Civil Engineering - Irrigation MCQs Part 3

1. If the straight sides of a triangular section of a lined canal with circular bottom of radius D, make an angle θ with horizontal, the hydraulic mean depth is

A.
D

B.
D/2

C.
D/3

D.
D/4

E.
D/5

 Answer Option B

2. If water table is comparatively high, the irrigation canal becomes useless, due to

A.
large amount of seepage

B.
water logging of the cultivated areas

C.
uncertain water demand

D.
spread of malaria

E.
all the above.

 Answer Option E

3. A river is said to be of

A.
aggrading type if it builds up its bed to a certain slope

B.
degrading type if it cuts its bed to a certain slope

C.
meandering type if it flows in sinuous curve

D.
all the above.

 Answer Option D

4. A land is said to be water-logged if its soil pores within

A.
a depth of 40 cm are saturated

B.
a depth of 50 cm are saturated

C.
root zone of the crops are saturated

D.
all the above.

 Answer Option C

5. In case of a trapezoidal notch fall

A.
top width of the notch is kept between 3/4 th of full water depth above the sill of the notch

B.
top length of the piers should not be less than their thickness

C.
splay up stream from the notch section is 45°

D.
splay down stream from the notch section is

E.
all the above.

 Answer Option E

6. If D1 and D2 are depths of water upstream and down stream of a hydraulic jump, the loss of head at the jump, is

A.

B.

C.

D.

 Answer Option D

7. If Dc is the critical depth, D is the depth of water down stream and HL is the total head loss at the cistern of a vertical fall, the depth x of the cistern below the bed level down stream suggested by Blench, is

A.

B.

C.

D.

 Answer Option B

8. The uplift pressure on the roof of an inverted syphon, is maximum when

A. drain in running dry

B. canal is running dry

C. canal is running with F.S.L.

D. drain is running with H.F.L.

 Answer Option D

9. In rigid module, the discharge

A. is independent of water levels in the distributary and water course

B. depends upon the water level in distributary

C. depends upon the water level in the water course

D. depends upon the water levels of both, i.e. distributary and water course

E. none of these.

 Answer Option A

10. The ratio of the rate of change of discharge of an outlet and parent channel, is known as

A. efficiency

B. sensitivity

C. flexibility

D. modular limit.

 Answer Option C

11. Cross regulators in main canals are provided

A. to regulate water supply in the distributaries

B. to increase water head upstream when a main canal is running with low supplies

C. to overflow excessive flow water

D. none of these.

 Answer Option B

12. The ratio of the head recovered to the head put in, is known as

A. efficiency

B. sensitivity

C. flexibility

D. modular limit.

 Answer Option A

13. The level of the fioor of a syphon aqueduct can be obtained

A. by subtracting the depth of the culvert from the canal bed level

B. by subtracting the thickness of culvert plus the depth of the culvert from the canal bed level

C. both (a) and (b)

D. none of these.

 Answer Option B

14. A fall which maintains its depth, is

A. a trapezoidal notch fall

B. a low weir fall

C. a rectangular notch fall

D. all the above.

 Answer Option D

15. The water face of the guide banks, is protected by

A. one men stone pitching

B. two man stone pitching

C. three man stone pitching

D. four man stone pitching

E. five man stone pitching.

 Answer Option A

16. Effective precipitation for a crop may be defined as

A. total precipitation minus the loss due to evaporation

B. total precipitation minus the loss due to infiltration

C. total precipitation during the crop period

D. available water stored in soil within root zone of the crop.

 Answer Option D

17. If average particle size of the silt in millimetres is m, the Lacey's silt factor f is proportional to

A. m

B. m3

C. m1/2

D. m1/3

E. m2/3

 Answer Option C

18. Lane's weighted creep theory assumes

A. equal weightage to horizontal and vertical creeps

B. double weightage to horizontal creep and one weightage to vertical creep

C. triple weightage to horizontal creep and one weightage to vertical creep

D. triple weightage to vertical creep and one weightage to horizontal creep

E. double weightage to vertical creep and one weightage to horizontal creep.

 Answer Option D

19. Disposal of extra excavated earth of canals, is utilised to provide a spoil bank on

A. left side

B. right side

C. both sides

D. all the above.

 Answer Option D

20. If A is the area of the surface, x is the depth of its C.G. from the surface of the water and ω is the density of water, then

A. total pressure on the surface is equal to ω x

B. depth of the point at which total pressure acts is equal to its moment of inertia divided by A x

C. depth of the centre of pressure is 2/3H vertically below the surface

D. all the above.

 Answer Option D

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

A.

B.

C.

D.

 Answer Option C

22. Pick up the correct statement from the following

A. Escapes are essential safety valves in a canal system

B. The capacity of escapes should not be less than the capacity of the canal at its location

C. The escapes must lead the surplus water to natural drainages

D. The escapes are aligned to take advantage of contours of lower values

E. All the above.

 Answer Option E

23. 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.

B.

C.

D.

