inscription
Portail d'information géographique

Résultats de la recherche (627 résultats)

Affinez votre recherche

Par Collection Par Auteur Par Date Par Sujet Par Titre
The development of subhorizontal shore platforms by waves and weathering in microtidal environments
  • The development of subhorizontal shore platforms by waves and weathering in microtidal environments
  • Coastal environment ; Coastal erosion ; Intertidal zone ; Model ; Shore platform ; Wave ; Weathering
  • A mathematical wave and weathering model was used to study the formation of subhorizontal platforms in microtidal environments. Backwearing (horizontal erosion) rates by wave erosion were calculated for different tidal levels using basic wave
  • equations. Downwearing (vertical erosion) rates by weathering and debris removal by waves at the same tidal levels were derived from long-term laboratory experiments and from field data. Model runs suggested that wave erosion was more important in the past
Wave climatology of the southeastern Mediterranean
  • Wave climatology of the southeastern Mediterranean
  • The wave climate of the southeastern Mediterranean is defined here for the first time by integrating 57 326 visual observations and gauge measurements including wave height, period and direction, from five different sources during the years 1948
A classification of sand wave in alluvial stream.
  • A classification of sand wave in alluvial stream.
  • The concept of sand waves in stream beds is discussed and the principles for their classification examined. The classification divides waves into two grades| the first covers two subdivisions and the second covers six. Each is defined and described
Wind and waves: influence of local and non-local waves on mesoscale beach behavior in estuarine environments
  • Wind and waves: influence of local and non-local waves on mesoscale beach behavior in estuarine environments
  • Coastal dynamics ; Coastal environment ; Current ; Estuary ; New Jersey ; United States of America ; Wave ; Wind ; Wind speed
  • A 29-day field investigation was conducted on a meso-tidal sand beach in Delaware Bay, New Jersey to document the contribution of local estuarine and non-local ocean waves to beach recovery following storms. Data were gathered on winds, waves, flow
Morphodynamics of intertidal bars in wave-dominated coastal settings - a review
  • Morphodynamics of intertidal bars in wave-dominated coastal settings - a review
  • Beach ; Coastal dynamics ; Coastal environment ; Earth surface processes ; Intertidal zone ; Sand bar ; Sediment transport ; Tide ; Wave
  • variations and wave processes in shallow water depths (swash and surf zone bores), rather than wave height variability and deeper water wave processes (breaking and shoaling waves), that constitutes the main difference between intertidal and subtidal bar
A laboratory study of formative conditions for characteristic ripple patterns associated with a change in wave conditions
  • A laboratory study of formative conditions for characteristic ripple patterns associated with a change in wave conditions
  • Coastal environment ; Experimentation ; Flow ; Hydrodynamics ; Micromorphology ; Ripple-mark ; Sedimentary ; Wave
  • A wave-flume experiment was conducted to examine the formative condition for 3 types of distinctive bedforms that emerged through deformation of existing ripples due to waning wave power. The experiment data were analysed taking asymetry of the flow
Errors of kinematic-wave and diffusion-wave approximations for steady-state overland flows
  • Errors of kinematic-wave and diffusion-wave approximations for steady-state overland flows
  • Steady-state flows occur in a variety of geophysical processes. Their mathematical treatment is usually based on either the dynamic-wave equations or their approximations: kinematic wave (KW) and diffusion wave (DW). Furthermore, when doing
  • hydrologic modeling it is not evident if the KW and DW approximations are valid for the entire length of the channel or a portion thereof. The objective of this study is to derive, under simplified conditions, errors for the kinematic-wave (KW
  • ) or the diffusion-wave (DW) approximations as a function of space.
Morphological controls on the downstram passage of a sediment wave in a gravel-bed stream
  • Morphological controls on the downstram passage of a sediment wave in a gravel-bed stream
  • Bank erosion ; Channel geometry ; Fluvial dynamics ; Fluvial processes ; River bed ; Scotland ; Sediment transport ; Stream ; United Kingdom ; Wave
  • This study documents the origin and downstream passage of an avulsion-generated sediment wave through a 374 m study reach of the Allt Dubhaig, Scotland. A nested survey framework was adopted, with volumes calculated from cross-sections spaced
  • between 10 and 40 m apart documenting the origin and downstream passage of the wave. The specific aims of this study are to : 1) assess the significance of local morphology upon the passage of the wave; 2) determine the extent of sediment exchange between
  • the recipient reach and the wave, and the effect of this upon wave magnitude; and 3) describe the channel response to wave input and assess the transience of these changes.
Wave flume experiments on the formation of longshore bars produced by breaking waves
  • Wave flume experiments on the formation of longshore bars produced by breaking waves
  • Mechanisms and processes of longshore bar formation were investigated in connection with vortices induced by breaking waves in the laboratory. Four kinds of wave-flume experiments were conducted using a two-video-camera system to examine
