Corridor development in Gauteng,South Africa

The development corridor concept has been regarded as an important development instrument in spatial planning and geography for many decades. Expanding literature on the theme indicates that development centres or nodes play an important role in the establishment of such corridors. Flows of goods and information between such centres are essential in creating conditions that are potentially favourable for further urban development along the communication axes connecting such centres. Combined, the various nodes form a unique flexible exchange environment allowing for dynamic synergies of interactive growth to achieve scope economies aided by fast and reliable corridors of transport and communication infrastructure. In the South African development sphere, there is strong belief that functional relationships between nodes can play a decisive role in the establishment of development corridors. The research showed that the degree to which economic activities are concentrated in the greater Gauteng region; the resulting current or emerging multinodal structural composition; and the flows of economic activities between the various nodes result in the creation of development corridors that channel and focus economic growth between networks of cities. This confirms the importance of corridors as spatial and economic development instruments. The research concluded that the core cities of Johannesburg and Pretoria are the central driving force in corridor development in Gauteng. They feature as the most dominant nodes, exerting great forces of attraction on the distribution of development and economic growth in the region. The research also suggests a degree of polycentrism whereby economic growth is channelled between networks of cities, however development potential is most favourable in areas in close proximity to primary centres and tends to be functionality driven.     

(Re)Connecting spatial literacy with children’s geographies: GPS,Google Earth and children’s everyday lives

This article sets out an agenda for research that (re)connects research on children’s geographies and childhood studies with studies of spatial literacy. Research on children’s environmental cognition and, latterly, spatial literacy, has been artificially and problematically separated from the majority of research in childhood studies. Our fundamental aim in this article is to argue for – and to evidence – greater attention to how spatial literacy and children’s everyday lives are embedded in one another. To support our broader call for a synthetic research agenda, we draw on some more focussed, qualitative empirical material taken from a large-scale project about children’s mobilities and everyday lives in newly-built urban communities. Our analysis focuses upon children’s interpretations of Global Positioning Systems (GPS) tracks of their mobilities, set against a background of Google Earth imagery. In doing so, we showcase one suite of ways in which research on environmental cognition and children’s geographies might proceed together. We demonstrate that children not only displayed analytical skills (for instance, in relation to scaling effects and pattern recognition) but that many also exercised higher-level, critical analysis, especially in relation to errors on Google Earth outputs. Simultaneously, we interrogate the recursive articulation of a range of qualitative indicators of spatial literacy, with children’s everyday mobilities, routines, emotions and memories. The paper analyses how new conceptual languages and technologies being propounded by spatial literacy scholars could afford a more enriched understanding of key contemporary concerns for children’s geographers, and, recursively, what spatial literacy scholars might gain from engaging with (especially qualitative) research prompted by those concerns.     

Effects of Pleistocene environmental changes on the distribution and community structure of the mammalian fauna of Mexico

Biological communities in Mexico experienced profound changes in species composition and structure as a consequence of the environmental fluctuations during the Pleistocene. Based on the recent and fossil Mexican mammal checklists, we determine the distribution, composition, diversity, and community structure of late Pleistocene mammalian faunas, and analyze extinction patterns and response of individual species to environmental changes. We conclude that (1) differential extinctions occurred at family, genus, and species level, with a major impact on species heavier than 100 kg, including the extinction all proboscideans and several ruminants; (2) Pleistocene mammal communities in Mexico were more diverse than recent ones; and (3) the current assemblages of species are relatively young. Furthermore, Pleistocene relicts support the presence of biogeographic corridors; important refugia existed as well as centers of speciation in isolated regions. We identified seven corridors: eastern USA–Sierra Madre Oriental corridor, Rocky Mountains–Sierra Madre Occidental corridor, Central United States–Northern Mexico corridor, Transvolcanic Belt–Sierra Madre del Sur corridor, western USA–Baja California corridor, Tamaulipas–Central America gulf lowlands corridor, and Sonora–Central America Pacific lowlands corridor. Our study suggests that present mammalian assemblages are very different than the ones in the late Pleistocene.     

