Are the Pieces in Place for a Perfect Drought? Insights from the Past and Prospects for the Future

Are the Pieces in Place for a Perfect Drought? Insights from Are the Pieces in Place for a Perfect Drought? Insights from the Past and Prospects for the Futurethe Past and Prospects for the Future

Glen M. MacDonaldGlen M. MacDonaldDepartment of GeographyDepartment of Geography

UCLAUCLAwww.biogeographer.comwww.biogeographer.com

Southern California Water Dialogue Southern California Water Dialogue July 2007July 2007

Los Angeles Times July 2007

MacDonald, G.M., Rian, S. and Hidalgo, H. 2005. Southern California and the perfect drought. Colorado Basin Climate, MacDonald, G.M., Rian, S. and Hidalgo, H. 2005. Southern California and the perfect drought. Colorado Basin Climate, California Department of Water Resources, pp 50-57 (Map).California Department of Water Resources, pp 50-57 (Map).

‘‘Perfect Droughts’ Impact all of Southern Perfect Droughts’ Impact all of Southern California Water SourcesCalifornia Water Sources

http://pangea.stanford.edu/courses/gp104/waterscape/users/shazy/LAwatersources.jpg

Jan. 1988 – Dec. 1991

MacDonald et al. in press

MacDonald, G.M., Rian, S. and Hidalgo, H. MacDonald, G.M., Rian, S. and Hidalgo, H. 2005. Southern California and the perfect 2005. Southern California and the perfect drought. Colorado Basin Climate, California drought. Colorado Basin Climate, California Department of Water Resources, pp 50-57.Department of Water Resources, pp 50-57.

MacDonald, 2007, Quaternary InternationalMacDonald, 2007, Quaternary International

Los Angeles 33o N

Is this the ‘Big One’?

http://www.ldeo.columbia.edu/res/div/ocp/drought/images/pme_ave.png

Crowley 2000 Science, 289: 270-277.

Mann et al. 2003

Cook, E. et al. 2004. Long-term aridity changes in the western United States. Science 306: 1016-1018

Colorado River

San Gorgonio

Sacramento River

.

Colorado River

San Gorgonio

Sacramento River

..

So. California PDSI

-8

-6

-4

-2

0

2

4

6

8

1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000Year AD

PD

SI

Sacramento River

0

5

10

15

20

25

30

35

40

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990

Year AD

MA

F

Colorado River

0

5

10

15

20

25

1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Year AD

MA

F

So. California PDSI

-8

-6

-4

-2

0

2

4

6

8

1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000Year AD

PD

SI

Sacramento River

0

5

10

15

20

25

30

35

40

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990

Year AD

MA

F

Colorado River

0

5

10

15

20

25

1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Year AD

MA

F

adjR2 0.39

adjR2 0.49

adjR2 0.50


So. California PDSI

-6

-4

-2

0

2

4

6

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Year ADP

DS

I

Sacramento River

0

5

10

15

20

25

30

35

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Year AD

MA

F

Colorado River

5

10

15

20

25

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Year AD

MA

F

So. California PDSI

-6

-4

-2

0

2

4

6

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Year ADP

DS

I

Sacramento River

0

5

10

15

20

25

30

35

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Year AD

MA

F

Colorado River

5

10

15

20

25

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Year AD

MA

F


Perfect Droughts

~AD 1012-1076~AD 1130-1192

25-Year Running Mean

800 1000 1200 1400 1600 1800 200075

80

85

90

95

100

105

110

115

120

Ending Year of 25-yr Period

Flo

w (

% o

f me

an

)

80% Confidence Interval

Reconstructed

Observed

Lowest Observed = 87% of 1906-2004 mean

• 13 consecutive years of below-normal flow (longest stretch in the gage record was 5 years)• 62-year window without any very wet years

Meko and Woodhouse, 2007

Nino 3

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000Year AD

Te

mp

era

tu

re

C

PDO

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Year AD

PD

OSo. Caliornia PDSI

-4

-3

-2

-1

0

1

2

3

4

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Year AD

PD

SI

Sacramento and Colorado Deviations

-20

-15

-10

-5

0

5

10

15

20

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Year AD

MA

F

Nino 3

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000Year AD

Te

mp

era

tu

re

C

PDO

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Year AD

PD

OSo. Caliornia PDSI

-4

-3

-2

-1

0

1

2

3

4

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Year AD

PD

SI

Sacramento and Colorado Deviations

-20

-15

-10

-5

0

5

10

15

20

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Year AD

MA

F

Depressed E Tropical and NE Pacific SST’s and prolonged droughts in California and Colorado Bsin during Medieval Warm Period. (Mann et al. 2005; MacDonald and Case, 2005, MacDonald et al. in press)

Perfect Drought Periods (~60 years)

~AD 1012-1075~AD 1130-1192

Crowley 2000 Science, 289: 270-277.

