A coupled tide-wave model for the NW European shelf seas     

M. Reza Hashemi  Simon P. Neill  Alan G. Davies 《地球物理与天体物理流体动力学》2015,109(3):234-253

Understanding the interaction of tides and waves is essential in many studies, including marine renewable energy, sediment transport, long-term seabed morphodynamics, storm surges and the impacts of climate change. In the present research, a COAWST model of the NW European shelf seas has been developed and applied to a number of physical processes. Although many aspects of wave–current interaction can be investigated by this model, our focus is on the interaction of barotropic tides and waves at shelf scale. While the COWAST model was about five times more computationally expensive than running decoupled ROMS (ocean model) and SWAN (wave model), it provided an integrated modelling system which could incorporate many wave–tide interaction processes, and produce the tide and wave parameters in a unified file system with a convenient post-processing capacity. Some applications of the model such as the effect of tides on quantifying the wave energy resource, which exceeded 10% in parts of the region, and the effect of waves on the calculation of the bottom stress, which was dominant in parts of the North Sea and Scotland, during an energetic wave period are presented, and some challenges are discussed. It was also shown that the model performance in the prediction of the wave parameters can improve by 25% in some places where the wave-tide interaction is significant.  相似文献   

Depth limit of littoral vegetation in a storage reservoir: A case study of Lipno Reservoir (Czech Republic)     

Monika Krolová  Hana ?í?kováJosef Hejzlar 《Limnologica》2012,42(2):165-174

Controlling factors for the occurrence of littoral macrophyte species were investigated in Lipno Reservoir (area: 46.5 km²; z_mean: 6.6 m; z_max: 22 m; water residence time: 0.6 yr), a dam impoundment with moderately fluctuating water level (amplitude up to 4 m) which is used for hydropower and downstream flow augmentation. The options of supporting littoral macrophyte growth for improving the reservoir's ecological potential were evaluated according to the European Water Framework Directive's definitions. Macrophytes were examined at 115 sites, each 50 m long, along the whole reservoir perimeter at regular 1 km intervals. Sites were surveyed for their phytocoenology, shore morphometry, pedological characteristics of substrate, transparency of water, and anthropogenic impacts. Most of the sites were characterised by a wide eulittoral zone with a tenuous cover of terrestrial hydrophilic, amphibious, and/or emergent macrophytes and a low proportion of silt, clay, and organic fractions in the substrate. Infralittoral submerged and floating-leaved macrophytes were restricted to a few sites within the mouths of the main and side tributaries where transparency was maintained by clear inflow water independent of reservoir pool fluctuations. Water transparency was low (1-2 m) compared to annual changes of water level (2 to >3 m). Multivariate statistical analysis (DCA, CCA) confirmed relationships between the occurrence of macrophyte species and morphological and substrate characteristics of the shore. Improvement of macrophyte cover and establishment of vital infralittoral zones requires improvements in water transparency and changes in reservoir operation, i.e., limiting the range of water level fluctuation to less than ca. 1 m.  相似文献   

Modelling the tidal mixing fronts and seasonal stratification of the Northwest European Continental shelf     

Jason Holt  Lars Umlauf 《Continental Shelf Research》2008

We investigate mixing processes under stratified conditions on the Northwest European Continental shelf using a numerical model (POLCOMS). Our results indicate that convection induced by vertical shearing of horizontal density gradients (‘shear-induced convection’) is a regularly occurring feature in the bottom and surface boundary layers in this open shelf-sea situation. Two types of turbulence models are investigated to study their capability for reproducing the observed location of tidal mixing fronts, and the physical processes occurring in seasonally stratified waters. The first model is a one-equation variant of the Mellor–Yamada model, whereas the second model combines a more recent second-momentum closure with a two-equation model. It is found that generally mean frontal positions (as estimated from ICES data) are predicted more accurately by the two-equation model. The one-equation model reproduces the mean frontal locations to 18.1 km (<3 grid spacings) and the two-equation model to 17.1 km; although in the Celtic Sea the accuracy is ∼33 and ∼12 km, respectively. Comparison with historical tide gauges, current metres, CTD stations, and thermistor chain data from the North Sea Project all show an improvement in accuracy when the two-equation model is used. This is particularly apparent in the model's ability to reproduce the spring–neap variability during stratification. We find that in the presence of shear-induced convection the routinely applied clipping of the turbulent length-scale, previously thought to be a minor ingredient in a turbulence model, has a dramatic effect on the results: if the length-scale clipping is not applied, substantial over-mixing is observed to occur. The causes and possible remedies of this effect are investigated. Overall our results demonstrate a sensitivity to the details of the turbulence model that is significantly greater than previously thought.  相似文献   

