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  • Mean and turbulent flow fields in a simulated ice-covered channel with a gravel-bed : some laboratory observations
  • Canada ; Cold area ; Experimentation ; Freezing ; Ice cover ; Ontario ; Roughness ; Simulation ; Stream ; Stream flow ; Turbulence
  • In this study, flume experiments of flows under a simulated ice cover are presented. Open water conditions and simulated rough ice-covered flows are discussed. Mean flow and turbulent flow statistics were obtained from an Acoustic Doppler
  • Velocimeter (ADV) above a gravel-bed surface. A central region of faster flow develops in the middle portion of the flow with the addition of a rough cover. The turbulent flow characteristics are unambiguously different when simulated ice covered conditions
  • 2012
  • Bedload transport and flow resistance in steep channels : introduction to the issues in the context of mountain basins of the Central European region
  • Carpathian Mountains ; Carrying capacity ; Central Europe ; Discharge ; Europe ; Flow resistance ; Headwater ; Hydrology ; River bed ; Runoff ; Sediment transport ; Stream
  • and power-law relationships) and critical conditions of the incipient motion of a bed particle (critical shear stress, stream power, flow velocity and discharge) are closely discussed in order to describe hydraulic and bedload transport conditions in steep
  • The authors attempt to review recent worldwide research of bedload and hydraulics the results of which could potentially be applied in local steep channels. Approaches to the calculation of flow resistance (Manning relationship, logarithmic
  • headwater streams. In the second part of the paper the authors present two pilot studies from the Western Carpathians and test potential applicability of specific formulas in this region. Results of the formulas point to relatively nonselective character
  • of bedload transport during high magnitude floods in Beskydian headwater streams. - (EN)
  • 2012
  • Topographic forcing of flow partition and flow structures at river bifurcations
  • Bifurcation ; Fluvial dynamics ; Numerical model ; Simulation ; Stream ; Stream flow ; Topography
  • The aim of this paper is to explore the interaction between bedform steered flow and bifurcation dynamics. The AA. present the predicted flow dynamics from the application of a Reynolds-averaged Navier–Stokes (RANS) model to a series of bifurcation
  • demonstrate the dominant effect bed discordance has upon flow division between the 2 distributaries. They also suggest that sand-bed river bifurcations are more likely to have an influence that extends much further upstream and have a greater impact upon water
  • 2012
  • The activation of ephemeral streams in karst catchments of semi-arid regions
  • Drainage network ; Ephemeral stream ; Flood ; Italy ; Karst ; Modelling ; Precipitation ; Puglia ; Runoff ; Semi-arid area ; Watershed
  • This work presents an analysis of the response to rainfall of ephemeral streams in a karst semi-arid regions of southeast of Italy by an innovative approach. The analysis is based on a 2D simulation model of the behavior of a network of ephemeral
  • streams. The used approach integrates the hydrological and hydraulic models in order to account first for the dynamic of catchment response to rainfall and activation of the streams, and then for the hydraulic behavior of the streams. Results show the slow
  • response of ephemeral streams to the rainfall, whereas more extreme rainfall events generate quick and high discharge responses of the ephemeral streams. In addition, modeling results emphasize the non-linearity of runoff generation, in particular for some
  • flow paths, which are biased by the local morphology as well as by the intensity of the rainfall event.
  • 2012
  • Channel geometry ; Experimental catchment ; Honshu ; Japan ; Lithology ; Longitudinal section ; Mountain ; Sediment load ; Sediment transport ; Stream ; Watershed
  • groundwater flow recharges stable stream flow in the sandstone area. Manual field measurements from sections of first-order streams and results of high-resolution analysis of long profiles using terrestrial laser scanning are discussed. The contrast in runoff
  • This study focuses on lithological contrasts of headmost channel morphology of 2 mountainous areas underlain by chert or sandstone. The areas have contrasting runoff processes : subsurface storm flow predominates in the chert area, whereas
  • processes, as well as grain-size distributions of weathering products between the 2 areas, influences dissimilar bed-load transport regimes and promotes spatial variations in channel profiles between headwater streams. These contrasting hydro-geomorphic
  • processes affect channel-step morphology, indicating that lithology plays a key role in the formation of channel steps and in variations between headwater streams.
