Pascale Biron | Concordia University (Canada) (original) (raw)

Papers by Pascale Biron

Integrating hydrogeomorphological principles into the restoration of degraded rivers can achieve ... more Integrating hydrogeomorphological principles into the restoration of degraded rivers can achieve sustainable results for a variety of objectives and human benefits that are consistent with the potential functioning of rivers as well as their uses. Despite recent management approaches inspired by these principles, several restoration projects largely involve controlling river processes and target specific one-dimensional objectives often associated with the habitat of a few high-valued fish species or with rivers steadiness and aesthetics. Although there is overall a lack of post-project monitoring, several projects appear to have failed or had mixed success. This research aims to answer the question: What are the real drivers behind river restoration projects? Four restoration projects in Quebec (Canada) were characterized through a qualitative research process of support and interviews with the organizations running them as well as with two representatives of ministries involved in...

Canadian Water Resources Journal, Feb 23, 2016

There is great interest worldwide to reconnect floodplain wetlands to their rivers. Whilst the su... more There is great interest worldwide to reconnect floodplain wetlands to their rivers. Whilst the surface water connection between rivers and wetlands is fairly well understood, the linkages via groundwater are not well known. In this study, it is hypothesized that the significance of the groundwater pathways between rivers and wetlands is largely determined by the geomorphic setting of the riverine corridor. This was tested by measuring the response of water levels and temperatures in floodplain groundwater and in wetlands to river pulses in two geomorphologically-distinct riverine corridors in

Ecology and the Environment, Aug 18, 2009

Despite the widespread use of in-stream structures in stream restoration projects to enhance the ... more Despite the widespread use of in-stream structures in stream restoration projects to enhance the quality of physical habitat, it is only recently that the hydraulics of these structures have been studied in detail, typically using simplistic geometries in laboratory experiments. The objective of this study is to examine hydraulics around complex flow deflectors using a combination of laboratory, field and three-dimensional (3D) Computational Fluid Dynamics (CFD) approaches. In the laboratory, Acoustic Doppler Velocimeter (ADV) measurements revealed that flow overtopping the structure modifies the scour zone and bed shear stress pattern compared to a greater structure height. In the field, a 3D CFD model, which was calibrated at low flow using ADV and Particle Image Velocimetry measurements, was used to investigate both low and high flow (overtopping) conditions. A complex 3D pattern in the recirculation zones downstream of the deflectors is observed in the overtopping simulations, highlighting the limits of habitat structure studies based on depth-averaged (2D) models. The comparison with laboratory data is complicated by the fact that a dug pool was used in the field, which does not correspond to the position of the pools that developed near deflectors over a mobile bed in the laboratory. As natural rivers exhibit a wide range of discharges with various overtopping ratios, it is essential to pursue work using 3D CFD to test how different deflector height, length and angle designs affect the position and dimension of scour zones and the long-term viability of fish-habitat restoration projects.

Journal of Computing in Civil Engineering, May 1, 2013

ABSTRACT Sharp open channel bend flows are highly three-dimensional because of the combined effec... more ABSTRACT Sharp open channel bend flows are highly three-dimensional because of the combined effects of secondary flow, large free-surface variations, and flow separation along the inner bend wall. A comprehensive analysis was performed to determine the best modeling parameters to study the open channel sharp bend flow. Comparisons of the simulation results were made from two commercial codes, three turbulence models [k-epsilon renormalization group (RNG), Reynolds stress model (RSM), and large eddy simulation (LES)], two flow domain representations [Cartesian and body-fitted coordinate (BFC) grids], and three water surface treatments [rigid lid, porosity, and volume of fluid (VOF)]. Based on a comparison with experimental data, the best results were obtained with software using the RSM and VOF approach. Adequate representation of counter-rotating secondary flow cells in the channel downstream of the bend requires both the appropriate treatment of the channel free surface and a turbulence model that can resolve the anisotropy of turbulence. DOI: 10.1061/(ASCE)CP.1943-5487.0000209. (C) 2013 American Society of Civil Engineers.

