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Résultats de la recherche (1004 résultats)

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  • Bank and near-bank processes in an incised channel
  • Bank erosion ; Channel geometry ; Geotechnics ; Infiltration ; Mississippi ; Model ; Pic discharge ; Porosity ; Precipitation ; Seasonal variation ; Stream ; United States of America
  • Gravitational forces acting on in situ bank material act in concert with hydraulic forces at the bank toe to determine rates of bank erosion. The interaction of these forces control streambank mechanics. Data from a study site on Goodwin Creek, MS
  • , USA clearly show the temporal variability of seepage forces and the lag time inherent in reductions in shear strength due to losses of matric suction and generation of positive pore-water pressures. A stable bank can be transformed into an unstable
  • bank during periods of prolonged rainfall.
  • Secondary analysis, data banks and geography
  • Utilization of data bank on grid square basis for regional planning in Methods and mapping.
  • The influence of bank strength on channel geometry : an integrated analysis of some observations
  • Bank erosion ; Channel geometry ; Discharge ; Gravel ; Model ; Multivariate analysis ; Riparian vegetation ; River bed ; Sedimentology ; Stream ; Vegetation
  • of a number of laterally stable streams are categorized on the basis of the bank sediment and vegetation, the multivariate model yields numerical indices of bank strength. Within the range of the data analysed, bank strength can produce a three-fold change
  • Bank strength exerts a significant influence on river channel geometry. In order to undertake an integrated analysis of wide-ranging field observations, this study applies a recently developed multivariate model of channel geometry. When the banks
  • Indexing the census: a by-product of the simulation of whole populations by means os SAS and SAR data
  • Computing ; Data bank ; Data processing ; Population census ; Simulation ; Statistical data ; United Kingdom
  • Megyei kornyezeti informacios rendszer és tematikus térkép adathank Environmental information system of counties and thematic map data bank
  • The general characteristic of geographical information system is that they work with data-base for the given territory. Only their integrated evaluation can give an acceptable information. - (DLO)
  • Enhanced application of root-reinforcement algorithms for bank-stability modeling
  • Algorithm ; Bank erosion ; Erosion control ; Massachusetts ; Model ; Riparian vegetation ; Stream ; United States of America
  • This paper describes a method developed to use root-architecture data, obtained in previous studies, to create regressions showing changes in the number of roots crossing a shear plane within in a stream bank over time. In addition, variations
  • in root density with depth are studied so that root-reinforcement estimates obtained by RipRoot can be correctly applied to the layering within model runs of the bank stability and toe erosion model (BSTEM). It was found that stream-bank varied the most
  • Seepage erosion in layered stream bank material
  • Bank erosion ; Experimentation ; North Carolina ; Slope gradient ; Soil properties ; Stream ; Underground water ; United States of America
  • and measured saturation data indicated an interaction between overburden pressure, seepage forces, and bank slope on bank stability. Future bank stability modeling would benefit by incorporating lateral seepage erosion and soil liquefaction prediction
  • Subaerial river bank erosion processes and their interaction with other bank erosion mechanisms on the River Arrow, Warwickshire, UK
  • Bank erosion ; England ; Flood ; Fluvial erosion ; Fluvial processes ; Freeze-thaw cycle ; Global change ; Meteorology ; Spatial variation ; Stream ; United Kingdom ; Warwickshire
  • The aim of this paper is to demonstrate that subaerial processes may be underestimated as an erosive agent, and process dominance has a temporal, as well as spatial, aspect. Bank erosion on the River Arrow was monitored for 16 months (December 1996
  • to March 1998) using erosion pins. Variations in the rate and aerial extent of erosion are considered with reference to meteorological data. Throughout the first 15 months all erosion recorded was subaerial. While the role of subaerial process
  • Bank erosion and channel width change in a tropical catchment
  • Australia ; Bank erosion ; Channel geometry ; Cross section ; Meander ; Model ; Queensland ; Sediment budget ; Stream ; Tropical zone
  • on bank erosion, 2) bench-marked cross-sections were used to evaluate annual changes in channel width and 3) historical aerial photos were used to place the short term data into a longer temporal perspective of channel change (1972-2000). The cross-section
  • data were compared against modelled SedNet bank erosion rates, and it was found that the model underestimated bank erosion and was unable to represent the variable erosion and accretion processes that were observed in the field data. The reach averaged
  • This paper presents the results of a 3 year field study examining bank erosion and channel change on the Daintree River, Australia. Three different methods were employed : 1) erosion pins were used to assess the influence of riparian vegetation
  • bank erosion rates were improved by the inclusion of locally derived bed slope and discharge estimates.
