inscription
PORTAIL D'INFORMATION GÉOGRAPHIQUE

Résultats de la recherche (9962 résultats)

Affinez votre recherche

Par Collection Par Auteur Par Date Par Sujet Par Titre Par ville ? Par pays ? Par continent ?
  • Analysis of bedload transport characteristics of Idaho streams and rivers
  • Carrying capacity ; Grain size distribution ; Idaho ; Model ; Mountain ; Sediment load ; Sediment transport ; Stream ; United States of America
  • Capacité de charge ; Charge solide ; Cours d'eau ; Etats-Unis ; Granulométrie ; Idaho ; Modèle ; Montagne ; Transport sédimentaire
  • Data collected for 33 sites on 31 mountain streams and rivers in Central Idaho have enabled the analysis of sediment transport characteristics in streams and rivers with different geological, topographic, morphological, hydrological, hydraulic
  • , and sedimentological characteristics. The particle size distributions of bedload and bed material, watershed and in-stream characteristics, sediment transport patterns and bedload transport rates are considered in this paper. The obtained results and conclusions
  • are used to identify different influences on bedload transport rates in analyzed gravel-bed rivers.
  • A conceptual model for meander initiation in bedload-dominated streams
  • Bank erosion ; Channel geometry ; Conceptual model ; Meander ; Model ; Sediment transport ; Stream
  • Cours d'eau ; Erosion des berges ; Géométrie hydraulique ; Modèle ; Modèle conceptuel ; Méandre ; Transport sédimentaire
  • A simple analytic model is presented relating local sediment transport capacity to variance in the transverse shear stress distribution in a stream channel. The model is used to develop a physically based conceptual model for the initiation
  • of meandering in straight, bedload-dominated streams as a result of a feedback mechanism.
  • Mechanics of sediment transportation and alluvial stream problems
  • Assessing potential abiotic and biotic complications of crayfish-induced gravel transport in experimental streams
  • Biogenic process ; Biomass ; Experimentation ; Fish ; France ; Population dynamics ; Rhône ; Sediment load ; Sediment transport ; Stream
  • Action biogène ; Biogéomorphologie ; Biomasse ; Charge solide ; Cours d'eau ; Dynamique des populations ; Expérimentation ; France ; Poisson ; Rhône ; Transport sédimentaire
  • This study used a representative and replicated design of artificial stream experiments to assess how an organism of intermediate size and abundance, a benthic crayfish, affects the transport of gravel across a gradient of an abiotic and a biotic
  • factor that potentially affect crayfish behaviour, and in turn could complicate the crayfish-induced gravel transport. This study also assesses how crayfish abundance in terms of their biomass affects the gravel transport across a variety of experimental
  • Bedload transport in two gravel-bedded streams
  • Capacité de charge ; Cours d'eau ; England ; Géographie physique ; Hydrodynamique ; Modèle ; Pennines ; Royaume-Uni ; Sédimentologie ; Transport sédimentaire
  • Bedload transport measurements in two upland streams are considered as a function of the excess stream power exerted on the bed by the flow. An inverse depth dependence in the efficiency of the transport process was noted but although bedload
  • calibre increased as a function of discharge its influence on efficiency could not be demonstrated. However it was suspected that the size-sorting relationships of the bed-material in a number of rivers in relation to the transport efficiency might
  • Channel flow competence and sediment transport in upland streams in southeast Australia
  • Australia ; Carrying capacity ; Flood ; Grain size distribution ; New South Wales ; River regime ; Sediment load ; Sediment transport ; Stream ; Stream flow
  • Australie ; Capacité de charge ; Charge solide ; Cours d'eau ; Crue ; Ecoulement fluvial ; Granulométrie ; New South Wales ; Régime fluvial ; Transport sédimentaire
  • Bedload transport data from planebed and step-pool reach types are used to determine grain size transport thresholds for selected upland streams in southeast Australia. Morphological differences between the reach types allow the effects
  • of frictional losses from bedforms, microtopography and bed packing to be incorporated into dimensionless critical shear stress value. Local sediment transport data are also included in a regime model and applied to mountain streams, to investigate whether
  • empirical data improve the delineation of reach types on the basis of dimensionless discharge per unit width and dimensionless bedload transport.
