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Experimental Inflow and Storage Forecasts Portal

Harminder SinghDepartment of Civil and Environmental Engineering

State Climate Office of NC

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Presentation Outline1. Introduction and Objectives2. Inflow Forecasting Model 3. Storage Forecasting Model4. Inflow and Storage Portal - Overview5. Inflow Forecasts (Monthly and Seasonal)6. Storage Forecasts (Monthly and Seasonal)7. Conclusion and Future Work

Falls

Jordan

Philpott

Kerr Scott

Rocky Creek

SF Catawba

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Presentation Outline1. Introduction and Objectives2. Inflow Forecasting Model 3. Storage Forecasting Model4. Inflow and Storage Portal 5. Inflow Forecasts (Monthly and Seasonal)6. Storage Forecasts (Monthly and Seasonal)7. Conclusion and Future Work

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Need for Inflow and Storage Forecasts• Need of Inflow and Storage Forecasts

– Recent Increase in Demand – Urbanization– Demand induced droughts even under normal inflow variability

• Streamflow Forecasts and Water Management– Daily to Weekly time scale – Flooding, Peak power generation– Monthly to Seasonal Time Scales – Allocation and Firm Power

• Provide Inflow and Storage forecasts for Reservoirs in the Southeast US

• Inflow and Storage Forecasts Portal– Portal Overview and Skill Assessment

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Inflow Forecasts - Challenges• Monthly to Seasonal Inflows

– Monthly to Seasonal Climate over the watershed– Current Basin Storage – Soil Moisture and Ground water

• Challenges in Seasonal Streamflow Forecasting– Climate Forecasts – Needs to be downscaled– Limited Basin Storage Data

• Streamflow Forecasts and Reservoir Management– Streamflow Forecasts needed at the reservoir site– Interest on net-inflows = Total streamflow - Evaporation– Inflow forecasts needs to be probabilistic

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Need for Storage Forecasts• Reservoirs in the east are within-year

– Humid basins – Fill it up by April 1st

– Winter is the critical filling period – good skill

• Why we need storage forecasts?– Inflow forecasts related to storage projections– Initial conditions in the reservoirs also influence

• Issues in developing storage forecasts– Need to consider end of the month/season target storage– Varies depending on the user-defined releases– Probabilistic information in meeting the target storage

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Presentation Outline1. Introduction and Objectives2. Inflow Forecasting Model 3. Storage Forecasting Model4. Inflow and Storage Portal 5. Inflow Forecasts (Monthly and Seasonal)6. Storage Forecasts (Monthly and Seasonal)7. Conclusion and Future Work

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Inflow Forecasting Model - Overview

Precipitation Forecasts (Pt) from GCMs

IRI Data Library

PredictandModel

Observed Streamflow (Qt-1)

Statistical Downscaling Model (PCR)

Forecasted Streamflow (Qt)

Training Period : Data up to previous year?Archived Forecasts : 1990-till date

Predictors

State Climate Office of NC

Portal automatically downloads Updated Monthly/Seasonal Precipitation Forecasts from GCMs between 15-18 of each month

Use for Storage Forecast

(Reservoir Model)

• Climate Data (GCMs): ECHAM 4.5• Observed Streamflow: USACE Site

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Inflow Forecasts – Statistical DownscalingStatistical Downscaling- Precipitation forecasts from ECHAM4.5

- forced with constructed analogue SST forecasts- Precipitation from the GCMs is spatially correlated - Principal component Regression

- Principal Component Analysis (PCA) is used to reduce the data

- PCA is applied on the predictors - Streamflow and ECHAM4.5 precipitation forecasts

- Principal component regression to obtain Inflow forecasts.- Inflow Forecasts are provides as Ensembles

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Presentation Outline1. Introduction and Objectives2. Inflow Forecasting Model 3. Storage Forecasting Model4. Inflow and Storage Portal 5. Inflow Forecasts (Monthly and Seasonal)6. Storage Forecasts (Monthly and Seasonal)7. Conclusion and Future Work

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Storage Forecasting Model• Net-Inflows Forecast: qtk; t=1…,T; k=1,…,N• Continuity Equation: t=1,2, …, T

• User will prescribe the releases or use observed releases• Critical variable: End of the season target storage

