Strahler stream order

Definition

The Strahler number of a mathematical tree is a numerical measure of its branching complexity. It is defined on nodes as follows:

• Leaves have a Strahler number of 1.
• For a nonleaf v:
  • If v has a child with Strahler number i and all other children have Strahler number less than i, then the Strahler number of v is i.
  • If v has two or more children with Strahler number i and there is no child with Strahler number greater than i, then the Strahler number of v is i + 1.

The definition can easily be extended to edges by defining the Strahler number of an edge to be the minimum of the Strahler numbers of its start and end nodes.

Example script and visualization

See an example beanshell script that you can test on a sample network named test_hydro.gdms. It is also helpful to visualize the results.