The fire not cut off by her wall of water disburses before it reaches her. Which was a risk, but an informative one. As Zuko moves backwards, shooting that wave in her direction, Katara keeps the wall of water between them while she takes several steps to her left. She hopes to continue to maneuver him back towards the river, and to that end sends out what's left of her watershield in an scythelike wave about shoulder height.

She doesn't anticipate that catching him, though, and decides to start closing the distance between them, stepping forward in the wake of that wave.