Cold waves and winter monsoon in East Asia : with special reference to south China
  • Cold waves and winter monsoon in East Asia : with special reference to south China
  • Definition of cold waves from the statistical and synoptic climatological standpoints| cold airmass movement stream lines and wind component for the main three types of cold waves in south China| cold waves by the Geostationary Meteorological
  • Satellite Himawari images in winter 1986/87 and typical cold waves in relation to winter monsoon situations such as the cases in January and February 1963.
Barchan-shaped ripple marks in a wave flume
  • Barchan-shaped ripple marks in a wave flume
  • Aeolian features ; Barchan ; Comparative study ; Dune ; Earth surface processes ; Experimentation ; Geomorphology ; Wave
  • The formation of barchan morphologies under the action of purely oscillatory wave motion has not yet been fully investigated. This study attempted to form barchan topography in a wave flume and to compare this with barchans in the field. Barchan
  • morphologies of ripple size, called the barchan ripples, were generated from a flat bed by the action of waves. This study will examine the migration speed of these laboratory and field morphologies through dimensional analysis.
Ireland's new wave of emigration in the 1980s
  • Ireland's new wave of emigration in the 1980s
Development of shore platforms on Kaikoura Peninsula, South Island, New Zealand. Part one : the role of waves
  • Development of shore platforms on Kaikoura Peninsula, South Island, New Zealand. Part one : the role of waves
  • Coastal dynamics ; Coastal environment ; Coastal erosion ; Marine hydrology ; New Zealand ; Shore platform ; South Island ; Wave
  • The role of waves in shore platform development has been investigated on Kaikoura Peninsula by direct measurement of waves in deep water and on platforms at high tide. This showed that the deepwater wave environment off the Kaikoura Peninsula
  • is very energetic, but the amount of energy delivered to platforms is very low. An analysis of the role of breaking waves revealed that these are ineffective as an erosional agent because the depth of water offshore causes breaking before waves arrive
Proglacial lake beach structures from solitary waves?
  • Proglacial lake beach structures from solitary waves?
Variations of spacings between beach cusps discussed in relation to edge wave theory
  • Variations of spacings between beach cusps discussed in relation to edge wave theory
  • Beach cusps ; Coastal dynamics ; Coastal environment ; Denmark ; Model ; Statistics ; Wave
  • Variations in cusp spacings of beach cusp systems have been examined, and the conclusion is that the apparent regularity of the spacings is not always real. Established edge wave theory predicts equal cusp spacings, and accordingly, the theory needs
Fizika i statistika neobyčnyh morskih vetrovyh voln
  • Geophysics ; Hydrodynamics ; Impact ; Oceanology ; Random process ; Statistics ; Wave ; Wind
  • Discussion des règles d'apparition des vagues inhabituelles dont les dénominations dans les publications en langue anglaise sont freak waves, rogue waves et même killer-wave, c'est-à-dire vagues tueuses.
Defining heat waves - different approaches
  • Defining heat waves - different approaches
  • Climate ; Definition ; Exceptional event ; Heat wave ; Poland ; Synoptic climatology ; Threshold
Low-frequency unstable planetary waves in realistic basic states
  • Low-frequency unstable planetary waves in realistic basic states
  • Atmospheric circulation ; Climatic warming ; Greenhouse effect ; Model ; Planetary wave ; Stratosphere ; Troposphere
  • This study investigates low-frequency, unstable planetary waves in realistic basic states of January 1979, using three-dimensional spectral primitive equations derived by orthonormal vertical structure functions and Hough harmonics. Three selected
  • unsable modes are extensively examined. One is the Green mode in the planetary waves, and the other two are deep Charney modes having different meridional structures. The results suggest that large-scale Pacific blocking during the winter are, at least
Resuspension, sediment fluxes, and suspended sediment diffusion coefficients under wave and current forcing in two coastal environments
  • Resuspension, sediment fluxes, and suspended sediment diffusion coefficients under wave and current forcing in two coastal environments
  • Atlantic Ocean ; Coastal dynamics ; Coastal environment ; Coastal sedimentation ; Denmark ; Grain size distribution ; North Sea ; Sea current ; Sedimentology ; Turbulence ; Wave ; Wind speed
  • This study presents results on sedimentation fluxes obtained during deployments of a tripod equipped with sediment traps and instruments for measuring wave and current parameters in each of two environments (Løgstør Broad and Amstrup Bay), dominated
  • respectively by surface waves and by currents.
Boulder deposits from large waves during the last interglaciation on North Eleuthera Island, Bahamas
  • Boulder deposits from large waves during the last interglaciation on North Eleuthera Island, Bahamas
  • Aminostratigraphy ; Bahamas ; Coastal dynamics ; Coastal environment ; Erratic boulder ; Interglacial ; Mass movement ; Pleistocene ; Rainstorm ; Stratigraphy ; Tsunami ; Wave
  • This paper presents a detailed description of the boulders of north Eleuthera and demonstrates that they were deposited by waves during the Pleistocene. It describes the time and stratigraphy related to boulder emplacement, and evaluates tsunamis
  • , slumpling of the bank margin, and storms as potential wave-generating mechanisms.