 Answer Option B

24. According to Lacey, depth of scour in a river depends upon the straightness of the reach. If D is the depth of scour in regime flow in a right angled bend, it is

A. 1.25 D

B. 1.50 D

C. 1.75 D

D. 2.00 D

 Answer Option D

25. The width of a dowla is generally kept between 30 to 60 cm and its height above the road level should invariably be more than

A. 10 cm

B. 20 cm

C. 30 cm

D. 40 cm

 Answer Option C

26. The field capacity of a soil depends upon

A. capillary tension in soil

B. porosity of soil

C. both (a) and (b)

D. neither (a) nor (b).

 Answer Option C

27. Finally formed berms in canals are provided for

A. protection of banks erosion by the waves

B. control of seepage losses

C. strengthening of banks

D. all the above.

 Answer Option D

28. An outlet is said to be proportional if its flexibility, is

A. zero

B. less than one

C. more than one

D. one

 Answer Option D

29. The ratio of the discharge over a trapezoidal crest to a rectangular crest of Sarda falls of identical parameters, is

A. 1.084

B. 1.074

C. 1.064

D. 1.054

E. 2.053

 Answer Option A

30. For standing crops in undulating sandy fields, the best method of irrigation, is

A. sprinkler irrigation

B. free flooding

C. check method

D. furrow method

E. none of these.

 Answer Option A

31. In a syphon aqueduct

A. drainage passes over the canal and F.S.L. of the canal is below the bottom of the drainage trough

B. drainage passes over the canal and F.S.L. of the canal is above the bottom of the drainage trough

C. canal passes over the drainage and H.F.L. of the drainage is above the bottom of the canal trough

D. canal passes over the drainage and H.F.L. of the drainage is below the bottom of the canal trough.

 Answer Option C

32. Which one of the following statements is correct ?

A. The canal system and the drainage system are complementary

B. The canal system runs on ridges, gets divided into smaller channels and spreads its water on the land

C. The drainage system runs along the lowest line, collects drainage water from the slopes and joins the main stream

D. All the above.

 Answer Option D

33. Garnett's diagrams are used for graphical solution of design equations of a canal by

A. Lacey's theory

B. Kennedy's theory

C. Gibb's theory

D. Lindlay theory.

 Answer Option B

34. A current meter measures the velocity of flow, if it is held

A. on the surface of water

B. at the bottom of channel

C. at any point within the cross-section

D. none of these.

 Answer Option C

35. In a concrete canal the approximate permissible velocity of water should not exceed

A. 0.5 m/sec

B. 1 m/sec

C. 1.5 m/sec

D. 2 m/sec

E. 2.5 m/sec

 Answer Option D

36. Pick up the correct sequence of the part of a canal system from the following

A. Head work-distributary-branch canal-minor

B. Head works-main canal-branch canal-dis-tributary-minor

C. Head works-main canal-branch canal-minor-distributary

D. Heads works-branch canal-main canal distributary, minor.

 Answer Option B

37. A counter berm is

A. a horizontal benching provided on the inside slope

B. a horizontal benching provided on the outside slope

C. a vertical benching provided on the outer edge of the bank

D. a vertical benching provided on the inner edge of the bank.

 Answer Option B

38. Pick up the correct statement from the following:

A. Water table generally follows the ground surface above it with a few exceptions

B. Static level of water in an open well indicates the position of the water table

C. Saturated pores of a soil in the capillary zone above water table have negative pressure

D. At water table, hydrostatic pressure is zero

E. All the above.

 Answer Option E

39. For diversion of flood water of rivers, the type of canal constructed, is

A. ridge canal

B. perennial canal

C. inundation canal

D. canal.

 Answer Option C

40. To control the silt entry into a distributary at head regulator, King's vanes are provided which are the walls

A. of R.C.C. or steel plate 8 cm thick

B. of height l/3rd to l/4th the depth of water in the main canal

C. spaced at interval of times their heights

D. extending about one metre beyond a line drawn at an inclination of 2 : 1 to the axis of main canal

E. all the above.

 Answer Option E

41. According to Lacey, in regime conditions

A. silt is kept in suspension by vertical components of eddies

B. entire cross-section of the channel is generated at all points by the forces normal to the wetted perimeter

C. both (a) and (b)

D. neither (a) nor (b).

 Answer Option C

42. Process of meandering is due to

A. sediment load of streams

B. discharge and hydraulic properties of streams

C. relative erodibility of the bed and banks

D. all the above.

 Answer Option D

43. 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.

B.

C.

D.

 Answer Option C

44. For cereal crops the most commonly adopted method of irrigation, is

A. free flowing method

B. check method

C. furrow method

D. sprinkling method.

 Answer Option B

45. While deciding the alignment of a proposed canal taking off from a river at B, three alignments of approximately equal lengths are available. These cross a drainages at C1, C2 and C3 where drainage bed levels C1 > C2 > C3, you will provide at site C3

A. an aqueduct

B. a syphon aqueduct

C. a super passage

D. a syphon.

 Answer Option A

46. The ratio of the rate of change of discharge of an outlet to the rate of change in level of water surface in a distributary at its normal depth, is known as

A. efficiency

B. sensitivity

C. flexibility

D. modular limit.

 Answer Option B

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

A. V = 10.8 R1/2 S1/2

B. V = 10.8 R2/3 S1/2

C. V = 10.8 R2/3 S1/3

D. V = 10.8 R1/3 S2/3

 Answer Option C

48. The most suitable section of a lined canal, is

A. triangular section with circular bottom for small canals

B. trapezoidal section with rounded corners for large canals

C. rectangular section with rounded corners for large canals

D. both (a) and (b)

E. both (a) and (c)

 Answer Option D

49. To hold hydraulic jumps, baffle walls are provided in

A. Sarda type falls

B. English type falls

C. Montague type falls

D. Vertical type falls.

 Answer Option B