Basin‐scale predictive models of alluvial architecture: Constraints from the Palaeocene–Eocene,Bighorn Basin,Wyoming, USA     

Amanda Owen  Adrian J. Hartley  Alena Ebinghaus  Gary S. Weissmann  Maurício G. M. Santos 《Sedimentology》2019,66(2):736-763

Basin‐scale models are required to interpret ancient continental sedimentary successions, and reduce uncertainty in assessing geological resources in basins. Recently, modern studies show distributive fluvial systems to comprise a substantial proportion of modern sedimentary basins, but their role in ancient basin fills has yet to be quantitatively documented at the basin scale. This study analysed key fluvial characteristics to construct a detailed basin‐wide model of the Palaeogene Fort Union and Willwood formations (Bighorn Basin, Wyoming), using observations from modern studies, and ancient system scale studies of distributive fluvial systems, to guide interpretations. Mapping showed these formations to be highly heterogeneous with channel‐body proportion (from 12 to 81%) and geometry types (large amalgamated bodies to isolated channels), grain size (silt to conglomerate), average channel‐body thickness (4 to 20 m) and average storey thickness (3 to 10 m) varying significantly across the basin. Distributive fluvial systems in the form of alluvial and fluvial fans in transverse configurations were recognized as well as a wide axial system, with heterogeneity in the formations being closely aligned to these interpretations. Furthermore, numerous individual depositional systems were identified within the formations (Beartooth Absaroka, Washakie, Owl Creek and axial). Predicted downstream distributive fluvial system trends (i.e. downstream decrease in channel proportion, size and grain size) were identified in the Beartooth, Absaroka and Owl Creek systems. However, predicted trends were not identified in the Washakie system where intrabasinal thrusting disturbed the sequence. Importantly, a wide axial fluvial system was identified, where reverse downstream distributive fluvial system trends were present, interpreted to be the result of the input of transverse systems of variable size. This study provides a new level of detail in the application of basin‐scale models, demonstrating their usefulness in trying to understand and predict alluvial architecture distribution and heterogeneity, with important implications for economic resources and palaeogeographic reconstructions.  相似文献   

A zone-specific fish-based biotic index as a management tool for the Zeeschelde estuary (Belgium)     

Jan Breine  Paul Quataert  Frans Ollevier  Ericia Van den Bergh 《Marine pollution bulletin》2010,60(7):1099-233

Fish-based indices monitor changes in surface waters and are a valuable aid in communication by summarising complex information about the environment (Harrison and Whitfield, 2004). A zone-specific fish-based multimetric estuarine index of biotic integrity (Z-EBI) was developed based on a 13 year time series of fish surveys from the Zeeschelde estuary (Belgium). Sites were pre-classified using indicators of anthropogenic impact. Metrics showing a monotone response with pressure classes were selected for further analysis. Thresholds for the good ecological potential (GEP) were defined from references. A modified trisection was applied for the other thresholds. The Z-EBI is defined by the average of the metric scores calculated over a one year period and translated into an ecological quality ratio (EQR). The indices integrate structural and functional qualities of the estuarine fish communities. The Z-EBI performances were successfully validated for habitat degradation in the various habitat zones.  相似文献   

