Paul R. Houser, Science AdvisorPaul R. Houser, Science Advisor

Western U.S.Observed Hydrology & Vegetation Changes

Less Spring Snowpack

Cayan et al., 2001

Earlier Greening

Stewart et al., 2005

Earlier Snowmelt Runoff Less Snow, More Rain

Increasing Temperature

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

Reclamation Climate Studies

• 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.

From USGS Circular 1331 (Brekke et al. 2009)

• 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

2009 SECURE Water Act (PL 111-11)

• Establishes Landscape Conservation Cooperatives, Climate Science Centers, and Basin Studies

Secretarial Order 3289 and 3297 – WaterSMART

http://www.usbr.gov/climate

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)

Peer

Rev

iew

Paul R. Houser, Science Advisor

Colorado River Change Through Time2020s 2050s 2070s

Temp

Precip

Snow

1950 2000 2050 2100

50

100

150

Colorado River above Imperial Dam

Annu

al M

ax. W

eek

Run

off,

kcfs

Water Year

• Flood Control Implications

• Environmental Flow Implications

HUGE CAVEAT – e.g. calibration, validation

Annual Max Weekly Runoff

1950 2000 2050 2100

6

8

10

Colorado River above Imperial Dam

Annu

al M

in. W

eek

Run

off,

kcfs

Water Year

Annual Min Weekly Runoff

Paul R. Houser, Science Advisor

SEC

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2050

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2070

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