When I am home I will make a short guide for it, attaching with photo's so it's good to follow
I found a thread at Boardgamegeeks about someone who had a river in his Inns&Cathedrals box and he compared it to the base game river, CarcII.
Well I didn't knew which river was in both compared it with the CarcI river. And found out that the river I from CarcI is the same as CarcII river. Except from the abbot.
So after all with the images I found it is quite strange they give you two rivers. But I can not guarantee I am right as I do not own anything from CarcII
Short. It's river 1