Land Cover Change Effects on Streamflow in Puget Sound

Drainage

Lan Cuo Dennis Lettenmaier

Marina Alberti

November 8 2006

• Objective Land cover change effects: 120 year ago

and current

• Methodology

• Results

• Conclusion

Methodology• Generate forcing data and land cover maps

for study area.• Calibrate model in pilot basins.• Validate model in pilot basins.• Apply the calibrated model to other basins,

calibrate again if necessary.• Remove the long term trend in temperature.

(Hamleaf ?)• Study land cover change effects on

streamflow.

Methodology• Study Area Puget Sound Drainage• Bounded by the Cascade and Olympic Mountains• 41,439 sqr.km• Temperate rainforest

ecosystemSubalpine forest, and Alpine Medows

• mollisol-ultisol-alfisolInceptisol-mollisol-spodosalinceptisol-mollisol-histosol

http://wa.water.usgs.gov/projects/pugt/images/studymap.gif

Population in 1900

0

20000

40000

60000

80000

100000

120000

City/T

own

Islan

d Cou

nty

Jeffe

rson

Cou

nty

King C

ounty

Kitsap

Cou

nty

Mas

on C

ounty

Pierce

Cou

nty

San Ju

an C

ount

y

Skagit

Cou

nty

Snoho

mish C

ount

y

Thurs

ton C

ount

y

Wha

tcom C

ount

y

Methodology

• Population

Population in 2000

0

200000

400000

600000

800000

1000000

1200000

1400000

1600000

1800000

City/T

own

Islan

d Cou

nty

Jeffe

rson

Cou

nty

King C

ounty

Kitsap

Cou

nty

Mas

on C

ounty

Pierce

Cou

nty

San Ju

an C

ounty

Skagit C

ount

y

Snoho

mish

Cou

nty

Thurs

ton

County

Whatc

om C

ounty

King county had almost 18 times more population in 2000 than 1900.

Puget Sound Upland Basins (13)

Cedar basin Green basinSpring Brook Creek basin

Methodology

Methodology• Model Structure

DHSVM Components

Interception Evapotranspiration

Energy and radiation balance

Unsaturated soil water movement

Saturation excess and infiltration excess runoff

Ground water recharge and discharge

Snow accumulation & melt

Methodology• Forcing Data 1-16th degree grid Tmin, Tmax, precipitation

and wind speed. Used 25 stations from 1927 to 2003

Precipitation rescaled using 30 arcsec PRISM product(Daly, 1994)

Gridded and station annual and seasonal precipitation (mm)

Mcmillin

Kent

Everet

Darrington

Cedar

Annual and seasonal precipitation (mm)

Quilcene

Olympia

Cushman

Centralia

Bremerton

High elevation stations:

Stampede

Paradise

2002 Land Cover Map in Puget Sound (Marina, 2004)

Land Cover Types percent

Dense urban (>75% impervious area)

1.20

Light-mediu urban (<75% impervious area)

2.23

Bare ground 0.70

Dry ground 1.03

Native grass 0.02

Grass/crop/shrub 7.36

Mixed/deciduous forest 30.04

Coniferous forest 32.78

Regrowth vegetation 0.48

Clear cuts 0.70

Snow/rock/ice 6.77

Wetlands 0.28

Shoreline 0.09

Water 16.32

Reconstructed 1883 land cover Land Cover Types 1883

Light-mediu urban (<75% impervious area)

0.22

Grass/crop/shrub 7.52

Mixed/deciduous forest 29.36

Coniferous forest 51.74

Snow/rock/ice 5.40

Water 5.75

Sourc: Department of Interior, Density of Forests-Washington Territory, 1883

Methodology• Pilot Study Areas

• Upland

Cedar Basin

1883 Land Cover

2002 Land Cover

Methodology• Pilot Study Areas• Lowland Urban basins

Mill Creek

Spring Brook Creek

Results: Calibration in Cedar Basin

Daily Statistics

12115000 12115500 12117000

Obs. Mean 7.92 2.96 2.92

Sim. Mean 8.55 2.35 3.12

RMSE 4.16 1.91 1.34

ME 0.75 0.35 0.73

Results: Validation in Cedar Basin

Daily Statistics

12115000 12115500 12117000

Obs. Mean 6.91 2.69 2.65

Sim. Mean 7.58 2.03 2.91

RMSE 4.89 2.55 1.55

ME 0.66 -0.14 0.66

Results: Green River Basin, Deschutes River Basin and Hammahamma River Basin

Daily Statistics

12104500 12072800 12054500

Obs. Mean 12.01 0.96 10.39

Sim. Mean 13.70 0.94 10.39

RMSE 9.43 0.52 5.74

ME 0.57 0.76 0.60

Results: Using gridded precipitation to calibrate model in urban basins

Mill Creek basin area 14.6 sq.kmSpring Brook Creek basin 21.9 sq.km

Daily Statistics 12113346 12113349

Obs. Mean 0.32 0.47

Sim. Mean 0.26 0.45

RMSE 0.26 0.34

ME 0.49 0.40

Results: urban basin simulation using Seatac station hourly precipitation

12113346

Results: land cover change effects on streamflow Cedar basin gage 12115000

Difference in Seasonal Q between 2002 and 1883

-0.2

0

0.2

0.4

0.6

0.8

1

10 11 12 1 2 3 4 5 6 7 8 9

Months

Q (

cms)

Daily Peaks (cms)

Difference in Seasonal Q between 2002 and 1883

-0.5

0

0.5

1

1.5

2

2.5

3

10 11 12 1 2 3 4 5 6 7 8 9

Months

Q (

cms)

Daily Peaks (cms)Results: Green basin Gage 12104500

Difference in Seasonal Q between 2002 and 1883

-0.04

0

0.04

0.08

0.12

0.16

10 11 12 1 2 3 4 5 6 7 8 9

Months

Q (

cms)

Daily Peaks (cms)

Results: Urban Basin Gage 12113346

Gages Land cover 1883 Land cover 2002

12104500 10.00 11.02

12113346 0.20 0.23

12115000 7.62 7.98

Mean Daily Q (cms)

Days having peaks

Gages Land cover 1883 Land cover 2002

12104500 4213 4251

12113346 1695 4189

12115000 3794 4251

Mean Monthly Q (cms)

Gages Land cover 1883 Land cover 2002

12104500 10.04 11.05

12113346 0.20 0.23

12115000 7.64 8.00

Conclusion

• Mean daily and mean monthly streamflow flow are higher under current land cover condition

• Chances of getting peak flow are higher under current land cover condition

• In upland basins, fall, winter and spring streamflow increases under current land cover condition

Thanks!

Questions?