Download The Pacific Northwest`s Changing Hydrology Marketa McGuire Elsner

The Pacific Northwest’s
Changing Hydrology
Marketa McGuire Elsner
University of Washington
JISAO/CSES Climate Impacts Group
Dept of Civil and Environmental Engineering
February 12, 2008
Climate Change Effects to Fish and Wildlife Resources –
FWS Training
Climate science in
the public interest
Recession of South Cascade Glacier
Upper Skagit River Basin, Washington
Source:
U.S. Geological Survey
http://ak.water.usgs.gov/glaciology/south_cascade/
Cool Season Climate of the Western U.S.
PNW
GB
CA CRB
DJF Temp (°C)
NDJFM Precip (mm)
Understanding
Climate Variability
Observed 20th century variability
°C
(~5.5°F)
+3.2°C
(~3.1°F)
(~1.2°F) +1.7°C
+0.7°C
0.9-2.4°C
0.4-1.0°C
Pacific Northwest
1.2-5.5°C
Observed 20th century variability
%
-1 to +3%
+1%
+6%
+2%
-1 to +9%
Pacific Northwest
-2 to +21%
Regionally Averaged Temperature Trends Over the
Western U.S. 1916-2003
PNW
Linear Trend (Deg. C per century)
3.00
2.50
Tmax
PNW
2.00
1.50
1.00
0.50
0.00
-0.50
-1.00
nov
dec
jan
feb
mar
apr
may
jun
jul
aug
sep
4.00
Linear Trend (Deg. C per century)
CA CRB
CRB
GBAS
oct
GB
CA
CA
3.50
CRB
Tmin
GBAS
3.00
PNW
2.50
2.00
1.50
1.00
0.50
0.00
oct
nov
dec
jan
feb
mar
apr
may
jun
jul
aug
sep
2000
1996
1992
1988
1984
1980
1976
1972
1968
1964
1960
1956
1952
1948
1944
CA
1940
PNW
1936
4
1932
1928
3
1924
1920
1916
Std Anomalies Relative to 1961-1990
Regionally Averaged Cool Season Precipitation
Anomalies
PRECIP
CRB
GB
2
1
0
-1
-2
-3
Global Climate Change Scenarios
and Hydrologic Impacts for the PNW
Trend in Apr 1
Snowpack
1950-2000
824 snow courses
73% – trends
Large – trends PNW
Some + trends SW
The warmer locations are most sensitive to
warming
2060s
+2.3C,
+6.8%
winter
precip
Planning Framework to Incorporate
Climate Information and Uncertainty
Emissions
Scenarios
X
GCMs
X Downscaling
Climate Scenarios
Approach provides
ensemble of variables
that can be used to
evaluate impacts of
climate change
• Precipitation
• Air Temperature
• Streamflow
Hydrology Modeling
• Soil Moisture
• PET
• VPD
• And more!
Hydrology and Water Resources
-Snowpack
Snowpack will
continue to
decrease.
Declines in
April 1 SWE
vary between
35%-41% for
the 2040s,
depending on
the emissions
scenario.
Hydrology and Water Resources
-Projected Changes in Soil Moisture
Changes in soil
moisture will
be mixed.
Declines may
be expected in
the 2040s in
mid-elevation
areas, while
increases may
be expected in
highest
elevation areas.
Simulated Changes in Natural Runoff Timing in the
Naches River Basin Associated with 2 C Warming
120
Simulated Basin Avg Runoff (mm)
100
80
Impacts:
•Increased winter flow
•Earlier and reduced peak flows
•Reduced summer flow volume
•Reduced late summer low flow
1950
60
plus2c
40
20
0
oct
nov
dec
jan
feb
mar
apr
may
jun
jul
aug
sep
250
Simulated Basin Avg Runoff (mm)
Chehalis River
200
150
1950
plus2c
100
50
0
oct
nov
dec
jan
feb
mar
apr
may
jun
jul
aug
sep
500
Hoh River
Simulated Basin Avg Runoff (mm)
450
400
350
300
1950
250
plus2c
200
150
100
50
0
oct
nov
dec
jan
feb
mar
apr
may
jun
jul
aug
sep
200
Nooksack
River
Simulated Basin Avg Runoff (mm)
180
160
140
120
1950
100
plus2c
80
60
40
20
0
oct
nov
dec
jan
feb
mar
apr
may
jun
jul
aug
sep
Mapping of Sensitive Areas in the PNW by Fraction of
Precipitation Stored as Peak Snowpack
HUC 4 Scale Watersheds in the PNW
Climate Change Impacts are Similar to
Impacts of Water Management in PNW Hydropower
Systems
30000
Streamflow (cfs)
25000
Estimated natural flows
20000
nat
15000
obs
10000
5000
Skagit River at Mt. Vernon
0
10
11
12
1
2
3
4
5
6
7
8
9
Summary of Flooding Impacts
Rain Dominant Basins:
Possible increases in flooding due to increased precipitation
variability, but no significant change from warming alone.
