Discharge (Q)

Q = A.V

Discharge = Area*Velocity

Lacey’s silt factor

There are three independent equations of Lacey’s Regime theory

Here, ‘f’ is lacey’s silt factor

‘d’ is diameter of silt or avg. particle size in mm

‘R’ is hydraulic mean depth or hydraulic radius i.e. A/P

‘Q’ is discharge and ‘V’ is velocity

Lacey’s formula for velocity

Lacey’s bed slope (S)

Chezy’s formula for velocity

Manning’s formula for velocity

Here, ‘n’ is manning’s coefficient

‘R’ is hydraulic mean depth or hydraulic radius i.e. A/P

‘S’ is slope of bed

For no scouring in channel, d= 11RS or R = d/11S

The value of ‘n’ may be given but also we can calculate it by Stickler’s formula

Kennedy’s formula for velocity

Wetted Perimeter

Tractive Force

Normal scour depth in alluvial channel