#### 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 omegais 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.