Patapsco and Back River HSPF Watershed Model

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Patapsco and Back River HSPF Watershed Model

• Part II Water Quality
• Maryland Department of the Environment

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Introduction

• Water Quality Data
• Model Inputs
• Calibration Procedure
• Model Comparisons
• Summary

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Water Quality Data

• Data Sources
• Department of Natural Resources
• Monthly values for NH3, NO3, TN, PO4, TP, TOC,
  DO, TSS, Temperature
• Baltimore City
• Storm event and base flow values for TSS, TOC,
  TN and TP
• City of Baltimore Comprehensive Wastewater
  Facilities Master Planning Project

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Model Inputs

• Atmospheric Deposition
• Septic Loads
• Point Sources
• Manure and Application

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Atmospheric Deposition

• Deposition is input as NO3 (wet and dry) and NH3
• Used CBP time series
• Avg. Annual NO3 7.05 lb/acre
• Avg. Annual NH3 2.08 lb/acre

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Septic Loads

• Number of septic users were calculated on County
  basis using Census data compiled by EPA.
• Used GIS to allocate to watershed segmentation
• Assume NO3 loading coefficient of 0.0256
  lb/person/day.
• Assume 60 reduction in NO3
• Assume 100 retention of Phosphorus

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Manure and Application

• Animal Counts Used to calculate Manure Acres
  which is simulated as an impervious land use
• Manure acres is a derived land use which
  represents what is susceptible to runoff from
  confined animals within a model segment.

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Manure/Mineral Fertilizer Application

• Manure Calculations (based on MDA and U of MD
  recommendations)

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Calibration Procedure

• Focus on predominant land uses
• Calibrate EOS loads to literature values
• Calibrate urban loads to Event Mean
  Concentrations (EMCs)
• Time series overlay

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Unit Loading Rates (Literature Values)
Literature Sources Jones Falls Water Quality
Management Plan, Loch Raven Water Quality
Management Plan, Baltimore County NPDES 2000,
Harford County NPDES 1999 and 2000, City of
Baltimore NPDES 1999, Center for Watershed
Protection and Ken Staver (University of MD).
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Patapsco/Back Estimated Average Annual Loads and
Percent Contributions
Load Loading Rate x Area
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Estimated and Final Model EOS Loads
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Urban EMCs
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Jones Falls Water Quality Calibration

• Calibration at Station JON0184
• Parameters calibrated
• DO, Temperature, TOC, TSS, PO4, TP, NH3, NO3,
  ChlA and TN

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Patapsco (Hollofield) Branch Water Quality
Calibration

• Calibration at Station PAT0285
• Parameters calibrated
• DO, Temperature, TOC, TSS, PO4, TP, NH3, NO3,
  ChlA and TN

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Summary/Comparisons

• Unit loads, EOS and Delivered loads compared to
  existing studies
• Discussion of model loads and comparison

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Comparison of Unit Loading Rates
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Total Average Annual EOS Loads Summary
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Total Delivered Loads Summary
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Back River Comparisons
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Comparison of CBP and MDE Model

• Model Scale
• Hydrology Calibration
• Water Quality Calibration
• Urban Calibration

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CBP Segmentation
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MDE Segmentation
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Hydrology Calibration
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Water Quality Calibration
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Urban Calibration

• NPDES Storm Water Data vs. National Urban Runoff
  Program (NURP) Data
• CBP reductions to Urban Loads
• - Reductions to Urban Loads of 15 TN and 30
  TP
• Based on numbers from Urban Watershed Group

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Summary

• MDE hydrology calibrated to 3 gages. CBP model
  hydrology calibrated to 1 gage.
• MDE water quality calibrated to 4 gages. CBP
  model water quality calibrated to 1 gage.
• MDE urban land use calibrated to local NPDES
  data. CBP calibrated to NURP data.
• It can be concluded that the final load
  differences between the MDE and CBP models are
  due to these factors.