Alan F. Hamlet JISAO/CSES Climate Impacts Group Dept. of Civil and Environmental Engineering

1. Quantifying the Effects of Climate Variability and Change on Hydrologic Extremes in the Pacific Northwest • Alan F. Hamlet • JISAO/CSES Climate Impacts Group • Dept. of Civil and Environmental Engineering • University of Washington

2. CBCCSP Research Team Lara Whitely Binder Pablo Carrasco Jeff Deems Marketa McGuire Elsner Alan F. Hamlet Carrie Lee Se-Yeun Lee Dennis P. Lettenmaier Jeremy Littell Guillaume Mauger Nate Mantua Ed Miles Kristian Mickelson Philip W. Mote Rob Norheim Erin Rogers Eric Salathé Amy Snover Ingrid Tohver Andy Wood http://www.hydro.washington.edu/2860/products/sites/r7climate/study_report/CBCCSP_chap1_intro_final.pdf

3. The Myth of Stationarity: 1) Climate Risks are stationary in time. 2) Observed streamflow records are the best estimate of future variability. 3) Systems and operational paradigms that are robust to past variability are robust to future variability.

4. The Myth of Stationarity Meets the Death of Stationarity Muir Glacier in Alaska Aug, 13, 1941 Aug, 31, 2004 Image Credit: National Snow and Ice Data Center, W. O. Field, B. F. Molnia http://nsidc.org/data/glacier_photo/special_high_res.html

5. Why a Focus on Hydrologic Extremes? Many human and natural systems are quite robust under “normal” conditions, but have the potential to be profoundly impacted by hydrologic extreme events.

6. Floods http://www.nps.gov/mora/parknews/upload/floodPP.pdf

7. Drought Evacuated Reservoir During the 2001 PNW Drought

8. Wildfire

9. Low Flow and Temperature Impacts to Fish Temperature/ Disease Related Fish Kill in the Klamath River in 2002

10. Dam Safety Aftermath of the Johnstown Flood 1889

11. Dilution Flows for Industrial Pollutants

12. Stormwater Management

13. Sediment Transport and Mudslides

14. Historical Perspectives: Changing Flood Risk in the 20th Century

15. References: Niemann, PJ, LJ Schick, FM Ralph, M Hughes, GA Wick, 2010: Flooding in Western Washington: The Connection to Atmospheric Rivers, J. of Hydrometeorology, (in review) Hamlet AF, Lettenmaier DP (2007) Effects of 20th century warming and climatevariability on flood risk in the western U.S. Water Resour Res, 43:W06427.doi:10.1029/2006WR005099

16. Observed Characteristics of Extreme Precipitation Events

17. Evidence of Changing Flood Statistics

19. Role of Atmospheric Rivers in Flooding (Nov 7, 2006) Niemann, PJ, LJ Schick, FM Ralph, M Hughes, GA Wick, 2010: Flooding in Western Washington: The Connection to Atmospheric Rivers, J. of Hydrometeorology, (in review)

20. Role of Atmospheric Rivers in Flooding (Oct 20, 2003) Niemann, PJ, LJ Schick, FM Ralph, M Hughes, GA Wick, 2010: Flooding in Western Washington: The Connection to Atmospheric Rivers, J. of Hydrometeorology, (in review)

21. Niemann, PJ, LJ Schick, FM Ralph, M Hughes, GA Wick, 2010: Flooding in Western Washington: The Connection to Atmospheric Rivers, J. of Hydrometeorology, (in review)

22. Modeling Studies of Changing 20th Century Flood Risk in the West

23. Schematic of VIC Hydrologic Model • Sophisticated, fully distributed, physically based hydrologic model • Widely used globally in climate change applications • 1/16 Degree Resolution (~5km x 6km or ~ 3mi x 4mi) General Model Schematic Snow Model

24. Evaluating the Hydrologic Model Simulations in the Context of Reproducing Flood Characteristics Ln (X100 / Xmean) OBS Avg WY Date of Flooding OBS Avg WY Date of Flooding VIC Ln (X100 / Xmean) VIC Red = PNW, Blue = CA, Green = Colo, Black = GB

25. 100-yr Red = VIC Blue = OBS 50-yr X100 GEV flood/mean flood 20-yr 10-yr 5-yr Zp

