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AGNPS Watershed Modeling with GIS Databases

AGNPS Watershed Modeling with GIS Databases. Second Federal Interagency Hydrologic Modeling Conference. Las Vegas, NV 28 Jul - 1 Aug 2002. AGNPS Watershed Modeling with GIS Databases. Michael P. Finn E. Lynn Usery Douglas J. Scheidt Thomas Beard Sheila Ruhl Morgan Bearden

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AGNPS Watershed Modeling with GIS Databases

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  1. AGNPS Watershed Modeling with GIS Databases Second Federal Interagency Hydrologic Modeling Conference Las Vegas, NV 28 Jul - 1 Aug 2002

  2. AGNPS Watershed Modeling with GIS Databases Michael P. Finn E. Lynn Usery Douglas J. Scheidt Thomas Beard Sheila Ruhl Morgan Bearden U.S. Geological Survey Mid-Continent Mapping Center Rolla, MO

  3. Outline • Introduction • Study Areas • GIS Databases for Parameter Extraction • AGNPS Parameter Generation • Creating AGNPS Input, Output, and Images • Results

  4. Objectives • Use GIS databases as input to AGNPS Pollution Model • Demonstrate automatic extraction of input parameters • Create a tool for generating input, executing the model, and analyzing output

  5. Introduction • Agricultural NonPoint Source (AGNPS) Pollution Model – USDA lead agency • AGNPS operates on a cell basis and is a distributed parameter, event-based model • AGNPS requires 22 input parameters • Elevation, land cover, and soil data served as the base of extraction for the input

  6. Study Areas • Four Watersheds • Little River, GA • Piscola Creek, GA • Sugar Creek, IN • EL68D Wasteway, WA • Watershed Boundaries • NAWQA Boundary • GIS Weasel

  7. Georgia Watersheds

  8. Indiana Watershed

  9. Washington Watershed

  10. GIS Databases for Parameter Extraction • USGS 30-m DEMs • USGS 30-m National Land Characteristics Data • Augmented with recent Landsat TM data • Soil databases from USDA soil surveys • Scanned separates, rectified, vectorized, and tagged • Resampled the 30-m data to 60, 120, 210, 240, 480, 960, and 1920 meters • 210-m roughly matches 10 acre grid size

  11. AGNPS Parameter Generation • AGNPS Data Generator • Input parameter generation • Details on generation of parameters • Extraction methods

  12. AGNPS Data Generator • Created to provide interface between GIS software (Imagine) and AGNPS • Developed interface for Imagine 8.4, running on WinNT/ 2000

  13. AGNPS Data Generator

  14. Input Parameter Generation • 22 parameters; varying degrees of computational development • Simple, straightforward, complex

  15. Input Parameter Generation

  16. Details on Generation of Parameters • Cell Number • Receiving Cell Number • SCS Curve Number • Uses both soil and land cover to resolve curve number

  17. Details on Generation of Parameters (continued) • Slope Shape Factor

  18. Details on Generation of Parameters (continued) • Slope Length • A concern; max value should be 300 ft. • Parameters 10, 11, 12, 14, 15, 16, and 17 • Uses Spatial Modeler to look up attributes from soils or land cover • Example: p10 is Overland Manning’s Coefficient • Parameters 13, 18, 19, 20, and 21 • Hard coded on advice from experts • Example: p13 is Practice Factor (conservation) coded to 1 (worst case)

  19. Details on Generation of Parameters (continued) • Type of Channel • Uses TARDEM program • Creates a Strahler steam order

  20. Extraction Methods • Used object-oriented programming and macro languages • C/ C++ and EML • Manipulated the raster GIS databases with Imagine • Extracted parameters for each resolution for both boundaries using AGNPS Data Generator

  21. Creating AGNPS Input, Output, and Images • Input Data File Creation • Format generated parameters into AGNPS input file • Use a “stacked” image file to create AGNPS data file (“.dat”) -- ASCII

  22. Creating AGNPS Input, Output, and Images (continued) • Output Image Creation • AGNPS Creates a nonpoint source (“.nps”) file • ASCII File like the input; tabular/ numerical form

  23. Creating AGNPS Input, Output, and Images (continued)

  24. Creating AGNPS Input, Output, and Images (continued) • Output Image Creation (continued) • Combined “.nps” file with Parameter 1 to create multidimensional images • Users can graphically display AGNPS output • Process: create image with “n” layers, fill layers with AGNPS output data, set projection and stats for image • Multi-layered (bands) images per model event

  25. Creating AGNPS Input, Output, and Images (continued)

  26. Creating AGNPS Input, Output, and Images (continued)

  27. Creating AGNPS Input, Output, and Images (continued)

  28. Creating AGNPS Input, Output, and Images (continued)

  29. Results • Collaboration continues to quantify the impact of spatial resolution on model results • Demonstrated the use of GIS databases as sources in watershed modeling, particularly with AGNPS • Demonstrated methods of automatic extraction of AGNPS input parameters from GIS databases • Showed implications of results for 4 watersheds • Demonstrated the practicality of AGNPS Data Generator as an AGNPS – GIS interface

  30. AGNPS Watershed Modeling with GIS Databases Second Federal Interagency Hydrologic Modeling Conference Las Vegas, NV 28 Jul - 1 Aug 2002

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