SJR DWSC DO Modeling HydroQual, Inc' Andy Thuman, P'E' Laurie De Rosa

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SJR DWSC DO ModelingHydroQual, Inc.Andy
Thuman, P.E.Laurie De Rosa
SJR Technical Working GroupMay 16, 2006
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SJR Models Study Area

• Downstream
• DSM2-delta
• ECOMSED/RCA
• Tidal portion from Vernalis to Jersey Island
• Upstream
• DSM2-sjr
• Free-flowing portion from Stevinson to Vernalis

Source Kratzer, et al. (2004) USGS WRI-03-4127
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Model Grid
R1
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Modeling Effort

• Models calibrated/validated from 2000-2001 on a
  continuous basis
• Hydrodynamic model includes tidal transport and
  calculation of temperature
• Water quality model uses tidal transport and
  includes the following parameters
• EC, BOD, DO, eutrophication (nutrients
  phytoplankton), TSS

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Model Calibration Period Flows
1923-2002

• USGS Vernalis Gage

Annual Average
2001
Summer Average (J-S)
Model Period
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DWSC Hydrodynamic Modeling

• Hydrodynamic model calibration
• Model output compared to observed stage, flow
  temperature
• Compares well with data and DSM2 output
• Reproduces daily temperature stratification
• Further work may be needed in the Turning Basin
  near Old River/Mossdale

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Temperature Calibration
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Temperature Calibration
2002 Data near R5
2001 Model near R5
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Flow Calibration
Increased Old River flow between Jun-Aug by 530
cfs
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DWSC Water Quality Modeling

• Water quality model calibration
• Model output compared to observed DO, BOD,
  nutrients, chl-a, TSS EC
• Focus on reproducing low DO events,
  stratification algal dynamics
• Includes a sediment flux submodel
• Post-processor to view output (HIMS)
• Including web-based viewer

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Light Extinction(Lehman, 2005)

• Ideally light data with depth
• Determine Ke using
• I Io e -KeH
• Actuality secchi depth data
• Determine Ke using
• Ke 1.8/secchi

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Light Extinction Relationship

• Used coupled secchi, TSS chla data to develop
  relationship (Di Toro, 1978)
• Ke 0.052NVSS 0.174VSS 0.031Chla
• VSS 0.2TSS (based on Vernalis data)
• Ke 0.0764TSS 0.031Chla
• Model calculates Ke as a function of modeled TSS
  and Chla

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Spatial Variation

• Secchi depth increases in DWC (lower chla TSS)
• Decreased Ke in DWSC vs upstream SJR

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Algal Stoichiometry

• Data from Vernalis
• Limited POC data in DWSC
• Redfield ratios
• C/N 5.7 (Data 3.1)
• C/P 41 (Data - 32)
• C/Chl Range 20-100
• Data 37, Lehman 40
• Used Redfield C/Chl40

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Other Model Inputs

• Solar radiation CIMIS Lodi West
• 100-700 ly/d, variations due to weather events
• Boundary Conditions
• Upstream based on Vernalis
• Downstream based on Jersey Potato Pt
• Internal sloughs based on river data
• Atmospheric Reaeration
• Based on wind speed formula (Banks, 1975 Banks
  Herrera, 1977)

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Hourly Wind Speed and KL at RR Island Source DWR
2000
2001
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Model Settling/Deposition

• Water column settling 2.5 m/d
• Deposition to sediment variable
• DWSC 0.25-0.5 m/d (higher in TB)
• SJR 0-0.05 m/d w/ adjustments to assist in TSS
  chla calibration
• Settling rates set based on calibration

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Model Parameters
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Stockton RWCF Effluent
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DWSC SOD Data Model Output(Litton, 2003)
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DO Chla Calibration
Vernalis (BC)
Mossdale
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R1
R2
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R3
R4
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R5
R6
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R7
R8
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Spatial DO Chla Transects(June-October Average)
2000
2001
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Spatial Nutrient Transects
2000
2001
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DO Deficit Components (R5)
Sink
Sink
Source
Sink
Ka Source SOD - Sink
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Summary

• DWSC WQ Model calibration completed final
  report issued (Task 4 May 2006)
• Provides finer temporal vertical resolution
  than previous modeling studies
• Stratification, diurnal variation, DO components
• Can be used to assess DO aeration device impacts
  (e.g., location, spreading, benefit)
• Links upstream downstream water quality for
  assessing management alternatives

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Recommendations

• Further testing of models to more recent DWSC
  data (hydro WQ)
• Different flow regimes, DO levels, etc.
• More detailed data/modeling of the Mossdale/Old
  River area of the SJR
• Algal growth between Vernalis Mossdale
• More information on carbon dynamics
• POC/DOC data, internal loads, DO effects

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Recommendations

• Investigate algal dynamics (2 species)
• Studies have shown different algal species
• Include more than 1 species in model with
  different algal growth dynamics
• May help Vernalis-Mossdale algal growth
• Use models in adaptive management approach
• Use models (as currently calibrated) to
  investigate potential controls while still
  collecting data completing modeling to improve
  the effective use of the DWSC model as a
  management tool

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Questions Answers
Contact info Andy Thuman Laurie De
Rosa HydroQual, Inc. Mahwah, NJ [phone]
x7184 athuman_at_hydroqual.com lderosa_at_hydroqual.com
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Light Extinction Comparison