land cover change and climate change effects on streamflow in puget sound basin, washington
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Land Cover Change and Climate Change Effects on Streamflow in Puget Sound Basin, Washington. Lan Cuo 1 , Dennis Lettenmaier 1 , Marina Alberti 2 , Jeffrey Richey 3 1 : Department of Civil and Environmental Engineering, University of Washington - PowerPoint PPT PresentationTRANSCRIPT
Land Cover Change and Climate Change Effects on Streamflow in Puget Sound Basin, Washington
Lan Cuo1, Dennis Lettenmaier1, Marina Alberti2, Jeffrey Richey3
1: Department of Civil and Environmental Engineering, University of Washington2: Department of Urban Design and Planning, University of Washington3: Department of Chemical Oceanography, University of Washington
February 21, 2007
University of Washington
• Background Early settlement started in the mid 1800s in the Puget
Sound Basin. Population has increased by 17 times since 1900. 70% of Washington state population lives in the Puget
Sound Basin. Land cover change is mainly caused by logging and
urbanization. Temperature is changing in the Puget Sound.
• Objectives How does land cover change affect streamflow in the Puget
Sound Basin? How does temperature change affect streamflow in the
Puget Sound Basin?
Methodology
• Study Area - Puget Sound Basin
• Area: 30,807 sqr.km
• Bounded by the Cascade and Olympic Mountains
• Maritime climate, annual precipitation 600 mm - 3000 mm, October – April
• Land cover: 82% vegetation 7% urban 11% other
Methodology• Generate forcing data and land cover maps for the
study area.• Calibrate hydrology model.• Study land cover change effects by removing the
long term trend in temperature. • Study climate change effects using temperature
regime detrended to 1915, temperature regime detrended to 2002, and historical temperature regime.
Methodology• Model: Distributed Hydrology Soil Vegetation Model
Interception Evapotranspiration Snow accumulation and melt Energy and radiation balance Saturation excess and
infiltration excess runoff Unsaturated soil water
movement Ground water recharge and
discharge
Forcing Data –Basin Averaged Historical Annual Precipitation
Eastern Puget Sound Basins
Forcing Data –Basin Averaged Historical Annual Precipitation
Western Puget Sound Basins
Forcing Data –Basin Averaged Historical Annual Tmin
Eastern Puget Sound Basins
Forcing Data –Basin Averaged Historical Annual Tmin
Western Puget Sound Basins
Forcing Data – Basin Averaged Historical Annual Tmax
Eastern Puget Sound Basins
Forcing Data – Basin Average Historical Annual Tmax
Western Puget Sound Basins
Data: 2002 Land Cover Map (Alberti et al., 2004)
Land Cover Types Proportion (%)
Dense urban (>75% impervious area)
2.41
Light-mediu urban (<75% impervious area)
3.97
Bare ground 0.42
Dry ground 1.30
Native grass 0.05
Grass/crop/shrub 5.36
Mixed/deciduous forest 32.19
Coniferous forest 36.41
Regrowth vegetation 0.61
Clear cuts 0.50
Snow/rock/ice 7.85
Wetlands 0.34
Shoreline 0.13
Water 8.46
Data: Reconstructed 1883 land cover
Land Cover Types Proportion (%)
Light-mediu urban (<75% impervious area)
0.40
Grass/crop/shrub 7.43
Mixed/deciduous forest 29.61
Coniferous forest 48.23
Snow/rock/ice 6.38
Water 7.96
Source: 1. Department of Interior, Density of
Forests-Washington Territory, 1883
2. Historical records of Puget Sound county population development
Results: Calibration
Results: Calibration
Results: Monthly Statistics of Calibrated and Measured Streamflow
Basin (gage) Observation Mean (cms)
Simulation Mean (cms)
Correlation Coefficient
RMSE (cms)
Model Efficiency
Cedar (12115000) 7.93 8.22 0.88 2.78 0.77
Deschutes (12078720) 0.97 0.99 0.89 0.41 0.80
Green (12104500) 12.03 12.42 0.86 4.96 0.67
Nisqually (12083000) 10.31 9.96 0.87 3.99 0.73
Puyallup (12094000) 12.12 12.36 0.78 4.33 0.54
Snohomish (12141300) 35.05 33.74 0.88 10.48 0.75
Stillaguamish (12161000) 32.48 32.91 0.81 11.74 0.58
Duckabush (12054000) 11.72 9.94 0.87 4.19 0.69
Quilcene (12052210) 4.34 4.03 0.81 2.17 0.64
Hamma Hamma (12054500)
10.40 10.27 0.82 3.91 0.65
Skokomish (12056500) 14.84 14.93 0.88 5.04 0.77
Results: Land Cover Change Effects: Seasonal Flow
Eastern Puget Sound Basins
Results: Land Cover Change Effects: Seasonal FlowWestern Puget Sound Basins
Results: Land Cover Change Effects: Seasonal Flow
Urbanization Affected Gages
71% urbanization
64% urbanization
31% urbanization
Results: Mean Annual StreamflowBasin (gage) 1883 Land Cover
(cms)2002 Land Cover
(cms)2002 vs. 1883Change (%)
Cedar (12115000) 6.66 7.06 6
Deschutes (12078720) 0.98 1.06 8
Green (12104500) 10.61 11.70 10
Nisqually (12083000) 10.26 11.58 13
Puyallup (12094000) 11.54 12.40 7
Snohomish (12141300) 29.46 31.85 8
Stillaguamish (12161000) 30.77 31.44 2
Quilcene (12052210) 2.29 2.75 20
Duckabush (12054000) 9.01 10.18 13
Hamma Hamma (12054500) 8.90 9.86 11
Skokomish (12056500) 13.24 14.87 12
Springbrook Creek (12113346) 0.27 0.33 22
Upper Mill Creek (12113349) 0.37 0.46 24
Results: Daily Peak Flow Eastern Puget Sound Basins
Results: Daily Peak FlowWestern Puget Sound Basins
Results: Daily Peak Flow
Urbanization Affected Gages
71% urbanization
64% urbanization
31% urbanization
Mann-Kendall Trend Analysis on Measurement and Model Residuals for Upland Gages
Gage Location Gage Start Period End Period Confidence level
Slope
Cedar river near Cedar falls
12115000 1945-10-1 2002-9-30 - 0.03
Duckabush river nearBrinnon
12054000 1938-7-1 2002-9-30 0.9 0.40
NF Skokomish atHoodsport
12056500 1925-10-1 2002-9-30 - 0.02
SF Skykomish at Index 12133000 1922-2-1 1982-9-30 - 0.14
SF Stillaguamish atGranite Falls
12161000 1928-8-1 1980-11-30 0.6 1.20
• No significant trend was found in monthly and annual streamflow at the above gages.• Although model simulation shows increase trend in AMDPF and annual streamflow for upland basins, the trend might not be statistically significant.
