300+ REAL TIME Irrigation Engineering Objective Questions & Answers 2023

250+ TOP MCQs on Regulation Modules – Metering Flumes Types and Answers

Irrigation Engineering Multiple Choice Questions on “Regulation Modules – Metering Flumes Types”.

1. For what purpose is the meter used?
a) Measuring the amount of Silt entering the Canal
b) Measuring the Velocity of the Flow
c) Measuring the Hydraulic Jump
d) Measuring Discharge
Answer: d
Clarification: The meter is a structure constructed in a canal for measuring the discharge of the canal accurately. It is an artificially flumed structure.

2. What is the slope of a throat?
a) From 0.5:1 to 1:1
b) From 1:1 to 3:1
c) From 1:1 to 2:1
d) From 1:3 to 1:2
Answer: c
Clarification: By using the masonry walls the normal section of the channel is narrowed with a slope of 1:1 to 2:1 to a rectangular section known as the throat.

3. After the throat the channel is diverged to avoid the loss of head in the flume.
a) True
b) False
Answer: a
Clarification: From the throat the channel is diverged so as to attain its normal section with the help of masonry wings with a slope of 2:1 to 10:1. Therefore due to gradual convergence and divergence the loss of head in the flume will be less.

4. Metering flumes works on the principle of venturi meter.
a) True
b) False
Answer: a
Clarification: Since we use the throat for converging purpose in the flume the velocity of the flow increases. After the throat the channel is diverged for expansion, thus again the velocity becomes normal. Due to this increase and decrease of the velocity we can measure the discharge of the flow. This is quiet the procedure on which the venturi meter works. Hence, the metering flumes works on the principle of venturi meter.

5. How many types of metering flumes are used?
a) 3
b) 2
c) 4
d) 5
Answer: b
Clarification: The two types of metering flumes used, which work on the principle of venturi meter are non-modular venturi flume and standing wave flume.

6. Which type of flume does the diagram depict?

a) Modular Venturi Flume
b) Free Flow Venturi Flume
c) Venturi Flume
d) Standing Wave Flume
Answer: c
Clarification: The diagram represents a gradual channel leading to throat and gradual expanding of channel leading away. Moreover stilling wells are provided at the entrance and at the throat for measuring the head.

7. What is the formula for discharge when venturi meter is used?
a) (Q = C_d (a_2/sqrt{(a_1^2 – a_2^2)})sqrt{2h})
b) (Q = C_d (a_1 * a_2/sqrt{(a_1^2 – a_2^2)})sqrt{2gh})
c) (Q = (a_1 * a_2/sqrt{(a_1^2 – a_2^2)})sqrt{2g})
d) (Q = C_d (a_1/sqrt{(a_1^2 – a_2^2)})sqrt{2gh})
Answer: b
Clarification: When the difference between the two stilling wells is h, then the discharge is given by the formula (Q = C_d(a_1 * a_2 / sqrt{(a_1^2 – a_2^2)})sqrt{2gh}) where, C_d = 0.95 to 1, a₁ = area at entrance, and a₂ = area at the throat.

8. What structure does the diagram represent?

a) Standing Wave Flume
b) Venturi Flume
c) Non modular Venturi Flume
d) Drowned Venturi Flume
Answer: a
Clarification: The standing wave or say the hydraulic jump forms on the downstream glacis in the diverging channel. Therefore this diagram is standing wave flume.

9. What is the main drawback of standing wave flume?
a) Loss of Hydraulic Jump
b) Loss of Velocity of Flow
c) Loss of Head
d) Loss of Discharge
Answer: c
Clarification: The main and only drawback of standing wave flume is that, it has a greater tendency for the loss of head (H_L) and if this loss is not available it acts as a venturi meter. Due to this reason the canal fall sites are used as standing wave flumes.

