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Résultats de la recherche (101 résultats)

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  • River of dreams : on the gulf between theoretical and practical aspects of an upland river restoration
  • Conceptual model ; Decision making process ; Ecology ; England and Wales ; Environmental management ; Gravel ; Model ; Rehabilitation ; River bed ; Stream ; United Kingdom ; Watershed
  • This paper is concerned with development and application of a conceptual model of the river restoration process and, through a specific case study, a demonstration of the challenges that arise when combining ecological and geomorphological
  • principles with social and economic issues. This, it demonstrates the difference between the ideal goals of river restoration and the practical determinants of the nature of a river restoration that derive from individual and community goals.
  • 2004
  • 20th century stage trends along the Mississippi River
  • This study compared 4 measures of river hydrology at the beginning (1910-1930) and at the end of the 20th century (1980-2000). River-stage data were statistically analyzed from 15 equidistant gauges along the main stem of the Mississippi River
  • . The findings revealed : significant changes in components of river hydrology between both time periods; varying patterns of change between the different river segments. Discussion of these results.
  • 2004
  • Braided channel ; Carrying capacity ; Channel geometry ; Comparative study ; Cross section ; Discriminant analysis ; Fluvial dynamics ; Longitudinal section ; Mathematical model ; Meander ; Model ; River bed ; Roughness ; Slope gradient ; Stream
  • The classic channel slope-discharge relationship proposed by Leopold and Wolman (1957) for channel pattern discrimination has been tested by a large database including 4 types of rivers : gravel-bed meandering rivers, gravel-bed braided rivers, sand
  • -bed meandering rivers and sand-bed braided rivers. The result shows that this relationship cannot discriminate channel patterns well when both gravel- and sand-bed rivers are considered. The channel width-bankfull discharge relationship suggested by XU
  • (1996) for discrimination of channel patterns of sand-bed rivers in China, is also tested in this study by the same database. Discussion of the results.
  • 2004
  • Water quality changes in the Elbe River Basin
  • Czech Republic ; Elbe ; Hydrology ; River basin ; Water pollution ; Water quality ; Years 1990-99
  • In the course of 90s, the Czech part of Elbe River Basin underwent a significal change in the quality of surface water. The scope and speed of such water quality changes is unprecedented in the Czech as well as in the Central European perspective
  • . Decrease in the pollution is however limited to the Elbe-River and its main tributaries. It is the area of small water-courses that has to be now in the centre of attention. - (MS)
  • 2004
  • Human activity transforming and designing river landscapes : a review perspective
  • The river landscape is a basis for introducing 7 ways in which river landscapes have been studied and researched, culminating in an eighth holistic phase. Conclusions from studies of impacts of human activity provide a basis for suggesting
  • that physical geographers should be more concerned with the design of river landscapes and ways in which this might be achieved are suggested.
  • 2004
  • Three-dimensional flow modelling and sediment transport in the River Klarälven
  • A three-dimensional flow model that uses the RNG turbulence model and a non-equilibrium wall function was applied to the River Klarälven in the southwest part of Sweden. The objectives were to study the nature of the flow in the river bifurcation
  • and to investigate the short-term sediment transport patterns in the river. The numerical models were built and verified using extensive field data. Based on model outputs, observations are made about the velocity vectors and the secondary flow patterns. The main
  • sediment transport patterns in the river were also investigated by solving the sediment continuity equation for the total sediment load.
  • 2004
  • Coastal dune fields at the São Francisco River strandplain, northeastern Brazil : morphology and environmental controls
  • Aeolian features ; Bahia ; Barchan ; Brazil ; Coastal deposit ; Coastal dune ; Coastal environment ; Geochronology ; Holocene ; Quaternary ; River mouth ; Sea level
  • dunes fields are recognized. This study suggests that the aeolian sedimentation is a relatively recent phenomenon at the Quaternary strandplain of the São Francisco River.