Annual Maximum Daily Peak Flow (AMDPF)
Climate Change Effects: Seasonal Flow
Eastern Puget Sound Basins
Climate Change Effects: Seasonal FlowWestern Puget Sound Basins
Climate Change Effects: Seasonal Flow
Urbanization Affected Gages
71% urbanization
64% urbanization
31% urbanization
Basin (gage) Detrended 1915 vs. Historical
Detrended 2002 vs. Historical
DJF JJA DJF JJA
Cedar (12115000) -25% 18% 33% -21%
Green (12104500) -10% 7% 10% -7%
Nisqually (12083000) -9% 14% 7% -9%
Puyallup (12094000) -8% 7% 9% -6%
Snohomish (12141300) -6% -3% 6% 3%
Stillaguamish (12161000) -10% 9% 10% -8%
Quilcene (12052210) -3% 11% 2% -7%
Duckabush (12054000) 1% -5% -1% 5%
Hamma Hamma (12054500) 2% -9% -2% 9%
Skokomish (12056500) 2% -15% -2% 14%
Deschutes (12078720) 0 -4% 0 4%
Springbrook Creek (12113346) -0.3% -0.5% 0.3% 1%
Upper Mill Creek (12113349) -0.2% -0.8% 0.4% 1%
DJF: winter months, JJA: summer months
Climate Change Effects: Daily Peak Flow
Eastern Puget Sound Basins
Climate Change Effects: Daily Peak FlowWestern Puget Sound Basins
Climate Change Effects: Daily Peak Flow
Urbanization Affected Gages
71% urbanization
64% urbanization
31% urbanization
Climate Change Effects: Mean Annual Flow Change
Basin (gage) Detrended 1915 vs. Historical
Detrended 2002 vs. Historical
Cedar (12115000) -3% 3%
Deschutes (12078720) -0.2% 0.2%
Green (12104500) -0.4% 0.5%
Nisqually (12083000) -0.9% 0.9%
Puyallup (12094000) -0.7% 0.7%
Snohomish (12141300) -0.7% 0.8%
Stillaguamish (12161000) -0.3% 0.3%
Quilcene (12052210) -0.2% 0.2%
Duckabush (12054000) -0.5% 0.5%
Hamma Hamma (12054500) -0.5% 0.4%
Skokomish (12056500) -0.7% 0.7%
Springbrook Creek (12113346) -0.4% 0.6%
Upper Mill Creek (12113349) -0.3% 0.5%
Mann-Kendall Trends of Raw Measurement: Combination of Climate Change Effects and Land Cover Change Effects
Gages Maximum Daily Peaks
Monthly Q Annual Q
Confidence level
Slope Confidence level
Slope Confidence level
Slope
12115000 - -0.06 0.95 -0.02 0.95 -0.03
12054000 0.60 0.27 - 0.003 - 0.01
12056500 0.90 0.52 0.90 0.02 0.80 0.02
12133000 - 0.89 0.80 0.10 - 0.06
12161000 0.60 1.17 0.60 0.04 0.60 0.06
For upland basins, land cover is not a dominant effect in changing streamflow.
Pacific Decadal Oscillation (PDO)
• Positive phase (+): warmer and dryer climate
• Negative phase (-): colder and wetter climate
• In upland basins, PDO perhaps play a more important role than land cover change effects.
Conclusions• In upland basins, fall, winter and spring streamflows are
higher under current land cover condition because of lower ET. Summer streamflow is lower in 2002 scenario because of less water storage in the basin.
• On average, mean annual streamflows are slightly higher under current land cover condition which might not be statistically significant.
• Peak flows are affected by the combination of ET and infiltration excess runoff. Peak flows tend to be higher under current land cover condition for most basins.
• Chances of getting peak flows are higher under current land cover condition.
Conclusions• Climate change mainly affects upland basins where snow
occurs. Temperature change mainly affects seasonal distribution of streamflow. Warmer temperature regime tends to generate higher winter flow but lower summer flow due to less snow occurrence, early snow melt and less basin snow storage.
• Simulation shows that land cover change might be more important than climate change in affecting the streamflow in lowland urbanizing basins.
• Trend study in upland gauged stations shows that land cover change is not the dominant factor that influences peak flows, monthly and annual flows in the upland basins.
• Regional climate system such as PDO perhaps plays a more important role in affecting streamflow in the upland basins.
Thank You !