Preprints
https://doi.org/10.5194/hess-2021-391
https://doi.org/10.5194/hess-2021-391

  16 Aug 2021

16 Aug 2021

Review status: a revised version of this preprint was accepted for the journal HESS and is expected to appear here in due course.

Choosing between post-processing precipitation forecasts or chaining several uncertainty quantification tools in hydrological forecasting systems

Emixi Sthefany Valdez1, François Anctil1, and Maria-Helena Ramos2 Emixi Sthefany Valdez et al.
  • 1Dept. of Civil and Water Engineering, Université Laval, 1065 Avenue de la Médecine, Québec, Canada
  • 2Université Paris-Saclay. INRAE, UR HYCAR, 1 Rue Pierre-Gilles de Gennes, 92160 Antony, France

Abstract. This study aims to decipher the interactions of a precipitation post-processor and several other tools for uncertainty quantification implemented in a hydrometeorological forecasting chain. We make use of four hydrometeorological forecasting systems that differ by how uncertainties are estimated and propagated. They consider the following sources of uncertainty: A) forcing, B) forcing and initial conditions, C) forcing and model structure, and D) forcing, initial conditions, and model structure. For each system's configuration, we investigate the reliability and accuracy of post-processed precipitation forecasts in order to evaluate their ability to improve streamflow forecasts for up to seven days of forecast horizon. The evaluation is carried out across 30 catchments in the Province of Quebec (Canada) and over the 2011–2016 period. Results are compared using a multicriteria approach, and the analysis is performed as a function of lead time and catchment size. The results indicate that the precipitation post-processor resulted in large improvements in the quality of forecasts with regard to the raw precipitation forecasts. This was especially the case when evaluating relative bias and reliability. However, its effectiveness in terms of improving the quality of hydrological forecasts varied according to the configuration of the forecasting system, the forecast lead time, and the catchment size. The combination of the precipitation post-processor and the quantification of uncertainty from initial conditions showed the best results. When all sources of uncertainty were quantified, the contribution of the precipitation post-processor to provide better streamflow forecasts was not remarkable and, in some cases, it even deteriorated the overall performance of the hydrometeorological forecasting system. Our study provides an in-depth investigation on how improvements brought by a precipitation post-processor to the quality of the inputs to a hydrological forecasting model can be cancelled along the forecasting chain, depending on how the hydrometeorological forecasting system is configured and on how the other sources of hydrological forecasting uncertainty (initial conditions and model structure) are considered and accounted for. This has implications for the choices users might make when designing new or enhancing existing hydrometeorological ensemble forecasting systems.

Emixi Sthefany Valdez et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2021-391', Anonymous Referee #1, 14 Sep 2021
    • AC1: 'Answer to the Anonymous Referee #1', Emixi Valdez, 12 Oct 2021
  • RC2: 'A comprehensive assessment of uncertainty sources in an operational streamflow forecasting system', Anonymous Referee #2, 16 Sep 2021
    • AC2: 'Answer to the Anonymous Referee #2', Emixi Valdez, 12 Oct 2021

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2021-391', Anonymous Referee #1, 14 Sep 2021
    • AC1: 'Answer to the Anonymous Referee #1', Emixi Valdez, 12 Oct 2021
  • RC2: 'A comprehensive assessment of uncertainty sources in an operational streamflow forecasting system', Anonymous Referee #2, 16 Sep 2021
    • AC2: 'Answer to the Anonymous Referee #2', Emixi Valdez, 12 Oct 2021

Emixi Sthefany Valdez et al.

Emixi Sthefany Valdez et al.

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Short summary
We investigated how a precipitation post-processor interacts with other tools for uncertainty quantification in a hydrometeorological forecasting chain. Four systems were implemented to generate 7-day ensemble streamflow forecasts, which vary from partial to total uncertainties estimation. Overall analysis showed that post-processing and initial condition estimation ensure the most skill improvements, in some cases, even better than a system that considers all sources of uncertainty.