Water Quality Modeling in GIS

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Water Quality Modeling in GIS

• Application of Schematic Network Processing
• Schema Links and Nodes have unique behaviors
  based on their type
• A framework for unifying watershed, stream, and
  estuary models

2
Two Case Studies

• Galveston Bay Bacteria Study
• Application of Model Builder (Arc Toolbox 9.0)
• Guadalupe River Nitrogen Study
• Application of SPARROW for load estimation

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Galveston Bay
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Model Builder
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Rainfall to Runoff
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Rainfall to Runoff (1 of 2)
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Rainfall to Runoff (2 of 2)
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EMC Grid
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Load Grid
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Zonal Statistics
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Process the Schematic Network
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Results
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SPARROW

• Regional-scale statistical water-quality model
• Developed by USGS
• Estimates load of pollutant for each sub
  watershed within a monitored basin using SAS
• Has been applied to continental US, Mississippi
  Basin, and Northeastern US

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414 National Stream Quality Accounting Network
(NASQAN) Stream Monitoring Locations
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The Guadalupe River at Victoria Texas Basin
Red represents along stream flow
Green represents land to channel flow
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Schematic Network Processing Algorithm
Upstream Load 50 kg/yr
Land Surface Load 100 kg/yr
Load 50 x dchannel 100 x dsurface
dchannel decay due to travel along river
channel transport dsurface decay due to land
surface to river channel transport
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Nitrogen Load Predictions
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Comparison with SPARROW Published Results
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Future Direction Improve Data Resolution
1500,000
124,000