  • Channel deposition induced by bank erosion in response to decreased flows in the sand-banked reach of the upstream Yellow River
  • Arid area ; Bank erosion ; China ; Fluvial adjustment ; Huang He ; Hydraulic works ; Sand ; Sediment transport ; Sedimentation ; Stream ; Suspended load
  • Using the profile data of 113 channel cross-sections taken in 1962, 1982, 1991 and 2000 in the Kubq desert reach of the Yellow River, the AA. show that the lateral channel erosion rate remained relatively constant despite flow decreases of 58
  • % and led to the development of a unique bank-to-channel sediment transfer (BCST). This BCST process, in combination with the decreased flow which caused suspended sediment effluxes to decrease by 30%, enhanced sediment deposition in the channel and provided
  • a mechanism of channel adjustment to decreased flow in sand-banked rivers. As the lateral channel erosion is a substantial sediment source of river sediments, about 64%, and leads to lateral channel shifts for sand-banked rivers, channel bank stabilization
  • should be a priority in river management and flood control in sand-banked rivers.
  • Insights into river bank erosion processes derived from analysis of negative erosion-pin recordings : observations from three recent UK studies
  • Bank erosion ; Erosion rate ; Freeze-thaw cycle ; Human impact ; Simulation ; Stream ; Survey ; United Kingdom ; Wales
  • Recent studies of river bank erosion in 3 catchments in the United Kingdom have been characterized by the persistent occurrence of negative erosion-pin results. The cause of these negative recordings is considered with reference to field data from
  • the Afon Trannon, Nant Tanllwyth and River Arrow, and to a laboratory study of freeze-thaw and dessiccation processes. The AA. analyse these data in order to seek and explain any patterns or relationships with subaerial or fluvial processes. They present
  • some cautionary advice to future users of erosion pins in river banks.
  • Seabed mapping and seafloor processes in the Kish, Burford, Bray and Fraser Banks area, south-western Irish Sea
  • Mapping of the seabed and sub-seabed strata in an area comprising offshore banks and intervening sediments in outer Dublin Bay is presented. Bathymetric comparisons, 7 acoustic seabed facies, grain-size data and bedform interpretations are presented
  • and discussed. Relationships are drawn with models of offshore bank evolution suggesting that the Irish examples are quasi-stable. Banks genesis, however, may relate more to former conditions of post-glacial rapid sea-level rise and high sediment input.
  • Data ; Data bank ; Documentation ; EEC ; Europe
  • Data ; Data bank ; Documentation ; Europe ; Statistics
  • Computer-assisted mapping;Automatic cartography ; Cultural geography ; Data bases;Data banks ; Digital mapping ; Geographical information system
  • Regionally representative selection of soil samples for an environmental specimen bank with particular reference to loess soils in Loess (INQUA).
  • Digital evaluation of a series of correlative geo-scientific maps in different scales and subsequent multivariate data processing in the form of entropy and neighbourhood analyses are the basis of a comparative selection of soil samples
  • for the environmental bank of the Federal Republic of Germany. By means of regionalisation algorithms the optimum location of sampling points was determined and the result corroborated on large scale maps or by visual inspection. In addition an index of representativity
  • Late Pleistocene and Holocene depositional systems and the palaeogeography of the Dogger Bank, North Sea
  • This paper will use 3D seismic data from the Dogger Bank, Southern North Sea, in order to demonstrate how the use of 3D seismic data, and the techniques developed by the petroleum industry for its analysis, can provide an efficient way of generating
  • regional models for the Late Pleistocene and Holocene. The data demonstrate that glacial processes resulted in the development of incised tunnel valley systems during the Weichselian and that these were subsequently modified by fluvial processes in a pro
  • Belgium ; Computer-assisted mapping;Automatic cartography ; Computing ; Data bases;Data banks ; Geographical information system ; Statistical data ; Wallonie
  • Discriminant function analysis of compositional data: an example from hydraulic geometry
  • Compositional discriminant function analysis of bank stability on the basis of hydraulic geometry had a success rate of 88%, making routinely archived measurements of stream width, cross-sectional area, mean velocity, and discharge a readily
  • available data base for predicting the stability of stream reaches.