GNAT

Generate Stream Branches

The Generate Stream Branches tool dissolves the line network based on GNIS name and stream order attributes, to create stream branches in the stream network polyline feature class. The resulting stream branches can then by used by the Segment Stream Network tool for splitting the stream network by the longest, continuous stretches of stream.

example

Usage

form

Input Parameters

Input Stream Network (with Stream Order)

Stream network polyline feature class with Stream Order Attributes (from stream order tool).

Input Stream Network Nodes (Optional)

Points representing nodes within the stream network. Ideally this should be the point shapefile output (i.e with the “_node.shp” suffix) from the Generate Network Attributes tool. Otherwise, the tool will dissolve all stream order segments that converge with the same stream order value.

Primary Stream Name Field (i.e. GNIS Name)

Attribute field with stream names (i.e. GNIS_Name). Not all stream reaches need to have a stream name - the tool will use stream order for segments without a stream name.

Stream Order Field (optional)

Attribute field that contains the stream order value for each linear stream feature.

Output Line Network with Branch ID

Network polyline feature class generated by the tool, with new attributed fields appended. Existing datasets will be overwritten.

Dissolve Output Network by BranchID? (optional)

  • Checked: The output stream network will contain all features dissolved by the BranchID. Feature attributes will be dropped due to the dissolve.

  • Unchecked: The output stream network will retain its original features and attributes, with the addition of the BranchID field.

Scratch Workspace (optional)

  • Can be a file geodatabase or folder, for saving temporary processing datasets.
  • If a workspace is not designated, the tool will use the “in_memory” workspace. Temporary files will not be accessible, but the tool’s processing speed will be improved.

Technical Background

Calculation Method

  1. Input polyline features are selected by GNIS_Name, then dissolved by GNIS_Name.
  2. The selection is switched, then dissolved by stream order, if present as an attribute
  3. Output datasets from 2 and 3 are merged.
  4. Split line at point, using the input junction points feature class

    This fixes the issue when two tributaries with the same stream order (and no GNIS) are dissolved together. Mainly occurs at the headwaters (i.e. stream order = 1).

  5. Add a unique ID field (BranchID) to identify each branch.
  6. The original input is intersected with the Branches feature class, if the output is not to be dissolved. Otherwise, the output is simply copied over from Branches.