A Vulnerability Interpretation of the Geography of HIV/AIDS in Ghana, 1986–1995

Ten years after the human immuno-deficiency virus (HIV) was first reported in Ghana, it continues to spread throughout the country following patterns that are rare in other African countries. HIV is seen in twice as many females as males, more frequently in rural than urban regions, and regions with high rates of polygamy have significantly lower rates. The evidence presented in this paper shows that HIV diffusion patterns probably reflect the spatial distribution and social networks of vulnerable social groups. While information-based campaigns are still necessary in the fight against HIV/AIDS, they fail to enable or empower vulnerable people to protect themselves against infection.     

Reconfiguring South Africa’s hotel industry 1990–2010: Structure,segmentation, and spatial transformation

One of the central challenges of a maturing tourism destination is to ensure continuous innovation and improvement of tourism products to meet the demands of an increasingly competitive global tourism economy The purpose of this study is to analyse a critical aspect of the improvement of tourism product competitiveness in South Africa, the changing tourism accommodation sector and specifically of the hotel industry. During the study period 1990–2010 it is shown that the hotel industry was restructured in terms of enhanced quality standards, the introduction of new hotel products and driven by the imperatives of market segmentation. Geographically, the hotel sector became more concentrated upon four key urban tourism nodes and in certain cities the over-production of hotel accommodation is an emerging problem.     

Image Segmentation for Hydrothermal Alteration Mapping Using PCA and Concentration–Area Fractal Model

Information extraction from processed remotely sensed images, in the case of missing initial spectra of pixels, can be a challenge for the users. In such situations, application of conventional methods based on spectral properties of pixels is impractical. We took advantage of the fractal theory for image segmentation of a principal component (PC) image for hydrothermal alteration mapping. The selected input images included short wave infrared bands of ASTER imagery covering the Darrehzar porphyry copper mine and surrounding areas with well-known hydrothermal alteration zones. Hydrothermal alteration like other geological processes can show spatial distribution with fractal properties. Principal component analysis was used to enhance hydrothermal alteration associated with the Darrehzar porphyry copper deposit. None of the resulting PCs were appropriate to portray clearly important alteration types in the study area. The PC1 image, which contains more than 98% of variance of the input bands, was selected for image segmentation using a digital number–area technique based on the established concentration–area fractal model. This technique was proposed based on frequency distributions and spatial correlation and variability of pixel values. The resulting hydrothermal alteration map indicates intense phyllic, weak phyllic, and propylitic as the main alteration types exposed at the surface of the Darrehzar area. In addition, the proposed technique delineated the phyllic zone in the exposed mine pit and a transition zone between inner phyllic and surrounding propylitic alteration zones. Field investigation and sampling in 23 locations including spectral measurements, XRD and thin section studies, confirmed the accuracy of the classified image by the proposed technique.     

Technology Integration in K–12 Geography Education Using TPACK as a Conceptual Model

There is a need for quality professional development programs and instructional models addressing the needs and challenges of K–12 technology integration in the geography classroom. This study used a mixed-methods design employing surveys and observations to evaluate teacher experiences within a professional development program focused on developing in-service geography teachers’ technological, pedagogical, and content knowledge (TPACK) through content-specific learning tools and resources. Results indicate that instructional scaffolding plays an important role in improving teachers’ ability to integrate technology in pedagogically meaningful ways geared toward enhancing students’ geographic inquiry skills.     

Monitoring grasshopper and locust habitats in Sahelian Africa using GIS and remote sensing technology†

Abstract

Development programmes in Sahelian Africa are beginning to use geographic information system (GIS) technology. One of the GIS and remote sensing programmes introduced to the region in the late 1980s was the use of seasonal vegetation maps made from satellite data to support grasshopper and locust control. Following serious outbreaks of these pests in 1987, the programme addressed a critical need, by national and international crop protection organizations, to monitor site-specific dynamic vegetation conditions associated with grasshopper and locust breeding. The primary products used in assessing vegetation conditions were vegetation index (greenness) image maps derived from National Oceanic and Atmospheric Administration satellite imagery. Vegetation index data were integrated in a GIS with digital cartographic data of individual Sahelian countries. These near-real-time image maps were used regularly in 10 countries for locating potential grasshopper and locust habitats. The programme to monitor vegetation conditions is currently being institutionalized in the Sahel.     

