The Flow Distance tool calculates the horizontal or vertical downslope distance from each cell to the stream into which they flow.
The output is a hosted imagery layer.
Usage notes
Flow Distance includes configurations for input layers, analysis settings, and the result layer.
Input layers
The Input layers group includes the following parameters:
Input stream raster is a raster layer that represents a continuous stream network.
It is recommended that you create the Input stream raster layer using the same Input surface raster layer that is input to the tool.
The Input stream raster layer can be created from the Input surface raster layer using the Flow Direction, Flow Accumulation, and Con tools, respectively.
To use streams from other sources, for best results, add them to theInput surface raster layer first. Then run the Flow Direction tool on the result.
The Input surface raster is the elevation raster that will be used for calculation.
If the Input surface raster layer is void of sinks, the distance measurements are to stream cells represented by the Input stream raster value.
If the Input surface raster layer has sinks present, some flow paths may be terminated by flowing into sinks before reaching streams. In such cases, flow distance measurements for these cells are calculated only up to the sink cells into which they flow.
- The Optional layer group includes the Input flow direction raster parameter.
The Input flow direction raster parameter specifies the raster that shows the direction of flow out of each cell. The flow direction raster can be created using the Flow Direction tool with the D8, Multiple Flow Direction (MFD), or D-Infinity (DINF) method. Use the Flow direction type parameter to specify the method that was used when the flow direction raster was created.
It is recommended that you use the Input surface raster layer that is input to this tool to create the Input flow direction raster layer.
The Input flow direction raster parameter limits the directions along which flow distance is measured.
If no Input flow direction raster layer is specified, flow distance is assessed considering all possible downslope flow paths from each cell to the cells on the stream into which they flow.
Flow distance settings
The Flow distance settings group includes the following parameters:
- Distance type specifies whether the vertical or horizontal component of flow distance will be calculated.
- Vertical—The flow distance calculations represent the vertical component of flow distance, following the flow path, from each cell in the domain to the cells on the stream into which they flow. This is the default.
- Horizontal—The flow distance calculations represent the horizontal component of flow distance, following the flow path, from each cell in the domain to the cells on the stream into which they flow.
- The Flow direction type parameter specifies the type of flow method that will be used when computing flow direction. Specify the method (D8, MFD or DINF) that was used when creating the raster specified in the Input flow direction raster.
- Statistic type specifies the statistic type that will be used to compute flow distance over multiple flow paths. The options are as follows:
- Minimum—Where multiple flow paths exist, minimum flow distance will be computed. This is the default.
- Weighted mean—Where multiple flow paths exist, a weighted mean of flow distance will be computed. Flow proportion from a cell to its downstream neighboring cells are used as weights for computing weighted mean.
- Maximum—Where multiple flow paths exist, maximum flow distance will be computed.
Result layer
The Result layer group includes the following parameters:
- Output name specifies the name of the layer that is created and displayed. The name must be unique. If a layer with the same name already exists in your organization, the tool will fail and you will be prompted to use a different name.
- Save in folder specifies the name of a folder in My content where the result will be saved.
Environments
Analysis environment settings are additional parameters that affect a tool's results. You can access the tool's analysis environment settings from the Environment settings parameter group.
This tool honors the following analysis environments:
- Output coordinate system
- Processing extent
Note:
The default processing extent is Full extent. This default is different from Map Viewer Classic in which Use current map extent is enabled by default.
- Snap raster
- Cell size
- Mask
- Parallel processing factor
Output
The Output raster name layer stores the flow distance from each cell to the stream into which they flow.
Usage requirements
This tool requires the following user type and configurations:
Resources
Use the following resources to learn more:
- Flow Distance in ArcGIS REST API
- flow_distance in ArcGIS API for Python
- Flow Distance in ArcGIS Pro with the Raster Analysis extension
- Flow Distance in ArcGIS Pro with the Spatial Analyst extension