ETG_Watershed

Watershed

Delineates Watersheds (Drainage basins) from a D8 Flow Direction raster for a set of Outlet points.

Input raster dataset
Output raster name and format
An optional Outlet Point Feature layer.
A Field in the Outlet feature layer with integer IDs to be assigned to Watersheds.

A Watershed Raster representing the contributing areas for each outlet (integer raster).

An example of Watershed output using Outlet points.

Watersheds are delineated from the D8 Flow Direction raster. An optional Outlets feature class can be specified as input. In this case Watersheds are delineated for the Outlet points. An ID is assigned to each Watershed from a field in the Outlets feature class.
If no Outlet points are specified, all Outlets for the DEM are determined (the points at which flow leaves the DEM) and Watersheds are delineated for them. In this case the Watersheds are assigned unique generated values starting from 1.
If Outlet points are specified it is recommended to ensure that they are within cells with sufficient flow to delineate a reasonable Watershed. Otherwise it is possible only a few cells (or even just one) to be delineated.
The Snap Pour Points function can be used to move the Outlet points to cells with higher flow within a specified distance based on the values of a reference raster.
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.

Parameters

Expression	Explanation
Function Name	Watershed
<input raster>	A String representing the input D8 Flow Direction Raster.
<output raster>	A String - the full name of the output raster.
{OutletPoints}	A String - the full path to a point layer with the Outlet points.
{OutletIDField}	A String - the name of an Integer Field in the Outlet Point layer with values to be assigned to the delineated Watersheds.

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

OutletPoints

Language	Syntax
Python	subprocess.call([ETSPath, "Watershed", "input raster", "output raster", "OutletPoints", "OutletIDField"])
.NET using ETSRun.exe	StartInfo.FileName = ETSPath StartInfo.Arguments = "Watershed" "input raster" "output raster" "OutletPoints" "OutletIDField"
.NET using ETSOutX.dll	Watershed(input raster, output raster, OutletPoints, OutletIDField)
ArcPy	arcpy.Watershed("input raster", "output raster", "OutletPoints", "OutletIDField")

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.