10. What is the formula for discharge, when standing wave flume is used?
a) Q = 1.7 x B x H^3/2
b) Q = 1.7 x C_d x B x H^3/2
c) Q = 1.7 x C_d x B x H
d) Q = 1.7 x C_d x H^3/2
Answer: b
Clarification: When the width of the throat (B) is known we can calculate the discharge in the standing wave flume using the formula, Q = 1.7 x C_d x B x H^3/2 where C_d = 0.95 to 1.

250+ TOP MCQs on Diversion Head Works – Weir and Barrage and Answers

Irrigation Engineering Multiple Choice Questions on “Diversion Head Works – Weir and Barrage”.

1. Into how many groups the gravity weir is sub-divided?
a) 5
b) 4
c) 3
d) 2
Answer: c
Clarification: According to the material used and certain design features, the gravity weir is sub-divided into three groups. They are vertical drop weir, sloping weir, and parabolic weir. Sloping weir is again classified into two groups, namely masonry slop weir and dry stone slope weir.

2. In gravity weir, the uplift pressure is due to the seepage of water.
a) True
b) False
Answer: a
Clarification: In gravity weir, the uplift pressure is due to the seepage of water below the floor and is resisted entirely by the weight of the floor.

3. The uplift pressure in non-gravity weir is resisted by the bending action.
a) False
b) True
Answer: b
Clarification: In non-gravity type weir the thickness of the floor is relatively kept less, and the uplift pressure is largely resisted by the bending action of the reinforced concrete floor.

4. Which type of weir is suitable for any type of foundation?
a) Sloping Weir
b) Vertical Drop Weir
c) Parabolic Weir
d) Masonry Sloping Weir
Answer: b
Clarification: This type of weir is suitable for kind of foundation because it is provided with or without crest gates, cutoff piles are provided at both upstream and downstream, to protect against scouring aprons are provided at both up and down streams, and at downstream to relieve uplift pressure graded inverted filter is provided.

5. What type of weir does the diagram represent?

a) Parabolic Weir
b) Gravity Weir
c) Dry Stone Slope Weir
d) Vertical Drop Weir
Answer: c
Clarification: The figure represents a sloping weir made up of dry stone or rock fill. It also represents body walls at both upstream and downstream sides and rock falls laid in the form of glacis with few intervening core walls.

6. What is the main difference between a dam and weir?
a) Height and Duration of Storage
b) Capacity of Water
c) Material used for Construction
d) Location of the Structure
Answer: a
Clarification: Weir is an obstruction across the river to raise its water level and divert into new channel. It can also store water for short duration of time of short supplies, known as storage weir. The only main difference between dam and weir is that dam can store water comparatively for longer duration than weir and the dam is at more height than the weir.

7. What is the difference between a weir and a barrage?
a) Discharge Capacity
b) No Solid Obstruction
c) Storage Capacity
d) Velocity of Flow
Answer: b
Clarification: Barrage is almost a similar structure like a weir, but the difference is that barrage is not a solid obstruction across a river and moreover the heading of the river is controlled by gates alone. The crest level in barrage is kept at low level. During floods the gates are kept for discharge of excess waters and when the flood recedes the gates are lowered, thus solving the silting problem.

8. In which type of weir energy dissipation takes place?
a) Barrage
b) Vertical Drop Weir
c) Sloping Weir
d) Parabolic Weir
Answer: d
Clarification: This weir is similar to the spillway section of a dam. The body of this weir is kept as a low dam. A cistern is provided at the downstream side for energy dissipation of the falling waters from upstream to the downstream side.

9. Which type of weir is of recent origin?
a) Vertical Drop Weir
b) Masonry or Concrete Sloping Weir
c) Parabolic Weir
d) Barrage
Answer: b
Clarification: This type weir is of recent origin. They are much suitable for soft and sandy foundations and are generally used when the difference between the weir crest and downstream river bed is limited to 3 metres.

10. What number of causes is responsible for the failure of weirs?
a) 2
b) 4
c) 3
d) 1
Answer: b
Clarification: Mainly four causes are responsible for the failure of weirs. They are piping, rupture of floor due to uplift, rupture of floor due to suction caused by standing wave, and scouring at the upstream and downstream side of the weir floor.

