Bruce MacVicar

University of Waterloo | UWaterloo · Department of Civil and Environmental Engineering

Wood is an essential component of rivers and plays a significant role in ecology and morphology. It can be also considered as a risk factor in rivers due to its influence on erosion and flooding. Quantifying and characterizing wood fluxes in rivers during floods would improve our understanding of the key processes but is hindered by technical chall...

The quantification of bedload sediment transport in rivers is possible from statistics of individual particle displacements. However, there is a lack of empirical basis for a universal relation between particle displacement distance and hydraulic drivers. Previous work suggests that a simple linear relation exists between the energy of a flood and...

Pool‐riffle units are naturally occurring topographical elements of rivers. Various hypotheses have been proposed to describe how the hydrodynamics in pool‐riffle units may lead to scour and sediment transport. However, most hypotheses have focused on time averaged properties, and a physical mechanism for observations of high near‐bed velocities ha...

Urbanization typically leads to erosion and instability in rivers, and many management and restoration strategies have been developed to dampen the worst impacts. Stream power, defined as the rate of energy expenditure in a river, is a promising metric for analyzing cumulative effects. In this paper we describe a spatial decision support system cal...

Radio Frequency Identification (RFID) transponders are now widely used to track sediment in a variety of environments. A recent innovation placed the transponder inside of a rotating inner mechanism that is designed to minimize missed detections due to burial and shielding or ‘signal collision’ effects between tracers, while also allowing a rapid m...

Pool-riffle sediment and flow dynamics have been studied for many years, but relatively little work has investigated how variations in flow and sediment regimes might lead to a diversity of pool-riffle morphologies. In this letter we analyse a database of quantitative and qualitative measurements from sites where pool-riffle morphologies have been...

Wood is an integral part of rivers that can have both positive and negative impacts on natural systems and infrastructures. Different techniques have been developed to quantify wood flux or discharge in rivers. Among them, the stream‐side video monitoring technique has proven effective for at‐a‐station wood monitoring with a high temporal and spati...

Flume experiments are popular tools for investigating questions of sediment transport and channel evolution but are less often used to assess the performance of river restoration projects. We present the design, construction, and preliminary results of a set of flume experiments that aim to test the performance of a river restoration design in Pent...

Successful watershed planning requires a watershed-scale approach to the assessment of erosion hazards. Stream power, or the rate of energy expenditure of flowing water, is a driver of river erosion and morphologic change. Stream Power Index for Networks (SPIN) is a newly developed GIS-based toolbox that uses simple inputs to calculate total stream...

Bedload particle tracking is a technique used to better understand sediment dynamics in rivers. Despite technical advances, tracers may be missed in field surveys. The missed tracers may bias the study results even where recovery rates are high, for example if they are preferentially buried close to the seeding site or transported downstream of the...

Wood is an essential component of rivers and plays a significant role in ecology and morphology. It can be also considered a risk factor in rivers due to its influence on erosion and flooding. Quantifying and characterizing wood fluxes in rivers during floods would improve our understanding of the key processes but are hindered by technical challen...

Natural dynamics of river floodplains are driven by the interaction of flow and patchy riparian vegetation, which has implications for channel morphology and diversity of riparian habitats. Fundamental mechanisms affecting the dynamics of flow in such systems are still not fully understood due to a lack of experimental data collected in natural env...

Wood flux (piece number per time interval) is a key parameter for understanding wood budgeting, determining the controlling factors, and managing flood risk in a river basin. Quantitative wood flux data is critically needed to improve the understanding of wood dynamics and estimate wood discharge in rivers. In this study, the streamside videography...

In partially-alluvial channels, an understanding of cover formation over a non-alluvial substrate is necessary for effective river management or restoration. Urban rivers, for example, are often sediment starved such that the underlying substrate may be exposed. Few experiments have investigated cover development in meandering channels, particularl...

Natural dynamics of river floodplains are driven by the interaction of flow and patchy riparian vegetation, which has implications for riverbed morphology and diversity of riparian habitats. Fundamental mechanisms affecting the dynamics of flow in such systems are still not fully understood due to a lack of experimental data collected in natural en...

The alluvial cover in channels with non‐alluvial beds is a major morphologic feature in these rivers and has important geomorphic and ecologic functions. Although controls on the extent of the alluvial cover have been previously researched, little is known about the role of channel meanders in shaping the three‐dimensional morphology and bedload tr...

A side orifice is an important type of hydraulic structure which is used widely in irrigation and waste management systems to divert desired discharges from a main channel or to distribute the flow within the basins. Circular pipes flowing partially full are often used in these systems, but existing predictive relations developed for rectangular ch...