– Initial storage can provide water for entire forecasting period

• Simulation Model estimates P(STL < ST < ST

U)

– Probability of having the storage within the conservation pool

n

ititttt REqSS

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Presentation Outline1. Introduction and Objectives2. Inflow Forecasting Model 3. Storage Forecasting Model 4. Inflow and Storage Portal – Individual Years5. Inflow Forecasts (Monthly and Seasonal)6. Storage Forecasts (Monthly and Seasonal)7. Conclusion and Future Work

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Spatial and Temporal Extent• Inflow and Storage Forecasts – Spatial Extent

– Neuse - Falls Lake – Fully Automated– Cape Fear - Jordan Lake – Fully Automated– Yadkin – Scott Keer Reservoir – Roanoke – Philpott – Catawba – South Fork and Rocky Creek

• Inflow and Storage Forecasts – Temporal Extent– Monthly (at 1, 2 or 3 month lead time) and seasonal– Available from 1990 to present, updated month – Individual year forecasts or Retrospective forecasts

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Inflow Forecasting Models• Inflow Forecasts Models

– Statistical Downscaling (PCR)• IRI Climate Forecasts – ECHAM4.5, Multimodel

– Monthly/Seasonal Climatology (No Forecasts)– Land Surface Models (Under Integration)

• NASA’s Land Information System – NOAH 3.2• Variable Infiltration Capacity Model

• Forecast Skills– Deterministic forecasts or as ensembles– Retrospective skill summary

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Experimental Inflow and Storage Forecasts Portal(http://www.nc-climate.ncsu.edu/inflowforecast)

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Inflow Forecasts (Individual Year)

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Inflow Forecasts (Individual Year)

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Forecast skill Evaluation

Month/SeasonObserved

Inflow (CFS)

Forecast 50th Percentile (CFS)

Relative RMSE MSSS RPSS

January '90 1310 754 0.425 -0.227 -0.313

Categorical Forecasts

Climatological PercentilePercentile Values (CFS) Model Probabilities

January '90 January '90<10% < 158 0.040

10-33% 158 - 700 0.42633-50% 368 - 700 0.09250-67% 857 - 1242 0.15867-90% 1242 - 1931 0.858>90% > 1931 0.142

Inflow Forecasts (Individual Year)

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Storage Forecasts (Individual Year)

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Storage Forecasts (Individual Year)

Stage Level(ft above MSL): Model Percentiles:

Below conservation pool: <236.5 0.00%Within limits of conservation pool: 236.5 - 251.5 79.40%Within limits of flood control pool: 251.5 - 264.8 19.00%Above flood control pool: >264.8 1.60%

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Inflow Forecasts (Retrospective)

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Inflow Forecasts (Retrospective)

January Forecast Skill EvaluationRelative RMSE RPSS Correlation MSSS

0.418 -0.148 0.663 0.156

January Forecast Probability Distribution

YearPercentiles

Observed Inflow (CFS)<33% 33-67% >67%

Percentile Flow Values < 700</td> 700 - 1242 > 1242 --

1990 0.466 0.250 0.284 1310

1991 0.342 0.256 0.402 2084

1992 0.290 0.250 0.460 1174

1993 0.322 0.256 0.422 1868

1994 0.404 0.258 0.338 784

1995 0.364 0.258 0.378 843

1996 0.506 0.242 0.252 1682

1997 0.450 0.254 0.296 1151

1998 0.172 0.194 0.634 3006

1999 0.586 0.218 0.196 1598

2000 0.552 0.228 0.220 1127

Inflow Forecasts (Retrospective)

This is the percentile range which was predicted to be the

most likely to occur

The observed flow falls between the percentiles

indicated by the column for each year

The observed flow was forecasted correctly by the

model for this yea23

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Storage Forecasts (Retrospective)

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Storage Forecasts (Retrospective)

Year Observed Outflow (cfs)

Observed Inflow (cfs)

Median Forecasted Inflow (cfs)