Mixed Rain and Snow Basins Along the Coast:
Strong increases due to warming and increased precipitation
variability (both effects increase flood risk)
Inland Snowmelt Dominant Basins:
Relatively small overall changes because effects of warming
(decreased risks) and increased precipitation variability
(increased risks) are in the opposite directions.
Landscape Scale
Ecosystem Impacts
Forests
• Wildfires are strongly associated
with climate, especially in eastside
forests.
• Mountain pine beetle poses a
significant threat to PNW pine
forests.
• Tree species composition will change
as species respond uniquely to a
changing climate.
• Productivity of Douglas-fir forests is
likely to decrease statewide.
Annual area (ha × 106) affected by MPB in BC
9.0
2005
Bark Beetle Outbreak in British Columbia
8.0
7.0
2004
6.0
5.0
2003
4.0
3.0
2.0
2002
1.0
2001
2000
1999
0
1910 1930 1950 1970 1990 2010
Year
(Figure courtesy Allen Carroll)
Temperature thresholds for coldwater fish
in freshwater
• Warming temperatures will increasingly stress coldwater
fish in the warmest parts of our region
– A monthly average temperature of 68ºF (20ºC) has been used as an upper
limit for resident cold water fish habitat, and is known to stress Pacific
salmon during periods of freshwater migration, spawning, and rearing
+3.1 °F
+4.1 °F
Salmon
Water temperature is
already a problem in
many WA stream
reaches.
Exceedences of WQ
criteria for temp,
especially in
summer, will
increase with
warmer summer
temperatures and
reduced low flows
due to earlier
snowmelt.
Projected Maximum Weekly Average Water
Temperatures – 2040s
49% of stations exceed the 21ºC (70°F) water
quality criteria (changes relative to 2001-2007)
Agriculture
• Irrigation supplies are likely to decline
significantly as a result of changes in
snowpack, resulting in more frequent
and more stringent prorationing of water
to junior water rights holders.
• For dryland agriculture, climate change
will force agricultural practices to adapt
to longer growing seasons, reduced
summer precipitation, and increasingly
competitive weeds.
• Diseases will generally become more
problematic over the next century,
especially as a result of warmer
temperatures.
Impact Pathways Associated with Climate
•Changes in water quantity and timing
Reductions in summer flow and water supply
Increases in drought frequency and severity
Changes in hydrologic extremes
Changing flood risk (up or down)
Summer low flows
Changes in groundwater supplies
•Changes in water quality
Increasing water temperature
Changes in sediment loading (up or down)
Changes in nutrient loadings (up or down)
•Changes in land cover via disturbance
Forest fire
Insects
Disease
Invasive species
Impact Pathways Associated with Climate
•Changes in water management practice
Hydropower production (energy demand)
Flood control operations (changing flood risk and
refill statistics)
Instream flow augmentation
Use of storage to control water temperature
•Changes in Ecosystem Protection and Recovery Planning
Design of fish and wildlife recovery plans
Habitat restoration efforts
ESA listings (as a process)
Monitoring programs
Approaches to Adaptation and Planning
•Anticipate changes. Accept that the future climate will be
substantially different than the past.
•Use scenario based planning to evaluate options rather
than the historic record.
•Expect surprises and plan for flexibility and robustness in
the face of uncertain changes rather than counting on one
approach.
•Plan for the long haul. Where possible, make adaptive
responses and agreements “self tending” to avoid repetitive
costs of intervention as impacts increase over time.
More information on the Climate Impacts
Group or WA State Climate Impacts
Assessment
The Climate Impacts Group
www.cses.washington.ed/cig
Marketa McGuire Elsner
[email protected]
Climate science in
the public interest
• Motivation for writing
grew out of October 2005
King County climate
change conference
• Written by the CIG and
King County, WA in
association with ICLEI –
Local Governments for
Sustainability
• Focused on the process
(not a sector), and written
for a national audience
www.cses.washington.edu/cig/fpt/guidebook.shtml
Hydrologic Scenarios Database for the
Columbia River Basin
Working in Coordination With
Regional Stakeholders





Ecology
BPA
NPCC
State of OR
British Columbia (BC Hydro,
Ministry of Environment)
Planning Framework
Incorporating Climate Information
and Uncertainty
 ~20 GCMs
 2 Emissions Scenarios
 2 Downscaling Approaches
 Large Scale Planning Studies
 WRIA Water Supply Planning
 Specific Planning Studies
Coasts
Rising sea levels will increase the
risk of flooding, erosion, and
habitat loss along coastline.
50”
40”
30”
Medium estimates of SLR for 2100:
+2” for the NW Olympic Peninsula
+11” for the central/southern coast
+13” for Puget Sound
Higher estimates (up to 4 feet in
Puget Sound) cannot be ruled out.
20”
13”
10”
6”
3”
6”
2050
2100