Alan F. HamletIngrid TohverSe-Yeun Lee

• JISAO/CSES Climate Impacts Group• Dept. of Civil and Environmental Engineering

University of Washington

Quantifying the Effects of Climate Variability and Change on Hydrologic Extremes in the Pacific Northwest Region of N. America

CBCCSP Research Team

Lara Whitely BinderPablo CarrascoJeff DeemsMarketa McGuire ElsnerAlan F. HamletCarrie LeeSe-Yeun LeeDennis P. LettenmaierJeremy LittellGuillaume MaugerNate MantuaEd MilesKristian MickelsonPhilip W. MoteRob NorheimErin RogersEric SalathéAmy SnoverIngrid TohverAndy Wood

http://www.hydro.washington.edu/2860/products/sites/r7climate/study_report/CBCCSP_chap1_intro_final.pdf

The Myth of Stationarity:

1) Climate Risks are stationary in time.

2) Observed streamflow records are the best estimate of future variability.

3) Systems and operational paradigms that are robust to past variability are robust to future variability.

Image Credit: National Snow and Ice Data Center, W. O. Field, B. F. Molniahttp://nsidc.org/data/glacier_photo/special_high_res.html

Aug, 13, 1941 Aug, 31, 2004

The Myth of Stationarity Meets the Death of Stationarity

Muir Glacier in Alaska

Why a Focus on Hydrologic Extremes?

Many human and natural systems are quite robust under “normal” conditions, but have the potential to be profoundly impacted by hydrologic extreme events.

Floods

http://www.nps.gov/mora/parknews/upload/floodPP.pdf

Drought

Evacuated Reservoir During the 2001 PNW Drought

Wildfire

Low Flow and Temperature Impacts to Fish

Temperature/ Disease Related Fish Kill in the Klamath River in 2002

Dissolved Gas Management

Tailrace below Bonneville Dam

Dam Safety

Aftermath of the Johnstown Flood 1889

Dilution Flows for Industrial Pollutants

Stormwater Management

Sediment Transport and Mudslides

Historical Perspectives:

Changing Flood Risk in the 20th Century

References:

Niemann, PJ, LJ Schick, FM Ralph, M Hughes, GA Wick, 2010: Flooding in Western Washington: The Connection to Atmospheric Rivers, J. of

Hydrometeorology, (in review)

Hamlet AF, Lettenmaier DP (2007) Effects of 20th century warming and climatevariability on flood risk in the western U.S. Water Resour Res,

43:W06427.doi:10.1029/2006WR005099

Observed Characteristics of Extreme Precipitation Events

Evidence of Changing Flood Statistics

Role of Atmospheric Rivers in Flooding (Nov 7, 2006)

Niemann, PJ, LJ Schick, FM Ralph, M Hughes, GA Wick, 2010: Flooding in Western Washington: The Connection to Atmospheric Rivers, J. of Hydrometeorology, (in review)

Niemann, PJ, LJ Schick, FM Ralph, M Hughes, GA Wick, 2010: Flooding in Western Washington: The Connection to Atmospheric Rivers, J. of Hydrometeorology, (in review)

Role of Atmospheric Rivers in Flooding (Oct 20, 2003)

Niemann, PJ, LJ Schick, FM Ralph, M Hughes, GA Wick, 2010: Flooding in Western Washington: The Connection to Atmospheric Rivers, J. of Hydrometeorology, (in review)

Modeling Studies of Changing 20th Century Flood Risk in the West

Snow Model

Schematic of VIC Hydrologic Model• Sophisticated, fully distributed,

physically based hydrologic model• Widely used globally in climate

change applications• 1/16 Degree Resolution

(~5km x 6km or ~ 3mi x 4mi)

General Model Schematic

Avg WY Date of Flooding VIC

Avg

WY

Dat

e o

f F

loo

din

g O

BS

Ln

(X

100

/ X

mea

n)

O

BS

Ln (X100 / Xmean) VIC

Evaluating the Hydrologic Model Simulations in the Context of Reproducing Flood Characteristics

Red = PNW, Blue = CA, Green = Colo, Black = GB

Zp

X1

00 G

EV

flo

od

/mea

n f

loo

dRed = VIC

Blue = OBS

5-yr

20-yr

10-yr

50-yr

100-yr

-1.00

-0.50

0.00

0.50

1.00

1.50

2.00

2.50

3.00

oct nov dec jan feb mar apr may jun jul aug sepL

inea

r T

ren

d (

Deg

. C p

er c

entu

ry)

