1. Water Management Section, Sacramento District, US Army Corps of Engineers Climate Impacts on Reservoir Rule Curves Stu Townsley Chief, Water Management Sacramento District

2. Water Management Section, Sacramento District, US Army Corps of Engineers Why I did this? 33 CFR 208.11(10) Revisions. The water control plan and all associated documents will be revised by the Corps of Engineers as necessary, to reflect changed conditions that come to bear upon flood control and navigation, e.g., reallocation of reservoir storage space due to sedimentation or transfer of storage space to a neighboring project.

3. Water Management Section, Sacramento District, US Army Corps of Engineers Pine Flat Flood Control Diagram Typical snowmelt influenced rule curve

4. Water Management Section, Sacramento District, US Army Corps of Engineers Conditional Flood Space =f(snowpack, demands) Rainflood Space Flood Space Developed from historical record (look-back) Conditional space dependent on B-120, irrigation demands Operation based on observed data (rainfall, snow pillows)

5. Water Management Section, Sacramento District, US Army Corps of Engineers Pine Flat Operations WY 2006 WY 1997WY 2004 WY 2005

6. Water Management Section, Sacramento District, US Army Corps of Engineers Potential Flood Implications Literature suggests Literature suggests Warmer regime, about the same annual precipitation Warmer regime, about the same annual precipitation Smaller snowpack, earlier melt, flow shift Smaller snowpack, earlier melt, flow shift Greater storm variability/intensity Greater storm variability/intensity Implications? Implications? Need more rainflood space? Need more rainflood space? Allow earlier fill? Allow earlier fill?

7. Water Management Section, Sacramento District, US Army Corps of Engineers Snowmelt Trends USGS Fact Sheet 2005-3018 Michael Dettinger U.S. Geological Survey Scripps Institution of Oceanography

8. Water Management Section, Sacramento District, US Army Corps of Engineers Mean Snowmelt Peak Full Natural Flows Mean Snowmelt Peak DayShastaOrovilleNew Bullards Period of Record2-Apr20-Apr22-Apr Last 20 years3-Apr15-Apr16-Apr

9. Water Management Section, Sacramento District, US Army Corps of Engineers San Joaquin Reservoirs Elevation Percentages N 58% below 6500’ New Melones 38% below 5000’ Equals 20% between 5000 ft and 6500 ft

10. Water Management Section, Sacramento District, US Army Corps of Engineers Shasta (purple = 5000<elev<6500)

11. Water Management Section, Sacramento District, US Army Corps of Engineers New Bullards (purple = 5000<elev<6500)

12. Water Management Section, Sacramento District, US Army Corps of Engineers Oroville Drainage (purple = 5000<elev<6500)

13. Water Management Section, Sacramento District, US Army Corps of Engineers Sacramento Reservoir Elevation Percentages % of basin between 5000 and 6500 ft Shasta 34% Oroville 50% New Bullards 33%

14. Water Management Section, Sacramento District, US Army Corps of Engineers New Bullards Data Set 1% Inflow (1000 cfs) Full95 Last 30 years 125 Model 07 (T) 2011-40 150 Model 07 (T) 2041-70 140 Model 07 (T) 2071-2100 150

15. Water Management Section, Sacramento District, US Army Corps of Engineers Oroville Data Set 1% Inflow 1000 cfs Full300 Last 30 years 370 Model 03 (P) 2011-40 370 Model 07 (T) 2041-70 320 Model 10 (T) 2071-2100 370

16. Water Management Section, Sacramento District, US Army Corps of Engineers Oroville operations under climate adjusted inflows E Elevation Release

17. Water Management Section, Sacramento District, US Army Corps of Engineers Climate adjusted diagram ? Rainflood Space Flood Space Conditional Space Jury still out – takes studies to resolve!

18. Water Management Section, Sacramento District, US Army Corps of Engineers What next? Given Given Climate change (mean is changing) Climate change (mean is changing) Climate variability (variance is increasing) Climate variability (variance is increasing) Need better climate models at watershed scale Need better climate models at watershed scale Increased process-based, distributed analysis Increased process-based, distributed analysis Less reliance on current statistical tools Less reliance on current statistical tools Move to adaptive rule curves? Move to adaptive rule curves?

19. Water Management Section, Sacramento District, US Army Corps of Engineers Adaptive curves Current rule curves Storage = f( inflow, channel capacity, measured precip, forecast snowmelt, forecast demand) Current rule curves Storage = f( inflow, channel capacity, measured precip, forecast snowmelt, forecast demand) Potential curves Storage = f( above plus Potential curves Storage = f( above plus short-term weather forecast, mid-range climate forecast, advanced release, and ???)

20. Water Management Section, Sacramento District, US Army Corps of Engineers Questions?