HyMet Runoff Volume
Forecast Model
October 2010 Presentation | by Wendell Tangborn
HyMet, Inc. | 19001 Vashon Hwy SW Suite...
Outline
 Introduction
 Structure of HyMet Model
 Characteristics of HyMet Model
 Forecast Examples
 Comparisons
 Con...
Introduction
Forecasts of
Columbia River inflow
at Grand Coulee,
Lower Granite and
The Dalles are
distributed on a
weekly basis
beginni...
4
Importance of Runoff Volume
 Importance of Columbia
River runoff volume in
the Pacific Northwest
region:
 Hydropower E...
6
Structure of Model
6
Runoff Model Flow Chart
7
Area Altitude Profile for The Dalles Basin
9
Characteristics of Model
 57 Precipitation stations are selected from a list
of 2197 stations located in Montana, Idaho,
Oregon, Wyoming and Washi...
Temperature Station10
Weather Stations Used in Model
1. Precipitation Multiplier
2. Precipitation Intercept
3. Fraction of Snowmelt or Rain to Soil
4. Maximum Precipitation Mu...
R2
= 0.9549
0
20
40
60
80
100
0 5 10 15 20 25
Basin Water Storage (Inches)
RunoffVolume(MAF)
12
Basin Water Storage vs. Fo...
14
Forecast Examples
 Weekly forecasts contain 7
pages
Forecast seasons:
 Forecast day- Sep30
 January- July
 April - July
 April - Septem...
 Grand Coulee, Lower
Granite and The Dalles
Basins
 Daily basin water storage from
beginning of water year to
September ...
16
Page 3 - Water Basin Storage
 Grand Coulee, Lower Granite
and The Dalles Basins
 Distribution of mean basin water
sto...
17
Page 4 - Hydrograph
 Grand Coulee, Lower Granite
and The Dalles Basins
 Mean (1969-2009)
 Actual natural flow condit...
18
Page 5 - Hydrograph
 Grand Coulee, Lower Granite
and The Dalles Basins
 Cumulated runoff volume charts
for each basin
19
Page 6 – Precipitation & Temperature Summary
 Average, observed and
deviation of each parameter
for the entire season,...
20
Page 7 - Confidence Levels
 Calculated from Forecast and
Error
 Example of 90% lower
confidence level for Jan-Jul
for...
22
Comparisons
22
Comparisons of HyMet Forecasts
 Comparison Charts of HyMet, RFC and ESP
methods for Jan-Jul and Apr-Sep forecast
seaso...
23
Comparisons – Grand Coulee Basin
24
Comparisons – The Dalles Basin
25
Comparisons – Lower Granite Basin
27
Conclusions
27
 HyMet forecasts have proven equally, if not more
accurate compared to other forecast methods
Accuracy
HyMet RFC ESP
W...
28
Advantages
 Advantages of HyMet forecasts over others:
 Equally, if not more accurate
 More informative
 Weekly del...
30
Visit our website to subscribe:
HyMet, Inc. | 19001 Vashon Hwy SW Suite # 201 | Vashon, WA 98070 | www.hymet.com
Making...
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HyMet, Inc. - Forecast Model Presentation

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  • Precipitation Stations used in the model
  • HyMet, Inc. - Forecast Model Presentation

