Climate Change, Streamflow,
and Connections to Ecology
Charles Luce
U.S. Forest Service
Boise, ID
Climate Change Vulnerability
Exposure
Vulnerability
Sensitivity
Adaptive
Capacity
Cascading Vulnerability and
Exposure
Precipitation
Snowpack
Forest Cover
Streamflow
Fish
Hydrologic Connections
Snowmelt
Timing
Precipitation
Tree Growth
Fire Extent
Peak Snow
Mortality
Flood
Seasonality
Temperature
Runoff
Timing
Soil
Moisture
Flood
Magnitude
Summer Low
Stream
Flow
Temperature
Water
Supply
Spawning
Success
Habitat
Quality
Western North America Temperature
IPCC AR 4 WGI 11.11
Water Supply: GCM Projection
IPCC AR 4 SYR 3.5
Annual Runoff compared to
1980-1999 (SRES A1B 2090-2099)
Future Precipitation
Precipitation
?
?
?
Now
Years
Relative Sensitivity
Precipitation
Vs.
Temperature
Sensitivity
Exposure
Vulnerability
Relative Sensitivity
Precipitation
Vs.
Temperature
Sensitivity
Exposure
Vulnerability
If sensitivity is small,
uncertainty about exposure is less important!
1950
1960
1970
1980
1990
2000
200
300
400
500
600
700
800
Annual Flow (mm)
Two Kinds of “Non-Stationarity”
Change in
Mean
Change in
Variability
Water Supply: Historical Trends
Change in
25th %ile
annual flow
Significant at
Not Significant at
0.1
0.1
-4.3 % to 4.3 %
-12.9 % to -4.3
-21.5 % to -12
-30.1 % to -21
-38.7 % to -30
-47.3 % to -38
ET or Precipitation?
Precipitation!
1. Changes too big to
be accounted for by
increased radiant
forcing.
Precipitation!
1. Changes too big to
be accounted for by
increased radiant
forcing.
Flow
2. Changes in wet
years inconsistent
with increased ET.
Historical April 1 Snowpack (SWE)
April 1 SWE (cm)
(1950-1999)
- +
Regonda et al, 2005
see also Mote et al, 2005
Correlation with
Temperature
Snowpack Sensitivity Diagram
Correlation with
Precipitation
Correlation with
Temperature
Snowpack Sensitivity Diagram
Correlation with
Precipitation
Temperature
Sensitive
Correlation with
Temperature
Snowpack Sensitivity Diagram
Correlation with
Precipitation
Precipitation
Sensitive
Temperature
Sensitive
Sensitivity of April 1 SWE
Mote et al., 2005
Streamflow Timing
Stewart et al., 2005
Seasonality Seesaw
Runoff
CT
Seasonality Seesaw
Seasonality Seesaw
Volume same
Timing change
Seasonality Seesaw
Volume same
Timing change
Seasonality Seesaw
Volume same
Timing change
Seasonality Seesaw
Seasonality Seesaw
Volume decreased in melt season
Seasonality Seesaw
Volume decreased in melt season
Seasonality Seesaw
Volume decreased in melt season
Seasonality Seesaw
Volume decreased in melt season
Center of Timing
16 Jun
01 Jun
16 May
01 May
16 Apr
01 Apr
Salmon R nr Salmon
16 Mar
100
150
200
250
Annual Streamflow (mm)
Past and ‘Future’ Hydrographs
Historical
Projected
60.00
40.00
20.00
0.00
-20.00
-40.00
-60.00
MF Boise River
Modeled
1990-2080
-80.00
-100.00
-120.00
UW CIG
Oct
Nov Dec
Jan
Feb Mar Apr May Jun
Jul
Aug
Sep
60.00
40.00
20.00
0.00
-20.00
-40.00
Modeled Flow Changes
1990s-2080s
-60.00
Observed Flow Changes
1950s-1990s
-80.00
-100.00
-120.00
Oct
Nov Dec
Jan
Feb Mar Apr May Jun
Jul
Aug
Sep
Longer Fire Season Effect?
1972-2003 large forest fires
Westerling et al, 2006
Burned Area Sensitivity
Precipitation
Annual
Runoff
Fire Extent
Temperature
Runoff
Timing
Holden et al., in revision
Burned Area Sensitivity
Precipitation
q = 0.49
Annual
Runoff
Fire Extent
= 0.53
Temperature
Runoff
Timing
q = 0.17
Holden et al., in revision
Summer Flows (July 15-Sep15)
Change in 25th Percentile, 1948-2006)
-50% to -60%
-40% to -50%
-30% to -40%
-20% to -30%
-10% to -20%
0% to -10%
Summer Flow to Annual Flow
Correlation
90 % to
80 % to
70 % to
60 % to
50 % to
100 %
90 %
80 %
70 %
60 %
40 % to 5
30 % to 4
20 % to 3
10 % to 2
0 % to 10
Floods
Historical 2-yr Flood Trend
47.6 % to
37 % to 47
26.4 % to
15.8 % to
5.2 % to 1
-5.4 % to 5
-16 % to -5
-26.6 % to
-37.2 % to
-47.8 % to
-58.4 % to
Midwinter Flood Frequency
Present
Wenger et al, submitted
From UW CIG data
2080 A1b
Aquatic Species Sensitivity
Wenger et al., submitted
Aquatic Species Sensitivity
Both metrics primarily
Temperature sensitive
Wenger et al., submitted
Precipitation
Sensitivity
Water
Supply
Peak Snow
Runoff
Timing
Fire Extent
Flood
Seasonality
Spawning
Success
Flood
Magnitude
Summer Low
Flow
Temperature
Key Items
• Projections as temperature sensitivity
– Projections are a partial description of
vulnerability
• Need for more explicit discussion of
uncertain precipitation
– Big differences in adapting to drier vs. wetter
future
VIC Streamflow Downscaling
1/16 degree
Wenger et al., 2010
PNW VIC Validation
PNW VIC Validation
PNW VIC Validation
PNW VIC Validation
Early
Snowmelt
Wenger et al., 2010
Snowmelt Bias Example
Available Downscaled
Streamflow Metrics
Historical
2040s A1b
2080s A1b
Ensemble
Miroc
PCM
http://www.fs.fed.us/rm/boise/AWAE/projects/
modeled_stream_flow_metrics.shtml