Free Hydraulics and Water Resources MCQs with Answers
78 Hydraulics and Water Resources MCQs from Civil Engineering, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Hydraulics studies fluid properties, pressure, buoyancy, continuity, Bernoulli's equation, momentum, pipe flow, open-channel flow and hydraulic machines. Water resources extends these principles to pumps, turbines, reservoirs, irrigation, floods and hydrology, while distinguishing laminar from turbulent flow and uniform from gradually varied channel flow.
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78 questions · page 4 of 4
- A. Cross-sectional area
- B. Pipe elevation
- C. Fluid temperature
- D. Pipe roughness
Explanation: A Venturimeter has a converging section and throat, so the change in area produces a velocity and pressure change that is used to…
Correct answer: Cross-sectional area- A. Discharge is zero
- B. Friction slope equals bed slope
- C. Froude number equals one
- D. Pressure head is zero
Explanation: At normal depth, the flow depth remains constant because the energy slope or friction slope balances the channel bed slope.
Correct answer: Friction slope equals bed slope- A. Power supplied by the generator
- B. Mechanical power lost in bearings
- C. Water power supplied to the turbine
- D. Power available at the tailrace
Explanation: Hydraulic efficiency compares runner power with the water power supplied at the turbine inlet.
Correct answer: Water power supplied to the turbine- A. Increase the atmospheric pressure at suction
- B. Increase the motor speed before starting
- C. Reduce water temperature in the casing
- D. Remove air from the casing and suction pipe
Explanation: Priming fills the pump casing and suction line with liquid and removes trapped air before operation.
Correct answer: Remove air from the casing and suction pipe- A. Maximum rate at which soil can absorb water
- B. Total volume of groundwater in the soil
- C. Rate at which water evaporates from soil
- D. Minimum rainfall needed to cause flooding
Explanation: Infiltration capacity is the maximum rate at which water enters the soil under given conditions.
Correct answer: Maximum rate at which soil can absorb water- A. Critical discharge
- B. Theoretical discharge
- C. Baseflow discharge
- D. Design flood discharge
Explanation: The coefficient of discharge accounts for departures from ideal flow and is defined as actual discharge divided by theoretical discharge.
Correct answer: Theoretical discharge- A. Floodplain drainage
- B. Sediment acceleration
- C. Seasonal regulation
- D. Groundwater evaporation
Explanation: Seasonal regulation stores surplus wet-season inflow and releases it during periods of lower inflow.
Correct answer: Seasonal regulation- A. Increase linearly with channel width only
- B. Decrease approximately as head to the three-halves power
- C. Remain constant at every head
- D. Increase approximately as head to the three-halves power
Explanation: For a broad class of sharp-crested spillways and weirs, discharge varies approximately as H raised to 3/2.
Correct answer: Increase approximately as head to the three-halves power- A. Q = A√(2gH)
- B. Q = 2gAH
- C. Q = AH²/(2g)
- D. Q = A√(H/2g)
Explanation: The theoretical orifice velocity is √(2gH), so multiplying it by area A gives Q = A√(2gH).
Correct answer: Q = A√(2gH)- A. hₑ = KₑD²/(2gV)
- B. hₑ = KₑV²/(2g)
- C. hₑ = 2gKₑV²
- D. hₑ = KₑV/(2gD)
Explanation: Entrance loss is represented by a dimensionless entrance-loss coefficient multiplied by the velocity head, giving hₑ = KₑV²/(2g).
Correct answer: hₑ = KₑV²/(2g)- A. The first power of speed
- B. The square of speed
- C. The cube of speed
- D. The inverse of speed
Explanation: The pump affinity laws give power proportional to the cube of rotational speed when the impeller diameter is unchanged.
Correct answer: The cube of speed- A. Condensation and precipitation
- B. Infiltration and groundwater flow
- C. Surface runoff and channel storage
- D. Evaporation and plant transpiration
Explanation: Evapotranspiration combines evaporation from soil and water surfaces with transpiration from vegetation.
Correct answer: Evaporation and plant transpiration- A. Direct surface runoff volume
- B. Total basin storage
- C. Groundwater recharge volume
- D. Potential evaporation volume
Explanation: The phi-index is an average infiltration rate selected so that rainfall above this rate equals the storm's direct runoff.
Correct answer: Direct surface runoff volume- A. Area irrigated by one unit discharge
- B. Total depth of water required by a crop during its base period
- C. Time between two consecutive irrigations
- D. Percentage of water lost in conveyance
Explanation: Delta is the total depth of water required over the cropped area during the base period of a crop.
Correct answer: Total depth of water required by a crop during its base period- A. Evaporation rate from the reservoir area
- B. Soil texture from the rainfall record
- C. Outflow hydrograph from the known inflow hydrograph
- D. Annual irrigation duty from crop data
Explanation: Reservoir routing uses the inflow hydrograph and storage relationship to calculate how the outflow changes with time.
Correct answer: Outflow hydrograph from the known inflow hydrograph- A. The flow depth
- B. Half the flow depth
- C. Three times the flow depth
- D. Twice the flow depth
Explanation: For the best hydraulic rectangular section, the width is twice the flow depth.
Correct answer: Twice the flow depth77. The theoretical power available from water passing through a hydraulic turbine is proportional to:
- A. ρgQH
- B. ρQ/(gH)
- C. gH/(ρQ)
- D. ρgH/Q
Explanation: The water power supplied to a turbine is ρgQH, where ρ is density, g is gravitational acceleration, Q is discharge, and H is head.
Correct answer: ρgQH- A. Rainfall volume to runoff volume
- B. Runoff volume to rainfall volume
- C. Infiltration volume to rainfall intensity
- D. Evaporation volume to storage volume
Explanation: The runoff coefficient expresses the fraction of rainfall that appears as runoff, so it is runoff volume divided by rainfall volume for…
Correct answer: Runoff volume to rainfall volume