Successful management of natural and engineered channels with discontinuous allu-vial cover requires knowledge of how the cover develops and evolves. We report on physical model experiments designed to compare alluvial cover dynamics in straight and sinuous fixed-bed channels at a range of gravel-bed material supply rates and constant discharge con...

This research is part of a project to understand urban channel degradation and assess the benefits of stormwater management and channel restoration. Specific objectives are to i) describe the development and field testing of a new Radio Frequency Identification (RFID) tracer with a self-righting inner ball (a 'Wobblestone') and ii) describe the var...

Wood in rivers plays a major role both ecologically and morphologically. In recent decades, due to human activities in the river channels and along the riparian zone, wood obstruction and jamming has exacerbated flooding hazards and infrastructure damage. Therefore, it is necessary to quantify the wood flux and discharge in rivers to improve wood h...

Early in their career, engineering students sometimes have difficulty linking academic concepts between courses and the interests that led to their enrollment. We present a design “interlude” event that is intended to improve experiential inductive learning and the vertical and horizontal integration of engineering courses. In this exercise, second...

Although there is increasing consensus that river restoration should focus on restoring processes rather than form, proven techniques to design and monitor projects for sediment transport processes are lacking. This study monitors bedload transport and channel morphology in a rural, an urban unrestored, and an urban restored reach. Objectives are t...

Watershed urbanization and stormwater management (SWM) alter the hydrologic processes of rivers. Although differences in channel morphology and total sediment yields pre- and post- urbanization have been documented, little is known about how the altered hydrology affects the grain-scale bedload transport dynamics. This study aims to characterize th...

Watershed urbanization and stormwater management (SWM) alter the hydrologic processes of rivers. Although differences have been documented in channel morphology and sediment yield pre‐ and post‐ urbanization, little is known about how the modified hydrology affects grain‐scale bedload transport dynamics. This study aims to characterize the bedload...

Motivation: Plunging flow, defined as the downward movement of high velocity fluid, has been observed in canyon pools, alluvial pools, and lab/numerical experiments and is thought to be important for pool scour and maintenance of alluvial forms. However, plunging flow is not always observed. A hydraulic explanation is needed for why it may or may n...

Radio frequency identification (RFID) tracer stones are an increasingly popular tool in sediment transport research. A key limitation of RFID tracers is the sensitivity of their detection zone shape to the orientation of the transponder. The variability in detection zone shapes reduces detection rates by obscuring tracer positions and creating comp...

Shear velocity and von Kármán’s coefficient can be considered as scaling parameters for the characterization of velocity and turbulence distributions. However, few studies have assessed their accuracy in rivers. We apply a finite ensemble averaging procedure to obtain statistically representative profiles for evaluating the effects of sampling peri...

Widespread growth of cities, the association of trace metals with urban runoff, and the potentially deleterious effect of metals on aquatic ecology have made it important to understand the distribution and transport of metals through surface water channel networks. The Don River in Toronto, Canada has been identified as an Area of Concern for pollu...

Sediment transport studies that use radio frequency identification (RFID) tracers are now common in hydraulic studies because of the information the technique provides on the spatial and temporal variability of sediment movement. The technique has been underused relatively in laboratory studies, however, because of issues related to tag orientation...

By numerical simulations of turbulent flow in isolated poolriffle units with various riffle heights, four different types of vortices were found and named as follows: surface rollers (SR), corner rollers (CR), ramp rollers (CR), and axial tails (AT). Surface rollers are shaped on the flow surface due to submerged hydraulic jump or any obstacles in...

Laboratory experiments were carried out in a small openchannel hydraulic flume at the Université de Sherbrooke. A PIV and an acoustic Doppler velocity profiler (Vectrino II (VII)) were used to measure high frequency velocities in profiles along the centreline of a small openchannel flume. Two background turbulence levels were tested. Comparisons we...

The impact of urbanization on stream channels is of interest due to the growth of cities and the sensitivity of stream morphology and ecology to hydrologic change. Channel enlargement is a commonly observed effect and channel evolution models can help guide management efforts, but the models must be used in the proper geologic and climatic context....

The change of land use from rural to urban tends to radically alter the implicated streams, typically infecting them with many symptoms of the “urban stream syndrome”. The key driver of the syndrome is hydrologic change, typically the product of increased imperviousness and efficient conveyance and characterized by frequent larger flows, increases...