26. Regionally Averaged Temperature Trends Over the Western U.S. 1916-2003 Tmax PNW GB Tmin CA CRB

27. Detrended Temperature Driving Data for Flood Risk Experiments “Pivot 2003” Data Set Temperature Historic temperature trend in each calendar month “Pivot 1915” Data Set 2003 1915

28. Simulated Changes in the 20-year Flood Associated with 20th Century Warming DJF Avg Temp (C) X20 2003 / X20 1915 DJF Avg Temp (C) X20 2003 / X20 1915 X20 2003 / X20 1915

29. Schematic of a Cool Climate Flood Precipitation Produces Runoff Precipitation Produces Snow Precipitation Produces Snow Snow Snow Freezing Level Snow Melt

30. Schematic of a Warm Climate Flood Precipitation Produces Runoff Precipitation Produces Snow Precipitation Produces Snow Snow Snow Snow Melt Freezing Level

31. Regionally Averaged Cool Season Precipitation Anomalies PRECIP

32. 20-year Flood for “1973-2003” Compared to “1916-2003” for a Constant Late 20th Century Temperature Regime DJF Avg Temp (C) X20 ’73-’03 / X20 ’16-’03 X20 ’73-’03 / X20 ’16-’03

33. Summary of Flooding Impacts Rain Dominant Basins: Increases in flooding due to increased precipitation intensity, but no significant change from warming alone. Mixed Rain and Snow Basins Along the Coast: Strong increases due to warming and increased precipitation intensity (both effects increase flood risk) Inland Snowmelt Dominant Basins: Relatively small overall changes because effects of warming (decreased risks) and increased precipitation intensity (increased risks) are typically in the opposite directions.

34. Effects of ENSO and PDO on Flood Risk

35. X100 wENSO / X100 2003 X100 nENSO / X100 2003 X100 cENSO / X100 2003 DJF Avg Temp (C) DJF Avg Temp (C) DJF Avg Temp (C) X100 wENSO / X100 2003 X100 nENSO / X100 2003 X100 cENSO / X100 2003

36. X100 wPDO / X100 2003 X100 nPDO / X100 2003 X100 cPDO / X100 2003 DJF Avg Temp (C) DJF Avg Temp (C) DJF Avg Temp (C) X100 wPDO / X100 2003 X100 nPDO / X100 2003 X100 cPDO / X100 2003

37. Scenarios of Flood Risk in the 21th Century

38. 21st Century Climate Impacts for the Pacific Northwest Region Mote, P.W. and E. P. Salathe Jr., 2010: Future climate in the Pacific Northwest, Climatic Change, DOI: 10.1007/s10584-010-9848-z

39. Seasonal Precipitation Changes for the Pacific Northwest Mote, P.W. and E. P. Salathe Jr., 2010: Future climate in the Pacific Northwest, Climatic Change, DOI: 10.1007/s10584-010-9848-z

40. Spatial Variability of Temperature and Precipitation Changes

41. http://www.hydro.washington.edu/2860/

42. Columbia Basin Climate Change Scenarios Project 297 Sites • Smaller basins down to • ~500 km2 • Monthly and daily streamflow time series • Assessment of hydrologic extremes • (e.g. Q100 and 7Q10)

43. Available PNW Scenarios 2020s – mean 2010-2039; 2040s – mean 2030-2059; 2080s – mean 2070-2099

44. Hybrid Downscaling Method • Performed for each VIC grid cell: Bias Corrected Future Monthly CDF Hist. Daily Timeseries 30 yr window 1916-2006 Projected Daily Timeseries Historic Monthly CDF Hist. Monthly Timeseries 1916-2006 1970-1999 1916-2006 “Base Case”

45. Monthly to Daily Precipitation Scaling SeaTac. Feb, 1996, hypothetical 30% Increase Daily Precipitation (mm) Day of Month

46. Schematic of VIC Hydrologic Model • Sophisticated, fully distributed, physically based hydrologic model • Widely used globally in climate change applications • 1/16 Degree Resolution (~5km x 6km or ~ 3mi x 4mi) General Model Schematic Snow Model

47. Watershed Classifications: Transformation From Snow to Rain Map: Rob Norheim

48. Flood Analysis: What’s In? What’s Out?

49. Low Flow Analysis: What’s In? What’s Out?

50. Simulate Daily Time Step Streamflow Scenarios Associated with Changes in Climate Fit Probability Distributions To Estimate Flood and Low Flow Risks Compare Flood Risks to Those in the 20th Century