Thank you -Thank you -

PERSPECTIVE FROM THE COLORADO RIVER AND THE SOUTHWEST

Connie A. Woodhouse Department of Geography and Regional

Development University of Arizona

Main Points

• The Colorado River, an important source of water for 7 US states and Mexico, is over-allocated, a situation exacerbated by growth and drought.

• Extended records of streamflow from tree rings place recent droughts in a 500-year context: 20th-21st c droughts are not unusual.

• A new longer reconstruction, 762-2005, offers a regional perspective on a period known for widespread drought: the most persistent Colorado River basin drought occurred in the 1100s.

• Understanding drought in the Colorado River basin: linked to El Nino/Southern Oscillation (ENSO), but other controls may be important also.

The Colorado River Compact, signed in 1922, was based a record of streamflow from a period of time with unusually high flows.

Over-allocation + increased demands + drought = stressed system

Tree-ring data extend the gage record back in time and allow the recent drought to be evaluated in a long-term context

Tree-Ring Reconstructed Colorado River Flow, 1490-1997

Lowest 5-yr mean in gage record, 2000-2004

Old And New Tree-Ring Networks Used To ProducePDSI Reconstructions For The North American Drought Atlas

Version 1 Tree-Ring Network Version 2 Tree-Ring Network

NW

SW

MX

<1/2 COVERAGE >2/3 COVERAGE

MCA aridity appears to be best expressed in the ‘SouthWest’ and Mexico where tropical Pacific SSTs have the strongest impact.

Palmer drought severity index (PDSI) (Dai et al. 1998)

Summer PDSI = JJA average (integrates winter-spring-summer)

Recent drought began in 1994 in Mexico

Most severe and sustained in Mexico

12 consecutive years in central Mexico (and not over)

Unmatched in the instrumental record

Intense warming over Mexico contributing to PDSI trend

Tree-ring reconstructed summer PDSI used to calculate Drought Area Index (DAI) for Mexico

Recent drought unprecedented in 500 years?

Predicted aridity trend already underway in Mexico?

Central Mexico

Mexico

0

100

200

300

400

500

600

1550 1600 1650 1700 1750 1800 1850 1900 1950 2000

Year

Prec

ipitat

ion (m

m)

-12 -8 -4

count / cc

0 1 2

Cal

yr

BP

clamsnail

Molluskabundance

vs. PDB

-8 -4 0

% organic

20 40

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

K I R M A N L A K E

d18O (clams)

LOI

8 12 16

= Late Holocene Drought Events (Stine 1990, 1994)

C:N Ratio(bulk sed.)

80 100120140-30 -20 1 2 3

vs. PDB

d13C (clams)

d13C(bulk sed.)

d15N(bulk sed.)

vs. PDBvs. PDB

0 4 8 12

Salinity(Diatoms)

Depth(Diatoms)

m mg/L

0 2 4

Pinus/ Artmemisia

Ratio

SS

T

6.0

7.0

8.0

9.0

10.0

11.0

12.0

13.0

14.00.001.00

2.003.00

4.005.00

6.007.00

8.009.00

10.0011.00

12.0013.00

14.0015.00

Northeastern Pacific SST

Depth (m)

0 4 8 12 16

Salinity (mg/L)

80 100 120 140 160

count / cc

0.0 0.5 1.0 1.5 2.0 2.5

Cal y

r BP

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

snail (/cc) clam (/cc)

Molluskabundance

vs. PDB

-12-8-40

d13C vs PDBd18O vs PDB

% organic

0 20 40 60

K I R M A N L A K E

Diatom-inferreddepth model

d18O, d13C Diatom-inferredsalinity model

LOI

8 10 12 14 16 18 20

= Late Holocene Drought Events (Stine 1990, 1994)

C:N Ratio

DroughtDrought Depressed NE Pacific SST’s and Continuous drought in California during Holocene Warm Period ~8000 – 3000 years ago. MacDonald, Moser, Bloom, Potito, Porinchu, Kremenetski

PC1

PC2

• Two patterns of circulation appear to be associated with drought in the Colorado River basin over the past five centuries. • The first: El Nino/Southern Oscillation (ENSO)-related conditions in the Pacific Ocean

• The second suggests ENSO may not be the only control on drought in the Colorado River basin.

Causes of drought in the Colorado River basin?

IPCCIPCC

Documents

Are the Pieces in Place for a Perfect Drought? Insights from the Past and Prospects for the Future