Land Cover Change Effects on Streamflow in Puget Sound Drainage
description
Transcript of Land Cover Change Effects on Streamflow in Puget Sound Drainage
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?