Modeling Urban Water Management: Using

Climate Change Information

Margaret Hahn and Richard PalmerUniversity of Washington

Department of Civil and Environmental Engineering

Contents

• Project Area and Background– Interconnection of Everett, Seattle and Tacoma

• Project process – Linked models

• Results of Reservoir Management model– Annual minimum storage

• Impacts on planning process– Existing plans may not be sufficient

Tacoma Seattle Intertie

HAH Reservoir

Pipeline 1

Pipeline 5

TSI

Cedar Reservoir

Lake Washington

Lake Youngs

TACOMA

SKCRWA

SEATTLE

Pipeline 4

Pipeline 2

Revised from Nelligan-Doran, 1999

N

Everett Seattle Intertie

ESSL

TPL 1

TPL 2 Tolt Reservoir

Seattle

Everett

Pipeline 5

Pipelines 2-4

ClearviewPipeline

Snohomish County

Spada Lake Reservoir

Proposed ESI Alignment

King County

N

Planning and Management Analysis

• 2020 and 2040 forecasted demands• 2020 and 2040 climate change based

stream flows– PCM– ECHAM

• Status quo system configuration• Tacoma Seattle Intertie• Everett Seattle Intertie

Overall Analysis Process

• Meteorological data

• Hydrology model

• Calibration

• Climate Shift

• Impacts Evaluation

Precip and temp

DHSVM

Historic vs Simulated

Downscaled GCM

CRYSTAL model

DHSVMDistributed Hydrology-Soil-Vegetation Model

Green River Flow into Howard Hanson Reservoir

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

10/1

/59

10/1

/60

10/1

/61

10/1

/62

10/1

/63

10/1

/64

10/1

/65

10/1

/66

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/67

10/1

/68

10/1

/69

Flo

w,

cfs

Observed

Current Climate - Modeled

Green River Flow into Howard Hanson Reservoir

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

10/1/59 12/1/59 2/1/60 4/1/60 6/1/60 8/1/60 10/1/60

Flo

w,

cfs

Current Climate - Modeled

PCM 2020s

PCM 2040s

ECHAM 2020s

ECHAM 2040s

Annual Average Hydrograph Green River Flows intoHoward Hanson Reservoir

0

500

1000

1500

2000

2500

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep

Infl

ow

, cf

s

Current Climate

PCM 2020

PCM 2040

ECHAM 2020

ECHAM 2040

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

Planning and Management Analysis

• 2020 and 2040 forecasted demands• 2020 and 2040 climate change based stream

flows– PCM– ECHAM

• Status quo system configuration• Tacoma Seattle Intertie• Everett Seattle Intertie

Results• Compare

– minimum annual storage– number of shortfalls– duration of shortfalls

• Reliability– 43 year record – any shortfall is considered a failure– no demand modification

Annual Minimum Storage Combined Seatle ReservoirsPCM Climate Change Scenario

30000

35000

40000

45000

50000

55000

60000

1951 1956 1961 1966 1971 1976 1981 1986 1991

Acr

e-fe

et

Current Climate

2020

2040

Chester Morse Reservoir

Annual Minimum Storage Combined Seattle Reservoirs ECHAM Climate Change Scenario

30000

35000

40000

45000

50000

55000

60000

1951 1956 1961 1966 1971 1976 1981 1986 1991

Acr

e-fe

et

Current Climate

2020

2040

Chester Morse Reservoir

Annual Minimum Storage Seattle Combined Reservoirs2020 Demands

30000

35000

40000

45000

50000

55000

60000

1951 1956 1961 1966 1971 1976 1981 1986 1991

Acr

e-fe

et

Current Climate - Status Quo

PCM - Status Quo

PCM - Tacoma Seattle Intertie

Chester Morse Reservoir

Annual Minimum Storage Combined Seattle Reservoirs 2020 Demands

30000

35000

40000

45000

50000

55000

60000

1951 1956 1961 1966 1971 1976 1981 1986 1991

Acr

e-fe

et

Current Climate - Status Quo

ECHAM - Status Quo

ECHAM - Tacoma Seattle Intertie

Chester Morse Reservoir

Annual Minimum Storage Combined Seattle Reservoirs 2040 Demands

30000

35000

40000

45000

50000

55000

60000

1951 1956 1961 1966 1971 1976 1981 1986 1991

Acr

e-fe

et

Current Climate - Status Quo

PCM - Status Quo

PCM - Tacoma Seattle Intertie

Chester Morse Reservoir

Annual Minimum Storage Combined Seattle Reservoirs 2040 Demands

30000

35000

40000

45000

50000

55000

60000

1951 1956 1961 1966 1971 1976 1981 1986 1991

Acr

e-fe

etCurrent Climate - Status Quo

PCM - Status Quo

PCM - Tacoma Seattle Intertie

PCM - Tacoma Seattle Everett Intertie

Chester Morse Reservoir

Status Quo TS Intertie TS & ES Intertie

Comparison of Scenarios for year 2040 climate change and 2040 demands

0

50

100

150

200

250

300

Current ECHAM PCM Current ECHAM PCM Current PCM

Num

ber

of F

ailu

res

76% 23% 38% 83% 23% 40% 100% 95%Annual Reliability

Planning Implications

• Ongoing regional planning efforts are important

• TSI will provide only a portion of supply needed

• Climate change results imply regional needs for cooperation and new approaches

• Without new supply or dramatic changes in demand, system reliability will be unacceptable