Irrigation Engineering MCQ With Answers for JKSSB Junior Engineer (Civil)

Technical · 2026-10-27 · 6 min read

Irrigation engineering carried 10 marks in the board's earlier Junior Engineer (Civil) syllabus, which lists crop water requirement, the hydrological cycle, dams, canals, headworks, cross-drainage works, river training, waterlogging and drainage, groundwater recharge and well hydraulics. Since 282 of the 458 posts in the 2026 notice are in the Jal Shakti Department, this subject deserves extra time. The board's 2025 paper had 120 one-mark questions in 120 minutes. Our guide to the 2026 notice shows where this section fits. This page gives a revision list, worked problems and solved MCQs.

Quick revision list

  • Crop water: duty, delta and base period, kor depth and kor period, consumptive use, and the kharif and rabi seasons
  • Efficiencies: water conveyance, water application and water use efficiency
  • Canals: alignment on a watershed or ridge so that the canal commands the land on both sides, Kennedy's and Lacey's theories, and the silt factor f = 1.76 √d (d in mm)
  • Headworks: weir versus barrage, and the divide wall, under-sluices and fish ladder
  • Dams: gravity, earth, arch and rock-fill dams, stability of a gravity dam, spillways and stilling basins
  • Cross-drainage works: aqueduct, siphon aqueduct, super-passage and level crossing
  • River training and drainage: guide banks, spurs, groynes, waterlogging, drainage and lining
  • Groundwater: open and tube wells, recharge, and the hydraulics of wells

Worked numerical problems

  • Delta: a crop with a base period of 120 days and a duty of 1,000 hectares per cumec has Δ = 8.64 × 120 ÷ 1,000 = 1.04 m
  • Lacey's silt factor: for silt of 0.25 mm, f = 1.76 × √0.25 = 0.88, and for 1 mm it is 1.76
  • Discharge: a canal with a flow area of 10 m² and a mean velocity of 0.8 m/s carries Q = A × V = 8 cumec
  • Application efficiency: if 4,000 m³ of water is delivered to a field and 3,000 m³ is stored in the root zone, the application efficiency is 3,000 ÷ 4,000 = 75%
  • Duty from delta: a larger delta for the same base period means a smaller duty, because D = 8.64 × B ÷ Δ
  • Command area: a canal with a discharge of 2 cumec at a duty of 1,500 hectares per cumec commands about 3,000 hectares

Canals and cross-drainage works in brief

A canal laid along a watershed line, or ridge, commands land on both sides and needs no cross-drainage works, which is why it is the preferred alignment. Where a canal still meets a natural drain, a cross-drainage work is needed. In an aqueduct the canal passes over the drainage, and in a super-passage the drainage passes over the canal. A siphon aqueduct is an aqueduct in which the drain runs below the bed of the canal, and a level crossing is used when the canal and drain are at about the same level, with regulators to control the flow.

Common mistakes

  • Using the wrong units in the delta formula: B is in days and D is in hectares per cumec
  • Mixing up an aqueduct (canal above the drain) with a super-passage (drain above the canal)
  • Treating a weir and a barrage as the same: a barrage has gates that control the river level
  • Forgetting the middle-third rule for a gravity dam

Dams and spillways in brief

A gravity dam is checked for overturning, sliding and the stress at the base. The forces on it are its own weight, the water pressure, uplift, silt pressure and the earthquake force. An earth dam has a wide section with a core or lining to control seepage, and its spillway is kept separate from the embankment. A spillway lets surplus flood water pass safely, and the ogee crest is the usual shape because it follows the underside of the falling sheet of water.

Practise

Work the solved questions below, then read the Junior Engineer (Civil) guide for the dates and the marks for every subject. The other subject pages in this series cover surveying, soil mechanics, fluid mechanics and RCC.

By Shivam · Written with AI assistance and fact-checked · Questions on this page are original · Editorial policy · Report an error

Practice questions

Q1. The duty of water is the:

  1. Depth of water applied to a crop
  2. Area irrigated per unit discharge of water
  3. Volume of a reservoir
  4. Time taken to irrigate a field
Show answer

Area irrigated per unit discharge of water — Duty is expressed in hectares per cumec over the base period.

Q2. The delta of a crop is the:

  1. Total depth of water required by the crop during its base period
  2. Area irrigated per cumec
  3. Time between two watering
  4. Discharge of the canal
Show answer

Total depth of water required by the crop during its base period — It is the depth of water, measured over the whole field, needed by the crop.

Q3. The relation between delta, duty and base period is:

  1. Δ = 8.64 D ÷ B
  2. Δ = B ÷ (8.64 D)
  3. Δ = 864 B × D
  4. Δ = 8.64 B ÷ D
Show answer

Δ = 8.64 B ÷ D — Δ is in metres, B in days and D in hectares per cumec.