CA

CRB

GBAS

PNW

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

oct nov dec jan feb mar apr may jun jul aug sep

Lin

ear

Tre

nd

(D

eg. C

per

cen

tury

)

CA

CRB

GBAS

PNWTmin

Tmax

PNW

CA

CRB

GB

Regionally Averaged Temperature Trends Over the Western U.S. 1916-2003

Tem

pera

ture

Historic temperature trend

in each calendar month

1915 2003

Detrended Temperature Driving Data for Flood Risk Experiments

“Pivot 2003” Data Set

“Pivot 1915” Data Set

X20 2003 / X20 1915

DJF

Avg

Tem

p (

C)

DJF

Avg

Tem

p (

C)

Simulated Changes in the 20-year Flood Associated with 20th Century Warming

X20 2003 / X20 1915 X20 2003 / X20 1915

Freezing Level

SnowSnow

Schematic of a Cool Climate Flood

Precipitation Produces Snow

Precipitation Produces Snow

Precipitation Produces Runoff

Snow Melt

Freezing Level

SnowSnow

Schematic of a Warm Climate Flood

Pre

cipi

tatio

n P

rodu

ces

Sno

w

Pre

cipi

tatio

n P

rodu

ces

Sno

w

Precipitation Produces Runoff

Snow Melt

-3

-2

-1

0

1

2

3

419

16

1920

1924

1928

1932

1936

1940

1944

1948

1952

1956

1960

1964

1968

1972

1976

1980

1984

1988

1992

1996

2000

Std

An

om

alie

s R

elat

ive

to 1

961-

1990

PNW

CA

CRB

GB

Regionally Averaged Cool Season Precipitation Anomalies

PRECIP

DJF

Avg

Tem

p (

C)

20-year Flood for “1973-2003” Compared to “1916-2003” for a Constant Late 20th Century Temperature Regime

X20 ’73-’03 / X20 ’16-’03

X20 ’73-’03 / X20 ’16-’03

Summary of Flooding Impacts

Rain Dominant Basins:Increases in flooding due to increased precipitation intensity, but no significant change from warming alone.

Mixed Rain and Snow Basins Along the Coast:Strong increases due to warming and increased precipitation intensity (both effects increase flood risk)

Inland Snowmelt Dominant Basins:Relatively small overall changes because effects of warming (decreased risks) and increased precipitation intensity (increased risks) are typically in the opposite directions.

Effects of ENSO and PDO on Flood Risk

DJF

Avg

Tem

p (

C)

DJF

Avg

Tem

p (

C)

DJF

Avg

Tem

p (

C)

X100 nENSO / X100 2003 X100 cENSO / X100 2003X100 wENSO / X100 2003

X100 nENSO / X100 2003 X100 cENSO / X100 2003X100 wENSO / X100 2003

DJF

Avg

Tem

p (

C)

DJF

Avg

Tem

p (

C)

DJF

Avg

Tem

p (

C)

X100 nPDO / X100 2003 X100 cPDO / X100 2003X100 wPDO / X100 2003

X100 nPDO / X100 2003 X100 cPDO / X100 2003X100 wPDO / X100 2003

Scenarios of Flood Risk in the 21th Century

Mote, P.W. and E. P. Salathe Jr., 2010: Future climate in the Pacific Northwest, Climatic Change, DOI: 10.1007/s10584-010-9848-z

21st Century Climate Impacts for the Pacific Northwest Region

Seasonal Precipitation Changes for the Pacific Northwest

Mote, P.W. and E. P. Salathe Jr., 2010: Future climate in the Pacific Northwest, Climatic Change, DOI: 10.1007/s10584-010-9848-z

http://www.hydro.washington.edu/2860/

• Smaller basins down to ~500 km2

• Monthly and daily streamflow time series

• Assessment of hydrologic extremes

(e.g. Q100 and 7Q10)

Columbia Basin Climate Change Scenarios Project

297 Sites

Available PNW Scenarios

2020s – mean 2010-2039; 2040s – mean 2030-2059; 2080s – mean 2070-2099

Downscaling ApproachA1B

Emissions Scenario

B1 Emissions Scenario

Hybrid Delta

hadcm cnrm_cm ccsm3 echam5 echo_g cgcm3.1_t47 pcm1 miroc_3.2 ipsl_cm4 hadgem1

2020s 10 9

2040s 10 9

2080s 10 9

Transient BCSD

hadcm cnrm_cm ccsm3 echam5 echo_g cgcm3.1_t47 pcm1

1950-2098+ 7 7

Delta Method

composite of 10

2020s 1 12040s 1 12080s 1 1

Hybrid Downscaling Method

• Performed for each VIC grid cell:

