Btw, if anyone else wants to work on this thread, the site I use to find all these little basins and rivers is called "
Databasins". They have a google earth type map with "datasets" which layer onto that map. You can zoom in and out and get the borders for the rivers and can get them to correspond with the political borders as well. For the purposes of this thread, the maps we'll need are called Hydrosheds which show basin boundaries or natural river flows, including showing pathways through reserviors and man-made lakes.
Here's how you use it:
1. Go to datasets
2. Type in the continent (e.i. europe) or just "hydrosheds"
3. Click on the one you want and then click open in map
4. It'll layer onto the map for you, so just add the other corresponding dataset to the one you have and you'll get the full river map
It's pretty easy to use so you won't need to reread this.