Water in the Columbia,
Effects of Climate Change and
Glacial Recession
John Pomeroy,
Centre for Hydrology
University of Saskatchewan, Saskatoon
@Coldwater Centre, Biogeoscience Institute, University of Calgary
with contributions from
Mike Demuth, Dan Moore, Masaki Hayashi, Al Pietroniro,
Laura Comeau, Chris Hopkinson, Katrina Bennett
Columbia Basin Snow and Ice
southernmost, interior
summer snow water reserves
Snow depth in January
Snow depth in June
Canadian
Rockies are
the
Hydrological
Apex of
North
America
Columbia River Basin
Annual Precipitation
Hicks
Sources of Mountain Streamflow
z
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Streamflow contribution related to glacier area
Study of Lake O’Hara (5% glacier cover on
Opabin Plateau)
Flow to Lake O’Hara
z
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60% snowmelt
35% rainfall
5% glacier melt
Hayashi
Water Input to the Opabin Watershed
snow melt
glacier melt
flux (m3/s)
1.5
1
0.5
0
5/1
5/21
6/10
6/30
7/20
8/9
8/29
9/18
10/8
2006
Hayashi
Water Input to the Opabin Watershed
snow melt
glacier melt
rain
flux (m3/s)
1.5
1
0.5
0
5/1
5/21
6/10
6/30
7/20
8/9
8/29
9/18
10/8
2006
Hayashi
Hydrograph of a Glacierised Stream,
Rockies
Young
Glacier Ice Wastage and Melt
contribution to streamflow
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Peyto Glacier
basin streamflow Aug 08
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Wastage increases the total annual
streamflow volume
Glaciers receding at an increasing rate
contribute increasing volumes of
wastage in the short term
Long term wastage contributions will
decrease past a threshold where the
declining glacier area limits the volume
of wastage produced
Melt does not contribute to the total annual streamflow volume
Snow is accumulated into the glacier system instead of melting and contributing
to streamflow in May and June due to the cooler ice surface temperature
The equivalent runoff volume contributes to streamflow as ice melt in July to
September
The glacier effectively delays runoff to the late summer months of otherwise low
flow, and contributes to seasonal streamflow in terms of Melt.
Contribution of the Melt of Snow and Ice on
a Glacier to Late Summer Streamflow
Comeau, 2008
Ice Wastage Contribution to Streamflow as a
Function of Glaciation of a River Basin
Comeau, 2008
Current Glacier
Contribution to River
Melt
Discharge
Fall
%
11.5
7.1
Fall
%
Annual
%
6.2
Mike Demuth, Natural Resources Canada
Annual
%
2.8
Regional climate change predictions
2080-2089 relative to 1980-1999
Annual
Winter - DJF
Summer - JJA
IPCC 2007
Warmer and Wetter generally; Drier in summer !
Rainfall versus Snowfall,
Kananaskis Valley
Temperature Change
Warmer winters = less snowfall
Warmer winters = more rainfall
Harder & Pomeroy
Streamflow Trends
Bennett, PCIC
Glaciers in the Rocky Mountains
Glacial Decline:
ƒ Glaciers receding in the Rocky Mountains
since the 19th Century
ƒ 1975-1998 total glacier loss:
NSRB 23% (395 – 306 km²)
SSRB 37% (141 – 89 km²)
ƒ Projected to continue into the future
Impacts:
ƒ Reduced river flows in late summer
months
ƒ Increased streamflow variability
ƒ
ƒ
ƒ
ƒ
Hydroelectric power plants
Ecology
Agriculture
Domestic
1896
W. Wilcox
2008
Peyto Glacier
Lateral Moraines
Glacier Retreat – Rocky Mountains
Mapped from
NASA LANDSAT
satellite
Glaciers are fed by
alpine snow
37% loss of glaciated
area of South Sask
River Basin
1975-1998
23% loss of glaciated
area of North Sask
River Basin
1975-1998
Demuth & Pietroniro
Demuth
Columbia
Icefield
Yesterday
Volume per time
Today
Moore et al
Tomorrow
