Setting GWIS/ArcHydro Environment Variables (and other gotchas!)

The following instructions will help insure that:

1- GWIS/ArcHydro databases are constructed on the approved SWFWMD Coordinate System, and

2- GWIS/ArcHydro feature classes are constructed based on the SWFWMD 5’ Digital Elevation Model Gridcell.

Please follow these directions and CHECK each time you open anArcHydro .MXD to insure that the correct environment settings arebeing enforced.

GWIS/ArcHydro Tips and Hints

Setting GWIS/ArcHydro Environment Variables (and other gotchas!)

1- Using ArcCatalog, right-click the properties of the original DEM that youare using as your foundation. Its extents should be multiples offive (5) and it should be projected into State Plane Florida West, NAD1983/HARN feet.

Setting GWIS/ArcHydro Environment Variables (and other gotchas!)

If the Projection of the foundation DEM is not correct (i.e. Harn meters), then…

1- Re-extract the DEM from your ESRI Terrain making sure that the export parameters are set properly, or

2- Use the ArcGIS/Spatial Analyst to re-project your DEM to: Florida State Plane West (feet), NAD1983/HARN units (Toolbox > Data Management Tools > Projections and Transformations > Raster > Project Raster)

make certain the Environments…General Settings > Extent is set correctly

If the extents of the foundation DEM are not correct (i.e. not multiples of 5), then…

1- Re-extract the DEM from your ESRI Terrain making sure that the export parameters are set properly, or

2- Use the Spatial Analyst Raster Calculator to multiply your DEM by 1 make certain that the export parameters are set to multiples of 5 (Spatial Analyst > Options > Extent)

Setting GWIS/ArcHydro Environment Variables (and other gotchas!)

Helpful Hint: The ESRI default unit for the NADV88 Projection file is METERS; The District specification is US Feet. To change the default:

1- Using Windows Explorer (not ArcGIS), navigate to:

C:\Program Files\ArcGIS\Coordinate Systems\Vertical Coordinate Systems\North America

2- Copy the NAVD 1988.prj file to a filename of your choice (ex. NAVD88ft.prj). Youmay leave this copy in the same folder or place it in your “Favorites” folder.

3- Using any text editor (NotePad, TextPad, ConText, etc.) open the file and scroll overto the end of the file. Change/Edit:

UNIT[“Meter”,1.0] toUNIT[“Foot_US”,0.30400609601219]

and save the file.

4- Use this new .PRJ file when specifying the Z-Projection for GWIS-related databases.

5- Check to make sure that the file is being read correctly when you create a new feature class or shapefile.

Setting GWIS/ArcHydro Environment Variables (and other gotchas!)

2- When starting a new project, insert the (proper) DEM first. This should setthe Data Frame properties to the extent and projection of the foundation DEM,but, check the properties anyway!

Setting GWIS/ArcHydro Environment Variables (and other gotchas!)

3- The Data Frame Properties should be set to the proper Projection andunits. If not, re-make the DEM!

Setting GWIS/ArcHydro Environment Variables (and other gotchas!)

4a- Check the Tools > Options > Geoprocessing > Environment Settings

Setting GWIS/ArcHydro Environment Variables (and other gotchas!)

4b – In the “General Settings”, check the “Output Coordinate System (makesure it is as below) and if the “Extent” is set to Default, change it!

Setting GWIS/ArcHydro Environment Variables (and other gotchas!)

4c – Using the drop-down, change the “Extent” setting to the foundation DEM (checking that the values are multiples of 5!)

FoundationDEM

Setting GWIS/ArcHydro Environment Variables (and other gotchas!)

5a – Open ArcToolbox

Setting GWIS/ArcHydro Environment Variables (and other gotchas!)

5b – Right-click anywhere in the white-space of the toolbox window and openthe “Environments”

Setting GWIS/ArcHydro Environment Variables (and other gotchas!)

5c – Final check on the Output Coordinate System and Extent. Note: We also recommend setting the Scratch Workspace onto an independent disk drive (whenpossible)