Flat meadows without a grand canyon?

Edit: 5 Days and thousand views later: Nobody knows!

Just saw that post asking about a mod to flatten mistlands and suddenly i remember that is a huge problem at meados as well.

Everyone likes big meadows and checking seeds online there be so much seeds with big meadows. But as always they have a little river in the middle with 2km wide and barren slopes left and right because the meadows are e narly snow high at the dumb river.

Is there a way to prevent rivers if meadows are above a certain height to avoid those big canyons? Or any other way/idea?