AGUSM, May 1, 2009

Stream restoration is a billion dollar industry in North America; despite this expenditure there ... more Stream restoration is a billion dollar industry in North America; despite this expenditure there remain questions regarding the effectiveness of current techniques such as the installation of instream structures. Assessing the effect that such structures have on physical habitat and on salmonid density are key ways of determining project success. The objectives of this research were to assess the impact of instream structures on physical habitat in the Nicolet River (Quebec) and to analyze physical habitat and fish density data from many stream restoration projects in North America. Results of intensive surveys of the Nicolet River show that the installation of weirs and deflectors results in a greater frequency of pools. These pools have significantly greater depths, lower velocities, larger sediment size and higher percent cover than those without structures. Meta analysis of data from 187 stream restoration projects in North America also show significant increases in percent pool area, average depth, and percent cover as well as decreases in channel width following the installation of structures. The physical changes observed in the Nicolet River resulted in improved trout habitat, as measured by applying habitat preference curves, but uneven stocking practices and fishing pressure confounded attempts to verify differences in trout density based on presence or absence of structures. The meta analysis, however, shows significant increases in salmonid density, measured as fish/m2, following the installation of structures. On average, density increased by 161%. Different structure types result in significantly different changes in physical habitat, with weir structures providing the largest density increase. Multiple linear regression analysis reveals that the combination of change in relative pool area and in width is the best predictor of change in salmonid density (r2=0.511). Instream structures are significantly more successful at increasing brook trout density than cutthroat and steelhead trout or coho salmon. Furthermore, salmonids over 15cm in length show significantly higher increases in density than smaller fish. These results highlight that restoration structures can play an important role in creating better habitat for salmonids and increasing their densities, but much work is needed to determine the best way to rehabilitate disturbed streams for various species.

Geomorphology, Aug 1, 1999

This paper addresses the recent trend in fluvial geomorphology towards using computational fluid ... more This paper addresses the recent trend in fluvial geomorphology towards using computational fluid dynamics to explore the adjustment between flow processes, sediment transport and river channel morphology. It aims to evaluate the extent to which three-dimensional (3D) models improve predictive ability and prediction utility compared to two-dimensional (2D) applications. This is achieved through comparing the predictions of both 3D and

When rivers collide, complex three‐dimensional coherent flow structures are generated along the c... more When rivers collide, complex three‐dimensional coherent flow structures are generated along the confluence's mixing interface. These structures mix streamborne pollutants and suspended sediment and have considerable bearing on the morphology and habitat quality of the postconfluent reach. A particular structure of interest—streamwise orientated vortices (SOVs)—were first detected in numerical simulations to form in pairs, one on each side of the mixing interface rotating in the opposite sense of the other. Since, it has proven difficult to detect SOVs in situ with conventional pointwise velocimetry instrumentation. Despite the lack of clear evidence to confirm their existence, SOVs are nevertheless considered important drivers of mixing and sediment transport processes at confluences. Additionally, their causal mechanisms are not fully known which hinders a complete conceptual understanding of these processes. To address these gaps, we analyze observations of strongly coherent SOVs filmed in aerial drone video of a mesoscale confluence with a stark turbidity contrast between its tributaries. Eddy‐resolved modeling demonstrates the SOVs' dynamics could only be accurately reproduced when a density difference (Δρ) was imposed between the tributaries (Δρ = 0.5 kg/m3)—providing compelling evidence the observed SOVs are indeed a novel density‐driven class of SOV. This work confirms that SOVs exist, expands understanding of their generative processes and highlights the important role of small density gradients (e.g., ≤0.5 kg/m3) on river confluence hydrodynamics.

Le Naturaliste Canadien, 2023

Despite significant progress made in the research conducted to understand the morphodynamics of m... more Despite significant progress made in the research conducted to understand the morphodynamics of meandering rivers using computer models, a number of challenges and limitations remain with respect to simulating lateral river channel adjustments. In particular, some biophysical processes critical to bank erosion (e.g. related to soil and vegetation) are often neglected or oversimplified, proxy variables such as flow velocity are used to predict lateral migration rates, non-physical assumptions are frequently made to simulate channel cut offs, and channel and floodplain processes are commonly studied separately. The objective of this paper is not to address all of these issues, but to present a new geotechnical model that was integrated into a numerical morphodynamic model to include lateral erosion due to mass wasting. The model accounts for floodplain morphology and river bank hydrology, without compromising computational efficiency. The integrated geotechnical component includes a s...

