sensitivity of water supply in the colorado river basin to warming greg mccabe u.s. geological...

Sensitivity of Water Supply in the Colorado River Basin to WarmingSensitivity of Water Supply in the Colorado River Basin to Warming

Greg McCabeU.S. Geological Survey, Denver, Colorado

Dave WolockU.S. Geological Survey, Lawrence, Kansas

Greg McCabeU.S. Geological Survey, Denver, Colorado

Dave WolockU.S. Geological Survey, Lawrence, Kansas

The Colorado River Basin

The Colorado River Basin

Source: D. Alles, 2007Source: D. Alles, 2007

Streamgage at Lee’s FerryStreamgage at Lee’s Ferry

Source: Steve Gray, University of WyomingSource: Steve Gray, University of Wyoming

The 20th century included the wettest and 3rd wettest periods in the Upper Colorado River Basin during the past 500 yearsThe 20th century included the wettest and 3rd wettest periods in the Upper Colorado River Basin during the past 500 years

12 3

tree ring reconstruction for Upper Colorado River basin

20th centuryW

ater

Yea

r F

low

(m

illi

on

acr

e fe

et)

Increasing water demand is stressing the Colorado River water supply, even during one of the wettest centuries.Increasing water demand is stressing the Colorado River water supply, even during one of the wettest centuries.

Source: Glen Canyon Institute, March 2005Source: Glen Canyon Institute, March 2005

Colorado River water supply minus consumptive use and losses,

1906-2004

Mill

ion

Acr

e F

eet

15

10

5

0

-5

-10

20

Calendar Year1915 1930 1975 19901945 1960

photos by John Dohrenwend, Southwest Satellite Imagingphotos by John Dohrenwend, Southwest Satellite Imaging

June 29, 2002June 29, 2002

December 23, 2003December 23, 2003

Are recent dry conditions in the UCRB anomalous, or more reflective of conditions experienced during previous centuries?Are recent dry conditions in the UCRB anomalous, or more reflective of conditions experienced during previous centuries?

Lake PowellLake Powell

Potential natural shift

to drier conditions

Potential natural shift

to drier conditions

++Increased

water demand

Increased water

demand

++Continued warming

Continued warming

Increased risk of water

shortages

Increased risk of water

shortages}}Issues and concerns for the Colorado River BasinIssues and concerns for the Colorado River Basin

Question: What is the sensitivity of water supply to

increases in temperature?

Question: What is the sensitivity of water supply to

increases in temperature?

Potential natural shift

to drier conditions

Potential natural shift

to drier conditions

++Increased

water demand

Increased water

demand

++Continued warming

Continued warming

Increased risk of water

shortages

Increased risk of water

shortages}}Issues and concerns for the Colorado River BasinIssues and concerns for the Colorado River Basin

Water-year flow for the Upper Colorado River Basin for 100-year periodsWater-year flow for the Upper Colorado River Basin for 100-year periods

McCabe and Wolock, Geophysical Research Letters, 2007McCabe and Wolock, Geophysical Research Letters, 2007

McCabe and Wolock, Geophysical Research Letters, 2007McCabe and Wolock, Geophysical Research Letters, 2007

Water-year flow for the Upper Colorado River Basin for 100-year periodsWater-year flow for the Upper Colorado River Basin for 100-year periods

Water-year flow for the Upper Colorado River Basin for 100-year periodsWater-year flow for the Upper Colorado River Basin for 100-year periods

McCabe and Wolock, Geophysical Research Letters, 2007McCabe and Wolock, Geophysical Research Letters, 2007

Water-year flow for the Upper Colorado River Basin for 100-year periodsWater-year flow for the Upper Colorado River Basin for 100-year periods

McCabe and Wolock, Geophysical Research Letters, 2007McCabe and Wolock, Geophysical Research Letters, 2007

Water-year flow for the Upper Colorado River Basin for 100-year periodsWater-year flow for the Upper Colorado River Basin for 100-year periods

McCabe and Wolock, Geophysical Research Letters, 2007McCabe and Wolock, Geophysical Research Letters, 2007

Water-year flow for the Upper Colorado River Basin for 100-year periodsWater-year flow for the Upper Colorado River Basin for 100-year periods

McCabe and Wolock, Geophysical Research Letters, 2007McCabe and Wolock, Geophysical Research Letters, 2007

Risk of Failure (percent of years)

Risk of failing to meet the delivery obligations of the Colorado Compact during a 100-year period

range of estimated risk of failure for all 100-year periods, 1490-1998

McCabe and Wolock, Geophysical Research Letters, 2007McCabe and Wolock, Geophysical Research Letters, 2007

Risk of Failure (percent of years)

20th century

range of estimated risk of failure for all 100-year periods, 1490-1998

Risk of failing to meet the delivery obligations of the Colorado Compact during a 100-year period

McCabe and Wolock, Geophysical Research Letters, 2007McCabe and Wolock, Geophysical Research Letters, 2007

Risk of Failure (percent of years)

20th century

20th century,

T+0.86oC

range of estimated risk of failure for all 100-year periods, 1490-1998

Risk of failing to meet the delivery obligations of the Colorado Compact during a 100-year period

McCabe and Wolock, Geophysical Research Letters, 2007McCabe and Wolock, Geophysical Research Letters, 2007

Risk of Failure (percent of years)

20th century

20th century,

T+0.86oC

20th century, T+2oC

range of estimated risk of failure for all 100-year periods, 1490-1998

Risk of failing to meet the delivery obligations of the Colorado Compact during a 100-year period

McCabe and Wolock, Geophysical Research Letters, 2007McCabe and Wolock, Geophysical Research Letters, 2007

Risk of Failure (percent of years)

20th century

20th century,

T+0.86oC

20th century, T+2oC

driest century from tree ring record, T+0.86oC

range of estimated risk of failure for all 100-year periods, 1490-1998

Risk of failing to meet the delivery obligations of the Colorado Compact during a 100-year period

McCabe and Wolock, Geophysical Research Letters, 2007McCabe and Wolock, Geophysical Research Letters, 2007

Risk of Failure (percent of years)

20th century

20th century,

T+0.86oC

20th century, T+2oC

driest century from tree ring record, T+2oC

driest century from tree ring record, T+0.86oC

range of estimated risk of failure for all 100-year periods, 1490-1998

Risk of failing to meet the delivery obligations of the Colorado Compact during a 100-year period

McCabe and Wolock, Geophysical Research Letters, 2007McCabe and Wolock, Geophysical Research Letters, 2007

Is a drier West on the horizon?Is a drier West on the horizon?