Pools and riffles are common morphologic units in rivers and restoration projects. The deeper parts of undulations in the bed are called pools, whereas the shallower parts are riffles. They can be shaped naturally or artificially to control the stream energy, improve fish habitats, or control the sediment transport rate. Previous studies in the fie...

High resolution velocity profiling instruments have enabled a new generation of turbulence studies by greatly increasing the amount and quality of simultaneous velocity measurements that can be obtained. As with all velocity profiling instruments, however, the collected data are susceptible to erroneous spikes and poor quality time series that must...

Velocity profiling instruments offer huge advantages over single point instruments in terms of the speed and resolution of data collection but continue to suffer from measurement errors. In practical terms, the rate at which we can collect data now greatly exceeds the rate at which we can clean and check its validity. A number of de-spiking algorit...

Instream channel restoration is a common practice in river engineering that presents a challenge for research. One research gap is the development of monitoring techniques that allow for testable predictions of sediment transport and supply. Here we use Radio Frequency Identification (RFID) transponders to compare the short-term (1-year) sediment t...

Pools and riffles are a common sedimentary bedform in gravel-bed rivers and a frequent template for stream restoration, yet researchers agree on surprisingly little about how they work. Sediment queueing mechanisms, size sorting, lateral concentration of flow, near-bed velocity reversal, and turbulence have all been invoked to explain how they main...

Pools and riffles are common morphological features in rivers that are frequently used but poorly specified analogs in restoration design. Here, straight two-dimensional (2D) bedforms are conceptualized as perturbations and flow recovery is measured in a laboratory flume with an array of ultrasonic Doppler velocity profilers (UDVPs). The objectives...

Pools and riffles are common morphological features in rivers that are frequently used but poorly specified analogs in restoration design. Here, straight two-dimensional (2D) bedforms are conceptualized as perturbations and flow recovery is measured in a laboratory flume with an array of ultrasonic Doppler velocity profilers (UDVPs). The objectives...

Since the earliest use of this technology, a growing number of researchers have employed Passive Radio Frequency Identification (RFID) transponders to track sediment transport in gravel rivers and coastal environments. RFID transponders are advantageous because they are inexpensive, durable and use unique codes that allow sediment particle mobility...

The Nortek Vectrino II™ (VII) is a commercially-available instrument designed for velocity profiling, yet few tests of the instrument performance have been published. The objectives here are to: 1) demonstrate the new analysis tool called the Multi Instrument Flow Turbulence Treatment Toolbox (MIFTTT); 2) detail an autoregressive moving average (AR...

Urbanized rivers are heavily impacted by human activities that modify their hydrology and morphodynamics. This study focuses on Wilket Creek, a small gravel-bed river (14.5 km2 drainage area, 12 m width, 1% slope, D50 = 0.039 m) located in the suburban area of Toronto. Existing infrastructures are threatened by incision and lateral migration of the...

Case studies of energy loss over bed forms in gravel-bed rivers are needed to determine local loss coefficients for modeling and design. In this study, an intense field campaign in two rivers is used to determine energy loss and calculate local energy loss coefficients (Ke) for riffle-pool units. Velocity head, water surface elevations, and energy...

Pools are common features of many rivers, yet a comprehensive understanding of the physical processes that lead to their formation has remained elusive. Such understanding is vital to address management objectives and guide restoration efforts. The objectives of this chapter are to (i) briefly review the dynamics of pool-riffle sequences; (ii) desc...

[1] The scaling relation between channel width and the spacing of macroscale bed forms has long interested earth scientists and engineers. The current paper conceptualizes flow over such macro bed forms using perturbation theory. The objectives are to characterize the response of flow to pressure gradients that occur in convectively accelerating fl...

The transport of wood in rivers during floods is an important process that underlies differences in habitat and morphology between water courses and regions. Quantitative data are needed to properly address management objectives and balance wood budgets. In this study we use a streamside video camera to detect wood passage and measure quasi-instant...

Quantitative data on the transport of wood in large rivers are needed to address management objectives and balance wood budgets. Streamside video cameras are suitable if image quality and wood visibility are suffi-cient. The objectives of this study are to verify a wood detection and measurement procedure and to quanti-fy the relation between wood...

Complex geometry exerts a strong influence on secondary flows in rivers. To examine this effect, studies that have adopted a reductionist strategy to isolate a single type of non-uniform geometry are reviewed. Five types of identified non-uniform geometries are curved side walls, a non-uniform flow depth, a non-uniform channel width, a non-uniform...

