Hristo Velev shows how to get wider volume whitewater by mixing smoke and FLIP velocities.

Houdini is a fantastic VFX tool that has a wide array of solvers for any physical effects. Water effects like oceans, rivers, and waterfalls rivers are not a problem for the procedural 3D app. Houdini also has some tools for creating the things that go along with running water, like foam and whitewater.

Check out this tutorial from Hristo Velev who shows how to get a quick set up for mixing FLIP and smoke velocities so that you can get a full volume for whitewater effects. Hristo shows the technique using a waterfall sim, of which he makes the project file available for download too.