Rivers look really good in Reforger, and the ability to sculpt the terrain to make rivers of varying width as well as deltas is superb. However, the data that describes the intersection between the terrain and the river entity to render it and to generate the flow maps currently do not reach Geometry2D export. As a result, an in-game map of a lush river-delta with varying widths and small islands affecting a single river-entity is not drawn on the map - only the entire width of the river-entity is.

The same problem affects lakes, but is at least avoidable with a well-placed spline. The river-issue, however, is not.