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AGNPS Watershed Modeling with GIS Databases

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Second Federal Interagency Hydrologic Modeling Conference ... Thomas Beard. Sheila Ruhl. Morgan Bearden. U.S. Geological Survey. Mid-Continent Mapping Center ... – PowerPoint PPT presentation

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Title: AGNPS Watershed Modeling with GIS Databases


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 Mannings 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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