  • 2012
  • Modelling the bulk flow of a bedrock-constrained, multi-channel reach of the Mekong River, Siphandone, southern Laos
  • Braided channel ; Channel geometry ; Laos ; Mekong ; Model ; Peak discharge ; Plant cover ; Riparian vegetation ; Roughness ; Stream
  • to significant changes in the bulk flow properties between and along the channels. The challenge to model the bulk flow in such a remote region was the lack of ideal boundary conditions. The flow models considered both low flow, high inbank and overbank flows
  • and were calibrated using SPOT satellite sensor imagery and limited field data concerning water levels. The application of the model highlighted flow characteristics of a large multi-channel network and also further indicated the field data that would
  • be required to properly characterize the flow field empirically : water surface slopes of the channels and in-channel hydraulic roughness coefficient.
  • 2012
  • Flow in a tightly curving meander bend: effects of seasonal changes in aquatic macrophyte cover
  • Aquatic vegetation ; Channel geometry ; Germany ; Meander ; Mecklenburg-West Pomerania ; Model ; Seasonal variation ; Stream ; Stream flow ; Vegetation
  • This study analyses a detailed field data set to provide new insights into primary velocity, secondary flow and shear stress distribution. The study site is a low-gradient peatland meander in north-east Germany, with substantial macrophyte cover
  • , semi-empirical models for the 3 predominant flow types were tested and discussed; velocity and stress models of vegetated mixing layers and plane turbulent jets, and Rozovskii's model for the transverse flow in bends.
  • 2012
  • Do alternate bars affect sediment transport and flow resistance in gravel-bed rivers ?
  • Bar ; Channel geometry ; Earth surface processes ; Model ; Numerical model ; Sediment load ; Sediment transport ; Stream ; Stream flow
  • , as compared to the equivalent one-dimensional (1D) case of a flat and straight bed, having the same channel slope and average flow velocity. The calculations result in a method for correcting 1D models to account for the total sediment transport and resistance
  • 2012
  • Channel geometry ; Colorado ; Fluvial dynamics ; Grain size distribution ; Meander ; Model ; Rocky Mountains ; Sediment transport ; Shear stress ; Spatial distribution ; Stream ; Threshold ; United States of America
  • Detailed topographic and hydraulic measurements were obtained in a bend of the Colorado River in Rocky Mountain National Park, Colorado, to characterize flow through the reach with a two-dimensional model. The distribution of excess shear stress
  • is examined and how this distribution is affected by flow stage and channel curvature is explored. The results suggest that small regions of the channel contribute disproportionately to the overall sediment flux at high flows, that the size of these regions
  • 2012
  • Accumulation rate ; China ; Cross section ; Grain size distribution ; Huang He ; Methodology ; Northern China ; Sediment load ; Sedimentation ; Stream ; Stream flow ; Suspended load
  • -bottom suspended sediment and bed-load. Based on annual data from the period 1952-1999, correlations between channel sedimentation rate and a number of flow and sediment indices have been established. Then, some multiple equations have been established
  • , which can be used to estimate channel sedimentation rate based on a number of influencing variables including suspended sediment load and its grain size compositing, water discharge and, hyperconcentration flow frequency. These equations may provide some
  • 2012
  • Spatial patterns of March and September streamflow trends in Pacific Northwest streams, 1958-2008
  • Climatic change ; Climatic warming ; Idaho ; Meltwater ; Model ; Oregon ; Precipitation ; Seasonal variation ; Spatial analysis ; Stream ; Stream flow ; United States of America ; Washington State ; Water ; Water resources
  • This study detects significant negative trends in September absolute streamflow in a majority of 68 stream-gauging stations located on unregulated streams in the pacific Northwest (PNW) from 1958 to 2008. The geographically weighted regression (GWR
  • 2012
  • Bedload transport measurements at the Erlenbach stream with geophones and automated basket samplers
  • Alps (The) ; Mountain ; Quantitative analysis ; Research technique ; Sediment load ; Sediment transport ; Stream ; Switzerland
  • In the Erlenbach stream, sediment transport has been continuously monitored with piezoelectric bedload impact and geophone sensors since 1986. In 2008-2009, the measuring system was enhanced by installing an automatic system to obtain bedload
