All Free Civil Engineering MCQs with Answers

• 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…

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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).

• 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).

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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…

• A. Mass of water to mass of dry soil
• B. Mass of water to mass of wet soil
• C. Mass of solids to mass of wet soil
• D. Mass of voids to mass of solids

Explanation: Water content is calculated as the mass of water divided by the mass of soil solids, usually expressed as a percentage.

• A. 25.0 percent
• B. 33.3 percent
• C. 50.0 percent
• D. 66.7 percent

Explanation: Porosity n is related to void ratio e by n = e/(1 + e). Therefore, n = 0.50/1.50 = 0.333, or about 33.3 percent.