Start-of-Month Elevation

End-of-Month

Elevation

1990 1291 1310 756 250.54 250.21991 2125 2084 999 245.57 250.111992 501 1173 1138 250.23 250.051993 1873 1867 1048 246.42 250.21994 121 783 864 247.31 250.621995 367 843 946 250.39 250.171996 1616 1682 690 250.64 250.451997 1126 1150 780 249.88 250.731998 1165 3006 1709 247.36 257.651999 886 1598 577 251.98 251.092000 693 1127 625 249.86 254.44

Reservoir Information for January:Storage Range Probabilities:

YearBelow

ConservationPool

Within Conservation

PoolWithin Flood Control Pool

Spilling Over Flood Control

PoolObserved

Storage (acre-ft)Median

Forecasted Storage (acre-ft)

1990 0.00% 77.80% 20.40% 1.80% 116020 87057

1991 64.00% 26.00% 8.20% 1.80% 114975 2370

1992 0.00% 31.60% 61.60% 6.80% 114278 155522

1993 48.00% 38.20% 11.60% 2.20% 116020 27816

1994 0.00% 49.40% 47.40% 3.20% 120895 132051

1995 0.00% 28.80% 66.40% 4.80% 115671 153849

1996 0.20% 85.60% 13.00% 1.20% 118922 64217

1997 0.00% 75.80% 22.40% 1.80% 122172 91101

1998 0.80% 53.40% 34.80% 11.00% 219366 120241

1999 0.00% 63.60% 35.00% 1.40% 126431 118481

2000 0.00% 70.40% 28.20% 1.40% 170804 108012

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Presentation Outline1. Introduction and Objectives2. Inflow Forecasting Model 3. Storage Forecasting Model4. Inflow and Storage Portal 5. Inflow Forecasts (Monthly and Seasonal)6. Storage Forecasts (Monthly and Seasonal)7. Conclusion and Future Work

Seasonal Inflow Forecasts - JFM

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Seasonal Inflow Forecasts - AMJ

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Seasonal Inflow Forecasts - JAS

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Seasonal Inflow Forecasts - OND

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Seasonal Inflow (Climatology)

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Seasonal Inflow Forecasts – Skill Summary

Falls Lake - SeasonJan - Mar Apr - Jun Jul - Sep Oct - Dec

R-RMSE 0.703 0.959 1.563 2.465RPSS 0.23 0.1 -0.13 0.1Correlation 0.861 0.547 0.42 0.413MSSS 0.408 0.146 0.159 0.076

• Relative-RMSE : A good forecast is expected to have R-RMSE closer to zero

• RPSS : If RPSS is positive, then the forecast skill exceeds that of the climatological probabilities.

• Correlation: A good forecast is expected to have a correlation around one.

• MSSS : A good forecast is expected to have MSSS be closer to one.

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Seasonal Inflow Forecasts - PCR vs. Climatology Falls Lake

YearPercentiles (Climatology)

<33% 33-67% >67%1990 0.314 0.388 0.2981991 0.314 0.388 0.2981992 0.314 0.388 0.2981993 0.314 0.388 0.2981994 0.314 0.388 0.2981995 0.314 0.388 0.2981996 0.314 0.388 0.2981997 0.314 0.388 0.2981998 0.314 0.388 0.2981999 0.314 0.388 0.2982000 0.314 0.388 0.2982001 0.314 0.388 0.2982002 0.314 0.388 0.2982003 0.314 0.388 0.2982004 0.314 0.388 0.2982005 0.314 0.388 0.2982006 0.314 0.388 0.2982007 0.314 0.388 0.298

Percentiles (PCR Model)<33% 33-67% >67%0.364 0.322 0.3140.160 0.270 0.5700.260 0.328 0.4120.412 0.322 0.2660.306 0.328 0.3660.226 0.300 0.4740.204 0.266 0.5300.458 0.284 0.2580.368 0.322 0.3100.210 0.248 0.5420.574 0.264 0.1620.624 0.244 0.1320.324 0.332 0.3440.334 0.332 0.3340.288 0.318 0.3940.532 0.290 0.1780.370 0.324 0.3060.402 0.328 0.270

Model Predicted Percentile

Observed Flow Percentile

Model Predicted and Observed Flow

Percentile

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Seasonal Storage Forecasts - JFM

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Seasonal Storage Forecasts – JFMFalls Lake