250+ TOP MCQs on Advantages of Lining and Answers

Irrigation Engineering Multiple Choice Questions on “Advantages of Lining”.

1. A lined canal costs about 2 to 2.5 times as much as the unlined canal.
a) True
b) False
Answer: a
Clarification: The construction of larger reservoirs and bigger dams will be necessary if there is heavy seepage loss in canals. Lining the canals reduces their impounding capacity and hence lower the construction costs of these works.

2. Which of the following is not an advantage of the lining of the canal?
a) Seepage control
b) Prevention of water-logging
c) Increase in channel capacity
d) Increased maintenance costs
Answer: d
Clarification: Huge expenditure is spent on annual repair and maintenance of the unlined canal. The provision of lining reduces expenditure required for removal of silt, minor repairs like plugging of cracks, cuts, and removal of weeds and water plants.

3. The capacity of the channel is a function of velocity.
a) True
b) False
Answer: a
Clarification: The vegetation on the sides and bottom of the canal retards the flow of water in unlined canals. The higher the velocity, the greater is the capacity of the channel and hence, capacity is a function of velocity.

4. What is the range of value of Manning’s coefficient for straight alignment for cast in-situ concrete lining?
a) 0.012 – 0.015
b) 0.015 – 0.018
c) 0.018 – 0.020
d) 0.020 – 0.025
Answer: b
Clarification: In absolutely straight reaches and with relatively higher discharges lower values of Manning’s constant may be attained. For cast in-situ concrete lining, the value of n varies from 0.015–0.018 and for cement plastered masonry the value varies from 0.012-0.015.

5. Lining decreases the channel capacity and consequently reduces the required channel section.
a) True
b) False
Answer: b
Clarification: The lining causes less resistance to the flow of water as it provides a smooth surface and consequently velocity is more. The capacity can be considerably increased by lining the canal section. A lined channel will require fewer dimensions and less earthwork.

6. Removal of silt considerably reduces the annual expenditure required on unlined channels for desilting.
a) True
b) False
Answer: a
Clarification: Lining protects the canal section against breaches and bank erosion. On account of the high velocities in lined-channels silts are readily carried away. This reduces the annual expenditure for desilting.

7. Which of the following statement is wrong?
a) A lined canal is not susceptible to erosion
b) The provision of adequate lining reduces the danger of breaches of channel
c) The lining does not reduce the money spent in removing weeds
d) Lining eliminates flood dangers
Answer: c
Clarification: The plants flow down the canal due to higher flow velocities in lined-canals due to which expenditure is reduced considerably. A strong concrete lining eliminates the dangers from flood and minor repairs like plugging of cracks, cuts and uneven settlements of banks (which results in breaches of the channel).

8. Which of the following statement is wrong?
a) The velocity varies inversely with the Manning’s coefficient
b) For unlined channels in good condition, the value of Manning’s coefficient is 0.015 for concrete
c) Flatter slopes can be provided without silting on a lined channel
d) The lining does not help to bring high areas under the command
Answer: d
Clarification: The longitudinal slope of a lined canal is flatter than the corresponding unlined canal. Flat slope raises the F.S.L of the lined canal and it brings high patches of the land under command.

250+ TOP MCQs on Canal Irrigation System – Alluvial and Non-alluvial Canals and Answers

Irrigation Engineering Multiple Choice Questions on “Canal Irrigation System – Alluvial and Non-alluvial Canals”.

1. Which of the following statement is not correct about alluvial soils?
a) It is formed by sediment deposition of silt from the flowing water
b) The area of alluvial soil is even
c) It has a flat surface slope
d) Hard foundations are generally available
Answer: d
Clarification: The process of silt deposition over a long period of time resulting in the formation of soil is called alluvial soil. It has a flat surface slope and even area. Hard foundations are generally not available in this kind of soil.

