Welcome to the Guild! I like the map, but yes, you are right, the rivers do not make much sense at all. They seem to blatantly violate the "water flows downhill" rule. Also, rivers don't usually split up (there are exceptions) and never connect two oceans (you don't have that issue here tho). Sorry, the River Police badge carries with it a certain responsibility.

Other than that, I'd say the ocean texture is just a little too repetive, mixing that one up could help a lot. Otherwise the textures are cool

Oh - one other thing that hit me; there are no small islands on the map, but in the real world you'd expect some.