Import river to UE4?

Hi! I created a river in my world created with World Machine, when I import the heightmap I can see the river in UE4, but I’m not sure how should I go to fill it with water?

I see that the UE4 water plugin expects rivers to be drawn directly in UE4 on a flat terrain (the plugin takes care to sculpt the river bed).

I googled a lot but I can’t find any tutorial that explains how to use a World Machine generated river bed as base for a UE4 river, could you guys help me please?