Paint Rivers

When the Paint Rivers box is selected, dragging your mouse over the map will paint a path for your river. This can be done on, and will show up on, the Terrain, Biome, Topography, and Height maps.

Since the river path will show up on all the above maps, you can compare each to better gauge how it will appear in the game before clicking the Generate Rivers button.

You can paint more than one river at a time, but when doing so, they will all use the same parameters for depth, width, and slope. Or you can do them separately to change the appearence of each.