Measurements of dust deposition in Gansu Province,China, 1986–2000

Dust samples, collected monthly for 15 years from 50 urban sites in 10 cities in Gansu Province, China, provide information on modern rates of dust deposition in the desert and Gobi areas and in the Loess Plateau. Dust deposition is highest during spring months and lowest during autumn months, in both the desert and Gobi areas and the Loess Plateau. There is a significant positive correlation between dust deposition and dust event, and an inverse correlation between dust deposition and precipitation. The 15-year mean maximums in the desert and Gobi areas and the Loess Plateau are 498.64 and 327.02 t km⁻² year⁻¹, respectively, and the mean minimums are 290.22 and 180.86 t km⁻² year⁻¹, respectively. Drought may have a widespread, major influence on the modern rates of the dust deposition.     

Using multiple archives to understand past and present climate–human–environment interactions: the lake Erhai catchment,Yunnan Province,China

A 6.48 m sediment core sequence from Erhai lake, Yunnan Province, provides a multi-proxy record of Holocene environmental evolution and human activity in southwest China. These sedimentary records provide proxy time series for catchment vegetation, flooding, soil erosion, sediment sources and metal workings. They are complemented by independent regional climate time-series from speleothems, archaeological records of human habitation, and a detailed documented environmental history. The article attempts to integrate these data sources to provide a Holocene scale record of environmental change and human–environment interactions. These interactions are analysed in order to identify the roles of climate and social drivers on environmental change, and the lessons that may be learned about the future sustainability of the landscape. The main conclusions are: lake sediment evidence for human impacts from at least 7,500 cal year BP is supported by a terrestrial record of cultural horizons that may extend back to ∼9,000 cal year BP. A major shift in the pollen assemblage, defined by detrended correspondence analysis, at ∼4,800 cal year BP marks the transition from a ‘nature-dominated’ to a ‘human-dominated’ landscape. From 4,300 cal year BP, a change in river discharge responses may signal the beginning of hydraulic modification through drainage and irrigation. Major increases in disturbed land taxa and loss of forest taxa from 2,200 cal year BP onward, also associated with the start of significant topsoil erosion, register the expansion of agriculture by Han peoples. It is also the start of silver smelting linked to trade along the SW Silk Road with Dali becoming a regional centre. Peak levels of disturbed land taxa, topsoil and gully erosion are associated with the rise and fall of the Nanzhao (CE 738–902) and Dali (CE 937–1253) Kingdoms, and the documented environmental crisis that occurred in the late Ming and Qing dynasties (CE 1644–1911). The crisis coincides with a stronger summer monsoon, but exploitation of marginal agricultural land is the main driver. These historical perspectives provide insight into the resilience and sustainability of the modern agricultural system. The largest threat comes from high magnitude-low frequency flooding of lower dry farmed terraces and irrigated valley plains. A sustainable future depends on reducing the use of high altitude and steep slopes for grazing and cultivation, maintaining engineered flood defences and terraces, and anticipating the behaviour of the summer monsoon. This article is based on a keynote address delivered by John Dearing at the 10th International Paleolimnology Symposium, June 2006, Duluth, Minnesota, USA.     

Population distribution patterns and changes in China 1953–2010

Journal of Geographical Sciences - This study uses six censuses (1953, 1964, 1982, 1990, 2000, and 2010) at the county level since the foundation of the People’s Republic of China to examine...     

Authigenic clays in East Africa: Regional trends and paleolimnology at the Plio–Pleistocene boundary, Olduvai Gorge, Tanzania

Ultrafine clays (<0.1 m) from six East African basins show wide chemical variability that can be conveniently described as the octahedral cation index (OCI), calculated as octahedral element ratio Mg/(Al+Fe). Values range from dioctahedral clays with OCI < 0.1 (upland soils/detrital sources) to trioctahedral clays with OCI > 4 (saline, alkaline lake deposits). The association of Mg-rich clays with saline, alkaline conditions provides a paleochemical proxy in sedimentary contexts. The octahedral chemistry of central-basin clays from paleolake Olduvai (1.79 Ma) records two lake expansions, with an intervening lake contraction, over 18,000 years. The initial lake expansion correlates well with the marine record of increased African humidity, but the subsequent drying episode does not, suggesting that some high-frequency environmental oscillations in East Africa may occur independent of obliquity and precession control. The clay record correlates well with the fossiliferous and archaeologically rich stratigraphy of the lake margin, and suggests that fossils and artifacts accumulated on the exposed lake margin over <4000 years. The chemistry of clays is a potentially powerful tool to add to multi-proxy studies in basins with alkaline waters, particularly in stratigraphic intervals that lack pollen, calcareous, or siliceous microfossils.     

