It is a single render. Do not forget that the water in the rivers is not horizontal, it is sloped, and it has a higher roughness.
What definitly is needed for the final TG2 is the possibility to drive the wave functions with another node, so that wavesize and roughness can made dependend from waterheight and slope.
The terrain is at all a more simple one. I hope I will soon have some time to make the full usuage of the isolines (even for details) and of cause, I am just improving the river calculation for the pre-release, it is still not, what I want it to be.
The render time did not exceed at the horizon but the near to the camera parts. May be, displacement has caused that. Next time I will simply disable displacement (detail adding) to the terrain.