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Seasonal outlooks for hydrology and water resources: streamflow, reservoir, and hydropower forecasts for the Pacific Northwest Andy Wood and Alan Hamlet.

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Presentation on theme: "Seasonal outlooks for hydrology and water resources: streamflow, reservoir, and hydropower forecasts for the Pacific Northwest Andy Wood and Alan Hamlet."— Presentation transcript:

1 Seasonal outlooks for hydrology and water resources: streamflow, reservoir, and hydropower forecasts for the Pacific Northwest Andy Wood and Alan Hamlet Department of Civil and Environmental Engineering for Climate and Water Resource Forecasts for the 2007 Water Year UW Climate Impacts Group October 3, 2006, Kelso, WA

2 Part I West Wide Hydrologic Forecast System

3 Experimental W. US Hydrologic Forecast System Soil Moisture Initial Condition Snowpack Initial Condition

4 Experimental Western US Hydrologic Forecast System ESP ENSO/PDO ENSO CPC Official Outlooks NCEP CFS CAS OCN SMLR CCA CA NSIPP/GMAO dynamical model VIC Hydrolog y Model NOAA NASA UW Multiple Seasonal Climate Forecast Data Sources

5 Hydrologic Model-based Forecasting ICs Spin-upForecast obs recently observed meteorological data ensemble of met. data to generate forecast hydrologic state

6 targeted statistics e.g., runoff volumes monthly hydrographs spatial forecast maps

7 Flow location maps give access to monthly hydrograph plots, and also to raw forecast data. Clicking the stream flow forecast map also accesses current basin-averaged conditions Applications: streamflow Introduction

8 Soil Moisture for last 2 weeks The daily update of surface conditions enables animationed views of recent changes

9 Other views of changing hydrologic conditions www.hydro.washington.edu/ forecast/monitor/ Soil moisture change in last month

10 WY 2007 Forecast

11 Average annual water cycle The PNW hydrologic cycle PNW Where we are now on average  soil moisture near annual low  runoff near low  nearly all water year precipitation yet to come  snow season not really underway  evaporation not a factor

12 The PNW hydrologic cycle  water balance Note that there is variability in soil moisture now… current

13 Oct. 1 Soil Moisture Comparison THIS YEAR LAST YEARTHIS YEAR

14 Sep 1 ESP / ESP-El Nino fcst: Summer Volumes Forecasts of April-September Flow Dalles: 100 / 88 ESPESP - El Nino

15 Sep 1 ESP / ESP-El Nino fcst: Summer Volumes Forecasts of April-September Flow Snake: 96 / 83 ESPESP - El Nino

16 Sep 1 ESP / ESP-El Nino fcst: Summer Volumes Forecasts of April-September Flow Upper Snake: 95 / 83 ESPESP - El Nino

17 Recap of WY 2006

18 Recap WY2006, Dec. 1 hydrologic conditions Soil MoistureSWE

19 Recap WY2006, Jan. 1 hydrologic conditions

20 Recap WY2006, Feb. 1 hydrologic conditions

21 Recap WY2006, Mar. 1 hydrologic conditions

22 Recap WY2006, Apr. 1 hydrologic conditions

23 Recap WY2006, May. 1 hydrologic conditions

24 Recap WY2006, Jul. 1 hydrologic conditions

25 Winter 2005-06: seasonal volume forecast for APR-SEP flow OBS Forecasts made on 1 st of Month

26 Winter 2005-06: seasonal volume forecast for APR-SEP flow OBS Forecasts made on 1 st of Month

27 Part II ENSO/PDO Forecasts

28 ENSO is typically very stable from Oct-Jan

29 Evaluation of Sept 1 ECMWF Nino3.4 Forecast for WY 2003-2005 WY 2003 WY 2004WY 2005

30 Used range: Jan3.4 >= -0.4 Jan3.4 <= 0.6 Evaluation of Aug 1 ECMWF Nino3.4 Forecast for WY 2006

31 Nino3.4 -0.4 to 0.6 Ensemble Streamflow Forecast for the Columbia River at The Dalles for WY 2006. (Nino3.4 anomalies between -0.4 and 0.6) Naturalized Flow (cfs) Black = Climatological Extremes Gray = Forecast Ensemble Members Red = Observed Blue = Ensemble Mean

32 Natural Flows at Milner 1928-1989

33 Natural Streamflow (KAF) WY 2006 Red = long term mean Blue = ensemble mean Gray = ensemble members Black = range of observations

34 October 1 Spin Up System Storage Forecast from SnakeSim: Jackson Lake Palisades Island Park Ririe American Falls Lake Walcott Nino3.4 anomaly between -0.4 and 0.6 C Demand aligned with water cond. Active Reservoir Storage (kaf) Obs. System Storage Oct 8, 2006

35 Nino3.4 0.0 to 0.6 Ensemble Streamflow Forecast for the Columbia River at The Dalles for WY 2006. (Nino3.4 anomalies between 0.0 and 0.6) Naturalized Flow (cfs) Black = Climatological Extremes Gray = Forecast Ensemble Members Red = Observed Blue = Ensemble Mean

36 WY 2007 Forecast

37 http://www.ecmwf.int/products/forecasts/d/charts/seasonal/forecast/plumes/

38 Natural Flows at Milner 1928-1989

39 Milner 2007 Nino3.4 Range 0.7 to 1.5 Natural Flow (KAF) Red = long term mean Blue = ensemble mean Gray = ensemble members Black = range of observations 2007 Forecast for Natural Flow at Milner

40 Milner 2007 Nino3.4 Range 0.7 to 1.5 Warm PDO Natural Flow (KAF) Red = long term mean Blue = ensemble mean Gray = ensemble members Black = range of observations 2007 Forecast for Natural Flow at Milner

41 Upper Snake Storage (KAF) 2007 System Storage Forecasts for the Upper Snake (Oct-Aug) Nino3.4 Range 0.7 to 1.5 Nino3.4 Range Warm PDO Full

42 Modified Flow (cfs) Ensemble Streamflow Forecast for the Columbia River at The Dalles for WY 2007. (Nino3.4 anomalies between 0.7 and 1.5) Black = Climatological Extremes Gray = Forecast Ensemble Members Red = LTM from 1950-1999 Blue = Ensemble Mean

43 All Years (‘60-’99) Nino3.4 Composite Long-Range Ensemble Forecasts of System-Wide Columbia Basin Hydropower Production for Water Year 2007.

44 Summary of Ensemble Average Hydropower Production for All Years (‘60-’99) Vs. Nino3.4 Composite Nino3.4 composite is about 7% lower

45 Regionally Averaged Cool Season Precipitation Anomalies PRECIP

46 Selected References on Compositing Techniques: Hamlet, A.F., Lettenmaier, D.P., 1999: Columbia River Streamflow Forecasting Based on ENSO and PDO Climate Signals, ASCE J. of Water Res. Planning and Mgmt., 125 (6) : 333-341 Werner, K., Brandon, D., Clark, M., et al., 2004: Climate index weighting schemes for NWS ESP-based seasonal volume forecasts, J. of Hydrometeorology, 5 (6): 1076-1090

47 Conclusions: The WY 2006 ESP forecast predicted a range of flows centered around near normal conditions. Actual flows in 2006 were towards the upper range of this forecast, probably due in part to an unusually large ENSO forecast error. A moderate warm ENSO event is expected for the winter of 2006-2007. ESP traces from 1960- 1999 associated with a forecasted range of Nino3.4 anomalies from 0.7-1.5 suggest elevated drought risks for WY 2007, and lower carryover storage in the upper Snake at the end of WY 2007.


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