Rademacher - Operational low flow forecasts
Transcription
Rademacher - Operational low flow forecasts
Operational low flow forecasts Silke Rademacher Department Water Balance, Forecasting and Predictions Federal Institute of Hydrology (BfG) Koblenz KHR-CHR Workshop Low flows and droughts 25 & 26 September 2007, Würzburg Operational low flow forecasts Page 1 Responsibility in Germany • Navigability of ships and maintenance of large rivers: Federal Waterway and Navigation Administration (WSV) • Flood defence, flood warning and forecasting service German Federal States Operational low flow forecasts Page 2 Water Level Forecasting System WAVOS Operational low water forecast HochwasserVorhersagezentrale Frankfurt (Oder) Bundesanstalt für Gewässerkunde, Koblenz Vorhersagezentrale Elbe, Magdeburg Hochwassermeldezentrum Rhein, Mainz WAVOS Saar Hochwassermeldezentrum Saarland, Saarbrücken Operational low flow forecasts HochwasserVorhersagezentrale Main, Hof Page 3 Low flow forecasting along the Rhine > 7 gauging stations: Oestrich, Kaub, Koblenz, Köln, Düsseldorf, Duisburg-Ruhrort, Emmerich > Forecasting horizon: 48 hours > Forecasting time: 7:00 > Daily Forecast: Water level at gauge Ruhrort ≤ 400cm Operational low flow forecasts Page 4 WAVOS Rhine > 1D hydrodynamic model >Rhine and Moselle (685 km) Operational low flow forecasts Page 5 WAVOS Rhine > Tributaries Rhine model > Maxau/Oberrhein > Rockenau/Neckar > Neubrück/Erft > Raunheim/Main > Hattingen/Ruhr > Grolsheim/Nahe > Schermbeck/Lippe > Kalkofen/Lahn > Trier u. Cochem/Mosel > Friedrichstal/Wied > Altenahr/Ahr > Menden/Sieg > Opladen/Wupper Operational low flow forecasts Page 6 WAVOS Rhine > 1D hydrodynamic model >Rhine and Moselle (685 km) Operational low flow forecasts Page 7 WAVOS Rhine > 1D hydrodynamic model >Rhine and Moselle (685 km) >Main (380 km) Operational low flow forecasts Page 8 WAVOS Rhine > 1D hydrodynamic model >Rhine and Moselle (685 km) >Main (380 km) >Moselle-Saar-Sauer (425 km) Operational low flow forecasts Page 9 WAVOS Rhine > 1D hydrodynamic model >Rhine and Moselle (685 km) >Main (380 km) >Moselle-Saar-Sauer (425 km) > Statistical model >Maxau/Rhein >Rockenau/Neckar >Fremersdorf/Saar Operational low flow forecasts Page 10 WAVOS Rhine > 1D hydrodynamic model >Rhine and Moselle (685 km) >Main (380 km) >Moselle-Saar-Sauer (425 km) > Statistical model >Maxau/Rhein >Rockenau/Neckar >Fremersdorf/Saar > External forecasts Operational low flow forecasts Page 11 WAVOS Rhine > 1D hydrodynamic model >Rhine and Moselle (685 km) >Main (380 km) >Moselle-Saar-Sauer (425 km) > Statistical model >Maxau/Rhein >Rockenau/Neckar >Fremersdorf/Saar > External forecasts > Forecaster’s estimate Operational low flow forecasts Page 12 WAVOS Rhine > 1D hydrodynamic model >Rhine and Moselle (685 km) >Main (380 km) >Moselle-Saar-Sauer (425 km) > Statistical model >Maxau/Rhein >Rockenau/Neckar >Fremersdorf/Saar > External forecasts > Forecaster’s estimate Operational low flow forecasts Page 13 WAVOS Rhine - Results 20 100 16 80 14 12 60 10 8 40 6 1-Tages-Vorhersage 20 Standardabweichung [cm] Anteil der Vorhersagen mit einer Differenz kleiner 10cm [%] 18 4 2-Tages-Vorhersage Standardabweichung (1-Tages-VHS) 2 Standardabweichung (2-Tages-VHS) 0 0 Oestrich Kaub Koblenz Köln D`dorf Ruhrort Emmerich Vorhersagepegel Operational low flow forecasts Page 14 WAVOS Rhine - Results Anteil der Vorhersagen mit einer Differenz zwischen