Let's start with the lake we did in an earlier lesson and add a river to it.
The simplest way to add a river is to just draw a line and use the linestyle to make it fat.You can use any type of line or a combination of them depening on what you want. In this example I've used a Fractal Line.
But to make it look alright we put the river behind the lake using the Send Backwards function.
This doesn't look that bad. The problem with this easy way to draw rivers is that the river will retain the same width regardless of zoom level so it can cause problems.The same technique can also be used to make roads.