Colin Rennie

• PhD
• Professor at University of Ottawa

Landscape scale bedrock erosion is the integration of bedrock erosion at the reach scale, which is driven by particle impacts from sediment transport caused by near‐bed hydraulics. Plunging flow hydraulics have been identified in bedrock canyons and cause velocity profile inversions, which enhance near‐bed velocities, sediment transport, and the po...

Optical and radar remote sensing are both used to map surface water features. Since use cases range considerably in the literature between applications, a direct comparison is warranted to assess how well each perform in a wide range of geographic settings using a range of classification methods. Thus, surface water maps generated from Sentinel-1 S...

Surface water maps are useful in a variety of disciplines from climate change analysis to water resource management. Multispectral satellite imagery can be used to derive such surface water maps using a variety of image processing methods. The medium resolution Sentinel-2 multispectral satellite imagery catalogue is currently used extensively for s...

A study on the amount of river hydrokinetic energy (HKE) available at a bedrock depth constriction was conducted on the Spanish River in Ontario, Canada. Far fewer, if any, river HKE analyses have been conducted at locations where a depth constriction creates high energy flow conditions compared to the number of HKE studies where slope or width cre...

The fluid dynamics of channel confluences are highly complex due to flow separation and secondary currents. Although numerous studies in the past few decades have focused on the numerical simulation of confluence flow, deformed beds were rarely used. This study attempts to address this issue through numerical simulation of the flow behavior in an o...

The fluid dynamics of channel confluences are highly complex due to flow separation and secondary currents. Although numerous studies in the past few decades have focused on the numerical simulation of confluence flow, deformed beds were rarely used. This study attempts to address this issue through numerical simulation of the flow behavior in an o...

The fluid dynamics of channel confluences are highly complex due to flow separation and secondary currents. Although numerous studies in the past few decades have focused on the numerical simulation of confluence flow, deformed beds were rarely used. This study attempts to address this issue through numerical simulation of the flow behavior in an o...

The scour due to the highly turbulent tsunami inundation is also a major threat to nearshore infrastructure [Nakamura, et al., 2008]. Research on local sediment erosion during tsunami events has shown a correlation between scour formation, pore pressure variations, and soil liquefaction [Mioduszewski and Maeno, 2003]. To understand the structures’...

The International Electrotechnical Commission standards for estimating river hydrokinetic energy resources have not yet been tested in practice. With the intent of providing practical considerations to communities and turbine developers of which river characteristics may impede hydrokinetic energy estimation, six river locations were surveyed with...

Woody debris pieces accumulated as a jam in front of a bridge pier block the bridge opening and may enhance the scour process, increasing the potential for bridge failure. This paper presents a numerical method using immersed boundary conditions for the debris jam with a mobile bed k-omega turbulence model to simulate the influence of dynamic debri...

Forecasting the time development of scour depth at bridge pier foundations is of great significance to mitigate or avoid the potential failure of bridges. Presently, several models have been developed to predict the scour depth at the base of bridge piers in the case of flood events. This study summarizes existing models for the temporal evolution...

Hydrokinetic energy resource assessment is a crucial prerequisite for strategic turbine deployment and energy extraction. Despite advancements in analytical tools, resource assessment is often completed without detailed investigation of spatial and temporal flow variation and implications on optimal turbine placement. A case study was conducted on...

Streamflow data is often the most critical input for hydrologic and hydraulic research, modeling, and design studies. Streamflow measurement using close range non‐contact sensing such as image velocimetry is a new technique that is yet far from maturity. Most current image‐based surface velocimetry techniques use correlation approaches that require...

A method is introduced to cluster instantaneous vortices using a density-based spatial clustering technique to better distinguish overlapping secondary circulation from different mechanisms. Applying the method to large eddy simulation results of a tight open channel bend, two secondary circulation sub-cells are distinguished: the inner bank cell a...

A woody debris jam around a bridge pier causes a change in flow structure and results in additional scour and an increase in the hydraulic head upstream of the pier, threatening its stability and safety. In the present paper, the spatio-temporal formation of a dynamic woody debris jam formed piece by piece of debris wood was used to investigate the...

Tailings dams (TD) are usually located in valleys that are not easily accessible and hence one global digital elevation model (DEM) is used in most of the TD breach outflow modelling studies but the challenges this impose when calibrating visco-plastic rheological models has not been fully investigated. Implications of using GeoBase DEMs for model...

The fluid dynamics of open channel confluences are highly complex due to the flow separation, mixing and secondary currents. Although numerous studies in the past few decades have focused on the numerical simulation of confluence flow, deformed beds were rarely used. This study attempts to address this issue through numerical simulation of the flow...