  • samples. Movable metal baskets are mounted on a rail at the downstream wall of the large check dam above the retention basin, and they can be moved automatically into the flow to take bedload transport samples. This upgraded measuring system permits
  • 2012
  • Canada ; Hydrodynamics ; Ice cover ; Numerical model ; Ontario ; Roughness ; Sediment load ; Sediment transport ; Stream
  • A numerical modeling approach with field data is used here to investigate the possibility of sediment movement in the St Clair River and assess the likelihood of morphological change under the current flow regime. A two-dimensional numerical model
  • was used to study flow structure, bed shear stress, and sediment mobility/armoring over a range of flow discharges. Boundary conditions for the numerical model were provided by detailed field measurements that included high-resolution bathymetry and three
  • -dimensional flow velocities. The results indicate that, without considering other effects, under the current range of flow conditions, the shear stresses produced by the river flow are too low to transport most of the coarse bed sediment within the reach
  • 2012
  • The response of braided planform configuration to flow variations, bed reworking and vegetation : the case of the Tagliamento River, Italy
  • Braided channel ; Channel geometry ; Discharge ; Flood ; Friuli-Venezia Giulia ; Italy ; Riparian vegetation ; Stream ; Vegetation
  • that wetted area increased almost linearly with water level in both reaches. The average number of branches per cross-section peaked at intermediate flow levels, increasing from 2 at low flow up to 6-7.
  • 2012
  • Bed evolution measurement with flowing water in morphodynamics experiments
  • Channel ; Channel geometry ; Earth surface processes ; Experimentation ; Italy ; Methodology ; Pool ; Runoff ; Stream flow ; Tidal creek ; Topography ; laser measures
  • tests, under either still- or flowing-water conditions, as well as increasing/decreasing water surface elevation, were carried out to evaluate the accuracy of the measurements. Finally, 2 relevant applications to movable bed experiments carried out under
  • 2012
  • . Climate conditions, such as the presence of Ocean waters upwelling and El Niño, cause sporadic rainfall events. Hence, the micro-watersheds and streams become active and function as torrential channels producing debris flows. Moreover, torrential systems
  • In the Caldera coastal district of Northern Chile, the marine terraces of Quaternary age are characterized by steep cliffs dissected by deep gullies, from which torrential streams are formed. The gullies are controlled by the scarps of the terraces
  • drain into the urban area of Caldera, causing flooding in the lower parts of the city. The city is growing into the area influenced by flooding and debris flows hazard and thus making vulnerable the resident population and infrastructure. - (NF)
  • 2012
  • Channel geometry ; Croatia ; Environmental management ; Grain size distribution ; Human impact ; Pollution ; River bed ; Sediment transport ; Stream ; Stream flow
  • in the mountainous region and flows down to the plains with braided channels. During the summer months, this potentially resourceful river is getting locally moribund and arrested within its course due to fall of river level and extremely uneven bed level
  • 2012
  • Alluvial cone ; Alps (The) ; British Columbia ; Canada ; Channel geometry ; Dendrogeomorphology ; Ecosystem ; Europe ; Forest production management ; Impact ; Mountain ; Riparian vegetation ; Sediment transport ; Spain ; Stream ; Stream flow
  • and more recent work on the dependencies and interactions between hydrogeomorphic processes and vegetation. In particular, the AA. address the role of vegetation in the initiation of hydrogeomorphic processes and its impact on stream morphology as well
  • 2012
  • Braided channel ; Channel ; Channel geometry ; Classification ; Fluvial geomorphology ; Fluvial hydrology ; Human impact ; Hydraulic works ; Natural hazards ; River bed ; Sediment transport ; Stream ; Stream flow ; Valley ; World
  • metamorphosis and produces anthropogenic channel types. New approaches to channel systemization involve hydrological parameters and sediment transport as well as stream power. The typology of channel reaches has several practical implications, including
  • 2012
  • Czech Republic ; Digital elevation model ; Drainage ; Flood ; Flood wave ; Floodplain ; Geographical information system ; Lužnice river ; Model ; Stream flow ; Topography ; Water retention
  • on flood wave transformation is flow retardation due to the flow velocity decrease, the retention in surface depressions within floodplain has been analyzed to get better overview of whole transformation process. Detailed digital relief model (DRM) has been
  • 2012