Hist. DailyTimeseries

Hist. MonthlyTimeseries

Historic Monthly CDF

Bias CorrectedFuture

Monthly CDF

Projected DailyTimeseries

1916-2006

1970-1999

30 yr window

1916-2006

1916-2006“Base Case”

Spatial Variability of Temperature and Precipitation Changes

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 290

10

20

30

40

50

60

70

80

90

100

hist

future

Dai

ly P

reci

pita

tion

(mm

)

Day of Month

Monthly to Daily Precipitation Scaling

SeaTac. Feb, 1996, hypothetical 30% Increase

Snow Model

Schematic of VIC Hydrologic Model• Sophisticated, fully distributed,

physically based hydrologic model• Widely used globally in climate

change applications• 1/16 Degree Resolution

(~5km x 6km or ~ 3mi x 4mi)

General Model Schematic

Watershed Classifications:Transformation From Snow to Rain

Map: Rob Norheim

Flood Analysis: What’s In? What’s Out?Issue Affecting Analysis Yes No

Based on explicit daily time step simulations of streamflow?

Yes

Changing freezing elevation?

Yes

Rain on snow captured? YesIncreases/decreases in storm intensity?

Yes (monthly statistics only)

Changes in tails of probability distributions affecting extreme daily precipitation ?

No

Changes in size and sequencing of storms?

No

Changes in small scale thunder storms?

No

Includes water management effects?

No

Low Flow Analysis: What’s In? What’s Out?Issue Affecting Analysis Yes No

Based on explicit daily time step simulations of streamflow?

Yes

Effects of changing snowmelt and soil moisture dynamics?

Yes

Effects of changing evaporation?

Yes, but some potential factors omitted (e.g. changes in cloudiness)

Changes in sequencing or duration of drought?

No

Includes shallow ground water?

No, but typically captures relevant affects to low flows anyway (well correlated)

Includes deep groundwater? No

Includes effects of glaciers? No

Includes water management effects?

No

Simulate Daily Time Step Streamflow Scenarios

Associated with Changesin Climate

Fit Probability Distributions To Estimate Flood and Low Flow

Risks

Compare FloodRisks to Those in the 20th Century

0.99

0.95

0.91

0.86

0.82

0.77

0.73

0.69

0.64

0.60

0.55

0.51

0.47

0.42

0.38

0.34

0.29

0.25

0.20

0.16

0.12

0.07

0.03

0

20000

40000

60000

80000

100000

120000

HIST

ECHAM5_2040

SNOMO

Str

eam

flow

(cf

s)

Probability of Exceedance

2040s Changes in Flood RiskSnohomish at Monroe

A1B B1

Historical

10 Member Ensemble Using the Hybrid Delta Downscaling Approach

A1B B1

2040s Changes in 7Q10Snohomish at Monroe

Historical10 Member Ensemble Using the Hybrid Delta Downscaling Approach

Chehalis at Grand Mound

Relationship Between Change in Q100 and Winter Temp

Changes in High Flows

Q100 values are projected to systematically increase in many

areas of the PNW due to increasing precipitation and

rising snowlines.

http://www.hydro.washington.edu/2860/products/sites/r7climate/study_report/CBCCSP_chap7_extremes_final.pdf

7Q10 values are projected to systematically decline in many areas due to loss of snowpack and projected dryer summers

Changes in Low Flows

http://www.hydro.washington.edu/2860/products/sites/r7climate/study_report/CBCCSP_chap7_extremes_final.pdf

Current and Future Research• Additional VIC calibration to improve simulations, and

comparison with DHSVM models (proposed)

• Estimate the effects of reservoir management using simulation models (in progress)

• Optimized flood control operations to rebalance complex multi-objective reservoir systems

• Incorporate more realistic effects to extreme precipitation from regional scale climate models (in progress)

• Incorporate the effects of sea level rise and high flows on inundation using hydrodynamic modeling (proposed)

Regional Climate Modeling at CIG WRF Model (NOAH LSM) 36 to 12 km

ECHAM5 forcing CCSM3 forcing (A1B and A2 scenarios)

HadRM 25 km HadCM3 forcing

Extreme Precipitation

Change from 1970-2000 to 2030-2060 in the percentage of total precipitation occurring when daily precipitation exceeds the 20th century 95th percentile

Salathé, E.P., L.R. Leung, Y. Qian, and Y. Zhang. 2010. Regional climate model projections for the State of Washington. Climatic Change 102(1-2): 51-75, doi: 10.1007/s10584-010-9849-y

Snohomish River Near Monroe, WA