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14b - HSPF Water Quality Model Development

14b - HSPF Water Quality Model Development. Virginia Tech Biological Systems Engineering Department 2013 DEQ TMDL Workshop. HSPF Water Quality Model Development. Calibration/Validation WQ stations – Select stations that represent critical conditions and seasonal variability

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14b - HSPF Water Quality Model Development

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  1. 14b - HSPF Water Quality Model Development Virginia Tech Biological Systems Engineering Department 2013 DEQ TMDL Workshop

  2. HSPF Water Quality Model Development • Calibration/Validation WQ stations – Select stations that represent critical conditions and seasonal variability • UCI Modification – Incorporate information into the UCI needed to simulate water quality • Water Quality Model Calibration & Validation – Discuss the essential steps in HSPF water quality model development • Diagnostic Model Runs and Contingencies – Describe the model runs used to verify that the model output is responding appropriately to model input

  3. Calibration/Validation WQ Stations Water Quality Stations • Select stations with numerous data • Several years • All seasons • Calibration & Validation

  4. Calibration/Validation WQ Stations • Spatial Considerations • Listing Stations • Other Stations

  5. Modifying the UCI for Bacteria Sources Pervious Land Segments Impervious Land Segments Reaches WSQOP = rate of runoff that will wash off 90% of quality constituent FSTDEC= in-stream first order decay rate

  6. Modifying the UCI for Bacteria Sources • Incorporate the information from the BSLC – Land Loads

  7. Modifying the UCI for Bacteria Sources • Incorporate the information from the BSLC – Direct Deposit to Stream • FILES Block • MUTSIN Block • NETWORK Block

  8. Modifying the UCI for Bacteria Sources • Incorporate any permitted sources (e.g. VPDES) • EXT SOURCES Block

  9. Water Quality Calibration Using HSPF • General Concepts • Output Management • Using the BSE Calibration Workbook • Calibrating the Model

  10. Water Quality Calibration – General Concepts • Considerations • Model should respond as expected • Calibration Period • Target bacteria • Matching Data • Point valued observed data • Mean valued simulated data • What to change in the UCI? • FSTDEC • WSQOP

  11. WQ Calibration - Output Management • Set up GENER for E. coli translator EC=(FC0.91905)×0.98814866 • GENER Block • NETWORK Block

  12. WQ Calibration – The BSE Calibration Workbook Consider more than just the basic plots Point valued vs. mean valued Five-day window concept Five-day range of values surrounding each observed point

  13. Five-day WQ Calibration Window

  14. WQ Calibration: Calibrating the Model • What to change in the UCI? • FSTDEC • WSQOP . . . And if that doesn’t work? • Initial Estimates • Better describe the watershed conditions ?

  15. Diagnostic Runs • Early runs to provide insight regarding model performance • Discover issues early and make adjustments if conditions on the ground warrant it • Examples: • Baseflow/interflow violations of WQS? • Wildlife only violations of WQS? • Extreme peaks followed by deep troughs? • In-stream contributions agree with BSLC?

  16. Contingencies • Adjustments to FTABLE(s) – stagnation • Stage cutoff • Revising BSLC based on Land Use or other factors 

  17. HSPF Exercise • Open file HSPF_Exercise.uci • Using the MON-ACCUM block, identify the daily rate of bacteria accumulation in June for PLS 109 (Forest Land Use in Subwatershed 2). • Using the GQ-GENDECAY block, identify the first order decay rate in the stream reaches being modeled. • How many VPDES-permitted facilities are being modeled in Old Womans Creek?

  18. HSPF Exercise Answers • Open file HSPF_Exercise.uci • Using the MON-ACCUM block, identify the daily rate of bacteria accumulation in June for PLS 109 (Forest Land Use in Subwatershed 2). 97E06 cfu/ac-day • Using the GQ-GENDECAY block, identify the first order decay rate in the stream reaches being modeled. 1.15 • How many VPDES-permitted facilities are being modeled in Old Womans Creek? None

  19. Questions/Comments

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