2. Non-alluvial soils are generally found in a mountainous region.
a) True
b) False
Answer: a
Clarification: The disintegration of mountainous rocks over a period of time resulting in the formation of a rocky plain area called non-alluvial soils. It has uneven topography and hard foundations are available in this soil.

3. Canal irrigation is generally preferred in __________
a) alluvial canal
b) non-alluvial canal
c) non-perennial canal
d) feeder canal
Answer: a
Clarification: Direct irrigation using a weir or barrage (canal irrigation) is generally preferred in alluvial soil as compared to storage irrigation. Alluvial soil is a fine-grained fertile soil and due to its porosity and texture provides good drainage making it highly productive and suitable for agriculture.

4. Which of the following combination is not correct?
a) Feeder canal – no direct irrigation is carried out
b) Protective canal – constructed as a relief work during the famine
c) Lined canal – provided with a lining of impervious material on its bed
d) Contour canal – provision of cross drainage works is not required
Answer: d
Clarification: A feeder canal is used to feed another canal and no direct irrigation is carried out from it. A protective canal is constructed to provide employment in the famine-affected area. A lined canal is provided with a lining of impervious material to prevent the seepage of water. A contour canal has to cross the drainage and hence, cross drainage works are required.

5. Which canal is not provided with any headworks for diversion of river water?
a) Permanent canal
b) Feeder canal
c) Perennial canals
d) Inundation canals
Answer: d
Clarification: An inundation canal is a canal which gets its supplies only when the water level in the river from which it takes off rises during floods. They obtain their supplies through open cuts in the banks of the river.

6. The velocity of the flowing water in a navigation canal should be __________
a) high
b) very high
c) small
d) medium
Answer: c
Clarification: A navigation canal is constructed to provide various navigation facilities. The velocity of flowing water should be small for easy movement of small ships and barges in the direction of flow of water as well as in the opposite direction.

7. Which one is well traded and is provided with permanent regulation and distribution works?
a) Inundation canals
b) Permanent canals
c) Alluvial canal
d) Navigation canals
Answer: b
Clarification: A permanent canal is the one that is fed by a permanent source of supply. The provision of permanent regulation and distribution works is made in the permanent canal. It is further classified as Perennial canals and non-perennial canals.

8. Which canal acts as an irrigation canal as well as a feeder canal?
a) Feeder canal
b) Carrier canal
c) Inundation canal
d) Permanent canal
Answer: b
Clarification: A carrier canal is a canal used for both direct irrigation and for feeding water to another canal. Thus, it acts as an irrigation canal as well as a feeder canal. Upper Chenab Canal is an example of this type of canal.

9. Hard foundations are generally available in non-alluvial soils.
a) True
b) False
Answer: a
Clarification: Non-alluvial soils are formed by the disintegration of mountainous rocks. Due to its uneven topography and rocky mass formed after disintegration, hard foundations are generally available.

10. A canal which when fully developed yields enough revenue to cover up its running cost is known as _____________
a) protective canal
b) productive canal
c) permanent canal
d) inundation canal
Answer: b
Clarification: After the development of the canal system the revenue obtained from the cultivators is such that it is more than the maintenance expenditure. This exceeding amount of revenue is so adjusted that it is about 2% of the cost of the canal system. With this rate, the total cost of the project will be recovered in about 50 years.

250+ TOP MCQs on Dam Outlet and Answers

Irrigation Engineering Multiple Choice Questions on “Dam Outlet”.

1. The bar screens used to cover the dam outlets to prevent entry of debris, or ice into the spillway conduits are called __________________
a) gate controlled ports
b) projecting collars
c) trash racks
d) intakes
Answer: c
Clarification: The trash racks are made from steel bars at a spacing of about 5 to 15 cm c/c in both the directions. The floating objects like debris, ice get collected on these racks and can be removed by manual labor as well as automatic power-driven system. The spacing depends upon the maximum size of debris required to be excluded.

