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Fluid Mechanics(8)Hydraulics(16)Hydrology(12)Irrigation(5)

Fluid Mechanics

8 Questions

GATE→2026→Water Resources Engineering→Fluid Mechanics

Q1

MCQ[1 Mark]

Two reservoirs having different water levels are connected by two long parallel pipelines of same length and same material but having diameters of 600 mm and 400 mm. Using Darcy-Weisbach equation, the ratio of flowrate of water in the bigger diameter pipe to that in the smaller diameter pipe is

(A)

0.54

(B)

1.22

(C)

1.84

(D)

2.76

Explanation

GATE→2026→Water Resources Engineering→Fluid Mechanics

Q2

MCQ[2 Marks]

In a laminar flow of a Newtonian fluid through a circular pipe of radius 5 cm, the maximum velocity is found to be 2 m/s. The velocity (in m/s) at a radial distance of 2.50 cm from the axis is

(A)

1.00

(B)

1.25

(C)

1.50

(D)

1.75

Explanation

GATE→2026→Water Resources Engineering→Fluid Mechanics

Q3

NAT[2 Marks]

Maximum demand 12 MLD. For rectangular sedimentation tank with depth 4 m, detention period 6 hours, and flow velocity 0.003 m/s, the width (in m) of the tank is

Explanation

GATE→2025→Water Resources Engineering→Fluid Mechanics

Q4

MSQ[1 Mark]

For Bernoulli's equation to be applicable in fluid flow, which conditions must be satisfied:

(A)

Fluid should be frictionless

(B)

Fluid should be incompressible

(C)

Flow should be steady

(D)

Flow should be rotational

Explanation

GATE→2024→Water Resources Engineering→Fluid Mechanics

Q5

MCQ[2 Marks]

Flow velocity vector $\vec{V} = 3\hat{i} + (5x)\hat{j}$. The correct statement is:

(A)

Fluid is incompressible and flow is rotational

(B)

Fluid is incompressible and flow is irrotational

(C)

Fluid is compressible and flow is rotational

(D)

Fluid is compressible and flow is irrotational

Explanation

GATE→2024→Water Resources Engineering→Fluid Mechanics

Q6

NAT[2 Marks]

A tank with inflow and outflow mechanisms modeled by differential equation. Mass of salt (in grams) in the tank at 75% of its capacity is

Explanation

GATE→2024→Water Resources Engineering→Fluid Mechanics

Q7

NAT[2 Marks]

A $5\text{ m} \times 5\text{ m}$ closed tank containing water and oil connected to overhead reservoir. Total force (in kN) due to pressure on side PQR is

Explanation

GATE→2022→Water Resources Engineering→Fluid Mechanics

Q8

MCQ[1 Mark]

Match fluid flow forces in Column X (P: Viscosity, Q: Gravity, R: Compressibility, S: Pressure) with dimensionless numbers in Column Y.

(A)

(P)-(II), (Q)-(IV), (R)-(I), (S)-(III)

(B)

(P)-(III), (Q)-(IV), (R)-(I), (S)-(II)

(C)

(P)-(IV), (Q)-(II), (R)-(I), (S)-(III)

(D)

(P)-(II), (Q)-(IV), (R)-(III), (S)-(I)

Explanation

Hydraulics

16 Questions

GATE→2026→Water Resources Engineering→Hydraulics

Q9

MSQ[1 Mark]

Which of the following options is/are NOT correct when matching GVF profiles (M1, M2, M3) with channel bed slopes?

(A)

(P)-(I); (Q)-(II); (R)-(I)

(B)

(P)-(I); (Q)-(II); (R)-(III)

(C)

(P)-(II); (Q)-(I); (R)-(I)

(D)

(P)-(I); (Q)-(III); (R)-(II)

Explanation

GATE→2026→Water Resources Engineering→Hydraulics

Q10

MCQ[2 Marks]

For a hydraulic jump formed in a rectangular horizontal channel, the sequent depth ratio is 2. The Froude number of supercritical stream is

(A)

$\sqrt{3}$

(B)

$\sqrt{5}$

(C)

$\sqrt{6}$

(D)

$\sqrt{8}$

Explanation

GATE→2026→Water Resources Engineering→Hydraulics

Q11

NAT[2 Marks]

A wide unlined channel carries water at depth 1 m. Max permissible bed tractive stress = $10 \text{ N/m}^2$. Maximum bed slope 1 in $n$. The value of $n$ is

Explanation

GATE→2025→Water Resources Engineering→Hydraulics

Q12

MCQ[1 Mark]

For a flowing fluid, a dimensionless combination of velocity ($V$), length scale ($l$), and acceleration due to gravity ($g$) would be

(A)

V^2/gl

(B)

