Alan F. Hamlet

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Observed Climate and Streamflow Variability in
the Sacramento, San Joaquin, and Colorado River
Basins and Projections for the 21st Century
JISAO Center for Science in the Earth System
Climate Impacts Group and Department of Civil
and Environmental Engineering University of
Washington November, 2003

Alan F. Hamlet Andrew W. Wood Dennis P.
Lettenmaier
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Observed Trends in Basin Average Temperature and
Precipitation in the Sacramento and San Joaquin
River Basins (Water Year 1916-1997)
Note Data is adjusted for topographic
variations, and corrections for spurious trends
associated with heat island effects, station
moves, instrumentation changes, different
groupings of stations, etc. have been applied.
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Observed Temperature Trends over the Sacramento
San Joaquin Basin 1916-1997
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Observed Precipitation Trends over the Sacramento
San Joaquin Basin 1916-1997
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Streamflow Reconstructions from the Paleoclimatic
Record
Thanks to Hugo Hidalgo, Scripps Institution of
Oceanography Dave Meko, Laboratory of Tree-Ring
Research, University of Arizona Connie Woodhouse,
Paleoclimatology Branch, NOAA National Climatic
Data Center
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Sacramento River Flow Reconstructed from Tree
Rings (6-year running mean)
Source Meko et. al, 2001, J. Amer. Water Res.
Association, 37(4) 1029-39 (Fig 5)
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Sacramento and Upper Colorado Annual Flow
Reconstructions
Concurrent periods of low flow are indicated by
pink bands
Meko, D.M. and C.A. Woodhouse, in review.
Tree-ring footprint of joint hydrologic drought
in Sacramento and Upper Colorado river basins,
western USA. Journal of Hydrology
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Overview of Streamflow Reconstructions for Water
Managers http//www.ncdc.noaa.gov/paleo/streamflo
w/study.html Sacramento River Reconstructions Me
ko, D.M., Therrell, M.D., Baisan, C.H., and
Hughes, M.K., 2001, Sacramento River flow
reconstructed to A.D. 869 from tree rings J. of
the American Water Resources Association, v. 37,
no. 4, p. 1029-1040. Meko, D.M. and C.A.
Woodhouse, in review. Tree-ring footprint of
joint hydrologic drought in Sacramento and Upper
Colorado river basins, western USA. Journal of
Hydrology Colorado River Reconstructions Water
Resources Bulletin, 31(5) (Special Issue on
climate variability and drought in the Colorado
River Basin) Stockton, C.W. and Jacoby Jr., G.C.
1976. Long-term surface-water supply and
streamflow trends in the Upper Colorado River
Basin based on tree-ring analysis. Lake Powell
Research Project Bulletin 18, Institute of
Geophysics and Planetary Physics, University of
California, Los Angeles.
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Some Selected Results from the Accelerated
Climate Prediction Initiative (ACPI)
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Accelerated Climate Prediction Initiative (ACPI)
NCAR/DOE Parallel Climate Model (PCM) grid over
western U.S.
A hydrologic simulation model and a reservoir
operations model were run in each portion of the
domain. Both sensitivity and adaptive response
capability were evaluated.
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Bias Correction
Note future scenario temperature trend (relative
to control run) removed before, and replaced
after, bias-correction step.
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Downscaling
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The Main Impact Pathway in the West Loss of
Snowpack.
Reductions in Pacific Northwest Snowpack for
PCM Scenarios (low sensitivity)
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Results for the Sacramento and San Joaquin
Basins Van Rheenen, N.T., A.W. Wood, R.N.
Palmer and D.P. Lettenmaier, 2004, Potential
Implications of PCM Climate Change Scenarios for
Sacramento - San Joaquin River Basin Hydrology
and Water Resources, Climatic Change (accepted)
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PCM Business-as-Usual scenarios California
(Basin Average)
BAU 3-run average
historical (1950-99)
control (2000-2048)
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PCM Business-as-Usual Scenarios Snowpack
Changes California April 1 SWE
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PCM Business-As-Usual Mean Monthly Hydrographs
Shasta Reservoir Inflows
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Sacramento River Basin
Trinity River
Clear Creek
Feather River
Sacramento River
American River
Folsom
Delta
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Delta San Joaquin R Basin
Mokelumne River
Pardee Camanche
Delta Outflow
Millerton Lake Storage 761 taf
New Melones Res Storage 2420 taf
Delta
Calaveras River
New Hogan
Stanislaus River
San Luis
San Joaquin River
New Melones
Dam Power Plant River/Canal Transfer
Tuolumne Merced Rivers
New Don Pedro McClure
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Current Climate vs. Projected Climate

• Storage Decreases
• Sacramento
• Range 5 - 10
• Mean 8
• San Joaquin
• Range 7 - 14
• Mean 11

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Current Climate vs. Projected Climate

• Hydropower Losses
• Central Valley
• Range 3 - 18
• Mean 9
• Sacramento System
• Range 3 19
• Mean 9
• San Joaquin System
• Range 16 63
• Mean 28

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Results for Colorado River Basin Christensen,
N.S., Wood, A.W., Voisin, N., Lettenmaier, D.P.
and R.N. Palmer, 2004, Effects of Climate Change
on the Hydrology and Water Resources of the
Colorado River Basin, Climatic Change, (accepted)
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PCM Projected Colorado R. Basin Termperature
ctrl. avg.
hist. avg.
Period 1 2010-2039 Period 2 2040-2069
Period 3 2070-2098
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PCM Projected Colorado R. Basin Precipitation
hist. avg.
ctrl. avg.
Period 1 2010-2039 Period 2 2040-2069
Period 3 2070-2098
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Changes to Seasonal Hydrograph
Simulated Historic (1950-1999) Period 1
(2010-2039)Control (static 1995 climate) Period
2 (2040-2069) Period 3 (2070-2098)
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Deliveries to Central Arizona Project Los
Angeles Metro. Water District
1 BCM 810,832 acre-ft
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Conclusions and Comparative Analysis

• 1) California system operation is dominated by
  water supply (mostly ag), the reliability of
  which would be reduced significantly by a
  combination of seasonality shifts and reduced
  (annual) volumes. Partial mitigation by altered
  operations is possible, but complicated by flood
  issues.
• 2) Colorado system is sensitive primarily to
  annual streamflow volumes. Low runoff ratio
  makes the system highly sensitive to modest
  changes in precipitation (in winter, esp, in
  headwaters). Sensitivity to altered operations
  is modest, and mitigation possibilities by
  increased storage are nil (even if otherwise
  feasible).
• 3) These potential impacts highlight the need for
  contingency planning to cope with reductions in
  water supply and flexible demand management
  strategies for the future.