Freshwater Biology, 2019

Aquatic plants (macrophytes) are known to affect flow dynamics, contributing to flow resistance. ... more Aquatic plants (macrophytes) are known to affect flow dynamics, contributing to flow resistance. Most studies on flow‐vegetation interactions are performed in laboratory flumes and focus on the flow field around plants, with little research at the level of vegetation patches in large aquatic ecosystems. In most hydrodynamic models, increased drag due to plants is modelled by increasing the Manning's n roughness coefficient. The objectives of this study were to: (1) develop a three‐dimensional hydrodynamic model (Delft3D) applicable to large water bodies including a novel approach to represent macrophyte resistance (modified k‐ε turbulence closure model); and (2) compare the modelled flow with field measurements for different vegetation configurations and patch arrangements. Work was carried out in Lake Saint‐Pierre, a large fluvial lake of the St Lawrence River in Québec, Canada. Results showed a marked increase in residence time in the zone affected by macrophytes when using th...

Canadian Geographies / Géographies canadiennes, 2017

There is growing support amongst scientists worldwide about the need for a shift in river managem... more There is growing support amongst scientists worldwide about the need for a shift in river management approaches to include hydrogeomorphic processes. However, the degree to which these concepts are transferred to governmental agencies and practitioners varies widely. In Quebec, for example, many stream restoration projects are based on the (incorrect) assumption that river mobility and its inevitable consequences (bank erosion of meanders, presence of woody debris in the channel) are problematic for salmonids. This paper presents examples drawn from current guidelines on stream restoration for fish habitat in Quebec to demonstrate the need to improve the knowledge exchange among scientists and decision makers about the positive impact of river mobility and large wood dynamics on biodiversity. Our observations reveal that existing guidelines for stream restoration in Quebec need to be revised to better integrate hydrogeomorphic concepts and to no longer assume that maintaining rivers...

Ecology and Society, 2009

Between 1990 and 2002, more than 200 moose-vehicle collisions occurred each year in Quebec, inclu... more Between 1990 and 2002, more than 200 moose-vehicle collisions occurred each year in Quebec, including about 50/yr in the Laurentides Wildlife Reserve. One cause is the presence of roadside salt pools that attract moose near roads in the spring and summer. Using the computer simulation technique of agent-based modeling, this study investigated whether salt pool removal and displacement, i.e., a compensatory salt pool set up 100 to 1500 m away from the road shoulder, would reduce the number of moose-vehicle collisions. Moose road crossings were used as a proxy measure. A GPS telemetry data set consisting of approximately 200,000 locations of 47 moose over 2 yr in the Laurentides Wildlife Reserve was used as an empirical basis for the model. Twelve moose were selected from this data set and programmed in the model to forage and travel in the study area. Five parameters with an additional application of stochasticity were used to determine moose movement between forest polygons. These included food quality; cover quality, i.e., protection from predators and thermal stress; proximity to salt pools; proximity to water; and slope. There was a significant reduction in road crossings when either all or two thirds of the roadside salt pools were removed, with and/or without salt pool displacement. With 100% salt pool removal, the reduction was greater (49%) without compensatory salt pools than with them (18%). When two thirds of the salt pools were removed, the reduction was the same with and without compensatory salt pools (16%). Although moose-vehicle collisions are not a significant mortality factor for the moose population in the Laurentides Wildlife Reserve, in areas with higher road densities, hunting pressure, and/or predator densities it could mean the difference between a stable and a declining population, and salt pool removal could be part of a good mitigation plan to halt population declines. This model can be used, with improvements such as spatial memory of salt pool locations and the addition of a road avoidance behavior, to assess the effectiveness of mitigation measures intended to reduce moose-vehicle collisions.