Download Water supply options for the future

Water Supply and
Allocation Issues
in the Puget
Sound
Richard Palmer
Michael Miller
University of Washington
Department of Civil and
Environmental Engineering
Objective and Outline
• What will be the climate and hydrology of
the Puget Sound in 2020/2040 and what are
the impacts of climate change on water
supply issues?
• How can mid-term forecasts improve
management of water supplies for people
and fish?
Objective and Outline
• What will be the climate and hydrology of
the Puget Sound in 2020/2040 and what are
the impacts of climate change on water
supply issues?
• How can mid-term forecasts improve
management of water supplies for people
and fish?
Current state of climate modeling
• Climate models are currently capable of credibly simulating
present climate at the continental scale.
• Models are continually improving, yet key physical
relationships remain poorly understood, the water vapor/cloud
formation and feedback process being the most significant.
• Greater resolution and more complex parameterization of
physical processes will continue as computing power increases
and study continues.
• Models are not predictions of future, but can be considered as
credible simulations of a multitude of possible futures.
GCMs - General Circulation Models
• IPCC discusses 34 GCMs
• Coupled Model Intercomparison Study
examines 29 in more detail
– Compares GCMs via historical observations for air
temperature, precipitation, sea temperature, air
pressure, ice extent.
• We have selected nine of the more prominent
models to demonstrate GCM selection process
Model
Developed by
Reference
CCSR/NIES2
Center for Climate System Research,
University of Tokyo/National Institute for
Environmental Studies
Emori et al, 1999
CGCM2
Canadian Centre of Climate Modelling and
Analysis
Flato and Boer, 2001
CSIRO mk2
Commonwealth Scientific & Industrial
Research Organisation
Gordon and O’Farrell,
1997
CSM1.3 *
NCAR – National Center for Atmospheric
Research
Boville et al., 2001
DOE PCM
NCAR , US Department of Energy, Los
Alamos, Naval Post Graduate Program, and
US Army Corps of Engineers.
Washington et al., 2000
ECHAM4
Netherlands center for Climate Research and Max Planck Institute (MPI)
Roeckner et al., 1996
GFDL_R30
Geophysical Fluid Dynamics Laboratory
(GFDL) & NOAA
Knutson et al., 1999
HadCM3
Hadley Centre for Climate Prediction and
Research
Gordon et al., 2000
MRI2
Meteorological Research Institute (Numerical
prediction Division)
Yukimoto et al., 2000
Evaluation of Climate Change
Climate Shift
Meteorological Data
Hydrology Model
Demand Model
Operations Model
2020 Climate Change
Temperature Change
for Climate Change Scenarios
4
2040 Climate Change
3.5
3
Degrees C
Temperatures will
increase by 2° C by
2040, with higher
temperatures in the
summer
2.5
2
1.5
1
0.5
Precipitation Fraction for
Climate Change Scenarios
2020 Climate Change
0
1.2
2040
Climate
Oct
NovChange
Dec Jan
Feb
Mar
Apr
May Jun
Jul
Aug Sep
Fraction Precipitation
1.15
1.1
Precipitation will
increase in the
winter and
decrease in the
summer.
1.05
1
0.95
0.9
0.85
0.8
Oct
Nov Dec
Jan
Feb
Mar
Apr
May Jun
Jul
Aug Sep
DHSVM
Distributed Hydrology-Soil-Vegetation Model
Sultan River Inflows into Spada Reservoir
Average Annual Hydrograph
2500
2000
Sultan Current Climate
Sultan pcm3dec4
Sultan echam4dec4
Sultan had2dec4
Sultan had3dec4
cfs
1500
1000
500
0
Oct Nov Dec Jan Feb Mar Apr May Jun
Jul
Aug Sep
Tolt River Inflows into Tolt Reservoir
Average Annual Hydrograph
300
250
cfs
200
Tolt Current Climate
Tolt pcm3dec4
Tolt echam4dec4
Tolt had2dec4
Tolt had3dec4
150
100
50
0
Oct Nov Dec Jan Feb Mar Apr May Jun
Jul
Aug Sep
Cedar River Inflows into Chester Morse Reservoir
Average Annual Hydrograph
Cedar Current Climate
Cedar pcm3dec4
Cedar echam4dec4
Cedar had2dec4
Cedar had3dec4
600
500
cfs
400
300
200
100
0
Oct
Nov Dec Jan
Feb Mar
Apr May Jun
Jul
Aug Sep
Green River Inflows into Howard Hansen Reservoir
Average Annual Hydrograph
Green Current Climate
2500
Green pcm3dec4
Green echam4dec4
Green had2dec4
Green had3dec4
2000
cfs
1500
1000
500
0
Oct Nov Dec Jan Feb Mar Apr May Jun
Jul
Aug Sep
Ranked Cumulative Winter Flow (JFM) 2040
35000
Sultan Current Climate
Sultan pcm3dec4
Sultan echam4dec4
Sultan had2dec4
Sultan had3dec4
30000
25000
cfsweeks
20000
15000
10000
43%
32%
5000
0
0
0.2
0.4
0.6
0.8
1
Ranked Cumulative Spring (AMJ) Flow 2040
25000
Sultan Current Climate
Sultan pcm3dec4
Sultan echam4dec4
Sultan had2dec4
Sultan had3dec4
20000
15000
cfsweeks
10000
-30%
5000
0
0
0.2
0.4
0.6
0.8
1
Results – Impacts on Hydrology
Percent difference from current climate
cumulative seasonal flows
JFM
AMJ
JFM
AMJ
2020
2020
2040
2040
Mean
Absolute
Percent
Difference
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
Conclusions
• Climate impacts on the four basins’ hydrology are similar
• Average percent difference in seasonal flows
– 2020 Winter : 28%
– 2040 Winter : 37%
2020 Spring : -20%
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)
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
Objective and Outline
• What will be the climate and hydrology of
the Puget Sound in 2020/2040 and what are
the impacts of climate change on water
supply issues?
