no rivers spawns

When I got on to test the custom world out it was good but it seemed like no rivers where spawning in all I saw was ravine like dirt patch area. What I expected to happen when I saw it was it should have had the river but it had just dirt and had grass spawning in it.
It should have spawned in the river but I don't know if it was the generation.

*What actually happened was it was just dirt and no water water lakes still spawned in.
Describe what happened here
It only spawned in dirt like in a ravine look place
Steps to Reproduce:
1. Just make a custom world
2. The rivers don't spawn then
3. ...