You just need to counter her like any other champ. The stronger you are in one area the easier you can be countered, especially if you are only strong in said area.
There are enough Champions who counter Riven's mechanics, Ryze, Olaf, Kennen, Pantheon, Fiora, Cho Gath, Yorick, and Lee Sin.
I took these examples from LoLCounter because I think they are true.
Also, you have to know how to play your Champion - If you're Garen, force her out of lane with your spin-to-win - and how to play your Champion against Riven.
-> She does that dash and slash trick, you rune prison her, fire a Q, walk back a bit and auto attack, so when she wants to do it again, you are far enough away.
Also don't push, because Riven may be mobile, but 1,2 Turret hits will still scare her.
Consider using brush, if you're ranged, or even if not. If Riven doesn't know where you are, it will be harder to poke you. But don't attack when you are inside the brush.
Not every champion who is very strong is exactly OP, they're just challenging and therefor good for your growth.
And if everything fails, consider maining or just banning her or any other champion you absolutly hate. That way you won't encounter them in ranked.