1. Assessment of Hydrologic Response to Climate Change in the Upper Deschutes Basin, Oregon M. Scott Waibel Marshall W. Gannett Heejun Chang Christina L. Hulbe

2. Purpose of Research There is broad interest on the part of resource managers and the general public regarding response of streams and groundwater to probable climate change. Most irrigation water in the upper Deschutes Basin comes from storage reservoirs that are supplied by streams flowing from the Cascade Range, many of which are groundwater fed. These interests are addressed here using coupled groundwater recharge and flow models driven by GCM output.

3. MODIS image, 25 November 2002, NASA Visible Earth archiveInset from Gannett et al. 2001 Upper Deschutes Basin, Central Oregon

4. Models and products used Global Climate Model (GCM) weather data downscaled to 1/16 th degree using the Bias-Correction and Spatial Disaggregation method. The Deep Percolation Model (DPM) of Bauer and Vaccaro (1987) as applied in the upper Deschutes Basin by Boyd (1996). A MODFLOW regional groundwater model calibrated to the upper Deschutes Basin by Gannett and Lite (2004).

5. Methods 8 GCMs 2 IPCC emission scenarios = 16 runs 2 ensembles: DPM hydrologic budget results from the eight runs are averaged for each emission scenario.

6. Downscaled GCMs used as ensembles for both emission scenarios Model NameInstitutionCountry CCSM3National Center for Atmospheric ResearchUSA CNRM-CM3Centre National de Recherches Meteorologiques France ECHAM5 / MPI-OMMax Planck Institute for Meteorology Germany ECHO-G Meteorological Institute of the University of Bonn Institute of KMA Model and Data Group Germany Korea HadCM3Hadley Centre for Climate Prediction and Research UK IPSL-CM4Institut Pierre Simon Laplace France MIROC 3.2Center for Climate System Research, University of Tokyo National Frontier Research Center for Global Change Institute for Environmental Studies Japan PCMNational Center for Atmospheric ResearchUSA

7. Ensemble means and medians generally outperform any single GCM model -adapted from Gleckler et al., (2007)

8. Methods (Continued) In-place recharge and runoff Examined using basin-wide averaged mean monthly hydrographs and seasonal spatial maps. DPM recharge and evapotranspiration output used for inputs to the regional groundwater flow model.

9. Methods (Continued) Changes in groundwater discharge to select stream reaches within the three main discharge areas of the basin were examined using mean monthly hydrographs. Statistical testing was employed to confirm changes between four climate periods in the 21 st century for basin-wide mean monthly and mean seasonal results.

10. DPM Essential Parameters –Elevation –Long term annual precipitation –Soil Properties –Land Cover Elevation

11. DPM Long term annual precipitation (inches)

12. DPM SoilsLand cover Important parameters for partitioning water

13. DPM Forcings Temperature and precipitation: downscaled GCM time series averaged basin-wide A1B TempB1 Temp B1 PrecipA1B Precip

14. Basin-wide average response to climate change 2 emission scenario ensemble means 4 climate periods

15. DPM basin-wide mean monthly change Precipitation

16. DPM basin-wide mean monthly change Snowpack

17. DPM basin-wide average changes Recharge Runoff A1B B1

18. Spatial distribution of changes in recharge and runoff 2050s relative to 1980s MODIS image, 25 November 2002, NASA Visible Earth archive

19. 1980s simulated recharge

20. SRES A1B 2050s change in recharge

21. 1980s simulated runoff

22. SRES A1B 2050s change in runoff

23. Changes in baseflow

24. Odell Creek A1B emission scenario

25. Inflow to Lower Deschutes River A1B Emission Scenario

26. A1B Mean annual changes in recharge 2020s2050s2080s percent change absolute change

27. Summary The DPM predicts a shift in timing of runoff and recharge for both emission scenarios with a shift toward earlier runoff and recharge.The DPM predicts a shift in timing of runoff and recharge for both emission scenarios with a shift toward earlier runoff and recharge. Shifts in the timing of recharge are observed primarily in the baseflow hydrographs of high elevation streams.Shifts in the timing of recharge are observed primarily in the baseflow hydrographs of high elevation streams. Volumetric changes in groundwater discharge to streams likely result from spatial changes in recharge.Volumetric changes in groundwater discharge to streams likely result from spatial changes in recharge.

29. References Bauer, H., and Vaccaro, J., 1987, Documentation of a deep percolation model for estimating ground-water recharge: US Geological Survey Open-File Report, p. 86-536. Boyd, T., 1996, Groundwater recharge of the middle Deschutes Basin, Oregon: Portland, Oregon, Portland State University: MS thesis, 86 p. Gannett, M. W., Lite, K. E., Jr., Morgan, D. S., and Collins, C. A., 2001, Ground-water hydrology of the upper Deschutes Basin, Oregon: United States Geological Survey, 77 p. Gleckler, P., Taylor, K., and Doutriaux, C., 2008, Performance metrics for climate models: Journal of Geophysical Research, v. 113, no. D6, p. D06104.

30. Range of basin-wide average recharge and runoff anomalies winter 2020s2050s2080s -0.10.71.0 1.42.02.6 spring 2020s2050s2080s 0.0-0.5-0.9 -1.3-1.7-2.2 winter 2020s2050s2080s -0.10.10.3 0.60.91.1 spring 2020s2050s2080s 0.0-0.2-0.4 -0.6-0.8 WinterSpringWinterSpring

31. —from Bauer and Vaccaro (1987) conceptual model of the water budget used by the DPM Deep Percolation Model basics

32. SRES A1B 1980s Evapotranspiration

33. SRES A1B 2050s Evapotranspiration

34. Acknowledgments Thesis CommitteeThesis Committee –Christina Hulbe, Department of Geology, PSU –Marshall Gannett, USGS Oregon Water Science Center –Heejun Chang, Department of Geography, PSU –Ken Cruikshank, Department of Geology, PSU Lenny Orzol, USGS Oregon Water Science CenterLenny Orzol, USGS Oregon Water Science Center Leslie Stillwater, Bureau of ReclamationLeslie Stillwater, Bureau of Reclamation This work was funded through a Bureau of Reclamation Science and Technology Grant.