Free Hydraulics and Water Resources MCQs with Answers

• A. A₁V₁ = A₂V₂
• B. A₁P₁ = A₂P₂
• C. V₁ + A₁ = V₂ + A₂
• D. P₁V₁ = P₂V₂

Explanation: The continuity equation states that discharge remains constant, so area multiplied by mean velocity is constant.

• A. It increases because velocity increases
• B. It decreases because velocity increases
• C. It remains constant because elevation is unchanged
• D. It becomes zero at the smaller diameter

Explanation: The smaller area causes velocity to increase according to continuity. Bernoulli's equation then shows that static pressure decreases when…

• A. ρμ divided by VD
• B. μVD divided by ρ
• C. ρVD divided by μ
• D. VD divided by ρμ

Explanation: The Reynolds number is Re = ρVD/μ, or equivalently VD/ν. It compares inertial effects with viscous effects and helps distinguish laminar…

• A. gh divided by ρ
• B. ρg divided by h
• C. ρh divided by g
• D. ρgh

Explanation: Hydrostatic gauge pressure equals the liquid's specific weight multiplied by depth, giving p = ρgh.

• A. Weight of the displaced fluid
• B. Weight of the submerged body
• C. Mass of the displaced fluid
• D. Pressure at the lower surface

Explanation: Buoyant force equals the weight of the fluid displaced by the body. The body's own weight determines whether it rises, remains suspended…

• A. Depth increases rapidly in the flow direction
• B. Depth and mean velocity remain constant along the channel
• C. The water surface is always horizontal
• D. The flow must have a Froude number of one

Explanation: Uniform flow has constant depth, velocity and discharge along the channel.

• A. Zero
• B. Less than one
• C. Equal to one
• D. Greater than one

Explanation: Critical flow is defined by a Froude number of one, where disturbances travel at the same speed as the flow.

• A. Electrical energy into potential energy
• B. Mechanical energy into hydraulic energy
• C. Thermal energy into pressure energy
• D. Hydraulic energy into mechanical energy

Explanation: A turbine extracts energy from flowing or falling water and delivers it as shaft mechanical power.

• A. Supercritical flow to subcritical flow
• B. Subcritical flow to supercritical flow
• C. Uniform flow to laminar flow
• D. Laminar flow to uniform flow

Explanation: A hydraulic jump rapidly changes shallow, fast supercritical flow into deeper, slower subcritical flow.

• A. (D/L)(V²/2g)
• B. (L/D)(V²/2g)
• C. (L/D)(2g/V²)
• D. (D/L)(2g/V²)

Explanation: The Darcy Weisbach relation is h_f = f(L/D)(V²/2g), where f is the friction factor.

• A. The sum of velocity, seepage and pressure heads
• B. The sum of pressure, friction and discharge heads
• C. The sum of pressure, velocity and elevation heads
• D. The sum of elevation, discharge and viscosity heads

Explanation: For steady, incompressible, frictionless flow, the pressure head, velocity head and elevation head have a constant sum.

• A. Hydraulic gradient of the channel
• B. Absolute pressure of the fluid
• C. Square of the flow velocity
• D. Rate of angular deformation

Explanation: A Newtonian fluid follows Newton's law of viscosity, in which shear stress equals dynamic viscosity multiplied by the rate of shear…

• A. Pipe centreline
• B. Pipe wall
• C. Midpoint between wall and centre
• D. Pipe entrance section

Explanation: The no-slip condition makes the fluid velocity zero at the pipe wall. The velocity increases toward the centreline, where it reaches its…

• A. Rate of change of pressure head
• B. Rate of change of momentum flux
• C. Total loss of mechanical energy
• D. Rate of change of fluid viscosity

Explanation: The momentum principle states that the resultant external force equals the rate of change of momentum of the fluid system.

• A. To convert hydraulic energy into shaft work
• B. To convert heat energy into pressure energy
• C. To convert shaft work into hydraulic energy
• D. To convert pressure energy into electrical energy

Explanation: A pump receives mechanical or shaft power and transfers energy to the liquid, increasing its pressure head, velocity head or elevation…

• A. Surface tension and capillary rise
• B. Viscosity and vapour pressure
• C. Density and atmospheric pressure
• D. Velocity and angular momentum

Explanation: The rotating impeller imparts velocity and angular momentum to the water.

• A. Storing excess water for later release
• B. Increasing rainfall over the catchment
• C. Removing all sediment from the river
• D. Preventing evaporation from the water surface

Explanation: Reservoir storage balances variations between inflow and demand by retaining water during periods of high flow and releasing it during low…

• A. Base flow
• B. Direct runoff
• C. Interception loss
• D. Groundwater recharge

Explanation: Direct runoff is the rainfall excess that reaches a stream soon after precipitation, producing the rapid rise of a flood hydrograph.

• A. Abruptly over a short distance
• B. Only at a hydraulic jump
• C. Slowly over a long distance
• D. Only when the channel is circular

Explanation: Gradually varied flow has a small change in depth over a relatively long channel distance, so hydrostatic pressure distribution is usually…

• A. Raise the downstream riverbed
• B. Increase the reservoir storage limit
• C. Measure groundwater infiltration
• D. Release surplus water safely

Explanation: A spillway conveys excess reservoir water downstream when the water level approaches or exceeds the safe operating level.