    1. 1. HyMet Runoff Volume Forecast Model October 2010 Presentation | by Wendell Tangborn HyMet, Inc. | 19001 Vashon Hwy SW Suite # 201 | Vashon, WA 98070 | www.hymet.com
    2. 2. Outline  Introduction  Structure of HyMet Model  Characteristics of HyMet Model  Forecast Examples  Comparisons  Conclusions  Accuracy  Advantages Over other Models  Differences 1
    3. 3. Introduction
    4. 4. Forecasts of Columbia River inflow at Grand Coulee, Lower Granite and The Dalles are distributed on a weekly basis beginning late November through mid-September for the upcoming 2010-2011 water year. 3 Runoff Volume Forecasts
    5. 5. 4 Importance of Runoff Volume  Importance of Columbia River runoff volume in the Pacific Northwest region:  Hydropower Electricity  Irrigation  Fisheries  Recreation
    6. 6. 6 Structure of Model
    7. 7. 6 Runoff Model Flow Chart
    8. 8. 7 Area Altitude Profile for The Dalles Basin
    9. 9. 9 Characteristics of Model
    10. 10.  57 Precipitation stations are selected from a list of 2197 stations located in Montana, Idaho, Oregon, Wyoming and Washington.  Calibration period of a selected precipitation station regressed with basin runoff: 1969-85  Verification period of a selected precipitation station regressed with basin runoff: 1986-2010  Forecast coefficients are first determined in calibration, then applied in verification for each precipitation station 9 Selection of Precipitation Stations
    11. 11. Temperature Station10 Weather Stations Used in Model
    12. 12. 1. Precipitation Multiplier 2. Precipitation Intercept 3. Fraction of Snowmelt or Rain to Soil 4. Maximum Precipitation Multiplier 5. Ablation from Temperature without Precipitation 6. Ablation from Temperature with Precipitation 7. Ablation from Temperature Range 8. Snowmelt Factor 9. Factor for Soil Moisture ET 10. Factor for Snowpack Sublimation 11. Fraction of Snowmelt or Rain to Groundwater Storage 12. Groundwater Outflow Multiplier 13. Groundwater Outflow Exponent 14. Lower Lapse Rate Threshold 15. Upper Lapse Rate Threshold 11 Model Calibration: 15 Coefficients
    13. 13. R2 = 0.9549 0 20 40 60 80 100 0 5 10 15 20 25 Basin Water Storage (Inches) RunoffVolume(MAF) 12 Basin Water Storage vs. Forecast Volume Grand Coulee Dam April 1, 2009
    14. 14. 14 Forecast Examples
    15. 15.  Weekly forecasts contain 7 pages Forecast seasons:  Forecast day- Sep30  January- July  April - July  April - September  January - September  Forecast in MAF  Forecast as % of (1971- 2000)Mean  R-square and Mean Error %  Confidence levels for forecast Season 14 Page 1 – Forecast Overview
    16. 16.  Grand Coulee, Lower Granite and The Dalles Basins  Daily basin water storage from beginning of water year to September 30 15 Page 2 - Water Basin Storage
    17. 17. 16 Page 3 - Water Basin Storage  Grand Coulee, Lower Granite and The Dalles Basins  Distribution of mean basin water storage with elevation
    18. 18. 17 Page 4 - Hydrograph  Grand Coulee, Lower Granite and The Dalles Basins  Mean (1969-2009)  Actual natural flow condition up to the forecast day  Actual regulated flow condition up to forecast day  Forecast hydrograph
    19. 19. 18 Page 5 - Hydrograph  Grand Coulee, Lower Granite and The Dalles Basins  Cumulated runoff volume charts for each basin
    20. 20. 19 Page 6 – Precipitation & Temperature Summary  Average, observed and deviation of each parameter for the entire season, and for previous week  Precipitation (inches)  Temperature (degrees)  Reconstructed Natural Inflows (MAF)
    21. 21. 20 Page 7 - Confidence Levels  Calculated from Forecast and Error  Example of 90% lower confidence level for Jan-Jul forecast:  CL90=Forecast-1.645 *Error  Forecast = 87% (Equal chance observed runoff will be above or below 87%)  CL=68% (9 in 10 chance runoff will be at least 68%  1 in 10 chance observed will be less than 68%)
    22. 22. 22 Comparisons
    23. 23. 22 Comparisons of HyMet Forecasts  Comparison Charts of HyMet, RFC and ESP methods for Jan-Jul and Apr-Sep forecast seasons  Grand Coulee Basin  The Dalles Basin  Lower Granite Basin
    24. 24. 23 Comparisons – Grand Coulee Basin
    25. 25. 24 Comparisons – The Dalles Basin
    26. 26. 25 Comparisons – Lower Granite Basin
    27. 27. 27 Conclusions
    28. 28. 27  HyMet forecasts have proven equally, if not more accurate compared to other forecast methods Accuracy HyMet RFC ESP WY/BASIN GCL LWG TDA GCL LWG TDA GCL LWG TDA 2005 2.8 11.0 4.5 5.8 10.1 7.4 2006 5.8 7.9 5.0 7.0 6.6 6.4 2007 3.9 21.8 5.3 2.0 13.2 4.8 5.4 15.8 8.4 2008 5.6 11.3 7.1 2.9 2.5 2.6 3.2 5.1 3.9 2009 7.3 13.9 3.9 8.1 11.2 2.5 7.8 9.0 4.3 2010 5.0 6.8 4.4 5.9 13.8 9.9 8.3 13.7 10.9 MEAN 5.1 12.1 5.0 5.3 9.6 5.6 6.2 10.9 6.9
    29. 29. 28 Advantages  Advantages of HyMet forecasts over others:  Equally, if not more accurate  More informative  Weekly delivery; directly to your email inbox  Longer forecast season  Excel worksheet available for any date in water year  Distribution to multiple users (5 per subscription)  Differences:  We do not incorporate the future varying weather conditions in the model and assume normal future precipitation for the season.
    30. 30. 30 Visit our website to subscribe: HyMet, Inc. | 19001 Vashon Hwy SW Suite # 201 | Vashon, WA 98070 | www.hymet.com Making Renewable Reliable.

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