1 Guadalupe Watershed Model Year 2 update Presentation to SPLWG May 27, 2009 Michelle Lent, John Oram, Lester McKee Item #7.

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Guadalupe Watershed ModelYear 2 update

Presentation to SPLWG May 27, 2009

Michelle Lent, John Oram, Lester McKee

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• Basic Objective (revised): – To understand the source, release, and transport of

suspended sediment, Hg and PCBs from a large, mixed land use watershed to San Francisco Bay

• Timeline:– Year 1 (2008): Hydrologic model – Year 2 (2009): Sediment and contaminants model

• Details:– Establish model input and calibration parameters to

assist in developing other local watershed models– Improve accuracy of mercury and PCB load

calculations– Addresses

• STLS Q1 (Impairment), Q2 (loads), Q3 (Trends), Q4 (Support for management actions)

• Modeling Strategy Q3 (Small tributary loads)

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Re-cap of last time

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Model Overview & Set-up• Software & data sets used• Delineation & segmentation

Model Calibration/Validation• Split data into two sets (2000-05, 2006-07)

Summary of Model Performance• Captures general watershed hydrology & storm events• Needs improvement for

–Annual flow volume and base flow–Storm event peak flow and timing

Model Improvement Plan• Extend calibration period• Add urban irrigation• Revise imperviousness estimates • Re-evaluate meteorological and calibration segmentation

Suggestion from Workgroup• Shift to spatial calibration/validation split

-Calibrate upstream, validate downstream

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Canoas Creek

Guadalupe Creek

Los Gatos Creek

Revised calibration &

validation sites:

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Upper Guadalupe River

Ross Creek

Lower Guadalupe River

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Extended simulation

period

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Added urban irrigation

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Revised imperviousness estimates

Land Use Type % T.I.A. % E.I.A. Residential - rural/estate 5 - 20 1 - 10 Residential - low density 20 - 45 10 - 32 Residential - med. density 45 - 70 32 - 60 Residential - high density 65 - 95 54 - 92 Commercial 85 - 95 79 - 92 Industrial 70 - 95 60 - 92 Public/Quasi-public 80 - 95 72 - 92 Park 10 - 30 4 - 18 Open space 2 0 Forest 0 0 Water/Wetland 0 0

E.I.A. = 0.15*(T.I.A.)1.14

(Alley and Veenhuis, 1983)

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Adjusted meteorological segmentation

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Re-evaluated calibration parameters & model parameterization

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7 model segments

12 model segments

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Example result of model revisions

Ross Creek flow with Vasona & Alamitos precipitation

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Compare model versions - Annual flow volumes for Guadalupe River

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Water Year

Prec (in)

Obs. Flow Volume (106 cf)

Sim. Flow Volume (106 cf)

% Diff. from Obs. Flow Volume

Rating Sim. Flow Volume (106 cf)

% Diff. from Obs. Flow Volume

Rating

2003 17.6 2,148 2,042 -4.9%Very good

2,342 9.0%Very good

2004 13.2 1,874 1,442 -23.1% Fair 1,828 -2.5%Very good

2005 20.5 2,590 2,431 -6.6%Very good

3,040 17.4% Fair

2006 16.3 4,474 4,371 -2.3%Very good

5,040 12.7% Good

2007 7.2 1,260 870 -30.9% Poor 1,027 -18.5% Fair

Old version (v1) New version (v2)

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Compare model versions - Observed versus simulated daily flow for Guadalupe River

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Old version (v1): WY 2003-2007 New version (v2): WY 1995-2007

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Compare model versions - Hourly flow for Guadalupe River

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Sediment model development: Data needs for parameterization & calibration

• Target sediment loading rates

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Natural AgriculturalLow Density

UrbanHigh Density

UrbanIndustrial

72 2,461 450 996 1,836

Sediment production rates estimated for land use classes (tonnes/km2/yr)

D.R. = 0.418*Area-0.135 - 0.127

Apply sediment delivery ratio

“edge of stream” inputs

• Particle Size Distribution

Soil Texture map Soil Texture % clay/silt/sand

Particle size distribution map

Fractionation ratio

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Next time, calibrated SSC…

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Next Steps

• Calibrate sediment portion of model• Extend model to Hg and PCBs• Calibrate contaminant portion of model

Deliverable

Draft report by November SPLWG meeting

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