The abrupt increase in depth of rapidly flowing water is called hydraulic depth.Flow at the jump changes from a supercritical to a subcritical stage with an accompanying loss of kinetic energy. The change in depth occurs over a finite distance, known as the length of jump. The upstream surface of the jump, known as the roller, is a turbulent mass of water.
The depth before a jump is the initial depth, and the depth after a jump is the sequent depth. The specific energy for the sequent depth is less than that for the initial depth because of the energy dissipation within the jump.
F=[ d22– d12]w/2
where d1 =depth before jump, ft (m)
d2 =depth after jump, ft (m)
w=unit weight of water, lb/ft3 (kg/m3)
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