Lacey's equation for calculating flood discharge in rivers, is
If the height of the hydraulic gradient line above the floor of thickness t is h and the specific gravity of the material of the floor is G, the minimum thickness t of the floor down stream of the crestwall, is given by the equation
According to Kennedy, the critical velocity (V_{0}) in
metres in a channel is the mean velocity which keeps the channel free
from silting or scouring. Its value is given by (where m is critical velocity ratio and D is the depth of the channel).
V and R are the regime mean velocity and hydraulic mean depth respectively in metres. Lacey's silt factor f is
If A is the area of the surface,`overline(x)` is the depth of its C.G. from the surface of the water and `omega`is the density of water, then