WMS:Maricopa County Modeling

Tips and Locations for Downloading Hydrologic Data

GSDA Site

HEC-1 Modeling with Green and Ampt

1. Read your DEM into WMS (You can download DEMs from the USGS Seamless site).
2. Convert coordinates of the DEM when reading:
   1. Convert from: Horizontal system of Geographic NAD 83 and vertical system of NAVD 88, Meters.
   2. Convert to: State Plane NAD 83, Arizona Central Zone, horizontal and vertical units of US Survey feet, NAVD 88.
3. Read any image data you want to use into WMS.
4. Run Topaz (Drainage module)
5. Set your flow accumulation threshold (Display Options | select DEM Data option)
6. Create your outlet(s) (Drainage module tools)
7. Use the delineate basins wizard
8. Read your Land Use shapefile. You can download land use shapefiles from here. The file ending in "giras.exe" will be the file you want. The soils shapefile will be in the file ending in "core31.exe". You will need a HUC number for your watershed, which you can get by search for your watershed on this site.
9. If needed, convert the coordinates of your land use data to State plane coordinates as described for DEMs above.
10. Create a new Land Use coverage and make sure it's set as the active coverage.
11. Go to the GIS module, drag a box around your watershed, and select the Mapping | Shapes->Feature Objects command.
12. Make sure the land use ID is mapped to the correct field in your land use coverage. You can also map the land use name if needed.
13. Read your soils shapefile. The soil shapefile for Maricopa County can be downloaded with a bunch of other data in the FCDMC.zip file here. The "statsgo" (statewide, less accurate than "ssurgo" data) soil shapefile for any watershed in the US can be downloaded with the file ending in "core31.exe" from this location. "Ssurgo" data can be downloaded from the soil data mart here.
14. If needed, convert the coordinates of your soil data to State plane coordinates as described for DEMs above.
15. Create a new Soil Type coverage and make sure it's set as the active coverage.
16. Go to the GIS module, drag a box around your watershed, and select the Mapping | Shapes->Feature Objects command.
17. Make sure the soil type ID is mapped to the correct field in your soil type coverage. You can also map the soil type name if needed.
18. Define the necessary Green and Ampt parameters for each land use type in the land use coverage. You do this by viewing the attributes of the land use type polygons in the land use coverage and viewing the Green and Ampt parameters. Several sample tables exist that give these Green and Ampt parameters for different land use types. One table is called "landusemagtable.tbl" in the FCDMC.zip file you can download here.
19. Define the necessary Green and Ampt parameters for each soil type in the soil type coverage. You do this by viewing the attributes of the soil type polygons in the soil type coverage and viewing the Green and Ampt parameters. Several sample tables exist that give these Green and Ampt parameters for different soil types. One table is called "soilwmsgreenapmt.tbl" in the FCDMC.zip file you can download here.
20. Go to the Hydrologic modeling module and select Calculators | Compute GIS Attributes from the menu. Change the computation type to "Green-Ampt Parameters" and select OK to compute the Green Ampt parameters.
21. Make sure your current model is set to HEC-1 in the drop-down box at the top of the WMS window.
22. Select the HEC-1 | Job Control menu option.
23. Select Initialize Maricopa County Precipitation Data.
24. Select a rainfall grid (from the FCDMC.zip file you have downloaded) such as "noaa100y24h", which means 100-Year, 24-Hour precipitation.
25. Select the "Compute Precipitation" button and select OK. Select OK to close the HEC-1 Job Control Dialog.
26. Double-click on your basin and view your basin data and loss method data to make sure they are setup correctly. Select the "Unit Hydrograph Method" button in the Edit HEC-1 Parameters dialog.
27. Select the Clark method. Then select "Compute Tc and R - Maricopa County". Enter the appropriate parameters and select OK to compute the Tc and R values.
28. Define routing if desired.
29. Run HEC-1.

Download Maricopa County Tutorials Here

More information about the Maricopa County interface development is located here