Abstract Confluences act as critical nodes in a river network they affect flow, sediment transport, water quality, and ecological patterns. A complete knowledge about hydro‐morpho‐sedimentary processes at confluences is still incompleted it has been usually accepted that secondary flows are weak because of the significant role form roughness large rivers. In this study, two field surveys were conducted on flow structure, suspended transport morphology confluence between Yangtze River (the...

Abstract This paper provides novel observations linking the connections between spatially distributed bed load transport pathways, hydraulic patterns, and morphological change in a shallow, gravel braided river. These shed light on mechanics of braiding processes illustrate potential to quantify coupled material fluxes using remotely sensed methods. The focuses upon 300 m long segment Rees River, New Zealand, utilizes dense from mobile acoustic Doppler current profiler (aDcp) map depth,...

A new technique has been developed to measure the apparent velocity of bed load (va) using an acoustic Doppler current profiler. The involves estimating bias in bottom tracking due a moving bottom. Mean va measured at sampling stations gravel-bed Fraser River correlated well (r2=0.93,n=9) with mean transport rates conventional samplers. was also (r2=0.44,n=19) boundary shear stress estimated by log-law fit profile. Estimates from individual 5 s ensemble averages were extremely variable:...

Spatial distributions of depth‐averaged water velocity, shear and apparent bed load velocity are mapped for the first time in a long reach wandering gravel river, lower Fraser River, British Columbia. Spatially intensive acoustic Doppler current profiler (aDcp) measurements were collected on falling limbs two freshets. Flow year was near threshold motion, whereas second discharge exceeded bankfull. interpolated from point data using kriging. Joint density functions flow depth throughout...

The development of a fully three-dimensional finite volume morphodynamic model, for simulating fluid and sediment transport in curved open channels with rigid walls, is described. For flow field simulation, the Reynolds-averaged Navier–Stokes equations are solved numerically, without reliance on assumption hydrostatic pressure distribution, curvilinear nonorthogonal coordinate system. Turbulence closure provided by either low-Reynolds number k−ω turbulence model or standard k−ε both which...

Key points1. Topography derived from high-resolution terrestrial laser scanning and aDcp 2. Horizontal eddy viscosity calibration essential to predict cross-channel velocities 3. Bed roughness length scales with 1.

Abstract Gold mining along 525 km of the Fraser River between 1858 and 1909 added an estimated 1.1 × 10 8 t tailings, half gravel rest finer, to river's natural sediment load. We simulate response using a 1‐D multigrain size morphodynamic model. Since premining conditions are unknown modern data insufficient for tuning process representation, we devised novel modeling strategy which may be useful in other data‐poor applications. start model from smoothed version longitudinal profile with bed...

This research compares the spatially distributed turbulent wake characteristics associated with a submerged bed-mounted cube at three flow stages. The experiments were conducted in large laboratory flat-bed flume high Reynolds numbers. velocity gradient under each condition was kept near constant, which yielded novel data that isolated effect of depth on structure wake. Spatially instantaneous three-dimensional velocities recorded using multiple acoustic Doppler velocimeters (ADVs). With...

Flow within an alluvial channel bend is significantly affected by geometry, including curvature ratio (bend radius/channel width, R/B) and aspect (channel width/flow depth, B/H). High bends (R/B≤3) can experience substantially more erosion than milder bends. This study employs a three-dimensional Reynolds-Averaged Navier-Stokes (RANS) model to investigate the effects of on flow with respect high (R/B=1.5) base case in 135° bend. Experimental data are used validate RANS predictions for flat...

River confluences are nodes where the unique hydrological processes of two rivers meet, resulting in complex flow structure and water quality mixing processes. Thus, greater food availability habitat complexity can occur at a confluence, making it hotspot for fish productivity diversity. Nonetheless, studies that relate community traits to specific characteristics large river limited. Two field surveys were conducted confluence between Yangtze Poyang Lake outflow channel involving...

Abstract The behaviour of velocity profiles and shear for non-uniform flow in gravel-bed rivers is studied, with the objectives: (a) to test a new method estimation that based on boundary layer parameters, compare it log law parabolic law; (b) consider influence non-uniformity outer region profiles; (c) investigate effect aspect ratio profiles. For primary study river, mid-channel were analysed relative submergence ranging from 9.7 33.3 channel sections ratios between 16.2 50. Velocity...

