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Titel |
Operational value of ensemble streamflow forecasts for hydropower production: A Canadian case study |
VerfasserIn |
Marie-Amélie Boucher, Denis Tremblay, Luc Perreault, François Anctil |
Konferenz |
EGU General Assembly 2010
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 12 (2010) |
Datensatznummer |
250034664
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Zusammenfassung |
Ensemble and probabilistic forecasts have many advantages over deterministic ones, both in
meteorology and hydrology (e.g. Krzysztofowicz, 2001). Mainly, they inform the user on the
uncertainty linked to the forecast. It has been brought to attention that such additional
information could lead to improved decision making (e.g. Wilks and Hamill, 1995; Mylne,
2002; Roulin, 2007), but very few studies concentrate on operational situations
involving the use of such forecasts. In addition, many authors have demonstrated that
ensemble forecasts outperform deterministic forecasts in terms of performance
(e.g. Jaun et al., 2005; Velazquez et al., 2009; Laio and Tamea, 2007). However,
such performance is mostly assessed on the basis of numerical scoring rules, which
compare the forecasts to the observations, and seldom in terms of management
gains.
The proposed case study adopts an operational point of view, on the basis that a novel
forecasting system has value only if it leads to increase monetary and societal gains (e.g.
Murphy, 1994; Laio and Tamea, 2007). More specifically, Environment Canada operational
ensemble precipitation forecasts are used to drive the HYDROTEL distributed hydrological
model (Fortin et al., 1995), calibrated on the Gatineau watershed located in Québec, Canada.
The resulting hydrological ensemble forecasts are then incorporated into Hydro-Québec
SOHO stochastic management optimization tool that automatically search for optimal
operation decisions for the all reservoirs and hydropower plants located on the
basin.
The timeline of the study is the fall season of year 2003. This period is especially relevant
because of high precipitations that nearly caused a major spill, and forced the preventive
evacuation of a portion of the population located near one of the dams. We show that the use
of the ensemble forecasts would have reduced the occurrence of spills and flooding, which is
of particular importance for dams located in populous area, and increased hydropower
production.
The ensemble precipitation forecasts extend from March 1st of 2002 to December 31st of
2003. They were obtained using two atmospheric models, SEF (8 members plus the control
deterministic forecast) and GEM (8 members). The corresponding deterministic precipitation
forecast issued by SEF model is also used within HYDROTEL in order to compare ensemble
streamflow forecasts with their deterministic counterparts. Although this study does
not incorporate all the sources of uncertainty, precipitation is certainly the most
important input for hydrological modeling and conveys a great portion of the total
uncertainty.
References:
Fortin, J.P., Moussa, R., Bocquillon, C. and Villeneuve, J.P. 1995: HYDROTEL, un modèle
hydrologique distribué pouvant bénéficier des données fournies par la télédétection
et les systèmes d’information géographique, Revue des Sciences de l’Eau, 8(1),
94-124.
Jaun, S., Ahrens, B., Walser, A., Ewen, T. and Schaer, C. 2008: A probabilistic view on the
August 2005 floods in the upper Rhine catchment, Natural Hazards and Earth System
Sciences, 8 (2), 281-291.
Krzysztofowicz, R. 2001: The case for probabilistic forecasting in hydrology, Journal of
Hydrology, 249, 2-9.
Murphy, A.H. 1994: Assessing the economic value of weather forecasts: An overview of
methods, results and issues, Meteorological Applications, 1, 69-73.
Mylne, K.R. 2002: Decision-Making from probability forecasts based on forecast value,
Meteorological Applications, 9, 307-315.
Laio, F. and Tamea, S. 2007: Verification tools for probabilistic forecasts of continuous
hydrological variables, Hydrology and Earth System Sciences, 11, 1267-1277.
Roulin, E. 2007: Skill and relative economic value of medium-range hydrological ensemble
predictions, Hydrology and Earth System Sciences, 11, 725-737.
Velazquez, J.-A., Petit, T., Lavoie, A., Boucher, M.-A., Turcotte, R., Fortin, V. and Anctil, F.
2009: An evaluation of the Canadian global meteorological ensemble prediction system for
short-term hydrological forecasting, Hydrology and Earth System Sciences, 13(11),
2221-2231.
Wilks, D.S. and Hamill, T.M. 1995: Potential economic value of ensemble-based surface
weather forecasts, Monthly Weather Review, 123(12), 3565-3575. |
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