• How can mid-term forecasts improve
management of water supplies for people
and fish?
Why do a Forecast?
• 6-month forecast applied to the PRISM
models
• Usefulness of forecasts
– Why forecasts are useful
– Who could use the forecasts
• How are the forecasts developed
• Examples of the forecasts
• Future direction with the forecasts
N
Renton
TSI
Auburn
Applying 6-month Forecast
• Prior to a forecast
– Water management decisions
• 50 years of meteorological records
• 73 years water supply and demand records
• With a forecast
– Water management decisions based on potential future
conditions
• Forecast continue using DHSVM and CRYSTAL
for water supply and management
PRISM
Usefulness of Forecast
• For policymakers
– M&I Demands
• During below average conditions
– Improve timing of water restrictions
– Provide more information as to the type of restriction
– HCPs
• During above average conditions
– Determine amount and length of large flow releases
• During below average conditions
– Revise timing of releases to minimize habitat damage
Usefulness of the Forecast
• For water managers
– During average and above average flow
• Forecast potential of these resources
• Discharge necessary to meet future flood control
– During below average flows
• Forecast initial drought conditions a couple months
sooner
• In the early summer months, forecasts could indicate
when fall and winter flows will increase
Forecast Development
• Developed by Andy Wood,
Edwin Maurer, Arun Kumar, and
Dennis Lettenmaier
• NCEP Data
– Bias Correction
– Downscaling
• DHSVM
NCEP Data
• National Center for Environmental Prediction
(NCEP)
– Global Spectral Models (GSMs)
– Hindcasts
• Temperature and precipitation
• 10 initial conditions
• 21 years (79 – 99)
– Forecasts
• 20 ensembles
• 6-month forecast
Bias Correction
Downscaling
• Forecasted meteorological data
– Based on month from the historic 21-year
record (79-99), most similar precipitation
– Precipitation is scaled (multiplicative process)
– Temperature is shifted (additive process)
• Preformed to each month of each ensemble
DHSVM
• Distributed Hydrologic Soil Vegetation
Model (DHSVM)
• Most recent year of actual data run prior to
the forecast
– To have the model set for the forecasted data.
– Keep model run time reasonable
DHSVM Output
• 20 forecasts of stream flow
• Forecasts are compared to historic average
flows
• Comparison used to forecast higher or
lower then average flow.
June Forecast – Cedar
June Forecast - Cedar
20000
18000
Ave. Monthly Flow (afw)
16000
14000
12000
10000
8000
6000
4000
2000
0
Apr-01
Jul-01
Nov-01
Feb-02
May-02
Months (June, 01 to Dec., 02)
Sep-02
Dec-02
Mar-03
Actual
Historic Max.
Historic Ave.
Forecast Aver.
Historic Min
Esmbl1
Esmbl 2
Esmbl 3
Esmbl 4
Esmbl 5
Esmbl 6
Esmbl 7
Esmbl 8
Esmbl 9
Esmbl 10
Esmbl 11
Esmbl 12
Esmbl 13
Esmbl 14
Esmbl 15
Ensmbl 16
Ensmbl 17
Ensmbl 18
Ensmbl 19
Ensmbl 20
June Forecast - Cedar
20000
18000
Ave. Monthly Flow (afw)
16000
14000
Forecast Aver.
Actual
Historic Max.
Historic Min
Historic Ave.
Forecast Start
12000
10000
8000
6000
4000
2000
0
Apr-01
Jul-01
Nov-01
Feb-02
May-02
Months
Sep-02
Dec-02
Mar-03
Summary
• Climate Change
– Initial results suggest significant impacts on
water supply
– Lower summer flows will challenge releases
for both fish and folks
– New management strategies are necessary
– Future planning should include this impact
Summary on Forecasting
• Forecasting with longer-range climate
indicators offers promise
Past forecasts did not provide sufficient lead
time for certain times of year
• Will have on line forecasts this quarter