A series of laboratory flume experiments were performed to study the effect stream barbs on flow field dynamics and sediment erosion in a 135° mobile-bed channel bend. Stream (also known as spur dikes or submerged groynes) are low-profile linear rock features that redirect high velocity away from outer bank bends. Unlike emergent groynes, nature these structures creates unique combination horizontal shear (plunging type flow) vertical (at groyne tip). Spatially dense, frequency data...

As gravel-bedded rivers fine in the downstream direction, they characteristically exhibit an abrupt transition from gravel- to sand-bedded conditions. The prevailing theory for why gravel-sand transitions emerge is based on bed load sorting of a bimodal sediment. abruptness thought be consequence sand overwhelming mixture once it reaches critical coverage bed. role suspension plays development has not been fully appreciated. Fraser River, British Columbia, archetypical with "diffuse...

Research Article| September 01, 2015 The influence of grain size on the velocity and sediment concentration profiles depositional record turbidity currents M. Tilston; Tilston 1Department Earth Sciences, University Ottawa, K1N-6N5 Ontario, Canada Search for other works by this author on: GSW Google Scholar R.W.C. Arnott; Arnott C.D. Rennie; Rennie 2Department Civil Engineering, B. Long 3Centre Eau Terre Environnement, INRS, Québec City, G1P-4S5 Québec, Author Article Information Publisher:...

Abstract Maps are presented of the spatial distribution two‐dimensional bedload transport velocity vectors. Bedload data were collected using bottom tracking feature an acoustic Doppler current profiler (aDcp) in both a gravel‐bed reach and sand‐bed Fraser River, British Columbia. Block‐averaged vectors, vectors interpolated onto uniform grid, revealed coherent patterns distribution. Concurrent Helley‐Smith sampling corroborated trends observed map. Contemporaneous 2D vector maps near‐bed...

Detailed mapping of bathymetry and three‐dimensional water velocities using a boat‐mounted single‐beam sonar acoustic Doppler current profiler (ADCP) was carried out in the vicinity two submerged wing dikes located Lower Missouri River near Columbia, Missouri. During high spring flows become submerged, creating unique combination vertical flow separation overtopping (plunging) conditions, causing large‐scale turbulent structures to form. On three different days for range discharges, sampling...

Abstract Experimental results of the mean flow field and turbulence characteristics for in a model channel bend with mobile sand bed are presented. Acoustic Doppler velocimeters (ADVs) were used to measure three components instantaneous velocities at multiple cross sections 135° two separate experiments different stages clear water scour conditions. With measurements through it was possible map changes both spatial distribution velocity Reynolds shear stresses. Turbulent stresses known...

Abstract Most rivers exhibit regions of strong channel curvature that are characterized by more complex and variable flow erosion patterns, compared to lower curvature. Studies investigating high‐curvature bends using eddy‐resolving techniques have been limited, the effect bend angle on has rarely investigated. This study investigates in a 135° nonerodible bank open high curvature: ratio radius curvature, R , width, B is 1.5. The bathymetry obtained during final stages clear water scour...

This study used fully spatially distributed three-dimensional (3D) velocity data for the improved calibration of a 3D hydrodynamic model. The conventional methods do not account spatial distribution flow field. compared results proposed approach with those in literature to show how choosing different can change model predictive capability. advance prediction complexity; consequently, it enhances potential estimation river processes such as channel morphodynamics and contaminant mixing. To...

Abstract Hydropower is considered a renewable form of energy production, but generating electricity from rivers not always environmentally benign. The global demand for renewables increasing rapidly as fossil fuels are gradually phased out, so will continue to be subjected the pressures imposed by hydropower decades come. Finding ways operating plants that limit impacts on downstream river ecosystems therefore pressing concern. Usually, these cause marked and rapid fluctuations in flow...

This study introduced a new riprap placement design for the purpose of reducing bridge pier scour. The consisted embedding layer around pier, flush with surrounding bed, depression to help guide horseshoe vortex. countermeasure was tested among other conventional designs in clear-water flow conditions and transition-flow conditions. condition is evolution period from clear water live bed where has yet reach an equilibrium state. found reduce greatly depth volume scour both conditions, up...

Abstract Streamflow data is often the most critical input for hydrologic and hydraulic research, modeling, design studies. measurement using close range non‐contact sensing such as image velocimetry a new technique that yet far from maturity. Most current image‐based surface techniques use correlation approaches require user to run algorithms. This can bias results if operator inexperienced. The main goal of this study develop novel, accurate fast river scheme called RivQNet does not...