李家峡水电站坝址环境水化学特征与演变

坝址环境水质及其时空变化隐含了丰富的信息,可以揭示水、岩、帷幕间的相互作用情况以及渗流条件的改变。以李家峡水电站为例,对坝址不同部位渗流水进行采样检测的基础上,综合运用水化学图示、统计分析等方法,研究了坝址环境水质空间分布特征,并与之前的检测结果对比分析水质变化趋势。研究显示,廊道内渗水总体上呈现出“高矿化”的特征,且坝基部位较两岸坝肩尤甚,表明两岸部位帷幕前后水力联系相对活跃;从时间演变看,左岸及坝基廊道部位的水质与此前检测分布较为一致,表明对应部位防渗性能变化稳定;右岸水样两次检测情况变化较大,表明右岸廊道部分部位渗流条件变化较大。     

Mobile policies and policy streams: The case of smart metering policy in Australia

Geographers have become increasingly engaged with the notion of policy mobility. It is argued that in a globalised world policies have become more internationally mobile: we now live in an era of ‘fast policy’. Drawing on core concepts of mobility, neoliberalisation, and globalisation - and with a background primarily in geography and urban studies - policy mobility scholars have developed new ideas about how policies circulate internationally. In the process, however, theories of policy change developed within political science have been rather overlooked. In this paper it is shown how a political science theory with a shared interest in flows – the Multiple Streams Approach (MSA) – is complementary to policy mobilities scholarship. Two issues in particular are illuminated by the MSA: first, what constitutes policy, and, second, the role of the nation state in structuring the possibilities for, and timing of, policy change. In turn, policy mobilities scholarship highlights the different geographies of the multitude of objects, ideas, problems, processes, organisations, and regulations that constitute policy. It also raises questions about the validity of analytically separating politics from policy proposals, as advocated by the MSA. These issues are considered using the empirical case of smart electricity metering policy in Australia, in the period 2000–2015.     

临江地下结构主被动联合抗浮方法及应用

临江场地的地下水位受外江水位影响,具有长期水位较低、短期汛期水位极高的特点。临江场地内的地下结构,若仅采用抗拔桩或抗拔锚杆等常规被动抗浮措施进行抗浮,将抗浮设防水位取为地表高程显然是偏危险的,但按50年一遇和100年一遇水位采用常规被动抗浮措施进行抗浮设计又显然是不经济的,成本极高。基于此,提出抗浮范畴临江结构的定义及其“排水廊道+常规抗浮措施”的主被动联合抗浮的方法。根据临江承压圆湖公式,考虑越流效应,给出了临江排水廊道简化计算分析方法并进行了有限元验证。临江地下结构利用排水廊道进行防洪渡汛,保证汛期地下结构水荷载稳定,消除汛期高水压对结构产生的极端水荷载,而对于平时非汛期水位的作用则利用常规抗浮措施进行考虑。廊道只在汛期高水位时起防洪渡汛作用,排水减压不会引起环境影响问题,同时其耐久性也容易保证。最后介绍利用此方法进行抗浮的实际工程。     

Palaeo-ice streams and the subglacial landscape mosaic of the North American mid-continental prairies

The analysis of the glacial landscape of southern Saskatchewan (Canada) through multiple data sets (e.g. digital elevation model, till compositional data) has revealed previously unrecognized subglacial sediment–landform assemblages. A southwest-trending corridor of mega-scale till lineations (Maskwa corridor) bounded on each side by hummocky terrain extends from the Canadian Shield to southwestern Saskatchewan. This landform assemblage is clearly cross-cut by a broad south to southeast trending corridor (Buffalo corridor) consisting of subparallel curvilinear till ridges. The carbonate content of the surface till is spatially consistent within these assemblages, suggesting a strong sediment–landform relationship. The two corridors are interpreted as the product of palaeo-ice streams. The Maskwa palaeo-ice stream flowed up the regional slope and across preglacial valleys, indicating it was thick and stable. Narrow dispersal trains extending across as well as down-glacier from the Athabasca Basin suggest that the Maskwa palaeo-ice stream extended far into the ice sheet across contrasting shield and platform terrains. In comparison, the Buffalo palaeo-ice stream was thinner and largely controlled by subglacial geology and topography. Its catchments were located at the Canadian Shield boundary and the system was oriented along-slope. It experienced lateral shifts and it was fed by a network of tributaries. The glacial dynamics shift from the Maskwa to the Buffalo system occurred at about 13.5 ¹⁴C kyr BP. The Buffalo system later evolved into thin outlet lobes until final deglaciation of the area. The proposed model has implications for ice-sheet reconstruction and the assessment of till properties in the prairies and in similar terrains.     

