ORCID Profile
0000-0002-7650-0824
Current Organisations
Université Laval
,
CentrEau - Quebec Water Management Research Centre
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Publisher: American Geophysical Union (AGU)
Date: 09-2013
DOI: 10.1002/WRCR.20405
Publisher: Elsevier BV
Date: 10-2021
Publisher: American Geophysical Union (AGU)
Date: 09-2017
DOI: 10.1002/2017RG000556
Publisher: California Digital Library (CDL)
Date: 09-02-2022
DOI: 10.31223/X5RG7Q
Abstract: Highly simplified approaches continue to underpin hydrological climate change impact assessments across the Earth’s mountainous regions. Fully-integrated surface-subsurface models may hold far greater potential to represent the distinctive regimes of steep, geologically-complex headwater catchments. However, their utility has not yet been tested across a wide range of mountainous settings. Here, an integrated model of two adjacent calcareous Alpine headwaters that accounts for 2D surface flow, 3D variably-saturated groundwater flow, and evapotranspiration is presented. An energy balance-based representation of snow dynamics contributed to the model’s high-resolution forcing data, and a sophisticated 3D geological model helped to define and parameterize the subsurface structure. In the first known attempt to calibrate a catchment-scale integrated model of a mountainous region automatically, numerous uncertain model parameters were estimated. The salient features of the hydrological regime could ultimately be satisfactorily reproduced – over an 11-month evaluation period, the Nash-Sutcliffe efficiency of simulated streamflow at the main gauging station was 0.76. Spatio-temporal visualization of the forcing data and simulated responses further confirmed the model’s broad coherence. Presumably due to unresolved local subsurface heterogeneity, closely replicating the somewhat contrasting groundwater level signals observed near to one another proved more elusive. Finally, we assessed the impacts of various common model simplifications and assumptions on key simulated outputs, finding strongly affected model performance in many cases. Although certain outstanding challenges must be overcome if the global uptake of integrated models in mountain regions is to increase, our work demonstrates the feasibility and benefits of their application in such complex systems.
Publisher: Elsevier BV
Date: 2022
Publisher: American Geophysical Union (AGU)
Date: 11-04-2017
DOI: 10.1002/2016RG000530
Publisher: Elsevier BV
Date: 07-2011
Publisher: American Geophysical Union (AGU)
Date: 29-03-2022
DOI: 10.1029/2020WR029390
Abstract: Highly simplified approaches continue to underpin hydrological climate change impact assessments across the Earth's mountainous regions. Fully‐integrated surface‐subsurface models may hold far greater potential to represent the distinctive regimes of steep, geologically‐complex headwater catchments. However, their utility has not yet been tested across a wide range of mountainous settings. Here, an integrated model of two adjacent calcareous Alpine headwaters that accounts for two‐dimensional surface flow, three‐dimensional (3D) variably‐saturated groundwater flow, and evapotranspiration is presented. An energy balance‐based representation of snow dynamics contributed to the model's high‐resolution forcing data, and a sophisticated 3D geological model helped to define and parameterize its subsurface structure. In the first known attempt to calibrate a catchment‐scale integrated model of a mountainous region automatically, numerous uncertain model parameters were estimated. The salient features of the hydrological regime could ultimately be satisfactorily reproduced – over an 11‐month evaluation period, the Nash‐Sutcliffe efficiency of simulated streamflow at the main gauging station was 0.76. Spatio‐temporal visualization of the forcing data and simulated responses further confirmed the model's broad coherence. Presumably due to unresolved local subsurface heterogeneity, closely replicating the somewhat contrasting groundwater level signals observed near to one another proved more elusive. Finally, we assessed the impacts of various simplifications and assumptions that are commonly employed in physically‐based modeling – including the use of spatially uniform forcings, a vertically limited model domain, and global geological data products – on key simulated outputs, finding strongly affected model performance in many cases. Although certain outstanding challenges must be overcome if the uptake of integrated models in mountain regions around the world is to increase, our work demonstrates the feasibility and benefits of their application in such complex systems.