NEITHER BIBLICAL PLAGUE NOR PRISTINE MYTH: A LESSON FROM CENTRAL EUROPEAN SPARROWS*     

BERND HERRMANN  WILLIAM I. WOODS 《Geographical review》2010,100(2):176-186

The historical superabundance of passenger pigeons in North America and of house sparrows in Central Europe is anthropogenic; that is, the result of human actions, in these cases with unintended consequences. In this article we concentrate on the superabundance of sparrows in the eighteenth and nineteenth centuries and outline the reasons for it. Both the passenger pigeon and the sparrow examples serve as ideal types for misplaced understanding of historical numbers of individuals as indicators of assumed pristine natural situations. Both examples reflect severe human impacts on the metapopulations of the bird species. Historical data on abundance can be misleading when they are used as guides in current conservation efforts. Selections of “right” numbers are arbitrary, because no points of reference exist in natural systems.  相似文献   

Opening up the secret city of Stepnogorsk: biological weapons in the Former Soviet Union     

Caitríona McLeish 《Area》2010,42(1):60-69

For almost 30 years, the Soviet government hid a large part of its biological weapons programme behind the façade of a network of civilian bio-technology facilities, called the All-Union Production Association Biopreparat, which were established to overcome deficiencies in molecular biology and genetics research. This paper, which is developed from a presentation given during an ESRC-sponsored seminar series, 'Locating Technoscience: The Geographies of Science, Technology and Politics', details the secret geography of one of those Biopreparat facilities located in Stepnogorsk, Kazakhstan. In doing this the paper illustrates how secret geographies can operate simultaneously, and at multiple scales. In the case of the Soviet bio-weapons programme, enacting secrecy at these multiple scales was made possible by the purposeful exploitation of 'dual use' technologies. By recounting a trip made to the Kazak facility, and using personal communications with UK and US experts involved with uncovering the Soviet bio-warfare programme, the author addresses some of the methodological challenges involved with researching secret geographies. This case study therefore looks in several directions – to work on the geographies of scale, research on the geographies of knowledge and work on secrecy in science and technology studies.  相似文献   

INFLUENCE OF CLIMATE AND CLIMATE ANOMALIES ON NORWAY SPRUCE TREE-RING GROWTH AT DIFFERENT ALTITUDES AND ON GLACIER RESPONSES: EXAMPLES FROM THE CENTRAL ITALIAN ALPS     

GIOVANNI LEONELLI  MANUELA PELFINI 《Geografiska Annaler: Series A, Physical Geography》2008,90(1):75-86

Climate change and climate anomalies are inducing strong variations in the high‐mountain environment, driving the responses of physical and biological systems differently. This paper assesses tree‐ring growth responses to climate for two Norway spruce (Picea abies (L.) Karst.) sites at different altitudes from an Ortles‐Cevedale Group (OCG; internal zones of the Central Italian Alps) valley site and reports some examples of climate impact on glacier dynamics in the OCG in recent decades. Growth–climate relationships between tree‐ring chronologies and meteorological data were established by means of Pearson's correlation and response functions. In the high‐altitude chronology we found a strong signal of July temperatures, whereas the low‐altitude chronology also contained a signal of summer precipitation. Climate anomalies occurring in these months proved to influence tree growth at the two sites differently. In summer 2003 extreme climatic conditions established over Europe and the Alps, strongly affecting physical and biological systems. Spruce responses to the climate anomaly of 2003 were more evident with a one‐year lag. The high‐altitude site profited from the warmer growing season, whereas trees at the low‐altitude site experienced water stress conditions and their growth was strongly inhibited also in the following year. Glacier mass loss in the OCG in 2003 was the highest since yearly measurement started. The examples reported confirm the strong and even divergent variations affecting the Alpine environment, induced by recent climate change.  相似文献   