  • 2004
  • Einflüsse der Landnutzung auf die Gewässerqualität des Grand River North West (GRNW) (Mauritius)
  • Les impacts de l'utilisation du sol sur la qualité de l'eau de Grand River North West (GRNW) (Ile Maurice)
  • The rapid economical and social processing on Mauritius has forced an enormous pollution. Especially rivers and lakes have been contaminated and because of that also in the lagoons and riffs in front of the island are affected. The main polluters
  • are the agriculture with enormous applications of fertilizers and herbicides and industrial and municipal sewage systems. Purpose of the study is to assess the current situation of pollution and to identify possible sources of pollution in the catchment of grand River
  • 2004
  • Asymmetrical valleys created by the geomorphic response of rivers to strike-slip fault
  • The larger rivers with higher erosional rates may widen their valleys asymmetrically downstream of strike-slip faults, rather than being beheaded or deflected. Examples are described from the Yellow River near the NE margin of the Tibetan Plateau
  • . River beheading and asymmetrical widening are 2 end-members of a fluvial valley's response to strike-slip faulting, whereas deflection is a combination of both. Recognition of the formation of such asymmetrical valleys related to strike-slip faulting
  • 2004
  • Evidence for Holocene megafloods down the Tsangpo River gorge, southeastern Tibet
  • Lacustrine and alluvial terraces and sediments record the extent of at least 2 Holocene glacially dammed lakes immediately upstream of the Tsangpo River gorge at the eastern syntaxis of the Himalaya. Catastrophic failure of the glacial dams
  • that impounded the lakes would have released outburst floods down the gorge of the Tsangpo River with big peak discharges. The erosive potential represented by the unit stream power calculated for the head of the gorge during such a catastrophic lake breakout
  • indicates that post-glacial megafloods down the Tsangpo River were likely among the most erosive events in recent Earth history.
  • 2004
  • Changes in the middle course of the River Vistula in historical times
  • . It was possible to document the time of the onset of the change in the character of the river from dominantly meandering to one that was characterised by braiding, suggesting the anthropogenic influences that have modified the natural processes (deformation
  • 2004
  • The frictional resistance characteristics of a bedrock-influenced river channel
  • Alluvial channel ; Braided channel ; Channel geometry ; Mpumalanga ; Riparian vegetation ; River bed ; Roughness ; Runoff ; South Africa ; Stream ; Stream flow
  • This paper presents the results of a detailed investigation of total flow resistance variation for 5 channel types on the Sabie River, South Africa (cohesive, mixed anastomosed, uncohesive mixed anastomosed, mixed pool-rapid, alluvial braided
  • 2004
  • Bed sediment sources and mixing in the glacierized upper Fraser River watershed, East-Central British Columbia
  • The geochemical, mineralogical and lithological composition of modern stream bed material is examined in order to characterize sources and evaluate downstream mixing of sediments in the upper Fraser River drainage basin. The lacustrine and alluvial
  • sedimentary records of the upper Fraser River watershed are the subject of ongoing palaeoenvironmental investigation and have pointed toward pronounced variations in glaciation in the drainage basin over Holocene time scales. The focus of this study
  • 2004
  • Comparison of hydraulic geometry between sand- and gravel-bed rivers in relation to channel pattern discrimination
  • A comparison has been made between the hydraulic geometry of sand- and gravel-bed rivers, based on data from alluvial rivers around the world. The results indicate a significant difference in hydraulic geometry. On this basis, some diagrams
  • 2004
  • Impact of hydroelectric power releases on the morphology and sedimentology of the bed of the Warche River (Belgium)
  • Ardenne ; Belgium ; Carrying capacity ; Channel geometry ; Dam ; Hydraulic works ; River bed ; Roughness ; Sediment transport ; Stream ; Stream flow
  • This study concerns a 7 km long stretch of the river below a dam constructed in 1932 to ensure an optimal supply of water for the production of electricity of another reservoir downstream. Large releases are made very regularly (almost every days
  • 2004
  • Late Quaternary downcutting rates of the Qianyou River from U/Th speleothem dates, Qinling mountains, China
  • Dating deposits in caves formed by rivers may yield insight into rates and processes of bedrock incision. Three cave passages at different levels have developed in the walls of the Qianyou River valley in the Qinling mountains, south of the city
  • 2004
  • Bank erosion ; Dendrochronology ; Meander ; Poland ; River bed ; Stream
  • The age of trees, which growth in 20th century paleochannels and on point bars has been determined within six meander bends of the Mala Panew River. The age of the oldest tree has shown the minimum age of each form of relief. The minimum rate
  • of lateral river bank erosion has been calculated on the base of this minimum age and distance of every paleochannel from the present river bank. - (BJ)
  • 2004
  • Floodplain sedimentation during an extreme flood : the 1999 flood on the Tar River, eastern North Carolina
  • This paper examines floodplain sedimentation following the 1999 flood of the century on the Tar River. Hurricane Floyd made landafall just 10 days after Hurricane Dennis in September 1999. The AA. used suspended sediment concentrations measured
  • on the Tar River from 1958-1967 to suggest that the seasonal timing and sequencing of flood events in 1999 are the most probable explanations for the minimal geomorphic impact of this extreme flood.
  • 2004
  • Changes in the settlement system and land use in the valley of Vistula river in historical time (on the segment batween Wargocin and Magnuszew)
  • The geoarcheology of river valleys
  • . Construction of the embankment limited river activity to a narrow inter-dike zone. - (BJ)
  • 2004
  • Recession rates of Kaminari Falls in the upper Matsukawa River, Takayama Village, Nagano Prefecture
  • 2004