Vg/l

(C)

gl^2/V

(D)

l/V^2g

Explanation

GATE→2025→Water Resources Engineering→Hydraulics

Q13

NAT[2 Marks]

Hydraulic jump in 5 m wide rectangular channel, discharge 15 m3/s, upstream depth 0.5 m. Power dissipated is

Explanation

GATE→2025→Water Resources Engineering→Hydraulics

Q14

NAT[2 Marks]

5 m wide rectangular channel carries 10 m3/s at 1.5 m depth. To produce critical flow without affecting upstream, channel bottom raised by

Explanation

GATE→2024→Water Resources Engineering→Hydraulics

Q15

MCQ[1 Mark]

The number of degrees of freedom for a natural open channel flow with a mobile bed is

(A)

2

(B)

3

(C)

4

(D)

5

Explanation

GATE→2024→Water Resources Engineering→Hydraulics

Q16

NAT[2 Marks]

Round bottom triangular canal with bed slope 1 in 200, Chezy coefficient $150\text{ m}^{1/2}/\text{s}$. Normal depth $y$ (in meters) for discharge $20\text{ m}^3/\text{s}$ is

Explanation

GATE→2024→Water Resources Engineering→Hydraulics

Q17

NAT[2 Marks]

A spillway has unit discharge $7.5\text{ m}^3/\text{s/m}$. Downstream flow depth is 0.5 m. Tail water depth (in meters) required to form hydraulic jump is

Explanation

GATE→2023→Water Resources Engineering→Hydraulics

Q18

MCQ[1 Mark]

When a supercritical stream enters a mild-sloped (M) channel section, the type of flow profile would become

(A)

M1

(B)

M2

(C)

M3

(D)

M1 and M2

Explanation

GATE→2023→Water Resources Engineering→Hydraulics

Q19

MCQ[2 Marks]

Wide rectangular channel ($q = 70\text{ m}^3/\text{s/m}$) bed slope changes from 0.0001 (mild) to 0.0009 (steep) at point P. Water surface profile(s) near point P:

(A)

M2 and S2

(B)

M2 only

(C)

S2 only

(D)

S2 and hydraulic jump

Explanation

GATE→2023→Water Resources Engineering→Hydraulics

Q20

MCQ[2 Marks]

A water jet of velocity $20\text{ m/s}$ strikes radial plates revolving at $15\text{ m/s}$ in same direction. Percentage efficiency of plates is

(A)

37.5

(B)

66.7

(C)

50.0

(D)

88.9

Explanation

GATE→2023→Water Resources Engineering→Hydraulics

Q21

NAT[2 Marks]

Hydraulic jump in 1.0 m wide horizontal rectangular channel, pre-jump depth 0.2 m, post-jump depth 1.0 m ($g = 10\text{ m/s}^2$). Specific force at pre/post-jump sections (in $\text{m}^3$) is

Explanation

GATE→2022→Water Resources Engineering→Hydraulics

Q22

MCQ[1 Mark]

Rectangular channel with GVF. If bed slope changes from steeper slope to steep slope, resulting GVF profile is

(A)

S3

(B)

S1

(C)

S2

(D)

either S1 or S2

Explanation

GATE→2022→Water Resources Engineering→Hydraulics

Q23

NAT[2 Marks]

Two reservoirs connected by two parallel pipes of equal length and diameters 20 cm and 10 cm. Water level difference 5 m. Ratio of discharge in larger to smaller pipe is

Explanation

GATE→2022→Water Resources Engineering→Hydraulics

Q24

NAT[2 Marks]

A 3 m wide rectangular channel carries $12\text{ m}^3/\text{s}$ at 2 m depth. Bed width at contraction causing critical flow without changing upstream water level is

Explanation

Hydrology

12 Questions

GATE→2026→Water Resources Engineering→Hydrology

Q25

NAT[2 Marks]

A fully-penetrating well in an unconfined aquifer with pumping rate $63 \text{ m}^3/s$ and drawdowns at observation wells. Transmissibility (in $\text{m}^2/s$) is

Explanation

GATE→2026→Water Resources Engineering→Hydrology

Q26

NAT[2 Marks]

A bridge with expected life of 50 years is designed for a flood corresponding to a return period of 100 years. The risk associated with this design is

Explanation

GATE→2026→Water Resources Engineering→Hydrology

Q27

NAT[2 Marks]

Rainfall intensity-duration relationship $I = 25/(t+10)$ on a 7 ha plot with runoff coefficient 0.60 and entry times. Design storm-sewer flowrate (in $\text{m}^3/\text{h}$) is

Explanation

GATE→2025→Water Resources Engineering→Hydrology

Q28

MCQ[1 Mark]

To derive total flood hydrograph at a catchment outlet, the order of applied methods from first to last is P (Hyetograph), Q (Baseflow), R (Losses), S (Unit hydrograph)