BOOK REVIEWS     

《The Professional geographer》1984,36(4):498-530

Book reviewed is the article: Small-State Security in the Balkans . Aurel Braun. South American Development: A Geographical Introduction . Rosemary D. F. Bromley and Ray Bromley. Interregional Migration, National Policy and Social Justice . Gordon L. Clark. Marketing Architectural and Engineering Services . Weld Coxe. A Geography of the Third World . J. P. Dickenson, C. G. Clarke, W. T. S. Gould, R. M. Prothero, D. J. Siddle, C. T. Smith, E. M. Thomas-Hope, and A. G. Hodgkiss. Wildlife and Man in Texas: Environmental Change and Conservation . Robin W. Doughty. At the Sea's Edge . William T. Fox. Englewood Cliffs Geography and Ecology . I. P. Gerasimov. Urbanization in Contemporary Latin America. Critical Approaches to the Analysis of Urban Issues . Alan Gilbert in association with Jorge E. Hardoy and Ronaldo Ramírez, eds. The Coming of the Transactional City . Jean Gottmann. College Park Visions of City and Country: Prints and Photographs of Nineteenth-Century France . Bonnie L. Grad and Timothy A. Riggs. Worcester Soviet Geography Today: Physical Geography . N. A. Gvozdetskiy, ed. Adaptive Responses of Native Amazonians . Raymond B. Hames and William T. Vickers, eds. Urban and Regional Industrial Research: The Changing UK Data Base . Michael Healey, ed. Cuando se Acaban los Montes . Stanley Heckadon Moreno. A Panama Forest and Shore: Natural History and Amerindian Culture in Bocas del Toro . Burton L. Gordon. Pacific Grove Mozambique: From Colonialism to Revolution, 1900–1982 . Allen Isaacman and Barbara Isaacman. Soviet Natural Resources in the World Economy . Robert G. Jensen, Theodore Shabad, and Arthur W. Wright, eds. The Changing Geography of the United Kingdom . R. J. Johnston and J. C. Doornkamp, eds. Pluralism and Political Geography—People, Territory and State . Nurit Kliot and Stanley Waterman, eds. Landmarks Preservation and the Property Tax . David Listokin. Irrigation Horticulture in Highland Guatemala: The Tablón System of Panajachel . Kent Mathewson. Her Space, Her Place: A Geography of Women . Mary Ellen Mazey and David R. Lee. Man, A Geomorphological Agent . Dov Nir. Dordrecht The Book of America: Inside the 50 States Today . Neal R. Peirce and Jerry Hagstrom. Rivers . Geoffrey E. Petts. Proceedings, United States/Australia Workshop on Design and Implementation of Computer-Based Geographic Information Systems . Donna Peuquet and John O'Callaghan, eds. Outdoor Recreational and Resource Management . John Pigram. Remaking the City: Social Science Perspectives on Urban Design . John S. Pipkin, Mark La Gory and Judith R. Blau, eds. The Crust of Our Earth: An Armchair Traveler's Guide to the New Geology . Chet Raymo. Englewood Cliffs Concepts and Themes in the Regional Geography of Canada J. Lewis Robinson. Vancouver Secondary Cities in Developing Countries: Policies for Diffusing Urbanization . Dennis A. Rondinelli. Beverly Hills Legal Foundations of Environmental Planning , Vol 1. J. G. Rose. Can We Delay a Greenhouse Warming? Stephen Seidel and Dale Keyes. Mobilizing Human Resources in the Arab World . R. Paul Shaw. Prairie Mosaic: An Ethnic Atlas of Rural North Dakota . William C. Sherman. The Future of Conflict in the 1980s . William J. Taylor, Jr. and Steven A. Maaranen, eds. The Visual Display of Quantitative Information . Edward R. Tufte. U.S. 40 Today: Thirty Years of landscape Change in America . Thomas R. Vale and Geraldine R. Vale. Madison Silent Violence: Food, Famine and Peasantry in Northern Nigeria . Michael Watts. Readings in Historic Preservation: Why? What? How? Norman Williams Jr., Edmund Kellogg and Frank Gilbert, eds.  相似文献   

    

Denisa Kostovicova 《GeoJournal》2004,61(1):23-30

This article explores the spatiality of post-Miloevi Serbian identity in the context of European integration. The fall of the Miloevi regime has prompted Serbias political rehabilitation in Europe, paralleled by its pursuit of European integration. The article posits that European integration of post-socialist newcomers is a two-sided spatial process. It includes a rediscovery and reassertion of the European identity as a form of symbolic spatial repositioning in Europe and a transformation of state territoriality as European integration relaxes the states absolute control over territory. The article shows that a symbolic Europeanisation of Serbian identity, underpinned by contested meanings of Europe, has not led to substantial transformation of state territoriality. Furthermore, European integration has been used as a justification for the pursuit of deeply territorial national politics, hindering the transition from modern to post-modern state territoriality.  相似文献