Small children need the freedom to explore with proper supervision. Yes, sometimes they will get hurt, even when supervised. Mistakes happen, but to erect fences, walls, padding, or bars around anything deemed "risky" is foolish. Where does it end? Fence of the entire waterfront board-walk because a child could fall into the harbour?
Let common sense prevail and keep the wave as it is. If you don't want your children on the Wave, tell them, then follow up with effective supervision.
(Photo Credit: Joshua Bousel, CC BY-NC-SA 2.0)