ETG_FlowAccumulationDinf

Flow Accumulation D-infinity

Generates a Flow Accumulation raster using the D-infinity algorithm (Tarboton, 1997).

Inputs:

A D-infinity Flow Direction raster dataset.
Stream Initiation Threshold value (optional)
A D8 Flow Direction raster dataset (optional)
Output raster name and format

Outputs:

A Floating raster representing the Flow Direction according to the D-infinity (Deterministic Infinity) method.

Example:

An example of Flow Accumulation D-infinity result (above) and Flow Accumulation D8 (below).
Note the dispersion of flow in the D-infinity result compared with the concentrated flow in D8.

Notes:

The value for each cell in the Flow Accumulation raster is the total number of cells which flow into it including the cell itself. So for a cell with no inflowing cells the value will be 1.
The D-infinity flow algorithm allows flow divergence. This means that the value accumulated in a cell can be directed to one or two neighboring cells depending on the flow direction angle. This is a better representation of flow on divergent slopes.
By applying a Threshold value to the Flow Accumulation raster we can determine the cells which form a Stream network. All cells with Flow Accumulation value above the threshold are considered to be part of a stream.
The flow direction after Stream Initiation is better represented by the D8 single flow algorithm. The function allows for the specification of a Stream Initiation Threshold value and the relevant D8 Flow Direction raster to be used after the threshold accumulation value is reached.
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

(Go to TOP)

Parameters

Expression	Explanation
Function Name	FlowAccumulationDinf
<input raster>	A String representing the input DEM raster dataset.
<output raster>	A String - the full name of the output raster.
{Stream Initiation Threshold}	A Double representing the Threshold value.
{Input D8 Flow Direction Raster}	D8 Flow Direction raster layer or raster dataset.

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")

UnitsDegrees

Language	Syntax
Python	subprocess.call([ETSPath, "FlowAccumulationDinf", "input raster", "output raster", "Stream Initiation Threshold", "Input D8 Flow Direction Raster"])
.NET using ETSRun.exe	StartInfo.FileName = ETSPath StartInfo.Arguments = "FlowAccumulationDinf" "input raster" "output raster" "Stream Initiation Threshold" "Input D8 Flow Direction Raster"
.NET using ETSOutX.dll	FlowAccumulationDinf(input raster, output raster, Stream Initiation Threshold, Input D8 Flow Direction Raster)
ArcPy	arcpy.FlowAccumulationDinf("input raster", "output raster", "Stream Initiation Threshold", "Input D8 Flow Direction Raster")

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.

(Go to TOP)

Reference:

Tarboton, D. G., (1997),"A New Method for the Determination of Flow Directions and Contributing Areas in Grid Digital Elevation Models", Water Resources Research, 33(2): 309-319