The wave isn't seawater is it? It's that juice that runs throughout her territory. Maybe that's how she circumvented the water restriction.
Just so everyone is clear water doesn't negate most fruit abilities. Still or running water(not rain or a little splash) will weaken the user and basically make them really lathargic to the point that they will barely be able to move.
Water prevents Croc from dissolving into sand, it dissolves Katikuri's mochi, and surely hurts Ace and Akainu.
Water does not prevent the effects of a devils fruit. Here is a list to remember:
1- White Beard quakes through the ocean causing the tidal waves.
2- Aokiji freezing the ocean.
3- Luffy stretching his neck while underwater at Arlong Park.
4- Robin summoning giant hands underwater(wearing her but not preventing her) to keep the Sunny from bashing into rocks.
5- Luffy using Elephant Gun underwater outside of his bubble(weakening him, not preventing him).
7- Robin and Luffy reaching with an arm and eye to catch Usopp in the White Sea.
8- Kizaru's lasers shooting through the ocean.
The river may be juice but much of it is composed of water. If Jimbei can manipulate water in the air, in the human body, and in a pot of tea, he can manipulate the water in juice.
