Richard Palmer Michael Miller University of Washington Department of Civil and Environmental...

Richard PalmerMichael Miller

University of Washington

Department of Civil and Environmental Engineering

Water Supply and Water Supply and Allocation Issues Allocation Issues

in the Puget in the Puget SoundSound

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?

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

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

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

Sultan River Inflows into Spada Reservoir Average Annual Hydrograph

0

500

1000

1500

2000

2500


cfs

Sultan Current ClimateSultan pcm3dec4Sultan echam4dec4Sultan had2dec4Sultan had3dec4

0

50

100

150

200

250

300


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


cfs

Cedar Current ClimateCedar pcm3dec4Cedar echam4dec4Cedar had2dec4Cedar had3dec4

Green River Inflows into Howard Hansen Reservoir Average Annual Hydrograph

0

500

1000

1500

2000

2500


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


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


-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

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)

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

TSI

Auburn

Renton

N

TSI

Auburn

Renton

N

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

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

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

Apr-01 Jul-01 Nov-01 Feb-02 May-02 Sep-02 Dec-02 Mar-03

Months (June, 01 to Dec., 02)

Ave

. M

onth

ly F

low

(af

w)

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

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

Apr-01 Jul-01 Nov-01 Feb-02 May-02 Sep-02 Dec-02 Mar-03

Months

Ave

. M

onth

ly F

low

(af

w)

Forecast Aver.

Actual

Historic Max.

Historic Min

Historic Ave.

Forecast Start

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

Richard Palmer Michael Miller University of Washington Department of Civil and Environmental...

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