NWSRFSNWSRFSEnsemble Streamflow PredictionEnsemble Streamflow Prediction

Gerald (Jay) Day

2290 East Prospect Road, Suite 1Fort Collins, Colorado 80525

Ensemble Probabilistic Ensemble Probabilistic ForecastingForecasting

Hydrologic simulation using historic precipitation and temperature

Frequency analysis using “conditioned” hydrologic time series traces

0

5

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15

20

1985

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1

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1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61

Day

Dis

char

ge

1987

1986

1985

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20

1986

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25

1987

Likelihood of Exceeding Flood Capacity

Exceedance Probability

Vo

lum

e

ESP Forecast ApplicationsESP Forecast Applications

Water Supply ForecastsSpring Flood OutlooksDrought AnalysisHydropower PlanningFisheries ManagementRecreationNavigationReservoir Inflow Forecasts

Water Management Water Management ConsiderationsConsiderations

Flood Control

HydropowerWater SupplyRecreation

HydropowerNavigationWater QualityFisheriesRecreation

Soil Moisture in the Lake Soil Moisture in the Lake Lanier BasinLanier Basin

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58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86

YEAR

JUN

E 1

SO

IL M

OIS

TU

RE

ST

OR

AG

E (

mm

)

June 1, 1988 Conditions

Lake Lanier Inflow Forecast – Lake Lanier Inflow Forecast – June 1988June 1988

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PROBABILITY OF EXCEEDANCE

ST

RE

AM

FL

OW

VO

LU

ME

(100

0's

of

acre

fee

t)

1 10 50 90 99

76%3%

CONDITIONAL FORECAST

HISTORICAL SIMULATION

NWSRFS StructureNWSRFS Structure

Hydrologic Operations

Operational Forecast System

Ensemble Streamflow Prediction System

Calibration System

NWSRFS Software OverviewNWSRFS Software Overview

AutomaticData EntryFunctions

ObservedDataFiles

PreprocessorFunctions

Pre-Processor Parameter

Files

Processed Data Files

Forecast Functions

ManualPreparation

Forecast Parameter

and Carryover

Files

OPERATIONAL FORECAST SYSTEM

Historical Data

Historical DataAccess Programs

Calibration Pre-processors and

Calibration Utility

Calibration Data Files

Manual Calibration Program

Automatic ParameterOptimizer

Parametric Data

ESP Functions

ESP Parameter

Files

ESP Initialization

Program

ESP Time Series Files

ENSEMBLE STREAMFLOW PREDICTION SYSTEM

CALIBRATION SYSTEM

ESP ProcedureESP Procedure

CURRENT CONDITIONS• SOIL MOISTURE• SNOW PACK• RESERVOIR LEVELS• STREAMFLOW

HISTORICALTIME SERIES

ALL YEARS OFRECORD

FORECASTTIME SERIES

MEAN AREALTIME SERIES

PRECIPITATIONTEMPERATURE

NWSRFSHYDROLOGIC

MODELS

POSITIONALCLIMATOLOGICAL

INFORMATION

FORECASTS ANDOUTLOOKS

• WATER SUPPLY• OTHER WATER MGMT

INFORMATION

STATISTICALANALYSIS

WINDOW

PRESENT

TIME

ST

RE

AM

FLO

W

ESP Analysis and Display ESP Analysis and Display Program (ESPADP)Program (ESPADP)

ESPADP Trace Ensemble PlotESPADP Trace Ensemble Plot

ESPADP Expected Value PlotESPADP Expected Value Plot

ESPADP Probability HistogramESPADP Probability Histogram

ESPADP Exceedance Probability ESPADP Exceedance Probability PlotPlot

ESPADP Analysis VariablesESPADP Analysis Variables

Instantaneous Peak Flow Mean Daily Peak

Number of days above flood stage

Volume of flow

Flood stage

Minimum instantaneous flow

Time

Number of days until flood stage is exceededFlow

ESP Computed VariablesESP Computed Variables Variables that can be calculated for specified window:

• Maximum mean daily value and number of days to maximum mean daily value

• Minimum mean daily value and number of days to minimum mean daily value

• Mean daily value

• Volume

• Maximum instantaneous value and number of days to maximum instantaneous value

• Minimum instantaneous value and number of days to minimum instantaneous value

• Number of days until time series gets above (or below) a specified criterion

• Number of days time series remains above (or below) a specified criterion

ESPADP Observed and Conditional ESPADP Observed and Conditional SimulationSimulation

ESPADP Observed and Historical ESPADP Observed and Historical SimulationSimulation

Meteorological Forecast Meteorological Forecast InformationInformation

1 to 5 Day Forecasts

6 to 10 Day Categorical Forecasts

Monthly / Seasonal Outlooks

1 –5 Day Forecasts1 –5 Day ForecastsTemperature Precipitation

6 – 10 Day Forecasts6 – 10 Day Forecasts

Temperature Precipitation

Seasonal OutlookSeasonal OutlookTemperature Precipitation

ESPADP Pre-adjustment ESPADP Pre-adjustment TechniqueTechnique

ESPADP Year WeightingESPADP Year Weighting Used to incorporate Climate Forecast Information

Post ESP analysis procedure

Weights are set based on the similarity of a historical year to the current year

Can be used to exclude historical years

ESP ExampleESP Example