YearBelow

ConservationPool

Within Conservation

PoolWithin Flood Control Pool

Spilling Over Flood Control Pool

2000 30.90% 33.50% 23.20% 12.40%

2001 0.00% 17.30% 62.20% 20.50%

2002 0.00% 18.10% 62.50% 19.40%

2003 18.60% 26.00% 30.50% 24.90%

2004 0.00% 18.60% 57.10% 24.30%

2005 7.50% 34.80% 40.20% 17.50%

2006 0.00% 12.40% 66.60% 21.00%

2007 4.80% 28.20% 43.20% 23.80%

2008 0.00% 34.90% 52.60% 12.50%

2009 6.10% 36.80% 39.00% 18.10%

2010 20.50% 24.20% 30.30% 25.00%

2011 0.00% 13.30% 68.90% 17.80%

2012 0.00% 7.50% 64.10% 28.40%

Model Predicted Percentile

Observed Storage Percentile

Model Predicted and Observed

Storage Percentile

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Seasonal Storage Forecasts: Climatology – JFM

Monthly Inflow Forecasts - 6/2007 (3 Month Lead)

Climatological Percentile Percentile Values (CFS) Model Probabilities June '07 June '07

<10% < 0 0.51810-33% 0 - 67 0.03633-50% 55 - 67 0.03250-67% 130 - 325 0.09867-90% 325 - 1093 0.93>90% > 1093 0.07

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Monthly Inflow Forecasts - 7/2007 (3-Month Lead)

Climatological Percentile Percentile Values (CFS) Model Probabilities July '07 July '07

<10% < 2 0.26210-33% 2 - 34 0.03433-50% 31 - 34 0.05850-67% 83 - 232 0.1967-90% 232 - 756 0.962>90% > 756 0.038

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Monthly Inflow Forecasts - 8/2007 (3-month Lead)

Climatological Percentile Percentile Values (CFS) Model Probabilities August '07 August '07

<10% < 0 0.40010-33% 0 - 28 0.03233-50% 21 - 28 0.1350-67% 139 - 291 0.16667-90% 291 - 795 0.978>90% > 795 0.022

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Monthly Storage Forecasts – JJA 2007- 3-Month Lead

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Monthly Inflow Forecasts: Sep 1996

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Inflow Forecasts- Sep 2012 – 1-Month lead

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Inflow Forecasts - Oct 2012 – 2 Month Lead

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Inflow Forecasts - Nov 2012 – 3 Month Lead

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Storage Forecasts - Nov 2012 – 3 Month Lead

Storage Forecasts - Nov 2012 – 3-Month Lead

Stage Level (ft above MSL): Model Percentiles:Below conservation pool: <236.5 10.60%Within limits of conservation pool: 236.5 - 251.5 24.80%Within limits of flood control pool: 251.5 - 264.8 57.80%Above flood control pool: >264.8 6.80%

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Overview of Forecasting• Individual Year or Retrospective Forecasts• Seasonal and Monthly Forecast

– Inflow forecast with skills summary– Storage forecast

• User defined outflow or observed outflow

• New Inflow and Storage Monthly Forecast – Available at the middle of month – Various lead times– Requires user defined outflows

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Presentation Outline1. Introduction and Objectives2. Inflow Forecasting Model 3. Storage Forecasting Model4. Inflow and Storage Portal 5. Inflow Forecasts (Monthly and Seasonal)6. Storage Forecasts (Monthly and Seasonal)7. Conclusion and Future Work

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Conclusion, Future Work

• Add Land Surface Models for Inflow Forecasts• Develop Multimodel Inflow Forecasts• Provide Inflow and Storage Forecasts for other

Reservoirs in the Southeast US• Available at the State Climate Office Website

(http://www.nc-climate.ncsu.edu/inflowforecast)

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Acknowledgements• Project Funded by: Water Resources Research Institute (WRRI)

and NC Urban Water Consortium (NC UWC)• Dr. Sankar Arumugam – Associate Professor - NC State

University • Dr. Ryan Boyles - State Climatologist and Director - State

Climate Office of North Carolina• Dr. Tushar Sinha - Postdoctoral Research Scientist - NC State

University • Simon Mason - Research Scientist - IRI • Andrew McNamara - Graduate Student - NC State University• Thomas Petersen - Prospective Graduate Student