Vorhersage- und Messwert kleiner 10 cm [%] 100 90 80 70 60 Pegel Oestrich Pegel Kaub Pegel Koblenz Pegel Köln Pegel Düsseldorf Pegel Ruhrort Pegel Emmerich 50 40 Auswertezeitraum: 01.07.2005 - 30.06.2007 30 12 Operational low flow forecasts 24 36 Vorhersagedauer [h] 48 Page 15 WAVOS Rhine > 1D hydrodynamic model >Rhine and Moselle (685 km) >Main (380 km) >Moselle-Saar-Sauer (425 km) > Statistical model >Maxau/Rhein >Rockenau/Neckar >Fremersdorf/Saar > External forecasts > Forecaster’s estimate Operational low flow forecasts 48h-Forecast ☺ Page 16 Low flow forecasting along the Rhine > 7 gauging stations: Oestrich, Kaub, Koblenz, Köln, Düsseldorf, Duisburg-Ruhrort, Emmerich > Forecasting horizon: 48 hours > Forecasting time: 7:00 96 hours > Daily Forecast: Water level at gauge Ruhrort ≤ 400cm > Dissemination via email to river headquarter and Internet (ELWIS) Operational low flow forecasts Page 17 WAVOS Rhine > 1D hydrodynamic model >Rhine and Moselle (685 km) >Main (380 km) >Moselle-Saar-Sauer (425 km) > Statistical model >Maxau/Rhein >Rockenau/Neckar >Fremersdorf/Saar > External forecasts > Forecaster’s estimate Operational low flow forecasts 96h-Forecast / Forecasting Range to short Only for 2 tributaries available .... Page 18 WAVOS Rhine > 1D hydrodynamic model >Rhine and Moselle (685 km) >Main (380 km) >Moselle-Saar-Sauer (425 km) > Statistical model >Maxau/Rhein >Rockenau/Neckar >Fremersdorf/Saar > External forecasts > Precipitation runoff model Operational low flow forecasts To obtain > a consistent forecast > with a adequate leadtime for all tributaries Page 19 NL HBV Rhine D Precipitation runoff model > Catchment upstream of Lobith ( more than 160.000 km²) L > 134 subbasins (each between 500 and 2.000 km²) > time step: 1 hour F A CH Operational low flow forecasts Page 20 NL HBV Rhine D Development in cooperation with RIZA: > Flood forecast RIZA > case studies >Transnational effects of extreme floods at the Lower Rhine > Climate change L F A CH Operational low flow forecasts Page 21 WAVOS Rhine – FEWS DE Operational low flow forecasts Page 22 External forecasts Hydro measurements Meteo forecasts Meteo measurements WAVOS Rhine – FEWS DE Hydro measurements FEWS – DE WAVOS Rhine forecast for tributaries Rhine forecast Operational low flow forecasts Page 23 FEWS DE Precipitation runoff model - input data Forecast Initialisation Phase Data Parameter Spatial Timestep Leadtime Resolution Measured TTRR station data P, T 45 stations 1h Measured synop station data P, T 204 stations 6 h / 12 h W 47 gauges ≤1h DWD weather forecast Local Model (LM) P, T ~ 7 km 1h 78 h DWD weather forecast Global Model (GME) P, T ~ 40 km 3h 174 h W gauge Rheinfelden 1h 67 h Measured water level BAFU external forecast Operational low flow forecasts Page 24 WAVOS Rhine – FEWS DE Results Pegel Köln (10 cm – Schwelle) 90 80 70 Pegel Köln (20 cm – Schwelle) 100 Pegel Köln 60 2-Tages-VHS (operat. 2007) GME + manuelle Anpassungen GME automatisch LM + manuelle Anpassungen LM automatisch HVZ + LM WAVOS + LM HVZ + WAVOS + LM 50 40 30 12 24 36 48 Anteil der Vorhersagen mit einer Differenz kleiner 20 cm Anteil der Vorhersagen mit einer Differenz kleiner 10 cm 100 90 80 70 Pegel Köln 60 60 Vorhersagedauer [h] 50 40 72 84 2-Tages-VHS (operat. 