Application of a High‐Resolution Distributed Hydrological Model on a U.S.‐Canada Transboundary Basin: Simulation of the Multiyear Mean AnnualHydrograph and 2011 Flood of theRichelieu River Basin

Abstract

During spring 2011, an extreme flood occurred along the Richelieu River located in southern Quebec, Canada. The Richelieu River is the last section of the complex Richelieu basin, which is composed of the large Lake Champlain located in a valley between two large mountains. Previous attempts in reproducing the Richelieu River flow relied on the use of simplified lumped models and showed mixed results. In order to prepare a tool to assess accurately the change of flood recurrences in the future, a state-of-the-art distributed hydrological model was applied over the Richelieu basin. The model setup comprises several novel methods and data sets such as a very high resolution river network, a modern calibration technique considering the net basin supply of Lake Champlain, a new optimization algorithm, and the use of an up-to-date meteorological data set to force the model. The results show that the hydrological model is able to satisfactorily reproduce the multiyear mean annual hydrograph and the 2011 flow time series when compared with the observed river flow and an estimation of the Lake Champlain net basin supply. Many factors, such as the quality of the meteorological forcing data, that are affected by the low density of the station network, the steep terrain, and the lake storage effect challenged the simulation of the river flow. Overall, the satisfactory validation of the hydrological model allows to move to the next step, which consists in assessing the impacts of climate change on the recurrence of Richelieu River floods.Plain Language Summary In order to study the 2011 Richelieu flood and prepare a tool capable of estimating the effects of climate change on the recurrence of floods, a hydrological model is applied over the Richelieu basin. The application of a distributed hydrological model is useful to simulate the flow of all the tributaries of the Richelieu basin. This new model setup stands out from past models due to its distribution in several hydrological units, its high-resolution river network, the calibration technique, and the high-resolution weather forcing data set used to drive the model. The model successfully reproduced the 2011 Richelieu River flood and the annual hydrograph. The simulation of the Richelieu flow was challenging due to the contrasted elevation of the Richelieu basin and the presence of the large Lake Champlain that acts as a reservoir and attenuates short-term fluctuations. Overall, the application was deemed satisfactory, and the tool is ready to assess the impacts of climate change on the recurrence of Richelieu River floods.

Will Evolving Climate Conditions Increase the Risk of Floods of the Large U.S.‐Canada Transboundary Richelieu River Basin?

“…The river discharges simulated using the gridded observations (Livneh et al 2015) are added to show the ability of HYDROTEL to reproduce the HIST river discharges. As shown in Lucas‐Picher et al (2020), HYDROTEL forced by the gridded observations is able to reproduce the sum18. Then, the simulation of the NBSs, which account for all the tributaries of the Lake Champlain, and also the evaporation and precipitation over the lake, are also well simulated by HYDROTEL when forced by the gridded observations.…”

“…All the details related to the LCRR basin, the distributed hydrological model (HYDROTEL; Fortin et al 2001; Turcotte et al 2007), and its calibration and validation are provided in Lucas‐Picher et al (2020). To summarize, since the discharge of the Richelieu River relies on the Lake Champlain level, the calibration of HYDROTEL was done over 18 tributaries of the Lake Champlain that contribute to 73% of the total lake inflow.…”

“…In this project, officially financed and finally launched in 2017, one fundamental question was raised to identify flood mitigation measures: Will climate change affect the hydrological regime, and particularly the flood risks, of the Richelieu River? To address this question, a state‐of‐the‐art hydrological model was implemented on the LCRR basin (Lucas‐Picher et al 2020) and driven by three large multi‐resolution ensembles of climate projections. One of the ensembles, ClimEx, consists of a large high‐resolution regional climate model (RCM) ensemble (Leduc et al 2019) and is particularly suited to estimate hydrological extremes by robustly covering the natural variability.…”

“…Mean daily maximum temperature is above 20°C in summer (June‐July‐August) and daily minimum temperature is below −10°C in winter (December‐January‐February) with, on average, slightly more precipitation in summer (3.5 mm/day or 322 mm/summer) than in winter (2.5 mm/day or 225 mm/winter). For more details about the LCRR basin, the reader is referred to Shanley and Denner (1999) and to Lucas‐Picher et al (2020). Since the paper has a special focus toward spring floods, most of the forthcoming analysis will pay attention to winter (December‐January‐February) and spring (March‐April‐May) weather conditions that contribute the most to floods.…”

“…To address the main question of this paper regarding the effects of climate change on the recurrence of floods over the LCRR basin, this study introduces a state‐of‐the‐art methodology and analysis to determine the impacts of climate change on river flows with a particular interest on floods. To reach this goal, a high‐resolution distributed hydrological model (HYDROTEL) was implemented over the LCRR basin (Lucas‐Picher et al 2020). The hydrological model was calibrated using a high‐resolution ~7‐km gridded observation reference (Livneh et al 2015) and then driven with the latest climate simulation ensembles CMIP5, CORDEX North America, and ClimEx for RCP 4.5 and 8.5 scenarios.…”