If a horizontal layer of water is pushed into a rigid, vertical wall there will be a step wave, or bore, produced that runs away from the wall. If the incident velocity is not too great, the bore front will have a well-behaved, undular shape, but at sufficiently high velocities the bore front will break and be highly irregular. In either case, conservation of mass and momentum principles may be used to derive "jump" conditions that should exist across the bore transition [19].