The process of cavitation in water has been involved in the damage of many types of man-made structures. Flow speeds greater than 30 m/s appear necessary for cavitation damage. Major damage can occur with flow depths of only a few meters but it decreases with flow depth, channel roughness and air bubble content of the water. A computer model predicting damage potential, calibrated qualitatively with actual damages to dam spillways, is used to indicate the locations and relative intensity of damage for several spillway profiles. While damage is more likely associated with steeply sloping channels, because of the high flow velocities achieved in them, damage can occur in nearly horizontal surfaces if there is some other mechanism for achieving the necessary flow speeds. In a hypothetical spillage of water over the rim of the Grand Canyon, there are numerous locations at which cavitation destruction of the rock would be as great or greater than the worst damage ever seen in actual dam spillway. A flow of water of only four meters (m) initial depth, approaching a rapid elevation drop of less than 100 m at an initial speed of only 10 m/s can be expected to produce major cavitation damage for a variety of natural land profiles. The process of damage by cavitation appears to be a likely mechanism for rapid removal of rock in channels experiencing catastrophic flows of high speed shallow water with little air bubble content.