WASasquatch,
Ah, ok. The word "rivers" distracted me.
To get deep cuts you need to use high values of Downcutting parameter. Hint: you can, and should use values higher, than 1.0, for example, 2.0, 4.0 or even 10.0 or 50.0. Deposition may look strange with these settings, to compensate this you can set high value of "Base level" parameter, I found that 0.4 from Downcutting is good, for example, Downcutting = 10, Base level = 4, but it requires more experimenting.
In the attached example I used these settings:
Duration = 0.2
Erosion strength = 1.0
Rock softness = 0.05 (to get thinner gullies and to change its distribution to emphasize the ones with more intensive flows)
Downcutting = 20
Base level = 8
Also I used quite aggressive thermal erosion here to make "walls" a bit more smooth and solid looking.
Daniil
P. S. I am pondering on making "Downcutting" parameter range wider, say, up to 10 or 20, and to make it non-linear and weighted towards lower values. It won't affect the behaviour and old projects compatibility, but will make using higher values easier. Possibly the same for Base level parameter.
P. P. S. Possibly I am wrong about such high values of Base level. It requires experimenting, possibly it is better to start with 1.0, and then try higher values.