margaret hahn and dr. richard palmer university of washington department of civil and environmental...
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Margaret Hahn and
Dr. Richard Palmer
University of Washington
Department of Civil and Environmental Engineering
Climate Impacts Climate Impacts on PNW on PNW
Municipal Municipal Water SuppliesWater Supplies
Objective and Outline
• Assess the impacts of climate change on three neighboring water supply systems
• Conclusions• Background• Method • Results• Response
Conclusions• Climate impacts on the four basins’ hydrology are similar • Average percent difference in seasonal flows
– 2020 Winter : 28% 2020 Spring : -20%– 2040 Winter : 37% 2040 Spring : -31%
• Absolute average percent difference– Sultan : 31%– Tolt : 18%– Cedar : 36%– Green : 32%
• Average supply system impact is 15-17% increase in System Use (surface storage, groundwater and/or system shortfalls)
BackgroundAverage Monthly Hydrograph,
Puget Sound Municipal Water Supply Watersheds
0
200
400
600
800
1000
1200
1400
1600
1800
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
cfs
Sultan Observed
Tolt Observed
Cedar Observed
Green Observed
Puget Sound Region Demand Projections
50
100
150
200
250
300
350
400
450
500
550
Demand Year
King County WA
Pierce County, WA
Snohomish County, WA
Total Three County Demand
Evaluation of Climate Change
Climate Shift
Meteorological Data
Hydrology Model
Demand Model
Operations Model
Precipitation will increase in the winter and decrease in the summer.
Temperatures will increase by 2° C by
2040, with higher temperatures in the
summer
Precipitation Fraction forClimate Change Scenarios
0.8
0.85
0.9
0.95
1
1.05
1.1
1.15
1.2
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
Fra
ctio
n P
reci
pita
tion
2020 Climate Change
2040 Climate Change
Temperature Changefor Climate Change Scenarios
0
0.5
1
1.5
2
2.5
3
3.5
4
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug SepD
egre
es C
2020 Climate Change
2040 Climate Change
DHSVMDistributed Hydrology-Soil-Vegetation Model
DHSVM Calibration
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
cfs
Sultan Observed Sultan Current Climate
Tolt Observed Tolt Current Climate
Cedar Observed Cedar Current Climate
Green Observed Green Current Climate
Sultan River Inflows into Spada Reservoir Average Annual Hydrograph
0
500
1000
1500
2000
2500
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
cfs
Sultan Current ClimateSultan pcm3dec4Sultan echam4dec4Sultan had2dec4Sultan had3dec4
0
50
100
150
200
250
300
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
cfs
Tolt Current ClimateTolt pcm3dec4Tolt echam4dec4Tolt had2dec4Tolt had3dec4
Tolt River Inflows into Tolt Reservoir Average Annual Hydrograph
Cedar River Inflows into Chester Morse Reservoir Average Annual Hydrograph
0
100
200
300
400
500
600
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
cfs
Cedar Current ClimateCedar pcm3dec4Cedar echam4dec4Cedar had2dec4Cedar had3dec4
Green River Inflows into Howard Hansen Reservoir Average Annual Hydrograph
0
500
1000
1500
2000
2500
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
cfs
Green Current ClimateGreen pcm3dec4Green echam4dec4Green had2dec4Green had3dec4
Ranked Cumulative Winter Flow (JFM) 2040
32%
0
5000
10000
15000
20000
25000
30000
