Streams tab default menu settings.
Any number of rivers can be created inside a node tree GUI, with dedicated parameters for each of them.
There are three types of rivers available, categorized into ‘Main’ and ‘Secondary’ rivers from this drop-down menu: Main: Settle Spline, Main: Perlin Worm and Secondary: Simple Distribute.
Main rivers can be art directed, and offer an awful lot of control, while secondary rivers are generated on top of the main rivers (like twigs on a tree's branches), and offer only few parameters.
This approach lets you control the course of the river using a simple spline; the spline can be as detailed or simplistic as you choose.
Iteratively, the spline is resampled, and its points slide downhill, thus settling in valleys and ravines.
The original spline remains untouched and can be edited at any time.
The Main: Settle Spline stream type, with the original spline on the left.
This approach provides a simpler and more simulated workflow.