  • Geologic influences on fluvial hydrology and bedload transport in small mountainous watersheds, northern New Mexico, USA
  • Stream power and shear stress estimates derived from bankfull discharge and bed-material size data suggest that higher bedload transport rates and larger bedload particle sizes exist in streams draining crystalline rocks than in streams draining
  • sedimentary terrane. It appears that source-area lithology, by controlling discharge production, also influences stream power, bedload transport capabilities, and therefore total amounts of bedload transport.
  • Bed load transport in braided gravel-bed stream models
  • This paper presents the results of bed load transport measurements from several small-scale gravel braided streams formed at various combinations of slope and constant discharge. These data present an opportunity to investigate the form of sediment
  • transport relationships for braided streams, assess the extent to which the model results may be directly applicable to field prototypes, and investigate the nature of temporal fluctuations around the mean transport rate.
  • Dynamics of wood transport in streams : a flume experiment
  • Carrying capacity ; Experimentation ; Fluvial dynamics ; Japan ; Model ; River bed ; River transport ; Stream ; Stream flow ; Transport ; Wood
  • Bois ; Capacité de charge ; Cours d'eau ; Dynamique fluviale ; Ecoulement fluvial ; Expérimentation ; Japon ; Lit fluvial ; Modèle ; Transport ; Transport fluvial
  • The AA. examine some dynamics of wood transport in streams through a series of flume experiments, at the Publish Works Research Institute (PWRI), Tsukuba, Japan, and observe 3 distinct woodtransport regimes : uncongested, congested and semi
  • of these experiments provide insight into how the depositional fabric of wood accumulations can be used to infer transport dynamics.
  • Materialtransportundersokelser i norske bre-elver 1976 Sediment transport in Norwegian glacier streams 1976
  • 1976 ; Ecoulement sous glaciaire ; Glacier ; Glaciologie ; Géographie de l'Europe ; Norvège ; Transport solide
  • Materialtransportundersokelser i norske bre-elver 1975 Sediment transport studies in Norwegian glacier streams 1975
  • 1975 ; Ecoulement sous glaciaire ; Glacier ; Glaciologie ; Géographie de l'Europe ; Norvège ; Transport solide
  • Steep mountain streams: processes and sediment
  • Alpes ; Capacité de charge ; Fluviatile ; Granulométrie ; Italie ; Lit fluvial ; Montagne ; Royaume-Uni ; Transport sédimentaire ; Wales
  • Alps (The) ; Carrying capacity ; Fluvial processes ; Grain size distribution ; Italy ; Mountain ; River bed ; Sediment transport ; United Kingdom ; Wales
  • The aim of this paper is to describe steep mountain streams in terms of bed morphology, sediment features and sediment transport processes. Field data and observations from Mid-Wales and Eastern Alps streams are reported. Channel morphology
  • , particle size and shape are investigated in the sediment reaches of bedrock controlled streams. The data relative to 87 bedload samples are reported and the main results discussed in terms of sediment sorting processes.
  • Dambreak flood impact on mountain stream bedload transport after 13 years
  • Carrying capacity ; Catastrophe ; Colorado ; Flood ; Grain size distribution ; Impact ; Mountain ; Sediment transport ; Stream ; United States of America
  • Capacité de charge ; Catastrophe ; Colorado ; Cours d'eau ; Crue ; Etats-Unis ; Granulométrie ; Impact ; Montagne ; Transport sédimentaire
  • Studies of the bedload transport regime of the Roaring River, Colorado, in 1984-88, following a dambreak flood in 1982, showed that bedload transport rates were an order of magnitude higher than under pre-flood conditions. Data collected in 1995, 13
  • years after the flood, are compared with measurements made during 1984-88 to investigate the longer term variation of transport regime. The measurements demonstrate both the control exercised by sediment supply on transport rates and the persistent long
  • -term impact of major floods on mountain streams.