2. Projecting collars are provided on sides of a rectangular tunnel of length L made through an earthen dam to increase the seepage path. Their projection length (X) and numbers (N) are decided so as to provide increased seepage path equal to 2NX where 2NX should generally be ______________________
a) greater than L/4
b) greater than L/3
c) greater than L/2
d) greater than L
Answer: a
Clarification: The seepage is reduced by increasing the length of the seepage path by at least 25%. The increase in seepage path must generally be greater than L/4.

3. The outlet provided in a dam body to release water for the downstream water demand is known as ______________________
a) spillway
b) sluiceway
c) under-sluice
d) waterway
Answer: b
Clarification: A sluiceway is a pipe or a tunnel that passes through the body of the dam or through some hillside at one end of the dam and discharges into the stream below. The sluiceways are preferred to place outside the limits of the embankments in case of spillways.

4. A 2 m diameter sluiceway at RL 300 m is provided through a concrete overflow dam section to release water to the downstream where tail water level is not more than 275 m. The discharge through this outlet when the water level in the reservoir is at FRL of 330 m is of the order of_________________
a) 20 cumecs
b) 40 cumecs
c) 50 cumecs
d) 80 cumecs
Answer: c
Clarification: The discharge passing through the dam outlet is given by using the equation-
Q = C_d. A. (2gH_L)^1/2 where C_d is the coefficient of discharge = 0.62 for free over-fall, H = Water head over centre line of sluice = 330 – 300 = 30 m and A = π/4 x 4 = 3.14 m²
Q = 0.62 x 3.14 x (2 x 9.81 x 30)^1/2 = 47.23 cumecs.

5. A 4 m diameter tunnel has been constructed through an earthen dam with a bell mouth entry. The water levels on the U/s and D/s sides of the dam are at RL 226 m and 210 m respectively. What will be the discharge through this outlet?
a) 64 cumecs
b) 104 cumecs
c) 165 cumecs
d) 216 cumecs
Answer: c
Clarification: The discharge through the outlet is given by –
Q = C_d. A. (2gH_L)^1/2 where H_L = 226 – 210 = 16 m
Q = 0.8 x (π/4 x 16) x (2 x 9.81 x 16) = 164 cumecs.

6. Which of the following entrance of the sluiceway is most superior?
a) A square-edged entrance
b) A Bell-mouthed entrance
c) A rectangular entrance
d) A circular entrance
Answer: b
Clarification: As compared to Bell-mouthed or other entrance, a square edge entrance is likely to cause more separation of flow and more danger of consequent cavitation. The shape of the bell-mouthed entrance is generally elliptical and the extra cost involved I shaping this entrance is usually justified except for small projects under low heads.

7. What is the correct Douma’s equation for rectangular tunnels or conduits?
a) X² + 10.4 Y² = d²
b) 4X² + 10.4 Y² = d²
c) 4X² + 44.4 Y² = d²
d) X² – 10.4 Y² = d²
Answer: a
Clarification: Douma has suggested the following equation –
i. For circular conduits: 4X² + 44.4 Y² = d² where d is the diameter of the circular conduit
ii. For rectangular tunnels or conduits: X² + 10.4 Y² = d² where d is the width or height of the conduit depending on whether the sides or top and bottom curves are being designed. Where X and Y are the coordinates of any point on the curve and d is the width or height of the conduit.

8. What is the value of head loss for the fully open gate and butterfly valves?
a) 0.5 V² / 2g
b) V² / 2g
c) 0.2 V² / 2g
d) 0.04 V² / 2g
Answer: c
Clarification: The head loss depends upon the type of gate and valves. For fully open gates and butterfly valves, a loss of about 0.2 V² / 2g (where V is the flow velocity through the conduit) may be taken and is taken as nil for ring follower gates.

250+ TOP MCQs on Gravity Dams – Galleries Construction and Answers

Irrigation Engineering Multiple Choice Questions on “Gravity Dams – Galleries Construction”.