(A)

PRSQ

(B)

PQRS

(C)

RPSQ

(D)

PSQR

Explanation

GATE→2025→Water Resources Engineering→Hydrology

Q29

NAT[1 Mark]

A water resources project with expected life of 25 years is designed for an acceptable risk of 5%. The return period for design flood is

Explanation

GATE→2025→Water Resources Engineering→Hydrology

Q30

MCQ[2 Marks]

Mean rainfall over a catchment estimated using 4 rain gauges with given Thiessen weights and rainfall values. Which statement is correct:

(A)

Estimate from Thiessen-mean method is greater than arithmetic-mean

(B)

Estimate from Thiessen-mean method is equal to arithmetic-mean

(C)

Estimate from Thiessen-mean method is less than arithmetic-mean

(D)

Thiessen-mean method cannot be applied

Explanation

GATE→2024→Water Resources Engineering→Hydrology

Q31

NAT[1 Mark]

A 30 cm diameter well fully penetrates an unconfined aquifer of thickness 20 m and $k = 10$ m/day. Steady drawdowns at 10 m and 100 m are 5 m and 1 m. Pumping rate (in $\text{m}^3/\text{day}$) is

Explanation

GATE→2024→Water Resources Engineering→Hydrology

Q32

NAT[2 Marks]

Return period of an earthquake is 200 years. Assuming Poisson's distribution, the probability that it will be exceeded at least once in 50 years (%) is

Explanation

GATE→2024→Water Resources Engineering→Hydrology

Q33

NAT[2 Marks]

Ordinates of a 1-hour unit hydrograph given. Peak discharge (in $\text{m}^3/\text{s}$) for derived 3-hour UH is

Explanation

GATE→2023→Water Resources Engineering→Hydrology

Q34

NAT[1 Mark]

One-hour unit hydrograph ordinates given. D-hour UH derived with ordinates $3\text{ m}^3/\text{s}$ at $t=1$ h and $10\text{ m}^3/\text{s}$ at $t=2$ h. Value of D is

Explanation

GATE→2023→Water Resources Engineering→Hydrology

Q35

NAT[2 Marks]

Horton's equation parameters: initial capacity $10\text{ mm/h}$, final $5\text{ mm/h}$, decay constant $0.5/\text{h}$. Total infiltration depth (in mm) from a 12h storm is

Explanation

GATE→2022→Water Resources Engineering→Hydrology

Q36

NAT[2 Marks]

Two-hour storm with 3 cm excess rainfall. Streamflow ordinates given. Constant baseflow $10\text{ m}^3/\text{s}$. Peak flow ordinate (in $\text{m}^3/\text{s}$) of 1-hour unit hydrograph is

Explanation

Irrigation

5 Questions

GATE→2026→Water Resources Engineering→Irrigation

Q37

MCQ[1 Mark]

An irrigation canal is to be designed to deliver 10 cumec to meet the peak demand of 7500 hectare of cropped area. The estimated canal losses are 50% of the head discharge. The duty (in hectare/cumec) on capacity of this canal is

(A)

375

(B)

1125

(C)

1500

(D)

1875

Explanation

GATE→2025→Water Resources Engineering→Irrigation

Q38

MSQ[2 Marks]

Regarding Lacey's regime equations ($D = 0.470(Q/f_s)^{1/3}$, $P = 4.75\sqrt{Q}$, $f_s = 1.76\sqrt{d}$), which statements are true:

(A)

D is depth of scour below existing riverbed

(B)

P is Lacey's waterway width

(C)

d is average grain size diameter in centimeters

(D)

D is depth of scour below design flood level

Explanation

GATE→2025→Water Resources Engineering→Irrigation

Q39

NAT[2 Marks]

Symmetrical trapezoidal canal 100 km long, bottom width 10 m, side slope 1H:1V. Depth 2.5 m in April. Evaporation 0.5 cm/day. Volume evaporated is

Explanation

GATE→2023→Water Resources Engineering→Irrigation

Q40

NAT[1 Mark]

Canal supplies 100 hectares over 120 days (35 cm depth). Most intense watering over 30 days requires 12 cm depth. Minimum canal discharge (in $\text{m}^3/\text{s}$) is

Explanation

GATE→2022→Water Resources Engineering→Irrigation

Q41

MSQ[2 Marks]

In the context of cross-drainage structures, the correct statement(s) regarding relative positions of natural drain and irrigation canal is/are

(A)

In aqueduct, natural drain goes under canal, in super-passage natural drain goes over canal

(B)

In level crossing, natural drain goes through canal

(C)

In aqueduct, natural drain goes over canal

(D)

In canal syphon, natural drain goes through canal

Explanation