35000
0 0.2 0.4 0.6 0.8 1
Sultan Current ClimateSultan pcm3dec4Sultan echam4dec4Sultan had2dec4Sultan had3dec4
43%
cfs-weeks
Ranked Cumulative Spring (AMJ) Flow 2040
0
5000
10000
15000
20000
25000
0 0.2 0.4 0.6 0.8 1
Sultan Current ClimateSultan pcm3dec4Sultan echam4dec4Sultan had2dec4Sultan had3dec4
-30%
cfs-weeks
Results – Impacts on HydrologyPercent difference from current climate
cumulative seasonal flows
JFM AMJ JFM AMJMean
Absolute Percent
Difference2020 2020 2040 2040
Sultan 32 -18 43 -30 31
Tolt 16 -16 20 -21 18
Cedar 36 -23 49 -36 36
Green 28 -25 37 -37 32
Average 28 -20 37 -31
Water Supply System Analysis
• CRYSTAL
Cascade Regional Yield Simulation and Analysis Model
• Simulation model of Puget Sound water supply
• Considers future demands, policies, supplies and infrastructures
• Uses weekly time step
• Developed in Powersim
• Picture of Crystal
Impacts of 2040Climate Change Scenarios
0
20,000
40,000
60,000
80,000
100,000
120,000
0.00 0.20 0.40 0.60 0.80 1.00
Acr
e-fe
et
Current Climate 2000 demandspcm3dec4 2000 demandsecahm4dec4 2000 demandshad2dec4 2000 demandshad3dec4 2000 demands
Sultan River, Spada Reservoir – Supply Used
Max – 37%Min – 0%Avg – 15%
Cedar/Tolt – Supply Used plus Shortfalls
Impacts of Climate Change, 2040
0
20,000
40,000
60,000
80,000
100,000
120,000
0.00 0.20 0.40 0.60 0.80 1.00
Acr
e-fe
et
Current Climate 2000 demands
pcm3dec4 2000 demands
ecahm4dec4 2000 demands
had2dec4 2000 demands
had3dec4 2000 demandsMax - 32%Min - 17%Avg - 12%
Green – Supply Used
Impacts of Climate Change, 2040
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
0.00 0.20 0.40 0.60 0.80 1.00
Acr
e-fe
et
Current Climate 2000 demandspcm3dec4 2000 demandsecahm4dec4 2000 demandshad2dec4 2000 demandshad3dec4 2000 demandsMax - 28%
Min - 2%Avg - 16%
Climate Impact on Water Supply
Average climate impact on Supply Used, Percent Difference from Current Climate
Basin Max Min Avg
Sultan 37 0 15
Cedar/Tolt 32 12 17
Green 28 2 16
Possible Reactions to Climate Change Information
• Supply – Tacoma to Seattle Connection (2nd Supply Project) – Seattle to Everett Connection– Water Reuse
• Demand– Conservation Measures– Pricing – Change Service Base
Impacts of Climate Change, 2040
0
20,000
40,000
60,000
80,000
100,000
120,000
0.00 0.20 0.40 0.60 0.80 1.00
Acr
e-fe
et
Current Climate 2000 demands
pcm3dec4 2000 demands
ecahm4dec4 2000 demands
had2dec4 2000 demands
had3dec4 2000 demands
• 10,000 acre-ft ~~ 3333 mgal difference in the amount of storage used due to climate change
• Assume 100 day storage drawdown period
• Assume 1.3 million customers
How much would each person have to conserve?
23 gal per capita during drawdown
Estimated Daily per Capita Water Use, Indoor/Outdoor 95 gpd
19Toilet
13Shower9
Faucet
7Leaks
2Dishwasher
30Outdoor
15Clothes Washer
Estimated Daily per Capita Water Use, Indoor/Outdoor 72 gpd
12Toilet
12Clothes Washer
10Shower9
Faucet
7Leaks
2Dishwasher
20Outdoor
Overall reduction 25%
72 gpd
Reduce outside use
33% 10 gpd
Upgrade toilets
37% 7 gpd
Upgrade clothes washer
20% 3 gpd
Upgrade shower head
23% 3 gpd
Total 23 gpd
Margaret Hahn and
Dr. Richard Palmer
University of Washington
Department of Civil and Environmental Engineering
Climate Impacts Climate Impacts on PNW on PNW
Municipal Municipal Water SuppliesWater Supplies