2007) GME + manuelle Anpassungen GME automatisch LM + manuelle Anpassungen LM automatisch HVZ + LM WAVOS + LM HVZ + WAVOS + LM 96 30 12 Operational low flow forecasts 24 36 48 60 Vorhersagedauer [h] 72 84 Page 25 96 FEWS DE One of the main sources for the increasing of uncertainty is the uncertainty in the weather forecast ⇒ Ensemble weather predictions ⇒ Project “Verification of Ensemble forecasting in the Rhine basin” ⇒ RIZA – BfG Cooperation /CHR -Project ⇒ WL | Delft hydraulics Operational low flow forecasts Page 26 Verification of Ensemble forecasting in the Rhine basin • ECMWF-EPS ensemble (re-sampled as used in FEWS-NL) • 50 ensemble members + 1 control run • timestep 12h 07 0 2 / • leadtime 240h 06 / 8 0 4 0 0 • Spatial resolution ~ 80km 6/2 0 / 7 0 • COSMO-LEPS ensemble • 16 ensemble members • timestep 3h • leadtime 5 1/2d • Spatial resolution ~ 10km 09/0 Operational low flow forecasts 7 0 0 1/2 07 0 2 / 5 21/0 Page 27 FEWS DE – Ensemble Operational low flow forecasts Page 28 FEWS DE - Ensemble Lahn Catchment Area Operational low flow forecasts Page 29 FEWS DE - Ensemble Operational low flow forecasts Page 30 FEWS DE - Ensemble Operational low flow forecasts Page 31 FEWS DE - Ensemble Operational low flow forecasts Page 32 FEWS DE - Ensemble Operational low flow forecasts Page 33 Verification of Ensemble forecasting in the Rhine basin •What is the skill, reliability and potential utility of the ensemble in predicting events at different lead times? •What are the effects of scale on the skill of the ensemble predictions? •Do the high resolution ensembles available through COSMO-LEPS indicate a higher skill than the low resolution ECMWF-EPS ensemble where the scale issue becomes apparent? Operational low flow forecasts Page 34 Verification of Ensemble forecasting in the Rhine basin •Several statistics commonly applied in verification of probabilistic forecasts were used • the Brier (Skill) Score, • the Ranked Probability • (Skill) Score • verification diagrams • Relative Operating Characteristic • Attributes diagram. Operational low flow forecasts Page 35 Verification of Ensemble forecasting in the Rhine basin - Results • At low flows it is shown that the ensemble forecasts are a reliable indicator, with a high forecast skill for long lead times. • For the smaller catchments the skill of the ensemble forecast was clearly shown to deteriorate faster than in the larger catchments. • In all cases the ensemble forecast were demonstrated to have positive skill, meaning that there is utility in using ensemble in forecasting for the Rhine basin. Operational low flow forecasts Page 36 Verification of Ensemble forecasting in the Rhine basin - Results • The period over which the ensembles have been verified is limited, with few events of significance occurring in the Rhine basin. As a result the skill in predicting rare events for which the forecasting system has been constructed has not been assessed, but can only be inferred on the results found for the evaluation period. • Relatively short period for which the COSMO-LEPS ensemble is currently available => Repeat the analysis in 1 to 1½ years when a more substantial set of ensembles is available, and if available a larger number of (extreme) events Operational low flow forecasts Page 37 Thank you for your attention ! Silke Rademacher Referat Wasserhaushalt, Vorhersagen und Prognosen Bundesanstalt für Gewässerkunde Am Mainzer Tor 1 56068 Koblenz Tel.: 0261/1306-5858, Fax: 0261/1306-5280 E-Mail: rademacher@bafg.de www.bafg.de Operational low flow forecasts Page 38