1. The provision of drainage gallery in a gravity dam helps in reducing ____________________
a) hydrostatic pressure
b) seepage pressure
c) silt pressure
d) both hydrostatic pressure and seepage pressure
Answer: b
Clarification: An opening or passage left in the dam which runs longitudinally is called the gallery. This is to provide space for drainage of water percolating through the upstream face of the dam or seeping through the foundation. It is also used for inspection purposes and for the mechanical equipment used in the operation of gates in spillways.

2. Which of the following attempts are made to reduce the uplift in order to economize on the provided section of a concrete gravity dam?
i. Providing drainage gallery to collect seepage water
ii. Constructing cut-off under upstream face
iii. Pressure grouting in dam foundation
iv. Provision of shear keys or keyways
a) i and ii
b) i, ii and iii
c) i, ii and iv
d) i, ii, iii and iv
Answer: b
Clarification: In a gravity dam, the grout curtain is provided near the toe to reduce the exit gradient. A drainage gallery with its drainage pipe system provided in gravity dam reduces the uplift pressure at all levels below the upstream water level. Vertical cut-off walls are the most effective to reduce seepage flow and uplift force.

3. Transverse joints in concrete gravity dams are the ___________________________
a) horizontal construction joints at each lift height
b) vertical construction joints of full height and width
c) diagonal construction joints for torsion
d) longitudinal construction joints of full width
Answer: b
Clarification: Transverse joints are vertical joints that run through the entire height and extend through the full width of the dam section. These joints are continuous from the upstream face to the downstream face.

4. Leakage through the transverse joints in a gravity dam is prevented by ____________
a) shear keys
b) keyways
c) water stops
d) galleries
Answer: c
Clarification: Water bars or water stops are provided in the transverse as well as horizontal joints in concrete adjacent to the upstream face of the dam. The openings of the joints are sealed properly with water stops to avoid passage of seepage of water through the body.

5. In order to reduce uplift on a gravity dam, the type of grouting done is ____________________
a) curtain grouting near the heel
b) consolidation grouting near the heel
c) curtain grouting near the toe
d) consolidation grouting near the toe
Answer: a
Clarification: Curtain grouting helps in forming a principal barrier against the seepage through the foundations and thus reduces the uplift pressure. This grouting can be accomplished from the foundation gallery or from other galleries within the dam.

6. The general value of lift for concrete is taken as __________________
a) 1.5 m
b) 2.5 m
c) 3 m
d) 4 m
Answer: a
Clarification: The concrete is poured from a certain height in the first attempt and this height is called a lift. Maximum height of single pour of concrete is usually about 1.5 m. If this is reduced, more horizontal joints will get developed.

7. The horizontal joints that extends through the entire width of the dam section and are developed at each lift height is called as ___________________
a) transverse joints
b) longitudinal joints
c) construction joints
d) contraction joints
Answer: b
Clarification: The longitudinal joint is developed at each lift height and extends through the entire width of the dam section. These joints shall run through the entire length of the dam but are staggered between transverse joints.

8. Which of the following joints justifies the two-dimensional analysis of gravity dams?
a) Longitudinal joints
b) Transverse joints
c) Construction joints
d) Contraction joints
Answer: b
Clarification: Transverse joints are vertical joints that divide the dam length into a number of vertical cantilevers each of which is independent of the other. It runs through the entire height and extends through the full width of the dam section. Hence, it justifies the two-dimensional analysis of gravity dams.

9. The foundation pressure used in the pressure grouting is equal to _________________
a) 2.0 D N/cm²
b) 2.5 D N/cm²
c) 5.0 D N/cm²
d) 3.0 D N/cm²
Answer: b
Clarification: The grouting pressure is kept as high as possible without lifting the foundation strata and the pressure used in this grouting is equal to 2.5D. It is carried out only after some portion of the dam section is laid and is generally done in stages of depth equal to 15 m or so.