Temporal, geomagnetic and related attributes of kimberlite magmatism at Ekati, Northwest Territories, Canada

This paper outlines the development of a multi-disciplinary strategy to focus exploration for economic kimberlites on the Ekati property. High-resolution aeromagnetic data provide an over-arching spatial and magnetostratigraphic framework for exploration and kimberlite discovery at Ekati, and hence also for this investigation. The temporal, geomagnetic, spatial and related attributes of kimberlites with variable diamond content have been constrained by judiciously augmenting the information gathered during routine exploration with detailed, laboratory-based or field-based investigations. The natural remanent magnetisation of 36 Ekati kimberlites has been correlated with their age as determined by isotopic dating techniques, and placed in the context of a well-constrained geomagnetic polarity timescale. Kimberlite magmatism occurred over the period 75 to 45 Ma, in at least five temporally discrete intrusive episodes. Based on current evidence, the older kimberlites (75 to 59 Ma) have low diamond contents and are distributed throughout the property. Younger kimberlites (56 to 45 Ma) have moderate to high diamond contents and occur in three distinct intrusive corridors with NNE to NE orientations. Economic kimberlite pipes erupted at 55.4±0.4 Ma along the A154-Lynx intrusive corridor, which is 7 km wide and oriented at 015°, and at 53.2±0.3 Ma along the Panda intrusive corridor, which is 1 km wide and oriented at 038°. The intrusion ages straddle a paleopole reversal at Chron C24n, consistent with the observation that the older economic kimberlites present as aeromagnetic “low” anomalies while the younger economic pipes are characterised as aeromagnetic “highs”. The aeromagnetic responses for these kimberlites are generally muted because they contain volcaniclastic rock types with low magnetic susceptibility. Kimberlites throughout the Ekati property carry a primary natural magnetic remanence (NRM) vector in Ti-bearing groundmass magnetite, and it dominates over vectors related to induced magnetisation. Magnetostratigraphic correlation of Ekati kimberlites may therefore present a powerful adjunct to existing exploration techniques, mainly because the diamond content of Ekati kimberlites apparently is related more to the age of eruption than to any other parameter investigated in this work.     

The local geographies of poverty: a rural case-study

Recent years have witnessed a renewed interest in the spaces of poverty in Britain. An increasing number of geographers have placed poverty back `on the map' by pointing to its complex spatial manifestations. In addition, the increased importance attached to the concept of social exclusion within UK social welfare discourse has led to social policy researchers thinking more critically about the broader social and spatial contexts of poverty and, consequently, new connections between poverty and space have been identified. However, within these new spatialised accounts of poverty in Britain, scant attention has been given to the local geographies of poverty. In fact, relatively little is known about the complex connections between poverty and place, and, more specifically, the ways that poverty is associated with different material forms, representations and experiences in particular local contexts. This paper develops these kinds of connection between poverty and place through an exploration of the local geographies of rural poverty in South-west England. Based on an analysis of local poverty data, in-depth interviews with a broad range of key agencies and a case-study of poverty in a particular village, the research highlights the complex socio-spatial nature of poverty, the different spatial scales and visibilities of poverty, and important connections between poverty and the shifting social composition of local space.     

Extending the margins of marketization: Frontier regions and the making of agro-export markets in northern Ghana

This paper demonstrates how the global commodity chain approach has mutated from a critical tool for studying the production of inequality in the global economy to an instrument of development policy that extends the frontiers of marketization to so-called “peripheries” in the Global South. Taking an outgrower scheme for the global production of organic mangoes in northern Ghana as point of departure, and situating this case study within the broader context of market experiments in the Ghanaian agricultural sector, it develops an account of global capitalism as a diverse, heterogeneous and messy arrangement of local borderlands. As a zone of inclusive exclusion these borderlands are brought into being by an economic discourse which separates the inside of the capitalist world from its supposed outside. The so-called integration of smallholders into global markets relies on exclusionary representations and the forging of new associations. First, economic practices in northern Ghana are portrayed by economists as defective and in doing so determine what lies outside the market. Second, within this “outside” – on which the “inside” actually depends – global capitalism mediated through the market models and rhetoric of international development organizations now literally touches the ground in specific geographical settings. Hence Frontier regions as represented by our case study bear the paradoxical character of the work of economics and are an instructive example for the performative power of economic theories. Marketization is revealed as a complex and socio-technically entangled process full of hidden prerequisites and unforeseen consequences that open up new social spaces of multiple ontological reconfigurations.     

