Create Stream Raster

Running programmatically

Delineates streams from a Flow Accumulation raster by applying a Stream Initiation threshold.

Inputs:

• A Flow Accumulation raster dataset.
• Output raster name and format
• Stream Initiation Threshold - a double

Outputs:

• A raster representing the Stream Network.

Example:

An example of Create Stream Raster output. The first image shows the output at Threshold value of 1000 cells and the second at Threshold value of 100 cells.

Notes:

• The Stream Initiation Threshold represents the minimum contributing area (number of cells) required to initiate and maintain a Stream.
• The determination of the threshold value will depend on several factors including the type of the terrain, climate, soils and the DEM resolution.
• Reviewing existing data and maps for the area and experimentation with different values are helpful for the determination of the threshold value. Lower values will result in denser Stream Network.
• The Stream Network in the output raster is represented with the value of 1 on a background of NoData.
• If the input Flow Accumulation raster was created using the D8 method, the resulting Stream Network will be properly connected because a cell can only flow to one of its neighbors and the increase in the accumulation value is guaranteed.
< Class="b">If the input Flow Accumulation raster was created using the D-infinity method it is possible to obtain unconnected streams in the output due to flow divergence. To avoid this when creating a Flow Accumulation raster with the D-infinity model, please  use the optional Stream Initiation Threshold above which the accumulation will be determined using the D8 Flow Direction method. In this case a D8 Flow Direction raster is also required.
• See Hydrological functions for more information on the hydrological functionality.
• The input format accepted are file based rasters - ERDAS IMAGINE or Tagged Image File Format (TIFF).
• The .NET ToolBox for ArcGIS Desktop accepts also FileGDB Raster inputs.
• For file based rasters initially the name of the output raster define the raster format:
  • .img extension (for example raster1.img) - ERDAS IMAGINE image.
  • .tif extension (for example raster1.tif - image.
  • The initial output raster format can be changed by selecting the desired output in the dialog.

Running Programmatically

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Parameters

Running the function

ETSPath used in the table below is the full path to ETSRun.exe (E.G. "C:\Program Files\ETSpatial Techniques\ETSurface\ETSRun.exe")

Notes:

• <> - required parameter
• {} - optional parameter
• See examples for Python , .NET or ArcPy

• The argument separator for StartInfo.Arguments is space. If a string might contain a space, you need to double quote it.

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