Publisher: Oxford University Press (OUP)
Date: 05-2021
Abstract: Antibody-mediated rejection (AMR) remains a major management challenge in heart transplantation given the complexity of pathological diagnosis and dearth of evidence for effective management. Eculizumab, an anti-C5 monoclonal antibody which inhibits terminal complement activation, has been reported to decrease early AMR in sensitized renal transplant recipients. We report a case of a 29-year-old gentleman with chronic AMR 8 years after heart transplantation, manifesting as significant graft dysfunction. Donor-specific antibodies to DQ7 were found to be causative. Antibody-mediated rejection was managed with quadruple oral immunosuppressive therapy (mycophenolate, prednisolone, everolimus, and tacrolimus) as well as a sequence of broad-spectrum immunological therapies intravenous (IV) methylprednisolone, plasmapheresis, IV immunoglobulin, rituximab, bortezomib, tocilizumab, and splenic irradiation. No treatment had a sustained impact on donor-specific anti-HLA antibodies (DSAs) or graft function. After testing showed the DQ7 antibodies were complement-binding, a trial of eculizumab was started. This improved DSAs somewhat, and improved graft function and New York Heart Association functional class substantially. The patient was relisted for heart transplantation and successfully retransplanted in March 2018. Specifically, the new organ and recipient were matched at DQ7. After discontinuation of eculizumab, the patient has remained healthy and well, with normal graft function 28 months after retransplantation. To the best of our knowledge, this is the first case of chronic AMR in a heart transplant patient, successfully stabilized with eculizumab and bridged to retransplantation.
Publisher: Cambridge University Press
Date: 09-09-2010
Publisher: Wiley
Date: 25-02-2010
DOI: 10.1111/J.1745-6584.2009.00644.X
Abstract: The accuracy with which MODFLOW simulates surface water-groundwater interaction is examined for connected and disconnected losing streams. We compare the effect of different vertical and horizontal discretization within MODFLOW and also compare MODFLOW simulations with those produced by HydroGeoSphere. HydroGeoSphere is able to simulate both saturated and unsaturated flow, as well as surface water, groundwater and the full coupling between them in a physical way, and so is used as a reference code to quantify the influence of some of the simplifying assumptions of MODFLOW. In particular, we show that (1) the inability to simulate negative pressures beneath disconnected streams in MODFLOW results in an underestimation of the infiltration flux (2) a river in MODFLOW is either fully connected or fully disconnected, while in reality transitional stages between the two flow regimes exist (3) limitations in the horizontal discretization of the river can cause a mismatch between river width and cell width, resulting in an error in the water table position under the river and (4) because coarse vertical discretization of the aquifer is often used to avoid the drying out of cells, this may result in an error in simulating the height of the groundwater mound. Conditions under which these errors are significant are investigated.
Publisher: American Geophysical Union (AGU)
Date: 28-08-2023
DOI: 10.1029/2023WR034920
Abstract: Groundwater models that simulate only saturated flow use groundwater recharge as an input parameter. In contrast, variably saturated subsurface flow models, including integrated surface and subsurface hydrologic models, can jointly simulate the movement of water in the saturated and unsaturated zones. Instead of recharge, they require climate data such as precipitation and potential evapotranspiration. Given that the latter models represent hydrological processes operating throughout the unsaturated zone and at the water table, one might expect that recharge can be readily extracted from them. In this paper, we demonstrate that it is not the case. When the commonly used definitions of groundwater recharge are implemented in variably saturated subsurface flow models, they do not yield meaningful results. Above all, the problems occur because of the storage dynamics in the capillary fringe above the water table. Despite this difficulty, variably saturated subsurface flow models can provide the information required for water resources management directly.
Publisher: Elsevier BV
Date: 05-2020
Publisher: Elsevier BV
Date: 08-2023
Publisher: Frontiers Media SA
Date: 31-07-2023
Publisher: Wiley
Date: 07-2008
DOI: 10.1111/J.1745-6584.2007.00430.X
Abstract: This article examines the required spatial discretization perpendicular to the fracture-matrix interface (FMI) for numerical simulation of solute transport in discretely fractured porous media. The discrete-fracture, finite-element model HydroGeoSphere (Therrien et al. 2005) and a discrete-fracture implementation of MT3DMS (Zheng 1990) were used to model solute transport in a single fracture, and the results were compared to the analytical solution of Tang et al. (1981). To match analytical results on the relatively short timescales simulated in this study, very fine grid spacing perpendicular to the FMI of the scale of the fracture aperture is necessary if advection and/or dispersion in the fracture is high compared to diffusion in the matrix. The requirement of such extremely fine spatial discretization has not been previously reported in the literature. In cases of high matrix diffusion, matching the analytical results is achieved with larger grid spacing at the FMI. Cases where matrix diffusion is lower can employ a larger grid multiplier moving away from the FMI. The very fine spatial discretization identified in this study for cases of low matrix diffusion may limit the applicability of numerical discrete-fracture models in such cases.
Publisher: Elsevier BV
Date: 08-2012
No related grants have been discovered for Rene Therrien.