Ghostly encounters: Dealing with ghost gear in the Gulf of Carpentaria

Ghost gear – abandoned, lost, or otherwise discarded fishing gear – has been recognised as a global environmental challenge since the mid-1980s, and yet little social science attention has fallen on the phenomenon. This paper explores how the burden of global fisheries, materialised through its gear, is experienced and managed. How is ghost gear encountered? How is it understood? What influence does it have, and what responses does it provoke? To consider these questions, the paper begins with detailing of an encounter with ghost gear and Aboriginal rangers on the eastern coast of the Gulf of Carpentaria, northern Australia. Understanding encounters as tangles of interlaced threads, rather than isolated intimacies, the paper also follows ghost gear beyond the experience of beach clean-up. How ghost gear journeys to this beach, and the mobilities and meetings that occur during its travels is explored, as well as the policy responses to ghost gear that figure it primarily as marine debris to be managed through territorial control as isolated ‘waste’. These more-than-human stories offer insights into the distributed agencies, complex relations, and differential responsibilities involved in the phenomenon of ghost gear, and efforts to deal with it as part of land-sea assemblies.     

Zoogeography and imperial defence: Tracing the contours of the Nearctic region in the temperate North Atlantic, 1838–1880s

This paper focuses on the ‘zoogeographic region’ and the ‘zoogeographical boundary-line’ as key biogeographical constructs of empire. More specifically, it investigates how army and navy officers stationed at Halifax and Bermuda on the North America and West Indies Station helped to create an imperial, militarized ‘New World’ region in the North Atlantic through zoogeography in the British post-emancipation era. The tracing of the boundary-line between the temperate (Nearctic) and tropical (Neotropical) North Atlantic involved designating Bermuda and Halifax as strategic winter and summer ‘homes’ on the Station, and highlighting the ‘natural’ connections between the two sites through mobile fauna, ocean currents, and weather systems. Making visible the geographic distribution of migratory animals, the Gulf Stream, and hurricanes – through maps, natural collections, sketches, and travel-writing – provided new ways of seeing and thinking about British imperial defence in the North Atlantic. This paper also considers the role of non-human mobilities in animating these regions.     

Turn up the heat! Contesting energy poverty in Buffalo,NY

Energy poverty – or the condition of households that cannot adequately heat their homes – is produced at the confluence of multi-scalar processes, from regional labor market restructuring, to urban disinvestment, to geopolitical and geoeconomic struggles over extraction. Critical theorization of the concept is in its nascent phase and the notion itself has received relatively little attention in the United States. Our paper aims to address these lacunae by mobilizing an urban political ecology framework to consider a community-based campaign that targeted residential energy conservation funds in Buffalo, New York. We analyze how the community campaign drew upon the “network crisis” of the energy-poor home to frame critical justice demands that foregrounded energy poverty as the product of uneven socionatural development. Through spatial claims and scalar strategies, the campaign highlighted the contribution of neoliberal conservation programs to deepening patterns of uneven development, and demanded redress of disinvestment in urban housing stock through funding of weatherization for low-income households. We argue that contests over urban energy metabolism offer a fruitful area to explore the possibilities of transforming uneven development from below.     

