Environment Canada Modelling Systems and the 2013 Alberta Floods

Transcription

1 Environment Canada Modelling Systems and the 2013 Alberta Floods Calgary, Alberta February 19, 2014 Bruce Davison (EC) Al Pietroniro (EC) Nick Kouwen (UW) Anthony Liu (EC) Muluneh Mekonnen (AB) Ron Goodison (EC) EC Montreal (CMC, RPN, National Lab) 2/24/2014 Page 1

2 Overview EC Numerical Weather Prediction Systems Precipitation Forecasts and Analysis During the Flood Hydrological Modelling Systems Streamflow Hindcasts of the Flood 2/24/2014 Page 2

3 Existing EC Products The CMC Numerical Output Database CaPA HRDPS RDPS REPS GEPS NAEFS Seasonal forecasting system

4 Observations at Calgary and Banff during the 2013 Southern Alberta Floods Daily precipitation amounts (from noon the previous day to noon the current day) at two measurement sites

5 Published precipitation map Max. precip: over 300 mm CaPA precipitation map June 16 June 30, 2013 Max. precip.: 221 mm

6 NAEFS 24H QPF Ending at 00Z 21 June 2013

7 Performance of Forecasting Systems during the 2013 Southern Alberta Floods At the medium-range (7-day lead time) The North American Ensemble Forecasting System (NAEFS) unambiguously forecasted strong precipitation over the area of interest Calgary June 2013

8 Performance of Forecasting Systems during the 2013 Southern Alberta Floods At the medium-range (5- to 10-day lead time) The experimental Extreme Forecast Index (EFI) calculated from the Global Ensemble Prediction System clearly indicated the possibility of extreme precipitation

9 Performance of Forecasting Systems during the 2013 Southern Alberta Floods At the short-range (3-day lead time) The Regional Ensemble Prediction System (REPS) indicated the probability of heavy precipitation (regions with 90% chances of at least 40 mm in 24 hours)

10 Performance of Forecasting Systems during the 2013 Southern Alberta Floods At the short-range (1-day lead time) The Regional Deterministic Prediction System (10-km grid spacing) forecasted extreme precipitations over significant areas Precipitation accumulation from 19 June 12Z to 22 June 12Z

11 Performance of Forecasting Systems during the 2013 Southern Alberta Floods At the short-range (1-day lead time) The High-Resolution Deterministic Prediction System (2.5-km grid spacing) forecasted extreme precipitations over significant areas Precipitation accumulation from 19 June 12Z to 22 June 12Z

12 Performance of Forecasting Systems during the 2013 Southern Alberta Floods Difference (HRDPS RDPS)

13 Hydrologic Modelling Systems Second Generation Land Surface Scheme SENSIBLE EXCHANGE Aerodynamic resistance ( r a ) Wind Leaf Drip T g Surface Soil Temperature Lower Soil Temperature Root Distribution Fn ( vegetation type) T gb CLASS WATFLOOD MESH RADIATIVE MOISTURE EXCHANGE EXCHANGE IR up r a Ponded Water Evaporation Infiltration Overland Flow α veg Interception Layer 1 Transpiration Leaves LAI Stomata T c Canopy Percolation Temperature and humidity r s ( light sensitivity Layer 2 changes r s ) Fraction vegetation cover & LAI IR down Fn ( temperature & season) IR up Stems SAI Infiltration Surface α soil Runoff Snow Fn ( soil wetness) Upper layer Upper soil layer wetness Full soil column Full column wetness CLASS WATFLOOD Layer 3 UZS Drainage LZS Interflow Base Flow Sellers et al Subsurface Runoff Sub-grid Variability Grid Square Computational Unit = Grid Square a c Individual Pixels Computational Unit = GRU Mixture of 4 sub-areas CS C GS G b Kouwen et al Mixture of 4 sub-areas CS C GS G Blend of 5 vegetation groups Blend of 5 vegetation groups

14 The MESH Modelling Platform 2/24/2014 Page 14

15 The approach - WATFLOOD Use existing watershed Manitoba Hydro WATFLOOD model for the headwaters of the North & South Saskatchewan rivers Convert CaPA precipitation and temperature data form its native format to Green Kenue (GK) r2c formats Re-calibrate the model parameters for the CaPA met data for Model the 2013 Calgary flood

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17 Model calibration approach The usual approach to calibrating WATFLOOD is to first obtain the proper overall volume using only those parameters that affect evapotranspiration, sublimation and lake evaporation The nest step is to adjust the timing of the hydrographs The next slides show the result of 10 Dynamically Dimensioned Search (DDS) runs with WATFLOOD

18 800 Computed Flow Observed Flow 33-05BH004 BOW RIVER AT CALGARY 7868 km^2 Dv = % 600 cms BB001 BOW RIVER AT BANFF 2210 km^2 200 cms 100 Dv = %

19 1000 Computed Flow Observed Flow 33-05BH004 BOW RIVER AT CALGARY 7868 km^2 Dv = % cms BB001 BOW RIVER AT BANFF 2210 km^2 200 cms Dv = %

20 Computed Flow Observed Flow 2000 Dv = -1.9 % 33-05BH004 BOW RIVER AT CALGARY 7868 km^ cms BB001 BOW RIVER AT BANFF 2210 km^2 400 cms 300 Dv = %

21 Dv = % Qlz SIM OBS BH004 BOW RIVER AT CALGARY 7868 km^2 cms BB001 BOW RIVER AT BANFF 2210 km^2 cms 400 Dv = %

22 The approach - MESH Use existing watershed MESH model for the South Saskatchewan River Convert CaPA precipitation and temperature data form its native format to Green Kenue (GK) r2c formats Calibrated the model parameters for the CaPA met data for Oct 2004 Oct 2006 Calibrated the model on other sub-basins Model the 2013 Calgary flood

23 Standalone MESH run Really a spatial validation