Paul R. Houser, Science Advisor
Reclamation Climate Change ActivitiesPaul R. Houser
Paul R. Houser, Science Advisor
The mission of the Bureau of Reclamation is to manage, develop, and protect water and related resources in an environmentally and economically sound manner in the interest of the American public.
Reclamation Mission
Paul R. Houser, Science Advisor
Mote, 2003
TRENDS (1950-97) in April 1 snow-water content at western snow courses
Less spring snowpack
Earlier snowmelt runoff
Stewart et al., 2005
Earlier greenup
Cayan et al., 2001
Figs. M. Dettinger (USGS)
Observed Hydrology & Vegetation ChangesLess snow/more rain
Paul R. Houser, Science Advisor
Implications for water supplies, water demands, operating constraints?
• Supplies– warming
• less snowpack less controllable water supply • more landscape evapotranspiration (ET) less runoff
– precipitation change? could be + or - , help or worsen…
• Demands– warming
• Irrigation: increased seasonal water demand (longer season, more ET)• Electricity: increased summer demand, decreased winter demand
• Operating Constraints– Environment – instream flow requirements?
• Reduction in cold-water supplies– Flood Protection – storage reservation requirement?
• All other things equal, warming leads to greater area contributing runoff during western winter storm events – greater winter reservoir drafts?
• Storm intensification could be + or -, worsen or help…
Paul R. Houser, Science Advisor
Key Challenges for Reclamation
• Understand how climate variability and change can affect Western water supply and demand, and Reclamation delivery of water given operational constraints (i.e. environmental constraints, flood constraints)
• Bring science and technology to bear on the needs of water resources managers
• Address goals of internal programs and authorizations where climate change is a factor
Paul R. Houser, Science Advisor
West-Wide Climate Risk Assessments (WWCRA) - Hydrologic Projections (2011)
http://www.usbr.gov/WaterSMART/wwcra.html
112 Transient Climate Projections…http://gdo-dcp.ucllnl.org/downscaled_cmip3_projections/dcpInterface.html
8 “big basin” VIC hydrology model-apps from Univ. of WA…
112 Transient Hydrologic Projections covering western U.S.…
Analyses of Period-changes in climate and hydrology
SECURE Report to Congress, 2011 focus on median changes; future reports have broader scope
Technical Report, data-development (TSC 86-68210, March 2011)
Data-service, Reclamation and broader public use (Summer 2011)
Paul R. Houser, Science Advisor
• Funding• WaterSMART Basin
Study Program – West-Wide Climate Risk Assessment
• Supporting:• Secretarial Orders
3289 and 3297
SECURE Report Production
Paul R. Houser, Science Advisor
Future Climate / Hydrology
Baseline Change Through Time
Temp
Precip
Snow
2020s 2050s 2070s
Paul R. Houser, Science Advisor
Tying to Impacts Example Colorado Flow Timing
• Flow timing shifts towards additional cool season runoff.
• Reduced warm season runoff
Competing Questions• Floods - Increased drawdown
requirements to maintain risk objectives
• Storage - Able to refill to supply objectives
Paul R. Houser, Science Advisor
Tying to ImpactsColorado River Example
Environmental and Flood Control
Implications for Flood Control Objectives
Implications for Environmental Flow Objectives
HUGE CAVEAT – e.g. calibration, validation
1950 2000 2050 2100
50
100
150
Colorado River above Imperial Dam
Annu
al M
ax. W
eek
Run
off,
kcfs
Water Year
1950 2000 2050 2100
6
8
10
Colorado River above Imperial Dam
Annu
al M
in. W
eek
Run
off,
kcfs
Water Year
Paul R. Houser, Science Advisor
SE
CU
RE
Rep
ort:
Wes
twid
e Im
pact
s (e
.g. a
nnua
l and
sea
sona
l run
off)
annual Dec-Mar Apr-Jul
2020
s-19
90s
2050
s-19
90s
2070
s-19
90s
Paul R. Houser, Science Advisor
Colorado River Basin Water Supply and Demand Study
Paul R. Houser, Science Advisor
Annual Colorado River Water Supply & Use
Paul R. Houser, Science Advisor
Water Supply Scenarios *
Observed Resampled: future hydrologic trends and variability
will be similar to the past 100 yearsPaleo Resampled: future hydrologic trends and variability
are represented by the distant past (approximately 1250 years)
Paleo Conditioned: future hydrologic trends and variability
are represented by a blend of the wet dry states of the paleo-climate record but magnitudes are more similar to the observed period
Downscaled GCM Projected: future climate will continue to warm with
regional precipitation trends represented through an ensemble of future GCM projections
Water Demand Scenarios *
Current Trends: growth, development patterns, and
institutions continue along recent trendsEconomic Slowdown: low growth with emphasis on economic
efficiencyExpansive Growth: economic resurgence (population and
energy) and current preferences toward human and environmental values *
Enhanced Environment and Healthy Economy:
expanded environmental awareness and stewardship with growing economy*
* Additional “branches” possible depending upon assumed trajectory of specific socio-economic
factors.
* Preliminary – Subject to change
Paul R. Houser, Science Advisor
Integration of Supply and Demand Scenarios
Recent Trends Recent
Trends
Water Supply Scenarios (multiple realizations for each scenario)
Climate indexing for demands
Water Demand Scenarios
Observe
d Resa
mpled
Downscaled G
CM Projected
Paleo Conditio
nedPaleo Resa
mpled
Current T
rends
Expansiv
e Growth
Enhance
d Environment a
nd
Healthy E
conomy
Economic
Slowdown
Paul R. Houser, Science Advisor
Addressing an Uncertain Future
• The path of major influences on the Colorado River system is uncertain and can not be represented by a single view
• An infinite number of plausible futures exist
• A manageable and informative number of scenarios are being developed to explore the broad range of futures
Scenario Funnel
Paul R. Houser, Science Advisor
Thank YouQuestions?
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