##### Canal design – Important formulas | Civil Crews

### 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**