  • Continuous measurement of sediment transport in the Erlenbach stream using piezoelectric bedload impact sensors
  • Alps (The) ; Carrying capacity ; Methodology ; Sediment load ; Sediment transport ; Stream ; Switzerland
  • Alpes ; Capacité de charge ; Charge solide ; Cours d'eau ; Détecteur piézoélectrique ; Méthodologie ; Suisse ; Transport sédimentaire
  • The AA. report on bedload transport observations using piezoelectric bedload impact sensors (PBIS), an indirect method of estimating the volume of bedload transport of coarse sediment. Sediment transport at the Erlenbach stream has been continuously
  • water discharge, and the critical discharge for the onset of sediment transport.
  • Coarse bedload transport in a mountain river
  • Carrying capacity ; Fluvial dynamics ; Gravel ; Montana ; Mountain ; Shear stress ; Stream ; Stream flow ; Turbulence ; United States of America
  • transport events associated with the daily rise and fall in stream discharge were investigated. This paper reports the results of this study designed to describe fully the adjustment of river bed and turbulent flow to the unsteady passage of a pebble bedload.
  • Coarse bedload transport dynamics are investigated utilizing hydrodynamic and sediment transport data obtained in an extensively instrumented study reach located in Sqaw Creek, Montana, USA. During 1991 and 1992, a number of discrete bedload
  • 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
  • according to its geometrical shape, formation and transportation. (TNC).
  • Critical specific stream power in gravel-bed rivers
  • Ardenne ; Belgium ; Hydrodynamics ; Hydrological regime ; Sediment load ; Sediment transport ; Shear stress ; Stream ; Tracer
  • Ardenne ; Belgique ; Charge solide ; Contrainte de cisaillement ; Cours d'eau ; Hydrodynamique ; Régime hydrologique ; Traceur ; Transport sédimentaire
  • Experiments with marked pebbles were carried out on different sized rivers of the Belgian Ardenne (catchment areas varying from less than 1 km2 to 2700 km2). Specific stream power required to cause bedload movement was evaluated and critical values
  • were obtained. Three types of relationship between critical specific stream power and grain size were established.
  • Measures of physical heterogeneity in appraisal of geomorphic river condition for urban streams : Twin streams catchment, Auckland, New Zealand
  • Aquatic ecosystem ; Auckland ; Environmental degradation ; Habitat ; Impact ; New Zealand ; North Island ; Sediment transport ; Stream ; Urban environment ; Urbanization ; Watershed
  • Auckland ; Bassin-versant ; Cours d'eau ; Dégradation de l'environnement ; Ecosystème aquatique ; Environnement urbain ; Habitat ; Impact ; North Island ; Nouvelle-Zélande ; Transport sédimentaire ; Urbanisation
  • Analysis was carried out at 27 sites in the Twin Streams catchment in West Auckland. The method successfully recorded the extent of degradation of physical structure following European settlement of the catchment. With the exception of one
  • subcatchment, streams were found to be largely intact in the headwaters. Geomorphic conditions is more degraded in downstream areas. Fine-grained sediment has smothered stream courses in the lower half of the catchment, covering bed material and creating
  • Evidence for transport of bedload in waves: analysis of fluvial sediment samples in a small upland stream channel
  • is relatively independant of the water discharge. Data pertaining to the transport of fluvial sediment sampled in detail during a five hour long event in a small upland stream channel in the extremely arid southern Negev are presented.
  • In extremely arid, rocky, high relief watersheds, coarse fluvial sediment, if initially entrained, tends to group itself in well defined waves which move discretly downstream. Above a certain threshold determined by stream power this movement
  • Feedbacks between erosion and sediment transport in experimental bedrock channels
  • Experimentation ; Fluvial erosion ; Roughness ; Sediment transport ; Stream ; Stream flow ; Topography ; Turbulence ; United States of America ; Utah
  • Cours d'eau ; Ecoulement fluvial ; Erosion fluviatile ; Etats-Unis ; Expérimentation ; Rugosité ; Topographie ; Transport sédimentaire ; Turbulence ; Utah
  • transported as bedload, a single erosion mechanism (abrasion) and sediment-starved transport conditions. They find that patterns of erosion both create and are sensitive functions of the evolving bed topography because of feedbacks between the turbulent flow
  • field, sediment transport and bottom roughness.