Irrigation

1

Lacey's equation for calculating flood discharge in rivers, is

A. `V = 10.8 R^(1//2) S^(1//2)`
B. `V = 10.8 R^(2//3) S^(1//2)`
C. `V = 10.8 R^(2//3) S^(1//3)`
D. `V = 10.8 R^(1//3) S^(2//3)`

2

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

A. `t = (h + 1)/(G + t)`
B. `t = (h - 1)/(G + t)`
C. `t = (h - 1)/(G - t)`
D. `t = (h + 1)/(G )`

3

According to Kennedy, the critical velocity (V0) 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).

A. `V_0 = 0.84 mD^0.64`
B. `0.55 mD^0.64`
C. `V = 0.84 mD^0.54`
D. `0.55 mD^0.54`

4

V and R are the regime mean velocity and hydraulic mean depth respectively in metres. Lacey's silt factor f is

A. `(2V^2)/(sqrt(3)R)`
B. `(3V^2)/(4R)`
C. `(5V^2)/(2R)`
D. `(2V^2)/(5R)`

5

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

A. total pressure on the surface is equal to `omega overline( x)`
B. depth of the point at which total pressure acts is equal to its moment of inertia divided by A `overline( x)`
C. depth of the centre of pressure is 2/3H vertically below the surface
D. all the above.