Watershed Monitoring and Watershed Monitoring and Modeling in Switzer, Chollas, Modeling in Switzer, Chollas, and Paleta Creek Watershedsand Paleta Creek Watersheds

Kenneth SchiffKenneth Schiff

Southern California Coastal Water Research ProjectSouthern California Coastal Water Research Project

www.sccwrp.orgwww.sccwrp.org

By The End Of TodayBy The End Of Today

• Review approach to sampling designs

• Basic agreements on most important elements- Opportunities for collaboration?

• Achieve sufficient detail for SCCWRP to write a workplan

Agreements From Our last MeetingAgreements From Our last Meeting

• Sediments at the mouth of several urban creeks draining to SD Bay are listed as impaired

- chemistry, toxicity, benthic community

• Two questions for the next phase- What are the loads of CPOCs to the creek mouth?

- How much of the total load deposits in the creek mouth?

• Several CPOCs- Chlordane, PAHs, PCBs, Cu, Pb, Zn,

- As, Hg

Road MapRoad Map

• Source question

• Fate and transport

• Prioritization

SourcesSources

• Chollas Creek watershed - Paleta and Switzer Creek watersheds

• Runoff directly to the Chollas Creek mouth- Navy, NASSCO

• Atmospheric deposition to the creek mouth- Deposition on the watershed and on the Bay

• San Diego Bay- tidal inputs

Watershed InputsWatershed Inputs

• Break into two parts

• Use combination of empirical data and wet weather modeling

- TSS, metals, PAHs

- Can we predict changes in loads and concentrations?

• Use empirical data- Chlorinated hydrocarbons

- Can we detect loads or concentrations?

Approach to Building a Approach to Building a Watershed ModelWatershed Model

• Physical data for the model domain- watershed delineation, stream properties, land use, etc.

• Calibrate flow and water quality at small homogeneous land uses

• Validate flow and water quality at the end of the watershed

- cumulative of all land uses

Data Collection Strategy for Data Collection Strategy for Wet WeatherWet Weather

• Physical data largely available

• Use previously collected data for land use information- requires certain assumptions

• Collect validation data at the end of each watershed- requires local data for validation

- Historical data is valuable

• Dynamic models necessitates dynamic water quality information

- requires multiple samples across the hydrograph

Modeled Land UsesModeled Land Uses

• High density residential

• Low density residential

• Industrial

• Commercial

• Agricultural

• Open

Sampling Design for Wet WeatherSampling Design for Wet Weather

• Four sites- North and South Fork Chollas, Switzer, Paleta

• Three storms each- continuous flow data

• Pollutograph for model validation - 10 to 12 samples per site event

- TSS, metals, and PAH

• Flow weighted composites for non-modeled components- large volume samples for low detection limits

Insert maps….

Direct Runoff To The Creek MouthDirect Runoff To The Creek Mouth

• Similar strategy for Navy and NASSCO as for Chollas Creek

• Combination of empirical data and wet weather modeling- Two choices for TSS, metals, PAHs

- Rely on existing monitoring data

- Collect additional data to support model

• Use empirical data- Can we detect any chlorinated hydrocarbons?

Sampling Design for Sampling Design for Atmospheric DepositionAtmospheric Deposition

• Focus will be deposition onto the water surface of creek mouth- Supplement with samplers in the watershed as an option

• One site as close to creek mouth as possible- Minimum of 12 sample events

• Use surrogate surfaces for metals- Supplement with atmospheric concentrations for confirmation

• Use high volume samplers for organics- Supplement with water samples for diffusion estimates

Sampling Design for Bay InputsSampling Design for Bay Inputs

• Two options

• Use existing data of bay water quality- Assume tidal forcing

• Collection of site specific data- Bay water quality at the boundary condition on incoming and

outgoing tides

- Supplement with velocity measurements if desired

Road MapRoad Map

• Source question

• Fate and transport

• Prioritization

Simple Elements of Simple Elements of An Estuary ModelAn Estuary Model

• Wet weather- Stormwater plume growth and dissipation

• Dry weather- Secondary mixing with tides and tugs

• Particle (and associated CPOCs) dynamics- Settling

- Diffusion

Approach To Building An Estuary Approach To Building An Estuary Model For Wet WeatherModel For Wet Weather

• Physical data- Geometry, bathymetry, substrate

• Calibration data- Hydrodynamic, particle, water quality, sediment quality data

• Validation data- Predict measured conditions based on calibration exercise

Data Collection Strategy for Data Collection Strategy for Physical ParametersPhysical Parameters

• Have creek mouth geometry

• Do we have bathymetry?

• Have substrate information

Data Collection Strategy for Data Collection Strategy for HydrodynamicsHydrodynamics

• Watershed and tidal forcing- Surface elevation

- Optional velocity information

• Stormwater plume dynamics- Horizontal and vertical profiles of salinity, temp, turbidity

• Calibration and validation data sets- Multiple storm events

Data Collection Strategy for Data Collection Strategy for Particle and Water QualityParticle and Water Quality

• Particles and water quality in the discharge- Particle size information

• Stormwater plume dynamics- Particle size and water quality

- Optional sediment traps

• Calibration and validation data sets- Multiple storm events

Special StudiesSpecial Studies

• Secondary mixing- Dye studies

- Tug resuspension

• Partition coefficients- Dissolved and particulate phases in water column and in sediments

- Acid volatile sulfides in sediments

• Other?

SummarizingSummarizing