Stream Link

Assigns unique values to sections of a raster linear network between intersections.

Learn more about how Stream Link works

Usage tips

Command line and Scripting

The input stream raster can be created by "thresholding" the results of the Flow Accumulation function. Refer to the Flow Accumulation topic for an example.

The stream raster linear network should be represented as values greater than or equal to one on a background of NoData.

The output of the Stream Link tool is an integer raster.

The following environment settings affect this tool:
- General: Current Workspace, Scratch Workspace, Output Coordinate system, Output Extent, Snap Raster.
- Raster Analysis: Cell size.
- Raster Storage: See the Raster Storage settings for the particular output raster format selected.

Map Algebra

The <net_grid> can be created by "thresholding" the results of FlowAccumulation. Refer to the FlowAccumulation command reference for an example.

The raster linear network should be represented as values greater than or equal to one on a background of NoData.

Learn more about how to specify the input raster dataset in the Map Algebra expression of Raster Calculator.

ArcObjects

The streamRaster can be created by "thresholding" the results of FlowAccumulation. Refer to the FlowAccumulation command reference for an example.

The raster linear network should be represented with values greater than or equal to one on a background of NoData.

The output from the ArcObjects method is a raster object.

Syntax

StreamLink_sa (in_stream_raster, in_flow_direction_raster, out_raster)

Parameter	Explanation	Datatype
Input stream raster (Required)	An input raster that represents a linear stream network.	Composite Geodataset
Input flow direction raster (Required)	The input raster that records the direction of flow out of each cell. This is created with the Flow Direction function.	Composite Geodataset
Output raster (Required)	The output stream link raster.	Raster Dataset

Parameter

Explanation

Datatype

Input stream raster (Required)

An input raster that represents a linear stream network.

Composite Geodataset

Input flow direction raster (Required)

The input raster that records the direction of flow out of each cell.

This is created with the Flow Direction function.

Composite Geodataset

Output raster (Required)

The output stream link raster.

Raster Dataset

Data types for geoprocessing tool parameters

Script Example

# StreamLink_sample.py
# Description: Assigns unique values to sections of a raster linear network between intersections.
# Requirements: None
# Author: ESRI
# Date: Sept 6, 2005

# Import system modules
import arcgisscripting

# Create the Geoprocessor object
gp = arcgisscripting.create()

try:
    # Set local variables
    InStreamRaster = "C:/data/stream"
    InFlowDirectionRaster = "C:/data/flowdir"
    OutRaster = "C:/data/streamlink"

    # Check out Spatial Analyst extension license
    gp.CheckOutExtension("Spatial")

    # Process: StreamLink
    gp.StreamLink_sa(InStreamRaster, InFlowDirectionRaster, OutRaster)

except:
    # If an error occurred while running a tool, then print the messages.
    print gp.GetMessages()

Map Algebra syntax

StreamLink(<net_grid>, <dir_grid>)

Parameter	Explanation
<net_grid>	A raster representing a linear stream network.
<dir_grid>	A raster showing direction of flow out of each cell. This can be created using the FlowDirection function.

Map Algebra example

streamlink(channel_grid, flow_dir)
streamlink(channel_grid, flowdirection(elev))

ArcObjects syntax

IHydrologyOp::StreamLink (streamRaster As IGeoDataset, directionRaster As IGeoDataset) As IGeoDataset

Parameter	Explanation
streamRaster	An input Raster, RasterDataset, RasterBand, or RasterDescriptor representing a linear stream network.
directionRaster	An input Raster, RasterDataset, RasterBand, or RasterDescriptor showing the direction of flow out of each cell. This can be created using the IHydrologyOp::FlowDirection method.

ArcObjects example

' Create the RasterHydrologyOp object
Dim pHydrologyOp As IHydrologyOp
Set pHydrologyOp = New RasterHydrologyOp

' Declare the input stream raster object
Dim pInputStream As IGeoDataset

' Calls function to open a raster dataset from disk
Set pInputStream = OpenRasterDataset ("D:\SpatialData", "inputstream")

' Declare the input direction raster object
Dim pDirection As IGeoDataset

' Calls function to open a raster dataset from disk
Set pDirection = OpenRasterDataset ("D:\SpatialData", "direction")

' Declare the output raster object
Dim pOutputRaster As IGeoDataset

' Calls the method
Set pOutputRaster = pHydrologyOp.StreamLink (pInputStream, pDirection)