Junior Engineer • 2025 • PAPER-III D (Technical Subject)
Which factor has the most significant impact on the duty of water in an irrigation system?
A)
Type of irrigation method
B)
Rainfall in the region
C)
Soil fertility
D)
Crop maturity duration
Option A is correct: Type of irrigation method.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
What is the typical range of Manning’s roughness coefficient for concrete-lined canals?
A)
0.002 — 0.005
B)
0.006 — 0.009
C)
0.012 — 0.017
D)
0.02 — 0.03
Option C is correct: 0.012 — 0.017.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
Using Manning’s formula, determine the velocity of flow in a canal with: Hydraulic radius (R) = 1.5 m, Slope (S) = 0.0003, Manning’s coefficient (n) = 0.025
A)
0.908 m/s
B)
0.851 m/s
C)
0.932 m/s
D)
0.899 m/s
Option A is correct: 0.908 m/s.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
The main source of irrigation in India is-
A)
Wells
B)
Canals
C)
Rainwater
D)
Lakes
Option C is correct: Rainwater.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
Calculate the intensity of irrigation if the Gross Command Area (GCA) is 5000 hectares and the Culturable Command Area (CCA) is 4000 hectares.
A)
80%
B)
75%
C)
85%
D)
90%
Option A is correct: 80%.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
If a rain gauge recorded 50 mm of rainfall in 10 hours, what is the average intensity of rainfall?
A)
2.5 mm/hr
B)
5 mm/hr
C)
7.5 mm/hr
D)
10mm/hr
Option B is correct: 5 mm/hr.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
Irrigation canals are generally aligned along-
A)
Ridgeline
B)
Valley line
C)
Contour line
D)
Both (a) & (b) as per the design requirement
Option D is correct: Both (a) & (b) as per the design requirement.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
Which of the following is NOT a type of irrigation?
A)
Drip irrigation
B)
Sprinkler irrigation
C)
Aquifer irrigation
D)
Surface irrigation
Option C is correct: Aquifer irrigation.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
Why does the duty of water increase as it moves downstream?
A)
Water loss due to infiltration
B)
Water use efficiency improves
C)
Reduction in seepage losses
D)
Increased evaporation
Option A is correct: Water loss due to infiltration.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
Why does sandy soil require more frequent irrigation than clayey soil?
A)
Sandy soil has a lower infiltration rate
B)
Sandy soil has a lower water-holding capacity
C)
Clayey soil allows rapid water movement
D)
Clayey soil loses more water due to evaporation
Option B is correct: Sandy soil has a lower water-holding capacity.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
Which of the following is NOT an effect of waterlogging?
A)
Reduced soil aeration
B)
Enhanced root respiration
C)
Increased salinity levels
D)
Stunted plant growth
Option B is correct: Enhanced root respiration.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
What happens if the base period of a crop is increased while keeping Delta constant?
A)
The duty increases
B)
The duty decreases
C)
The duty remains unchanged
D)
The depth of irrigation increases
Option B is correct: The duty decreases.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
How does drip irrigation help in reducing field irrigation requirement?
A)
By minimizing runoff
B)
By increasing infiltration
C)
By delivering water directly to the root zone
D)
All of the above
Option D is correct: All of the above.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
What is the major disadvantage of side slope canals?
A)
High construction cost
B)
Excessive water loss due to seepage
C)
Prone to landslides and slope instability
D)
Requires pumping stations
Option C is correct: Prone to landslides and slope instability.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
Which of the following factors does NOT influence canal alignment?
A)
Topography of the region
B)
Type of soil
C)
Number of people in the command area
D)
Availability of cross-drainage structures
Option C is correct: Number of people in the command area.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
Which statement best describes the relationship between Delta, Duty, and Base Period?
A)
Higher Delta leads to lower Duty
B)
Lower Base Period increases Delta
C)
Duty is independent of Base Period
D)
Higher Duty reduces Base Period
In irrigation engineering, Duty (D), Delta (Δ), and Base Period (B) are related by the standard relation: D = 8.64 B / Δ (with consistent units). This shows that for a given base period, Delta is inversely proportional to Duty, and for a given Delta, Duty is directly proportional to Base Period. Therefore, if the Base Period is lower, the Delta required for the same duty becomes higher; equivalently, lower Base Period increases Delta. Hence option (b) is correct.
Why the others are incorrect:
- (a) Higher Delta leads to lower Duty: this is true in general from the formula, but the option asks for the best relationship among the given statements; option (b) is the direct and correctly framed implication here.
- (c) Duty is independent of Base Period: incorrect, because Duty is directly proportional to Base Period.
- (d) Higher Duty reduces Base Period: incorrect, because for a fixed Delta, higher Duty implies a higher Base Period, not a lower one.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
A wheat crop has a base period of 120 days and requires a total depth of water (Delta) of 60 cm. Calculate the Duty (in hectares per cumec).
A)
172.8 ha/cumec
B)
185.5 ha/cumec
C)
150.2 ha/cumec
D)
160.0 ha/cumec
Option A is correct: 172.8 ha/cumec.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
Why do crops grown in dry climates typically develop deeper root systems compared to crops grown in humid climates?
A)
Dry climates have higher soil fertility
B)
Dry climates provide more groundwater recharge
C)
Roots grow deeper to access moisture stored at lower depths
D)
Higher temperature forces roots to extend horizontally
Option C is correct: Roots grow deeper to access moisture stored at lower depths.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
What is waterlogging in agricultural fields?
A)
Condition where soil lacks organic matter
B)
Condition where soil contains excessive water, reducing air availability
C)
A method of irrigation
D)
Process of adding fertilizers to soil
Option A is correct: Condition where soil lacks organic matter.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
Which of the following irrigation methods is best suited for sandy soil?
A)
Sprinkler irrigation
B)
Drip irrigation
C)
Flood irrigation
D)
Furrow irrigation
Option B is correct: Drip irrigation.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
What is the significance of Kennedy’s silt theory in canal design?
A)
It determines the amount of sediment in a canal
B)
It helps design non-scouring and non-silting canals
C)
It calculates the velocity of flow in irrigation canals
D)
It determines the type of canal lining to use
Option B is correct: It helps design non-scouring and non-silting canals.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
Which formula is used to calculate the velocity of flow in an open irrigation canal?
A)
Bernoulli’s equation
B)
Chezy’s formula
C)
Darcy’s law
D)
Reynolds number
Option B is correct: Chezy’s formula.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
Which of the following is NOT a type of canal alignment?
A)
Watershed canal
B)
Contour canal
C)
Side slope canal
D)
Lateral canal
Option D is correct: Lateral canal.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
What does a hydrograph represent?
A)
Changes in groundwater table over time
B)
Flow variations in a stream over time
C)
Rainfall intensity variations
D)
Soil moisture variations
Option B is correct: Flow variations in a stream over time.
Junior Engineer • 2025 • PAPER-III D (Technical Subject)
Which is the most water-efficient irrigation method?
A)
Furrow irrigation
B)
Sprinkler irrigation
C)
Drip irrigation
D)
Flood irrigation
Option C is correct: Drip irrigation.
