Pressure fields due to the impingement of free falling jets on a riverbed

Free overflow spillways are commonly used in arch dams. The jet gains velocity as it falls, and it can generate a big impact over the rock downstream the dam. To avoid this, plunge pools are usually constructed in order to absorb a certain amount of the energy and to spread the jet. The more compact the jet is, the more severe is the impact it can generate. Some experiments have been done in order to evaluate the pressure fields over the plugeplunge pool floor. The energy dissipation due to the flight in the atmosphere has not been taken into account in most of these tests. This paper presents some results about the pressure field one can expect in these effects are considered.