Transcript ppt - Houser

Reclamation’s Role in Managing
Western Water in Evolving Climate
Conditions
• Reclamation’s Mission
• Observed Climate Changes
• Managing Water in a Changing Climate
Paul R. Houser, Science Advisor
• Established in 1902, to promote settling and
development of the west
• Best known for 600 dams, powerplants, and
canals it constructed in 17 western states.
• Largest water wholesaler in the country
• Second largest hydroelectric producer in the
western United States.
• Mission: assist in meeting the increasing
water demands of the West while protecting
the environment and the public's investment
in these structures.
Observed Hydrology & Vegetation Changes
Less snow/more rain
Earlier greenup
Cayan et al., 2001
Less spring snowpack
TRENDS (1950-97) in
April 1 snow-water content at
western snow courses
Earlier snowmelt runoff
Stewart et al., 2005
Mote, 2003
Figs. M. Dettinger (USGS)
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…
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
Reclamation Climate Studies
2009 SECURE Water Act (PL 111-11)
• Federal agencies that conduct water management have a
responsibility to take a lead role in assessing risks to the water
resources and to develop adaptation and mitigation strategies
From USGS Circular 1331 (Brekke et al. 2009)
• Climate Change and Water Working Group (CCAWWG): NOAA,
USGS, USACE, EPA, NASA, FEMA collaboration
• Climate change is occurring; effects differ regionally.
• Water resources management could be affected; hydroclimate
conditions becoming non-stationary.
• Climate change is one of many challenges facing water managers.
Secretarial Order 3289 and 3297 – WaterSMART
• Establishes Landscape Conservation Cooperatives, Climate Science
Centers, and Basin Studies
http://www.usbr.gov/climate
Adjusted Framework needed for relating global
climate change to local system…
West-Wide Climate Risk Assessments (WWCRA) Hydrologic Projections (2011)
http://gdo-dcp.ucllnl.org/downscaled_cmip3_projections/dcpInterface.html
112 Transient Hydrologic
Projections covering
western U.S.…
SECURE Report to
Congress, 2011
focus on median
changes; future
reports have broader
scope
Analyses of Periodchanges in climate
and hydrology
8 “big basin” VIC
hydrology model-apps
from Univ. of WA…
Data-service,
Reclamation and
broader public use
(Summer 2011)
http://www.usbr.gov/WaterSMART/wwcra.html
Technical Report,
data-development
(TSC 86-68210,
March 2011)
Peer Review
112 Transient Climate Projections…
Colorado River
Annual Max. Week Runoff, kcfs
Annual Max Weekly Runoff
Change Through Time
2020s
Temp
Colorado River above Imperial Dam
150
100
50
1950
2000
2050
2100
Precip
Water Year
•
Flood Control Implications
Annual Min. Week Runoff, kcfs
Annual Min Weekly Runoff
Colorado River above Imperial Dam
Snow
10
8
6
1950
2000
2050
2100
Water Year
•
Environmental Flow Implications
HUGE CAVEAT – e.g. calibration, validation
2050s
2070s
2070s-1990s
http://www.usbr.gov/climate
2050s-1990s
2020s-1990s
SECURE Report: Westwide Impacts
(e.g. annual and seasonal runoff)
annual
Dec-Mar
Apr-Jul
SECURE Water
Future Work
• Analyze demands utilizing legacy
tools with climate projections
• Put activities within broader context
of scenario planning (similar to CO
Basin Study Approach).
• Include AR5 climate projections.
• Next Secure Water report due in
2016 (every 5 years)
Sector Impacts
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http://www.usbr.gov/climate
Hydropower
Ecological Resiliency
Endangered Species
Recreation
Water Deliveries
Water Quality
Colorado River Basin Water Supply
and Demand Study
Annual Colorado River Water Supply & Use
Water Supply Scenarios *
Water Demand Scenarios *
Observed Resampled:
Current Trends:
 future hydrologic trends and variability
will be similar to the past 100 years
 growth, development patterns, and
institutions continue along recent trends
Paleo Resampled:
Economic Slowdown:
 future hydrologic trends and variability
are represented by the distant past
(approximately 1250 years)
 low growth with emphasis on economic
efficiency
Paleo Conditioned:
 economic resurgence (population and
energy) and current preferences toward
human and environmental values *
 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
* Preliminary – Subject to change
Expansive Growth:
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.
Integration of Supply and Demand
Scenarios
Water Supply Scenarios
(multiple realizations for each scenario)
Recent
Trends
Water Demand Scenarios
Recent
Trends
Climate indexing for demands
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
Thank You
Questions?