Computes the Strahler order and/or Horton order of streams in a river network.

This recursive algorithm processes vector river networks for Strahler stream order values. The algorithm requires the vector network to be topologically correct to successfully process. The network must be a center-lined network where each arc (sometimes referred to as an edge) must be joined at their node (sometimes referred to as a junction). No left and right banks or lake side shores should be present.


The image below demonstrates a map representation of a river network, an invalid network where lake and river bank sides have been digitally captured and a valid, topologically correct, center-lined river network which the algorithm can process.

If the network is "broken" (arcs not connecting) then the output will be incorrect. The algorithm would treat the disconnected catchment as a separate river system, so it is important to check the connectivity of the river network before attempting to compute Strahler order values.


Input Ports

This transformer only takes linear features and one destination node per group.

Input Line features must be a topologically noded network with features connecting at line ends only. That is, all features must be split at junctions.

Output Ports


Editing Transformer Parameters

Using a set of menu options, transformer parameters can be assigned by referencing other elements in the workspace. More advanced functions, such as an advanced editor and an arithmetic editor, are also available in some transformers. To access a menu of these options, click beside the applicable parameter. For more information, see Transformer Parameter Menu Options.

Defining Values

There are several ways to define a value for use in a Transformer. The simplest is to simply type in a value or string, which can include functions of various types such as attribute references, math and string functions, and workspace parameters. There are a number of tools and shortcuts that can assist in constructing values, generally available from the drop-down context menu adjacent to the value field.

Dialog Options - Tables

Transformers with table-style parameters have additional tools for populating and manipulating values.


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Keywords: Strahler Horton