Multiple hypotheses have been advanced to explain the occurrence of pools in gravel bed rivers. These hypotheses were developed without a hydrodynamic model of how open channel flow is affected by pools, and it is not clear why and when the flow phenomena they describe might occur. Laboratory experiments are warranted to improve our understanding o...

The transport of wood in rivers during floods is an important process that underlies differences in habitat and morphology between water courses and regions. Quantitative data are needed to properly address management objectives and balance wood budgets. In this study we use a streamside video camera to detect wood passage and measure quasi-instant...

Forced riffle-pools occur in gravel-bed rivers where a large nonalluvial element leads to local scour and deposition. To manage rivers where this type of morphology is found and to specify restoration measures that mimic this process, more field data on sediment mobility in forced riffle-pools is needed. The objectives of this study are to describe...

Riffles and pools are defined by changes in bed elevation. We present clear evidence that bulk flow velocity cannot be assumed to be related to shear stress in pools and riffles due to the variability in channel bed morphology and to the presence of nonuniform flow. A criterion based on the bulk velocity that is driven by changes in channel width,...

Wood plays an important role in stream ecology and geomorphology. Previous studies of wood in rivers have quantified spatial distributions but temporal dynamics remain poorly documented. The lack of such data is related to limitations of existing methods, especially when applied to large rivers. Five techniques are field-tested to assess their util...

Previous work in the field and in laboratory experiments has demonstrated the central role that convective acceleration and deceleration have on the hydraulic characteristics of many macro-bedforms such as pools and riffles. However, although macro-bedforms are known to scale with channel width, no experimental research has yet isolated the effect...

Sediment transport is of fundamental importance to river dynamics. Tracers are frequently used to characterize this process, but existing techniques are subject to a number of limitations that result in low recovery percentages. The use of Passive Integrated Transponders (PITs) has been shown to be more effective than other techniques, but this met...

Le transport sédimentaire est une composante fondamentale de la dynamique morphologique des cours d’eau. Des traceurs sont fréquemment utilisés pour caractériser ce transport, mais les techniques existantes sont soumises à de nombreuses limites méthodologiques et présentent notamment de faibles taux de retours. L’utilisation de transpondeurs passif...

Sediment transport is of fundamental importance to river dynamics. Tracers are frequently used to characterize this process but existing techniques are subject to a number of limitations that result in low recovery percentages. The use of Passive Integrated Transponders (PITs) has been shown to be more effective than other techniques, but this meth...

Riffle pools are fundamental units of many gravel bed rivers. Considerable debate exists as to an appropriate hydrodynamic model for this bed form type. Sampling designs in previous studies have not always anticipated the degree of spatial variability of flow parameters in riffle pools nor considered the effect of the nonuniform boundary on hydrody...

In the companion article, we present mean velocity and turbulence intensity statistics at a range of discharges in a forced riffle pool unit and show that the distributions of mean velocity and turbulence are characteristic of nonuniform flows. The objectives of this paper are to describe the spatial and temporal variability of the structure of tur...

Two field tests were completed to compare the performance of an electromagnetic current meter (ECM) with that of an acoustic Doppler velocimeter (ADV) in gravel-bed rivers. Research was particularly motivated by the need to measure flow properties in highly energetic turbulent flows. Measurements were made at two field sites, one at moderate veloci...

The formation of bed forms in gravel bed rivers acts as a control on stream ecology and the response of rivers to floods. Available models do not reproduce the range of observed bed forms and do not consider interactions between the bed and flow hydraulics. The model presented here considers a gravel bed river as a complex system in which sediment...

This thesis is a study of organization in rivers. Riffle-pool sequences determine the macro-scale structure in a broad range of gravel-bed rivers. They are defined by a scaling relation with stream width, sorting of sediment by size, and the formation of lateral bars. These features are of interest because they exert a significant control on stream...

In gravel-bed rivers, measuring the displacement of individual grains by fluid flow is essential in order to understand sediment transport processes and to investigate changes in channel morphology. We present preliminary results of a new technique that traces pebble movements by inserting 23 mm passive integrated transponders (PIT) into individual...

Contributions by Canadian fluvial geomorphologists between 1999 and 2003 are discussed under four major themes: sediment yield and sediment dynamics of large rivers; cohesive sediment transport; turbulent flow structure and sediment transport; and bed material transport and channel morphology. The paper concludes with a section on recent technical...

An analytical method for determining the stable hydraulic geometry of restored river channels is presented and is offered as an alternative to intuitive or empirical methods. A design chart is produced, and its application to river restoration is demonstrated through application to a hypothetical river.