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NWRFC Water Supply Forecast Procedure for Dworshak Inflow Steve King, Hydrologist Rick van der Zweep, Hydrologist Northwest River Forecast Center.

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Presentation on theme: "NWRFC Water Supply Forecast Procedure for Dworshak Inflow Steve King, Hydrologist Rick van der Zweep, Hydrologist Northwest River Forecast Center."— Presentation transcript:

1 NWRFC Water Supply Forecast Procedure for Dworshak Inflow Steve King, Hydrologist Rick van der Zweep, Hydrologist Northwest River Forecast Center

2 NWRFC Water Supply Forecast Process  Regression Model  Stepwise linear  Combined Index vs Observed Flows  Manual Adjustment  Forecasts QC inputs  Forecasters adjust output based on a variety of inputs  Inter-basin Cross Plots  Forecast Coordination

3 Regression Model Combined Index incorporates: Precip, Snow, & Runoff Step-wise Linear Approach

4 Single Equation for Entire Forecast Period One Single Equation Applied Through Forecast Season Observed Precip, Snow, Runoff Normal Subsequent Precip Feb 1 Fcst Mar 1 Fcst

5  Oct-Nov Fall Runoff  Natural Flow = 174%  Feb 1 Snow Water Equivalent (70% Combined Winter Precip Term)  Pierce (.27 rel wt) = 77%  Shanghai Summit (.20 rel wt) = 86%  Lolo Pass (.19 rel wt) = 86%  Hoodoo Creek (.11 rel wt) = 83%  Lost Lake (.10 rel wt) = 82  Nov-Jan Precipitation (30% Combined Winter Precip Term)  Avery R.S. (.40 rel wt) = %  Orofino (.30 rel wt) = %  Pierce (.30 rel wt) = %  Kooskia R.S. (.25 rel wt) = %  Fenn R.S. (.20 rel wt) = %  Feb-Jun Mean Subsequent Precipitation  Assumption of 80% Normal for February  Assumption of 100% Normal for March-June Dworshak Forecast Components (Feb 1, 2007 states) Weighted Mean = 82% Seasonal Wt Mean = 124%

6 Dworshak WS Forecast Trend 2.46 MAF (93%)

7 Dworshak ESP Forecast Trend 2.43 MAF (92%)

8 Dworshak Forecast Verification Feb 1 Final Forecast of Apr-Jul Period Feb Final Forecast, Apr-Jul Period (KAF) Observed Adj. Apr-Jul Volume (KAF)


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