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Different sets of calibrated model parameters can yield divergent hydrological simulations which in turn can lead to different operational decisions or scientific conclusions. In order to obtain reliable hydrological results, proper calibration is therefore fundamental. This article proposes a new calibration approach for conceptual hydrological models based on the paradigm that hydrological process representation, along with the reproduction of observed streamflows, need to be taken into account when assessing the performance of a hydrological model. Several studies have shown that complementary data can be used to improve hydrological process representation and make hydrological modeling more robust. In the current study, the process of interest is actual evapotranspiration (AET). In order to obtain a more realistic representation of AET, meteorological variables and the AET mean annual cycle simulated by a regional climate model (RCM) driven by reanalysis are used to impose constraints during the optimization procedure. This calibration strategy is compared to a second strategy which relies on AET derived from reference data and to the classical approach based solely on the reproduction of observed discharges. The different methodologies are applied to calibrate the lumped conceptual model HSAMI, used operationally at Hydro-Québec, for six Canadian snow-dominated basins with various hydrometeorological and physiographical characteristics. [ABSTRACT FROM AUTHOR]

The impacts of climate change on medium-term reservoir operations for the Peribonka water resource system (Quebec, Canada) were evaluated with annual and seasonal hydropower production indicators and flood control criteria. According to simulations under the current operating rules in a climate change context, the tendency is for a reduction in mean annual hydropower production and an increase in spills, despite an increase in the annual average inflow to the reservoirs. The main results indicate that annual mean hydropower would change by -12 to +2%, and spills by -49 to +152%. A broad range of climate projections—a combination of five general circulation models with two greenhouse gas scenarios each—were used in order to evaluate the uncertainty of these future potential climates on floods and hydroelectric production. Climate projections were downscaled with the change factor method (also called the Delta method) at a horizon centered in 2050. To represent natural variability, a stochastic weather generator was used to produce 30 synthetic climate series of 30 years each, representative of each climate change projection as well as of the climate of the control period. The hydrological impacts of climate change were evaluated with a lumped hydrological model and the hydrological regimes were analyzed according to spring flood characteristics and the average inflows. In general, the projections indicate an increase in annual inflow, earlier peaks and greater volumes during the spring flood. The analyses show that a power plant managed with a reservoir is sensitive to the operating rules and that these rules should be re-examined in order to take account of new seasonal hydrological contexts. [ABSTRACT FROM AUTHOR]

Summary: The impact of climate change on the hydrology of the Chute-du-Diable watershed (Quebec, Canada) is studied by comparing statistics on current and projected future discharge resulting from a wide range of climate change scenarios. The use of 10 equally weighted climate projections from a combination of 5 general circulation models (GCMs) and 2 greenhouse gas emission scenarios (GHGES) allows for the definition of an uncertainty envelope of future hydrologic variables. GCM data is downscaled using the change factor approach for 30-year time slices centered around years 2020, 2050 and 2080. To estimate natural variability, synthetic time series are then computed for each horizon and for each climate change scenario, using a stochastic weather generator (30 series of 30 years), and are entered into a hydrology model. Future hydrological regimes are then compared to the control period (1961–1990) using the annual and seasonal mean discharge, peak discharge and timing of peak discharge criteria. Results indicate a 1–14°C increase in seasonal temperature and a −9 to +55% change in seasonal precipitation. The largest increases in both temperature and precipitation are observed in the winter and spring seasons. The main hydrologic impact observed is a spring flood appearing 1–5 weeks earlier than usual and a modification of its amplitude from −40 to +25%. Most scenarios suggest increases in the winter, spring and fall discharge, whereas summer is expected to see a decrease in discharge. While there is still a large scatter in projected values, the uncertainty analysis projects a better view of the most probable future hydrologic behaviour of the watershed. Of all sources of uncertainty considered in this study, the largest comes from the choice of a GCM. Accordingly, all impact studies based on results from only one GCM should be interpreted with caution. [Copyright &y& Elsevier]

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