A hydraulic jump is a discrepancy in water depths. When water in a stream flows over a rock, the water may reach supercritical speed - that is, the speed of the water may exceed the speed that waves propagate at. If so, there will be a sudden change in the water's height so that the speed of the water is reduced to subcritical speed. | A hydraulic jump is a discrepancy in water depths. When water in a stream flows over a rock, the water may reach supercritical speed - that is, the speed of the water may exceed the speed that waves propagate at. If so, there will be a sudden change in the water's height so that the speed of the water is reduced to subcritical speed. |