Drivers of Change and Sustainability in Linked Social–Ecological Systems: An Analysis in the Volta River Basin of Ghana,West Africa

Understanding the nature and relative importance of various drivers of change is crucial for sustainable management of natural resources and in prioritizing management efforts, allocating limited resources, and understanding cumulative effects. For this article, we employed structured an expert judgments approach to identify, characterize, and assess the relative importance of the key biophysical and socioeconomic drivers of change within the Volta River Basin, West Africa. Precipitation variability, water availability, land use change, drought events, and population growth were perceived as most important, while biodiversity loss, social conflicts, pest and disease occurrence, urbanization, and pollution were viewed as less critical. A majority of these drivers were characterized as “slow” acting processes as compared to rapidly changing drivers. Intra- and interexpert groups agreement were found to be significant and convergent, indicating the reliability of the results. The implications of these results for sustainable water resources management and agricultural production are discussed.     

Spatial distribution of maize in response to climate change in northeast China during 1980–2010

Based on county-level crop statistics and other ancillary information, spatial distribution of maize in the major maize-growing areas (latitudes 39°–48°N) was modelled for the period 1980–2010 by using a cross-entropy-based spatial allocation model. Maize extended as far north as the northern part of the Lesser Khingan Mountains during the period, and the area sown to maize increased by about 5 million ha. More than half of the increase occurred before 2000, and more than 80% of it in the climate transitional zone, where the annual accumulated temperature (AAT) was 2800–3400 °C·d. Regions with AAT of 3800–4000 °C·d became more important, accounting for more than 25% of the increase after 2000. The expansion of maize was thus closely related to warming, although some variation in the distribution was noticed across zones in relation to the warming, indicating that maize in northeast China may have adapted successfully to the warming by adjusting its spatial distribution to match the changed climate.     

Disparities in accessibility of public high schools,in metropolitan Baton Rouge,Louisiana 1990–2010

In this study, we use a Geographic Information System-based index to measure spatial accessibility of public high schools. The index is applied to the Baton Rouge Metropolitan Statistical Area in 1990, 2000, and 2010. Overall, urban areas had consistently worse accessibility scores compared with suburban and rural areas. High schools with more African American students tended to have poorer accessibility levels. Schools with lower accessibility tended to be associated with poorer average student performance, and the effect strengthened between 2000 and 2010. In developing a better understanding of the accessibility of public high schools, this paper reaffirms the significance of space, place, and race, and challenges the notion of declining relevance of accessibility in Louisiana public education policymaking.     

Analysis of water consumption using a regional input–output model: Model development and application to Zhangye City,Northwestern China

Based on a regional input–output model, we developed a method to identify the relationships between production activities and the related water consumption, as well as the relationships established between different sectors concerning water resources (i.e. indirect consumption). This method is applied to Zhangye City, an arid area of northwestern China that is characterized by water shortages. Our results confirm that although Zhangye suffers from a serious water shortage, the city's economic structure is based on sectors that consume large quantities of water. On the one hand, food production and forestry consume large quantities of water, reflecting the large scale of these water-intensive forms of land use. On the other hand, the industrial and service sectors use a smaller amount of water directly in production, but to produce the intermediate inputs that they incorporate into their production processes, a high consumption of water is often necessary. At present, there is no evidence that the city alleviates its water scarcity by importing virtual water in the form of economic inputs produced in other regions, suggesting that planners should include both direct and indirect water consumption in their resource allocation planning.     

Beyond the Edge and in Between: (Re)conceptualizing the Rural–Urban Interface as Meaning–Model–Metaphor

As examinations of the rural–urban interface move beyond a focus on the rural or urban fringe as a location and move toward examining the patterns and processes that both divide and link rural and urban places, a broader (re)conceptualization of the rural–urban interface becomes increasingly important. Thus far the question of boundaries and interfaces between so-called urban and rural locales has mostly revolved around where and when such boundaries occur (including significant coverage of the differences and conflicts between urban vs. rural people), rather than asking what physical or social functions are being served by the rural–urban interface itself. In response, I (re)frame the rural–urban interface not only as a boundary between two distinct spaces but also as a conduit, a place of exchange, and a flux point between them. Using a particular case of contested ecologies in the exurban Sierra Nevada foothills of California, I (re)conceptualize the rural–urban interface as meaning, model, and metaphor (MMM), situating contrasting people and places in an ongoing negotiation of place and environmental meaning along the (ex)urbanizing edge. Although the differences between rural and urban are increasingly unclear, the division continues to be compelling from environmental and sociopolitical standpoints. I argue that (perceived) boundaries are instrumental in understanding physical–material change and for mitigating social conflicts occurring across them. As such, attention to the patterns, processes, and flows that connect or separate rural and urban areas is critical to forging effective and long-lasting solutions to contemporary social, economic, and environmental problems.     

