Geospatial analysis of a coastal sand dune field evolution: Jockey's Ridge, North Carolina     

Helena Mitasova  Margery Overton  Russell S. Harmon 《Geomorphology》2005,72(1-4):204-221

Preservation and effective management of highly dynamic coastal features located in areas under development pressures requires in-depth understanding of their evolution. Modern geospatial technologies such as lidar, real time kinematic GPS, and three-dimensional GIS provide tools for efficient acquisition of high resolution data, geospatial analysis, feature extraction, and quantification of change. These techniques were applied to the Jockey's Ridge, North Carolina, the largest active dune field on the east coast of the United States, with the goal to quantify its deflation and rapid horizontal migration. Digitized contours, photogrammetric, lidar and GPS point data were used to compute a multitemporal elevation model of the dune field capturing its evolution for the period of 1974– 2004. In addition, peak elevation data were available for 1915 and 1953. Analysis revealed possible rapid growth of the dune complex between 1915–1953, followed by a slower rate of deflation that continues today. The main dune peak grew from 20.1 m in 1915 to 41.8 m in 1953 and has since eroded to 21.9 m in 2004. Two of the smaller peaks within the dune complex have recently gained elevation, approaching the current height of the main dune. Steady annual rate of main peak elevation loss since 1953 suggests that increase in the number of visitors after the park was established in 1974 had little effect on the rate of dune deflation. Horizontal dune migration of 3–6 m/yr in southerly direction has carried the sand out of the park boundaries and threatened several houses. As a result, the south dune section was removed and the sand was placed at the northern end of the park to serve as a potential source. Sand fencing has been an effective management strategy for both slowing the dune migration and forcing growth in dune elevation. Understanding the causes of the current movements can point to potential solutions and suggest new perspectives on management of the dune as a tourist attraction and as a recreation site, while preserving its unique geomorphic character and dynamic behavior.  相似文献   

New Zealand Historical Atlas: Visualising New Zealand     

John Overton 《New Zealand geographer》1998,54(1):56-57

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Concentrations of trace metals in the bowhead whale     

C. Byrne  R. Balasubramanian  E. B. Overton 《Marine pollution bulletin》1985,16(12):497-498

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Reflection experiment on a floating ice platform     

Z. Hajnal  A. Overton 《Geophysical Journal International》1987,89(1):201-208

Summary. Preliminary analysis of a multifold seismic survey on a floating ice platform, northwest of Axel Heiberg Island, along the Canadian portion of the continental margin of the Arctic Ocean revealed a structurally complex basement at a depth beyond 4000 m. The basement is covered with high velocity (5000 m/sec) rock types. The results conform to the anticipated geologic model for regions of passive margins.  相似文献   

The consumption of space: Land, capital and place in the New Zealand wine industry   总被引：1，自引：0，他引：1  

John Overton 《Geoforum》2010,41(5):752-762

Geographers have developed a keen interest in the social production of space - in the way meanings and values are ascribed to places as a result of changing social, cultural and political processes. There is a need to explore this approach further, seeing how social and economic values of places are inter-related and how these values are constructed in often deliberate and concerted ways. There is also a need to explore how such values are consumed: how the values in place are traded, appropriated and redistributed, both through the products of places and in land markets. This paper examines the New Zealand wine industry where certain wine regions have been identified and developed in ways which attempt to emphasise their distinctiveness in terms of wine quality and thus enhance the value of the wine produced. Different strategies have been employed in this process of place construction and this reflects the differential role of capital, striving on the one hand to increase the price and marketability of the products of distinctive places but, on the other, careful not to over-inflate land values and thus restrict further expansion. The paper suggests that the issue of consumption of space, involving a complex relationship amongst land, capital and place, is worthy of further exploration.  相似文献   

Integration or Self-Sufficiency? Peninsular Malaysia and the Rice Trade in Southeast Asia     

John Overton 《Singapore journal of tropical geography》1999,20(2):169-180

The issue of food self-sufficiency has recently come under scrutiny as global trade liberalisation has been in conflict with national development strategies founded on protection and encouragement of staple food production. This paper examines the case of rice in Peninsular Malaysia from an historical perspective. It traces the evolution of self-sufficiency strategies from colonial times tothe present and notes how and why such policies have been questioned both in the past and in recent years. It then suggests that a more integrated Southeast Asian regional rice economy may evolve as support for national self-sufficiency wanes and, in this, there may be much to learn from the colonial era when such a regional rice trade thrived.  相似文献   

The changing role of ecohydrological science in guiding environmental flows     

M.C. Acreman  I.C. Overton  J. King  P.J. Wood  I.G. Cowx  M.J. Dunbar 《水文科学杂志》2014,59(3-4):433-450

Abstract

The term “environmental flows” is now widely used to reflect the hydrological regime required to sustain freshwater and estuarine ecosystems, and the human livelihoods and well-being that depend on them. The definition suggests a central role for ecohydrological science to help determine a required flow regime for a target ecosystem condition. Indeed, many countries have established laws and policies to implement environmental flows with the expectation that science can deliver the answers. This article provides an overview of recent developments and applications of environmental flows on six continents to explore the changing role of ecohydrological sciences, recognizing its limitations and the emerging needs of society, water resource managers and policy makers. Science has responded with new methods to link hydrology to ecosystem status, but these have also raised fundamental questions that go beyond ecohydrology, such as who decides on the target condition of the ecosystem? Some environmental flow methods are based on the natural flow paradigm, which assumes the desired regime is the natural “unmodified” condition. However, this may be unrealistic where flow regimes have been altered for many centuries and are likely to change with future climate change. Ecosystems are dynamic, so the adoption of environmental flows needs to have a similar dynamic basis. Furthermore, methodological developments have been made in two directions: first, broad-scale hydrological analysis of flow regimes (assuming ecological relevance of hydrograph components) and, second, analysis of ecological impacts of more than one stressor (e.g. flow, morphology, water quality). All methods retain a degree of uncertainty, which translates into risks, and raises questions regarding trust between scientists and the public. Communication between scientists, social scientists, practitioners, policy makers and the public is thus becoming as important as the quality of the science.