Try to prevent instead of dealing with. Be sure you keep her well feed, hydrated, and rested. When you see she is in sensory overload, find a quite shady spot and let her chill for a little bit. If she is a child that needs routine, try to keep her on it. Adults can stay up two hours late and deal, babies can not.
If she does melt down, handle it as you would at home. Rock, distract or whatever. Do however rememeber to be a little more fexable in you tollerace.