Structural corridors in Landsat lineament interpretation

In plots of symbolised geo-data which have variations in density of symbol population, structural corridors are defined by relatively narrow belts in which the density of symbol population is in marked contrast to that of surrounding areas. Some corridors are of high population density (HPD), some of low population density (LPD), whilst others are serial composites. In geology, corridors are to be seen in ancillary plots of gravimetrics, magnetics, photolineaments, Landsat lineaments and allied data. Those related to ore deposits are commonly 100–200 km in length, with aspect ratios (length/breadth) from 20 to 40. They are distinguished from conventional anomaly trends by not necessarily defining absolute highs or lows in individual symbol measurements. Rather do they reflect dislocations in the pattern of material distributions which the symbols represent, and are therefore related more to gradient functions. They must be distinguished from random trends which pervade ordinary patterns of material distributions. Corridors defined for the one area by different sets of geo-data frequently do not coincide, and this is anticipated by differences in the particular qualities measured, and the geological times at which these qualities were established. Field observations show structural corridors to correspond to subsurface dislocations, and, depending on the type of geological environment, either edges or centres of corridors are significantly related to mineral and oil deposits. In airphoto and Landsat lineament plots, the best data for revealing corridors are the smaller features at the high frequency end of the symbol dimensional range. In such cases, structural corridors are hard to preconceive, and emerge only after the assembly of data is complete. This greatly reduces the problem of subjectivity of the interpreter. Photolineament corridors in the Kalgoorlie goldfield of Western Australia are discussed and compared with Landsat corridors related to metal and oil occurrences in North America.     

Delineation of arsenic-contaminated zones in Bengal Delta, India: a geographic information system and fractal approach

Groundwater extracted from shallow aquifers in the Bengal Delta is contaminated with arsenic. The fluviodeltaic process that creates aquifers, ironically, extends its role to also contaminating them with arsenic. The arsenic distribution maps show a spatial association of arsenic-contaminated wells with palaeo/cut-off/abandoned channels. Weight-on-evidences analysis indicates that the zones of contamination occur around palaeo-channels within a corridor of 500–700 m that contains most of the contaminated wells. These corridors are interpreted to be the zone of channel shifting. Contaminated wells represent point fractal geometry that can be separated into isolated points and clusters. Clusters occur within the zone of channel shifting as obtained by weight-on-evidences analysis. Isolated points occur within floodplain or back swamp areas. Clusters and isolated point fractals are interpreted to reflect the process of arsenic release into groundwater. The migration of biomass within the permeable sandy domain of channel deposits is proposed to be the predominant process in generating clusters. The isolated points represent restricted biomass spreading in less permeable clay-silt dominated floodplains.     

(Un)bundling Bangalore: Infrastructure bundling ‘best practices’ and assembling novel scapes

This paper focuses on the socio-material, political and spatial implications of urban infrastructure bundling practices. Our work examines how network bundling best practices piloted in the Indian city of Bangalore (Bengaluru) have been deployed as a policy model for urban road re-engineering. Drawing on work in actor-network theory (ANT)-inspired assemblage urbanism and policy mobilities, we examine the assembling of Bengaluru's Vittal Mallya (VM) Road in conjunction with Tender-SURE (Tender Specifications for Urban Road Execution) as showcase projects for bundled network infrastructures. Our paper introduces an ‘infrastructurescape’ typology – boundaries, intersections, cul-de-sacs and peopling – as an analytic for examining the socio-material and spatio-political implications of bundling. Our findings discuss the rise of powerful local infrastructure coalitions of private and civic interests in Bengaluru. Besides the low accountability of these coalitions, we identify the potential problematic effects of infrastructure bundling including: spatial exclusions and fragmentation; the valorization of commercial space and automobility; and the limited participation of wider publics in shaping urban infrastructural futures. Bundling urban networks and setting local urban infrastructural priorities, we suggest, represent politically-charged processes that reconfigure specific city streets and scapes. Infrastructure bundling practices have important implications for the city-at-large and the city-region of the future in India and beyond.     

Canberra: a city for the future?

Present development and future planning of Canberra, the Australian National Capital, is described as an example of modern town planning emphasising the spatial and functional organisation of the urban area. Canberra is a rapidly growing city and is being expanded by the creation of new dispersed satellite towns which are grouped around Inner Canberra in three growth corridors. The towns are structured into a hierarchical order of centers and provide a large range of services and facilities as well as a concentration of employment opportunities. Although the towns are self-supporting to a great degree, they remain integral parts of the metropolis with the City center providing the greatest range of services and facilities, as well as employment. One of the main problems facing the Capital is the inefficiency of public transport and accordingly the strong reliance on private motor vehicles, which will be difficult to overcome If present population densities are not substantially increased.     

