 因素共同作用的结果。代表体制因素的户口类型对3 类城市的社会贫困均起到影响, 东中部城市中家庭因素也有一定作用。体制因素对城中村的社会贫困起显著影响, 而家庭因素在内城居住区和企业配套居住区中作用更大。     

Everyday space–time geographies: using mobile phone-based sensor data to monitor urban activity in Harbin,Paris, and Tallinn

This paper proposes a methodology for using mobile telephone-based sensor data for detecting spatial and temporal differences in everyday activities in cities. Mobile telephone-based sensor data has great applicability in developing urban monitoring tools and smart city solutions. The paper outlines methods for delineating indicator points of temporal events referenced as ‘midnight’, ‘morning start’, ‘midday’, and ‘duration of day’, which represent the mobile telephone usage of residents (what we call social time) rather than solar or standard time. Density maps by time quartiles were also utilized to test the versatility of this methodology and to analyze the spatial differences in cities. The methodology was tested with data from cities of Harbin (China), Paris (France), and Tallinn (Estonia). Results show that the developed methods have potential for measuring the distribution of temporal activities in cities and monitoring urban changes with georeferenced mobile phone data.     

产业演进对旅游城市空间形态演变的作用机理——以黄山市为例

运用历史分析方法,借助GIS等手段,对黄山市城市空间形态演变过程进行梳理,并结合黄山市1978-2012年城市产业发展的动态数据资料,就黄山市产业演进对城市空间形态演变的作用机理进行分析探讨。研究发现：城市产业演进,特别是产业结构的调整与升级和组织形式的演化与更替,影响了城市空间的物质与功能要素,进而推动了城市空间形态的演变;旅游产业的主导地位决定了旅游城市的功能,从而引起城市用地结构的变迁;旅游产业的升级改变了生产资源在城市产业间的流动,引发城市产业空间格局的变化;旅游产业组织方式的优化进一步促使城市产业空间的融合和集聚。在此基础上,构建了产业演进对旅游城市空间形态演变的作用机理模型和相应的逻辑函数。     

重庆都市区地域结构问题及其优化

重庆都市区位于三峡水库的库尾区,是长江上游的经济中心。近几年,随着社会经济的发展,都市区的地域结构发生了很大的变化,产生了一系列突出的问题,已影响到都市区的可持续发展。文章详细地探讨了都市区地域结构的变化特点,揭示了地域结构演变过程中存在的主要问题,即城市功能区混杂、人居环境拥挤、热岛效应突出等;针对存在的问题,从用地结构、产业结构和功能结构8个方面提出了都市区地域结构优化调控的途径与对策。