Where are the rivers in Wilbur ?

[Deadshade]

Precipiton erosion as implemented works best for terrain with large height differences (1000 or more units between highest and lowest). It works at lower levels, but becomes progressively less effective. What happens is that eventually the soil mover pushes up a hill and then the flow stops. It's technically a bug, but it doesn't usually cause too many problems. You should always do a basin fill before river finding to ensure connected networks.

I didn't use precipiton, I used the normal erosion.
And as I said, I used basin fill - I always use it before doing any erosion.
Yet the map was full of low points where the rivers ended - actually a river ending in the middle of land was the rule and a river flowing to the sea an exception. I wondered whether the use of the raise/lower tool somehow perturbed the topology so that the fill basin didn't work correctly everywhere.
Will have to check it by redoing the same process with a new map.