The frequency, severity and causes
of extreme droughts in the
Winnipeg River basin
Scott St. George
Geological Survey of Canada

2003

geosciences

EARTH SCIENCES RANKINGS
1. California Institute of Technology
2. Massachusetts Institute of Technology
3. Stanford University
4. University of California - Berkeley
5. Columbia University
6. University of Michigan
7. Pennsylvania State University
8. University of Arizona
9. Harvard University
10. University of Texas - Austin
US News and World Report, 2006

2008

The frequency, severity and causes
of extreme droughts in the
Winnipeg River basin
Scott St. George
Geological Survey of Canada

FU N DI N G A GE NCI ES
Manitoba Hydro
Manitoba Geological Survey
Natural Resources Canada
National Science and Engineering Council of Canada
Prairie Adaptation Research Collaborative

WINNIPEG RIVER STREAMFLOW

South Saskatchewan River at Saskatoon
relative change
in summer flow
Schindler and Donahue, 2006, PNAS

LOW HIGH
HIGH LOW
St. George, 2007, Journal of Hydrology

trends

Annual discharge since 1924

Annual discharge since 1924
+ 58%
NO TREND
+ 52%
+ 46%
NO TREND
NO TREND
NO TREND
NO TREND

“
For monthly and annual
average flow based on
adjusted disaggregated flow
data, upward trends are
detected for the entire period
from 1912 to 2006.
Liu, 2007

Winnipeg River
≠ Saskatchewan River
Western Hudson Bay
Canadian Prairies

1892

what happened
before that?

paleoclimatology
the study of the Earth’s climate prior to the
period of instrumental measurements

R ECO R D S F RO M ANCIEN T TR EES

never trust
one tree

975
trees

286,420
tree rings

Photograph courtesy Kurt Kipfmueller

1783

755 m3/s
847 m3/s
809 m3/s
770 m3/s
823 m3/s
787 m3/s
901 m3/s
3

TREE R I N G S A N D P R A IRI E DRO UG HT

Martin-Philippe Girardin
Canadian Forest Service
Greg Pederson
United States Geological Survey
Glen MacDonald David Sauchyn Emma Watson
UCLA University of Regina Environment Canada
Erik Nielsen Jacques Tardif
Manitoba Geological Survey University of Winnipeg

2,860
trees

Prairie tree-ring network

755 m3/s
847 m3/s
809 m3/s
770 m3/s
823 m3/s
787 m3/s
901 m3/s
3

CLIMATE
direct
HYDROLOGY

CLIMATE
direct direct
PROXIES HYDROLOGY

CLIMATE
direct direct
PROXIES HYDROLOGY
indirect

“ This
must
be
voodoo. ”
Anonymous water
manager

How good are
drought records from
tree rings?

geography matters

Prairie tree-ring network

Palmer
Drought
Severity
Index

10 southern Alberta 3
2
5
1
Ringwidth
PDSI
0 0
-1
-5
-2
-3
-10
1900 1920 1940 1960 1980 2000
St. George et al., (accepted), Journal of Climate
Year (A.D.)

10 southern Alberta 3
2
5
1
Ringwidth
PDSI
0 0
-1
-5
r = 0.62 -2
-3
-10
1900 1920 1940 1960 1980 2000
St. George et al., (accepted), Journal of Climate
Year (A.D.)

northwestern Ontario 3
6
2
4
1
Ringwidth
2
PDSI
0 0
-2 -1
-4 r = 0.40
-2
-6
-3
1900 1920 1940 1960 1980 2000
St. George et al., (accepted), Journal of Climate Year (A.D.) 59

755 m3/s
847 m3/s
809 m3/s
770 m3/s
823 m3/s
787 m3/s
901 m3/s
3

How bad has
drought been?

‘Now’ ‘Then’
(AD 1900 - present) (AD 1500 - 1900)

1783

How bad has
drought been?

1910

1720s

How bad has
drought been?

more persistent
more severe eds
ter sh
me wa
in so

73

74

P R O D U C T S AND APPLICATIONS

data

WORLD
D ATA C E N T E R f o r
PA L E O C L I M AT O L O G Y

Publications

Scott St. George
Streamflow in the Winnipeg
River basin, Canada: trends,
extremes and climate linkages
Journal of Hydrology 332, 396-411, 2007

Scott St. George, Dave Meko and Mike Evans
Regional tree growth and
inferred summer climate in
the Winnipeg River basin,
Canada since AD 1783
Quaternary Research 70, 158-172, 2008

Scott St. George, Dave Meko, Martin Girardin, Erik
Nielsen, Greg Pederson, Dave Sauchyn, Jac Tardif,
and Emma Watson
The tree-ring record of
summer drought in the
Canadian Prairies
Journal of Climate, in press

does the past
really matter?

3
main
applications

climate change
YOU CAN TOUCH

BENCHMARKS
for recent events and trends

starting points for
‘paleo’ scenarios
91

VIC BAKER
UNIVERSITY OF ARIZONA

“ HAPPEN AGAIN
Common sense holds that what has really happened
CAN
VIC BAKER
UNIVERSITY OF ARIZONA

F U TURE DI REC TION S

Prairie tree-ring network

northwestern Ontario 3
6
2
4
1
Ringwidth
2
PDSI
0 0
-2 -1
-4 r = 0.40
-2
-6
-3
1900 1920 1940 1960 1980 2000
St. George et al., (accepted), Journal of Climate Year (A.D.) 95

Can we do
better ?

drought
f ring width

drought
f ring width
ring chemistry

drought
f ring width
ring chemistry
ring density

CLIMATE
direct direct
PROXIES HYDROLOGY
indirect

HYDROLOGY

?
climate change
geological

The frequency, severity and causes
of extreme droughts in the
Winnipeg River basin
Scott St. George
Geological Survey of Canada