Historical variations
of Illecillewaet
Glacier
http://www.geog.utoronto.ca/info/facweb/Harvey/Harvey/harvey_images.htm
coefficient b2
Increase in streamflow
for an increase in air temperature
Sensitivity of August streamflow to August air
temperature as influenced by glacier cover
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
0
5 10 15 20 25 30 35 40 45 50 55 60 65
glacier cover (%)
Moore
Streamflow response to climate warming:
hypothesis
160
Q (% of pre-shift mean)
140
120
100
80
60
40
Onset of warming and shift
to negative mass balance
20
0
Time
Moore
Mistaya River
M
onthlyF
low(C
M
S
)
25
20
15
10
5
0
8/1/80
12/1/83
Time (month)
8/1/90
Siffleur River
40
M
onthlyFlow(C
M
S
)
4/1/87
30
20
10
0
8/1/80
12/1/83
Time (month)
8/1/90
Ram River
100
M
onthlyF
low(C
M
S
)
4/1/87
80
60
40
20
0
8/1/80
1998 extent
12/1/83
Time (month)
1975 Extent
4/1/87
8/1/90
None
Pietroniro and Demuth
Meteorological Stations
Hydrological Observation
New Observations Needed
Station density is too low. To meet World Meteorological Organisation standards for
mountain regions we need
4.5 fold increase in streamflow (hydrometric) stations
22.5 fold increase in precipitation stations
z
z
0.04
0.035
S ta ti o n D e n s i ty p e r k m
2
Weather Station
0.03
Hydrometric Station
0.025
Snow Station
0.02
0.015
0.01
0.005
0
<500
500-999
1000-1499 1500-1999 2000-2500
Elevation
2500-3000
3000+
Observations Clustered in Small
Basins Improve Understanding
Prediction
2003
0.5
Q [m3/s]
0.4
Obs
Aggregated
Distributed
0.3
0.2
0.1
0.0
4/17/03 4/26/03 5/05/03 5/14/03 5/23/03 6/01/03
Time [days]
Modelling in Columbia
z
Models should be physically based
z
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Temperature index unsuited for climate change or
land use change snowmelt calculations
Radiation can estimated accurately from temperature
range and output from climate models
Models should have realistic snow and glacier
components
Models must explicitly recognize the influence of
topography, slope and aspect on watershed
response
CRHM Coupled Blowing Snow and
Snowmelt Modelling for Mountains
Meteorological Inputs T, RH, U, P, K↓
Latitude, elevation, slope,
aspect, vegetation, fetch, area
Radiation, windflow and temperature recalculations
Spatially Distributed K↓, L↓, u*, T, q, snowfall, rain
Albedo Decay
Blowing Snow Model Sublimation, Transport
Snobal Snowmelt Model
ΔSWE, Melt, Sublimation
Winter Warming Scenario Impact on
Mid-Alpine Ridge Snow Regime
200
reference simulation
150
+ 1°C
+ 2 °C
SWE (mm)
+ 3°C
100
+ 4 °C
50
0
30/11/06
30/12/06
29/01/07
28/02/07
30/03/07
29/04/07
29/05/07
GCM scenario results – hydrological model
2039 – 2070 cumulative flows of South
Saskatchewan River
Red Deer at Bindloss
-13%
(-32% to 13%)
South Sask a
Diefenbaker
-8.5%
(-22% to 8%)
Bow River at mouth
-10%
Oldman at mouth
- 4%
(-19% to 1%)
(-13% to 8%)
Columbia Icefield Research Initiative
Jasper
Columbia Icefields
Visitor Centre
k
La
e
e
uis
o
L
Conclusions
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Glacier contribution to streamflow depends on climate &
glacierised area – this contribution is incompletely
quantified in the Columbia basin.
Further deglaciation likely to result in lower and more
variable late summer streamflow
Change in hydrology due to climate change and
deglaciation depends on what land cover replaces
glacier cover (tundra, forest, rock)
Current hydrological modelling has simple or no
representation of glaciers, snow and alpine energy
balance – adds considerable uncertainty to estimating
the future water resources of the region.