Quantitative Limits to Qualitative Engagements: GIS,Its Critics,and the Philosophical Divide∗

Heated exchanges between critical theorists and GIScientists over geographic information systems (GIS) in 1990s geography gave rise to calls for increased communication between critics and practitioners of the technology and most recently for “hybrid” qualitative–quantitative GIS practices. Although GIS scholars have successfully addressed mid-1990s critiques of the technology by developing a series of critical GIS practices that involve nuanced and reflexive deployments of GIS and assessments of its visual products, theoretical critiques of GIS remain fixated on the epistemological deficiencies of the technology. Despite references to loosening metaphysical tensions across the discipline, this difference in assessments reveals the discourses of critical-theoretic geography and GIScience to remain separated by a trenchant philosophical divide, across which ontological and epistemological commitments are inviolable. The inability to fully reconcile a critical–theoretic epistemology with the explicitly ontological metaphysics of GIS further complicates qualitative engagements with the technology by addressing a series of inconsistencies into GIS praxis arising from the quantitative limits to representation encountered in the formal universe of computing. The persistence of metaphysical tensions in critical engagements with the technology questions the degree to which qualitative methods can be seamlessly hybridized with the quantitative architectures of GIS.     

Spatiotemporal patterns and characteristics of land-use change in China during 2010–2015

Land use/cover change is an important theme on the impacts of human activities on the earth systems and global environmental change. National land-use changes of China during 2010–2015 were acquired by the digital interpretation method using the high-resolution remotely sensed images, e.g. the Landsat 8 OLI, GF-2 remote sensing images. The spatiotemporal characteristics of land-use changes across China during 2010–2015 were revealed by the indexes of dynamic degree model, annual land-use changes ratio etc. The results indicated that the built-up land increased by 24.6×10³ km² while the cropland decreased by 4.9×10³ km², and the total area of woodland and grassland decreased by 16.4×10³ km². The spatial pattern of land-use changes in China during 2010–2015 was concordant with that of the period 2000–2010. Specially, new characteristics of land-use changes emerged in different regions of China in 2010–2015. The built-up land in eastern China expanded continually, and the total area of cropland decreased, both at decreasing rates. The rates of built-up land expansion and cropland shrinkage were accelerated in central China. The rates of built-up land expansion and cropland growth increased in western China, while the decreasing rate of woodland and grassland accelerated. In northeastern China, built-up land expansion slowed continually, and cropland area increased slightly accompanied by the conversions between paddy land and dry land. Besides, woodland and grassland area decreased in northeastern China. The characteristics of land-use changes in eastern China were essentially consistent with the spatial govern and control requirements of the optimal development zones and key development zones according to the Major Function-oriented Zones Planning implemented during the 12th Five-Year Plan (2011–2015). It was a serious challenge for the central government of China to effectively protect the reasonable layout of land use types dominated with the key ecological function zones and agricultural production zones in central and western China. Furthermore, the local governments should take effective measures to strengthen the management of territorial development in future.     

Looking beyond the neighbourhood: income inequality and residential segregation in Swedish metropolitan areas, 1991–2010

In recent years, residential segregation has become a major issue in the Swedish policy debate. The prevailing view is that residential segregation is a crucial contributing factor to the development of income inequality, since individual income prospects are thought to be influenced by the population characteristics of their neighbourhoods. This study takes the opposite approach and analyses the extent to which, in the period 1991–2010, rising income inequality contributed to the development of residential segregation by income in Swedish metropolitan areas. The period was characterized by unprecedented growth in income inequality, which was associated with a decline in the redistributive power of the welfare state. Residential segregation by income mirrored locally the general trend in income inequality. Another factor was the change in income dispersion in neighbourhoods, relative to the metropolitan areas as a whole, which indicates a tendency towards increased population homogeneity in neighbourhoods with respect to income.     

Spatial and Longitudinal Patterns in County Age-Specific Net Migration in the United States 1950–2010

Many migration studies describe various counties by adopting a priori county typologies, such as the U.S. Department of Agriculture Economic Research Service county typology, which might not be suitable for identifying different age migration patterns of the U.S. counties. This study employs a spatial clustering method that exhaustively compares all U.S. counties on their age migration similarity and spatial proximity to investigate signature age-specific net migration profiles across six decades of U.S. county age-specific net migration data from 1950 to 2010. All of the six-decade data are integrated into a common spatial county boundary on which counties below a population threshold are merged with the nearest county to mitigate the small population problem in net migration rates. As counties are merged by increasing large population thresholds, the Getis-Ord Gi* spatial autocorrelation statistic is applied to examine how the spatial migration patterns are affected. It is found that U.S. county age-specific net migration profiles exhibit four signature patterns. Although these patterns are persistent across the past six decades, their spatial distributions have experienced dramatic variation. The small population problem in net migration rates affects the extent and location of the significant spatial migration patterns.