The Bow River's 2013 flood was the costliest natural disaster in the City of Calgary's history. Flood-induced bar growth and subsequent riparian vegetation colonization at many locations has constricted the river channel, which increases flood risk. Although bar removal has been widely employed as a flood mitigation strategy, its effectiveness and...

Plain Language Summary Incision in bedrock rivers sets the pace of landscape evolution by controlling the rate of geomorphic responses to climatic and tectonic signals, yet the processes driving incision occur at much finer scale than those captured by landscape evolution models. Local bedrock river incision is driven by flow structures that are no...

A reach of the Rouge River in Quebec, Canada, was numerically modelled and physically surveyed to understand how consideration of multiple flow conditions affect the estimation of hydrokinetic energy in a river reach. Field measurements of velocity, bed elevation, and water surface elevation were collected using an acoustic Doppler current profiler...

Current research investigating ice-covered bridge pier scour has focused on the effects of fully developed ice jams. However, based on observations at various stages of development, ice covers are not always fully developed. This experiment investigated pier scour at various stages of a simulated floating ice jam’s development, with a constant flow...

The present paper aims to investigate the evolution of velocity fields as well as secondary flows in an open channel bend under the influence of negatively buoyant jets. A 135-degree open channel bend was used for experiments, and the jet nozzle was located along the outer bank in the straight section upstream of the bend. Efforts were made to spec...

A field investigation was carried out in March 2019 at the large river confluence between the Yangtze River and the outflow channel with a large inner-side floodplain of Poyang Lake using acoustic Doppler current profiling (ADCP) and water quality sampling. The study was intended to complement previous field studies carried out under different flow...

This study introduced a new riprap placement design for the purpose of reducing bridge pier scour. The design consisted of embedding a layer of the riprap around the pier, flush with the surrounding bed, with a depression to help guide the horseshoe vortex. The new countermeasure design was tested among other conventional riprap placement designs i...

Approximation of bed and wall (bank) stresses in confined, narrow bedrock rivers is key to accurately assessing hydraulic roughness, sediment transport, bedrock erosion and the morphodynamics of bedrock channels. Here, we partition bed and wall stresses using the ray‐isovel model (RIM) and field observations. We used the RIM to calculate the distri...

The width and depth of rivers is generally inversely related. For a given discharge, wider rivers tend to be shallower than narrower rivers, which are correspondingly deeper. This is particularly true in bedrock and mixed bedrock‐alluvial channels where deep pools occur downstream of lateral constrictions, downstream of which the channel becomes wi...

Experimental and numerical studies of flow structures in a strongly curved 135-degree laboratory flume were carried out to investigate the influence of negatively buoyant jets using the finite volume method. The performance results of three different turbulence models were investigated by comparing the numerical results with the experimental measur...

Hydrokinetic energy resource assessment is a crucial prerequisite for strategic turbine deployment and energy extraction. Despite advancements in analytical tools, resource assessment is often completed without detailed investigation of spatial and temporal flow variation and implications on optimal turbine placement. A case study was conducted on...

Dynamic ice processes can significantly affect various river characteristics such as hydraulics, sediment transport, water quality and morphology. River ice can also impede ship navigation and can induce flood hazard. Study of ice processes is thus crucial for understanding rivers in cold regions. These processes vary according to the four differen...

Confluences act as critical nodes in a river network as they affect flow, sediment transport, water quality and ecological patterns. A complete knowledge about hydro‐morpho‐sedimentary processes at river confluences is still incompleted and it has been usually accepted that secondary flows are weak because of the significant role of form roughness...

Bridge pier scour is a complex process, which is influenced by many parameters, including the presence of ice cover around piers. To better understand the influence of ice on bridge pier scour, an artificial ice cover, equipped with either a smooth or a rough surface, was constructed and tested experimentally. The ice cover was positioned on the su...

Hydropower is considered a renewable form of energy production, but generating electricity from rivers is not always environmentally benign. The global demand for renewables is increasing rapidly as fossil fuels are gradually phased out, so rivers will continue to be subjected to the pressures imposed by hydropower for decades to come. Finding ways...

Pore pressure and scour formation around coastal structures have been investigated in the past which led to a relationship between the hydrodynamics of tsunami waves and sediment erosion around coastal structures. With the objective of developing a comprehensive model to assess the interaction of hydrodynamic conditions, induced scour, soil pore pr...

