Unfair treatment at work, help!

[devinrain]

Hello, I work at a supermarket, and have been working on my department now for 12 years. In the last couple of weeks a colleague from another department has joined my department, working outside on the car park. He has kept the same hours working 38 hours, and he is working a lot of the shifts I work, even though there is not enough work for three of us to do. There has also been a message up in our canteen that our department needs to drop 550 hours, but still they have added him to our department. Well it turned out he had an accident on his department moving some heavy boxes and is claiming compensation, and he would only agree to working outside. The issue I have is I have been told by a section leader that she believes that one if not two of us will have to move onto another department for this new guy. I want to be prepared, I do not want to be moved around at work, so would appreciate any advice or information you can give me. thank you.

Also to give you a better image of the situation.
There are 6 of us who work on the car park in total, all working much working less than 38 hours.