Transcript Effects of Climate Change on Water Management Strategies

Impacts of Climate Change on the
Tualatin River Basin
Nathan VanRheenen,
Erin Clancy,
Richard Palmer, PhD, PE
Dept. of Civil and Environmental Engineering
University of Washington
www.tag.washington.edu
Talk Overview
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Background
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Research Approach
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Impacts on Meteorology
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Impacts on Hydrology
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Impacts on System Yield
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Final Conclusions
Insight from a Notable American Philosopher
The future ain't what it used to be.
-Yogi Berra
It's time for those of us who work on climate
change to help the public and policymakers
understand the evidence: Climate change is
real, well underway, and poses severe risks to
the United States and the world.
Dr. Peter Gleick
Director, The Pacific Institute
2003 MacArthur Fellowship Award Winner
Translating the Challenge to Regional Analysis
What are the likely impacts of climate change
on regional watersheds?
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Types of impacts
Magnitude of impacts
Mitigation responses
Case Studies
 Seattle Water Department
 Portland Water Bureau
 Tualatin Basin
Setting
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Rain-driven watershed (no snow impacts)
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Multiple uses: M&I, Ag, Fish, Recreation
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Current system is fully allocated
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500,000 customers (M&I)
Agriculturally productive
Water Quality Concerns (temperature)
M&I demands expected to increase 400% by 2050
Ag demands, 50% by 2050
System highly sensitive to changes in summer
flows
System expansion is under consideration
Models for Evaluating Climate Change

General Circulation Models
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Hydrology Model, EPA BASINS
 Tualatin River Integrated
Management System (TRIMS)
Impacts on Meteorology
•Global climate
models operate
at a scale of
2-5° latitude
•Global data
must be
downscaled to
the local station
scale in order to
assess the
impacts of
climate change
on water
resources.
From Climate Signals to Runoff
Historical
Meteorology
Climate Signals
Predicted
Meteorology
Hydrology
Model
Predicted
Runoff
Temperature Signals from GCMs
Temperature Increase (F)
7
6
5
2000
2020
2040
2060
4
3
2
1
0
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
Month
Precipitation Signals from GCMs
Change in Precipitation
20%
10%
2000
2020
2040
2060
0%
-10%
-20%
-30%
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
Month
Impacts on Hydrology
Hydrology Model
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EPA BASINS
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Watershed and subwatershed delineation: ArcGIS
add-on
Rainfall-runoff simulation: HSPF (Stanford
Watershed Model)
Can be extended to model water quality
Calibrated to match monthly flows at six
stations
BASINS Model Nodes
Impacts on Hydrology: Hagg Lake Inflows
Monthly Average Flows into Hagg Lake
300
2000 (modeled)
2020
2040
2060
Average Flow (cfs)
250
200
150
100
50
0
Jan
Feb
Mar
Apr
May
Jun
Jul
Month
Aug
Sep
Oct
Nov
Dec
Impacts on Hydrology: Summer Flows
Average Flow (cfs)
Flows at Mouth of Dairy Creek
(July-October)
130
120
127
125
110
114
100
105
90
2000
(modeled)
2020
2040
Climate
2060
Impacts on Water Resources System
Tualatin River Integrated Management System
(TRIMS)
TRIMS Description
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Dynamic model of the basin
Purpose: Calculate system yield
Incorporates
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Major system features and operations
BASINS inflows
M&I and Ag water supply demands
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Present, Contracted, 2050
CWS environmental targets (Present, 2050)
Instream flow targets
Scoggins Dam expansion alternatives
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Increase dam elevation by 20 ft, 40 ft
Hagg Lake Storage – Current System
Hagg Lake Storage – 40 ft Expansion
Hagg Lake Yield – Current System
98% Reliable Yield
97% Reliable Yield
95% Reliable Yield
90% Reliable Yield
50,000
40000 acre-ft/100 days = 130mgd
40000 acre-ft/150 days = 87 mgd
Safe Yield (acre-feet)
45,000
40,000
35,000
30,000
2000
2020
2040
2060
Hagg Lake Yield – Current System
Current Demands
Contracted Demands
2050 Demands
40,000
97% Reliable Safe Yield (acre-feet)
38,000
36,000
34,000
32,000
30,000
28,000
26,000
24,000
2000
2020
2040
2060
Hagg Lake Yield – 20 ft Expansion
Current Demands
Contracted Demands
2050 Demands
60,000
97% Reliable Safe Yield (acre-feet)
59,000
58,000
57,000
56,000
55,000
54,000
2000
2020
2040
2060
Hagg Lake Yield – 40 ft Expansion
Current Demands
Contracted Demands
2050 Demands
97% Reliable Safe Yield (acre-feet)
75,000
74,000
73,000
72,000
71,000
70,000
2000
2020
2040
2060
Hagg Lake “Expansion Schedule”
Current, 2000 climate
Current, 2060 climate
20 ft raise, 2000 climate
20 ft raise, 2060 climate
40 ft raise, 2000 climate
40 ft raise, 2060 climate
Safe Yield, 97% Reliable (acre-feet)
75000
70000
65000
60000
55000
50000
45000
40000
Projected Demand Curve, 2000-2060
35000
30000
25000
2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050 2055 2060
Conclusion
Conclusion
Impacts on Temperature and Precipitation
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Increase in temperature of 2-4 °F
Wetter winters, drier summers
Impacts on Streamflow
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10-20% lower flows in summer, wetter winters
Impacts on Yield
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Decreases 1.5% per decade for current system
and current demands
Conclusion
System Expansion without climate change
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System Expansion with climate change by
2040
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97% reliable yield increased from 38,000 acre-ft
per year to 60,000 acre-ft (20-ft expansion) and
73,000 acre-ft (40-ft expansion)
Yield shifts downward by about 4,000 acre-ft
Climate change impacts suggest expansion
needed 5-8 years earlier