The influence of channel side slope on flow in strongly curved channel bends is studied numerically. The performances of five different turbulence models are investigated. Comparison to experimental measurements demonstrates that the fully 3D numerical model can reliably simulate a channel bend flow field. Among the tested turbulence models, the re...

This research focuses on the development of a novel approach for monitoring and classifying different kinds of sea ice interacting with bridge piers in Northumberland Strait. Different ice types can have a varying impact on the navigability of a vessel or the loads on a structure. As such, the ability to monitor and classify different ice types aut...

Bridge pier scour poses major concerns for public safety and riverine communities because of its ability to undermine pier foundations. A new collar design is introduced as an improvement on the existing Flat Plate Collar (FPC). Uniquely, the three-dimensional collar is specifically designed to contain the horseshoe vortex and guide it safely downs...

Two acoustic Doppler current profilers working at three frequencies (3 MHz and 1MHz by Sontek M9 run at three different configurations and 2 MHz by StreamPro RDI) were deployed simultaneously to measure bedload characteristics in a laboratory flume. Seven different transport conditions were simulated using fine gravel and medium sand as sediment be...

This paper presents a model for local scour at submerged weirs with downstream slopes that uses a coupled moving-mesh and masked-element approach. In the developed model, the fluid-sediment interface is tracked using a moving-mesh technique, and the effects of the structure on the hydrodynamics and bed morphology are resolved using a masked-element...

Part of the difficulty in simulating or understanding the erosion of cohesive soils is the near impossibility of replicating field conditions, including the constantly varying pore water pressure and resulting seepage pressures in response to changing overlying flow depth and groundwater conditions. Unlike granular soils, for which pore pressures r...

This work reports on a computational fluid dynamics (CFD) model for flow and local scour around a pipeline in steady currents that uses a mixed moving-mesh and fixed-grid method. It performs mesh motions for bed conforming without considering the pipeline and then simulates the pipeline with a fixed-grid approach after the mesh motion process has b...

This paper provides an evaluation of a hydro-acoustic technique for efficient quantification of the bedload transport in riverine environments. Stationary bedload measurements were conducted simultaneously at different study sites, using three different acoustic Doppler current profilers (ADCP) working at four different frequencies. The raw apparen...

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...

This study aims to develop a surrogate methodology for quantification of the bedload transport in riverine environments by using acoustic devices. Bedload transport experiments were performed in laboratory conditions to test the capabilities of the acoustic current Doppler profilers (ADCP) to quantify the bedload velocity, concentration, and active...

This study aims to develop a surrogate methodology for quantification of the bedload transport in riverine environments by using acoustic devices. Bedload transport experiments were performed in laboratory conditions to test the capabilities of the acoustic current Doppler profilers (ADCP) to quantify the bedload velocity, concentration, and active...

It is reasonable to expect that hydro-morphodynamic processes in fluvial systems can affect fish habitat availability, but the impacts of morphological changes in fluvial systems on fish habitat are not well studied. Herein we investigate the impact of morphological development of a cohesive meandering stream on the quality of fish habitat availabl...

Stormwater ponds (SWPs) are widely utilized for flood and water quality control. Low-flow rates are common in SWPs, sometimes causing wind-driven currents to become the dominant hydrodynamic force during ice-free periods. Hence, it is essential to understand the influence of the wind-induced flow on stratification and dissolved oxygen (DO) concentr...

In cold climate, river ice can drastically affect flow regimes in various ice formation and breakup processes. Advent of high-quality monitoring systems in recent years has led to the vast application of imagery in river ice studies. Longterm shore-based monitoring along with the application of Unmanned Air Vehicles (UAVs) have been widely used rec...

Several studies have investigated the use of the bottom tracking (BT) mode of acoustic current Doppler profilers (ADCPs) for evaluating bedload transport. The raw apparent bedload velocity is usually noisy and contains erroneous data. This study investigates how bedload dynamics influence acoustic processes occurring at the riverbed (i.e., volume a...

Mixing in rivers is an important issue with many applications in water quality and water resource management. Mixing of effluents with ambient river water is especially important, particularly in river bends, where secondary circulation complicates the mixing process. By comparing measured trajectories from dye tests to velocimetry data measured wi...

A 524-km reach of Fraser River, British Columbia, was traversed, where the channel alternates between gravel-bedded reaches that are incised into semiconsolidated glacial deposits and bedrock-bound reaches, including Fraser Canyon. Continuous centerline acoustic Doppler current profiler survey and observations of bedrock confinement, supplemented w...