Q4. A crop with a base period of 120 days and a duty of 1,000 hectares per cumec has a delta of about:

  1. 0.104 m
  2. 10.4 m
  3. 1.04 m
  4. 0.52 m
Show answer

1.04 m — Δ = 8.64 × 120 ÷ 1,000 = 1.0368 m.

Q5. The crops sown in October-November and harvested in March-April belong to the:

  1. Kharif season
  2. Rabi season
  3. Zaid season
  4. Monsoon season
Show answer

Rabi season — Kharif crops are sown with the monsoon in June-July.

Q6. The first watering given to a crop soon after its sowing is called:

  1. Kor watering
  2. Palewa
  3. Delta
  4. Base watering
Show answer

Kor watering — Kor watering is the first watering after sowing. Palewa is the watering given before sowing.

Q7. Water application efficiency is the ratio of:

  1. Water delivered to the field to water diverted at the headworks
  2. Water used by the crop to water lost to evaporation
  3. Rainfall to water applied
  4. Water stored in the root zone to water delivered to the field
Show answer

Water stored in the root zone to water delivered to the field — It measures the losses in the field itself.

Q8. A canal aligned along a watershed:

  1. Needs many cross-drainage works
  2. Commands only one side
  3. Commands land on both sides and needs few cross-drainage works
  4. Cannot carry water
Show answer

Commands land on both sides and needs few cross-drainage works — A ridge canal is the best alignment for this reason.

Q9. In Lacey's regime theory, the silt factor for silt of size d mm is:

  1. 0.55 d
  2. 1.76 √d
  3. 1.76 d²
  4. 0.55 √d
Show answer

1.76 √d — f = 1.76 √d, so a coarser silt has a higher silt factor.

Q10. The silt factor of 0.25 mm silt is:

  1. 0.88
  2. 1.76
  3. 0.44
  4. 0.50
Show answer

0.88 — f = 1.76 × √0.25 = 1.76 × 0.5 = 0.88.

Q11. A canal with a cross-section of 10 m² and a mean velocity of 0.8 m/s carries a discharge of:

  1. 12.5 cumec
  2. 80 cumec
  3. 0.08 cumec
  4. 8 cumec
Show answer

8 cumec — Q = A × V = 10 × 0.8 = 8 m³/s.

Q12. The main difference between a weir and a barrage is that a barrage:

  1. Has no gates
  2. Is built of earth
  3. Has gates to control the river level
  4. Is built only on hill streams
Show answer

Has gates to control the river level — A barrage regulates the flow with gates, while a weir holds up the water with a fixed crest.

Q13. A gravity dam resists the water thrust mainly by:

  1. The arch action
  2. Its own weight
  3. The tensile strength of concrete
  4. Steel reinforcement
Show answer

Its own weight — The dam's weight and the thrust give a resultant that must stay within the middle third of the base.

Q14. For a gravity dam to have no tension at the base, the resultant should fall within the:

  1. Middle third of the base
  2. Upstream third of the base
  3. Downstream edge of the base
  4. Centre of the dam only
Show answer

Middle third of the base — A resultant inside the middle third gives compression over the whole base.

Q15. The structure that carries a canal over a natural drainage is called an:

  1. Super-passage
  2. Level crossing
  3. Inlet
  4. Aqueduct
Show answer

Aqueduct — In a super-passage the drainage passes over the canal.

Q16. In a super-passage:

  1. The canal passes over the drainage
  2. The canal and drain meet at the same level
  3. The drainage passes over the canal
  4. The canal is carried in a tunnel
Show answer

The drainage passes over the canal — It is the reverse of an aqueduct.

Q17. Waterlogging of irrigated land is caused mainly by:

  1. Heavy rain in winter
  2. A rise of the water table to the root zone
  3. A fall of the water table
  4. Excess use of fertiliser
Show answer

A rise of the water table to the root zone — Seepage from canals and over-irrigation raise the water table.

Q18. The purpose of lining an irrigation canal is to:

  1. Reduce seepage losses and control erosion
  2. Increase the seepage
  3. Increase the roughness
  4. Make the canal wider
Show answer

Reduce seepage losses and control erosion — A lined canal also has a higher velocity and needs a smaller section.

Q19. River training works such as guide banks are used to:

  1. Increase the silt load
  2. Reduce the water depth
  3. Store the river water
  4. Guide the river flow and protect structures
Show answer

Guide the river flow and protect structures — Guide banks train the river through a bridge or headworks.

Q20. A stilling basin below a spillway is provided to:

  1. Store the water
  2. Increase the velocity
  3. Dissipate the energy of the falling water
  4. Raise the water level
Show answer

Dissipate the energy of the falling water — A hydraulic jump forms in it and destroys the excess energy.

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