基于生态网络构建与优化的太仓国土空间生态保护修复关键区域诊断与识别

以江苏太仓作为研究区域,基于生态系统服务评估确定生态源地,采用最小累积阻力模型（MCR）和重力模型构建生态廊道,提出生态网络优化模式和对应管控策略。经计算和分析,提取面积30 365.46 hm2的重要生态功能区作为生态源地;识别生态源地161.46 km2,其中水域生态源50个、陆域生态源地47个;提取水域生态廊道53条、陆域生态廊道56条,且水域生态廊道相较于陆域生态廊道更为完善,连通性和稳定性更高;识别需优先保护的生态夹点25个,优先修复的生态障碍点18个。研究成果可为系统性开展国土空间生态保护修复提供借鉴和指导。     

Spatial distribution of kimberlite in the Slave craton, Canada: a geometrical approach

Exploration within the Slave craton has revealed clusters of kimberlite intrusions, commonly with internally consistent geochemical and temporal characteristics. Translation diagrams (“Fry analysis”) allow an unbiased geometrical examination of the distance and direction between each kimberlite occurrence and all others in the database. Recurrent patterns are visually accentuated due to the square function in data density. Circular histograms quantify the azimuthal density of kimberlite at various distances. For this study, the database comprises the geographic position of 212 kimberlite occurrences of which 70% are from the Lac de Gras field (LDG). Analyses are presented separately for the LDG data and for all non-LDG data in order to test for regional variations and to avoid overwhelming the craton-scale studies by the high density of LDG data.

Empirical grouping of kimberlite locations results in delineation of five elliptical clusters that encompass all but four kimberlite occurrences. Clusters within the western part of the craton are elongate to the north–northeast and align within a narrow zone (“Western Corridor”). Elsewhere, the clusters are elongate to the northwest or west–northwest and appear to be arranged en echelon within a poorly defined north–northwest trending zone (“Central Corridor”). Geometrical spatial analyses of kimberlite locations highlight the craton-scale pattern of emplacement within the two main corridors. At regional and local scales, individual intrusions are preferentially located towards the west–northwest (ca. 280°) and north–northeast (ca. 015°) of other intrusions, and these orientations are interpreted to reflect upper mantle trends in magma generation. At local scales (10–25 km), kimberlite of the central and southern craton tends to be located to the northeast (ca. 045°), and possibly weakly to the east–northeast (ca. 070°), of other intrusions, and these orientations correspond to major crustal fractures systems. It is proposed that kimberlite emplacement is controlled primarily by the interaction of elongate 280° and 015° source regions with near-surface deviations influenced by crustal fracture systems.

The 015° trend evident at craton, regional, and local scales is parallel to a swarm of alkaline diabase dykes that are concentrated in a ca. 30-km-wide corridor passing through Lac de Gras. A profound spatial association between significantly diamondiferous kimberlite and the margins of the dyke corridor suggests the corridor is the surface expression of a mantle-depth structure. It remains unclear whether the proposed mantle structure coincides with a diamond-rich zone near the base of the lithosphere, or delineates pathways favorable for diamond preservation during emplacement. The linear array of kimberlite within the western craton forms a parallel corridor that may be an analogous mantle structure, but which to date has failed to yield economic diamond concentrations.     

Rhyolitic volcanic corridors in magmatic arcs: comparing North Wales and North Island, New Zealand

Exceptionally voluminous arc-related rhyolitic eruptions from clusters of caldera complexes, as seen in Snowdonia, North Wales (mid-Caradoc), and North Island, New Zealand (late Neogene-Quaternary), are characteristically confined within transient, fault-controlled corridors in continental crust. New Zealand rhyolitic corridors (Coromandel, Central, Taupo) have developed in response to the spearheading of an oceanic arc into continental crust, combined with subduction rollback-induced extension during clockwise rotation pivoting around central North Island. Inherited high heat flow from earlier arc magmatism, intracrustal plastic deformation, and mantle-derived magma ponding and fractionation beneath a less dense, fracture-toughened crust, all contribute synergistically to crustal fusion and catastrophic volcanism. A similar scenario is suggested for the Snowdonia volcanic corridor where at least six major rhyolitic centres were restricted in space and time (Soudleyan-Woolstonian). After the climactic Snowdonian eruptions, arc magmatism was extinguished in Wales: a fate predicted for New Zealand rhyolitic volcanism as subduction rollback continues.