Forum papers are thought-provoking opinion pieces or essays founded in fact, sometimes containing speculation, on a civil engineering topic of general interest and relevance to the readership of the journal. The views expressed in this Forum article do not necessarily reflect the views of ASCE or the Editorial Board of the journal.

The catastrophic 2013 Alberta flood that inundated downtown Calgary was Canada's most costly flood and second most costly natural disaster. The flood caused five deaths, required evacuation of 100,000 people, and resulted in $6B in estimated damages. Subsequently, the Province of Alberta and City of Calgary have undertaken extensive engineered miti...

Stormwater retention ponds can play a critical role in mitigating the detrimental effects of urbanization on receiving waters that result from increases in polluted runoff. However, the benthic oxygen demand of stormwater facilities may cause significant hypoxia and trigger the production of hydrogen sulfide (H2S). This process is not well-document...

This study used fully spatially distributed three-dimensional (3D) velocity data for the improved calibration of a 3D hydrodynamic model. The conventional calibration methods do not account for the spatial distribution of the fully 3D flow field. This study compared the results of the proposed calibration approach with those in the literature to sh...

Validation and scaling of sophisticated physical and numerical fluvial hydraulic models to real field conditions are limited by temporal and spatial constraints of field measurement technologies. These limitations increase when analyzing hydraulic properties of complex river forms such as submerged bedrock canyons. The analysis of flow under these...

Despite several decades of intensive study of the morphological changes in meandering rivers, less attention has been paid to confined meanders. This paper studies the hydro-morphodynamics of two adjacent sub-reaches of a meandering creek, located in the City of Ottawa, Canada. Both of these sub-reaches are meandering channels with cohesive bed and...

The response of the semi-alluvial clay-bed Watts Creek is assessed subject to climate change. Climate impacts are expected to have regional variability, and few studies have assessed the impacts of future climate in a small urban watershed. The 21 km2 watershed located in Ottawa, Ontario, Canada is highly urbanised (68%) and agricultural (20%) with...

The pace of landscape evolution is set by bedrock erosion in canyons. This phenomenon occurs by various geological processes including plucking of bedrock blocks and abrasion by saltating bedload and suspended load in highly turbulent flows. For a better understanding of the river flow characteristics in bedrock rivers, a comprehensive study of flo...

This study aims at hydrodynamic modelling of Bow River, which passes through the City of Calgary, Canada. Bow River has a mobile gravel bed. Erosion and deposition processes were exacerbated by a catastrophic flood in 2013. Channel banks were eroded at various locations, and large gravel bars formed, which could lead to water level changes and acco...

Due to progressive erosion of the new Urucurituba Channel, the Amazon River has recently captured almost all discharge from the lower Araguari River (Amapá-AP, Brazil), which previously flowed directly to the Atlantic Ocean. These recent geomorphological changes have caused strong impacts on the landscape and hydrodynamic patterns near the Araguari...

Improper design and maintenance of stormwater ponds (SWPs) may lead to hypoxic conditions, poor water quality and the production of hydrogen sulfide (H2S). The objective of this study is to develop a comprehensive understanding of hypoxic conditions of SWPs, with a focus on the potential for H2S production and emission. This study was conducted at...

In comparison to sand and gravel, cohesive soils, and clays in particular, present significant challenges when critical entrainment thresholds and erosion rates are to be determined for a particular basin or modeled in the laboratory. A wide variation in cohesive soil characteristics and behavior is usually encountered, even within relatively short...

Given the importance of pressure gradients in driving secondary flow, it is worth studying how the modelled flow structures in a natural river bend can be impacted by the assumption of hydrodynamic pressure. In this paper, the performance of hydrostatic versus nonhydrostatic pressure assumption in the three-dimensional (3D) hydrodynamic modelling o...

River hydraulics is drastically influenced by the presence of river ice, which inevitably occurs in cold regions. Terrestrial monitoring of river ice, using a time-lapse camera system on the Lower Nelson River, northern Manitoba, Canada, was conducted for a comprehensive study of the effects of river ice cover on hydraulic characteristics. An autom...

Stormwater retention ponds have become an integral component of stormwater management across the world. Under prolonged hypoxia, these ponds are capable of releasing large quantities of hydrogen sulfide (H2S) gas. In this study, water quality constituents and bacterial communities in sediment were analyzed in two stormwater retention ponds, RSP1 (r...

Acoustic Doppler velocity profilers (ADVP) measure the velocity simultaneously in a linear array of bins. They have been successfully used in the past to measure three-dimensional turbulent flow and the dynamics of suspended sediment. The capability of ADVP systems to measure bedload sediment flux remains uncertain. The main outstanding question re...