Your work is magnificent, but the rivers aren't working for me. Don't get me wrong, as I'm a new nobody here, but the non-forested rivers are very hard to see and the forested ones still seem to float above the trees like strings or aquaducts. I'm thinking there are two good solutions:
1. Represent them at their sources in the mountains and where they exit the forest, or
2. Cut the tree line back around them in spots so you get the effect and course of the rivers through the forests.
Hope this helps.