What is an appropriate punishment for 14yr old girl caught drinking by parent?

Talk to her first, don't just blow up. Kids are going to drink regardless of how much they get smacked or yelled at or grounded. They're going to rebel and sneak out to do what they want to do. Let her know you don't think its okay and that you want her to be responsible about the decisions she is making, but she can call you if she needs to. I remember when I drank when I was younger. I got caught and just got better at hiding it because I got into fights with my mom. Or if that doesn't work or it seems to much like a pushover thing to do, you can always take away things you used to trust her with since she took advantage of that trust. Don't let her do things, give her a curfew, no people over at your house, no going out at all on school nights or stuff like that.