Civil Engineering PE Hydraulics and Open-Channel Flow Questions and Answers

Question 1

A trapezoidal concrete channel has a bottom width of 8 ft, side slopes of 2H:1V, and a longitudinal slope of 0.0016.
If the channel is flowing at a uniform depth of 4 ft and has a Manning's roughness coefficient (n) of 0.013, the discharge (Q) is most nearly:

Accepted Answer

1,640 cfs

Answer

425 cfs

Answer

810 cfs

Answer

1,250 cfs

Question 2

Water flows in a rectangular channel at a velocity of 20 ft/s and a depth of 1.5 ft. A hydraulic jump forms downstream. The depth of flow immediately after the jump (the sequent depth) is most nearly:

Accepted Answer

6.9 ft

Answer

3.8 ft

Answer

5.1 ft

Answer

8.2 ft

Question 3

A horizontal pipe experiences a sudden enlargement from a diameter of 6 inches to 12 inches. If the velocity in the 6-inch pipe is 10 ft/s, what is the head loss due to this sudden expansion?

Accepted Answer

0.87 ft

Answer

0.29 ft

Answer

0.58 ft

Answer

1.16 ft

Question 4

Which of the following statements is true regarding the Hydraulic Grade Line (HGL) and the Energy Grade Line (EGL) for a steady, uniform flow in a straight, prismatic open channel?

Accepted Answer

The HGL is parallel to the EGL, and both are parallel to the channel bed.

Answer

The EGL is horizontal, while the HGL slopes downward.

Answer

The HGL coincides with the water surface, and the EGL is horizontal.

Answer

The HGL and EGL are coincident and slope downward.

Question 5

Flow in an open channel is defined as critical when:

Accepted Answer

The discharge is maximum for a given specific energy.

Answer

The Reynolds number is equal to 2000.

Answer

The specific energy is at its maximum for a given discharge.

Answer

The velocity head is equal to twice the hydraulic depth.

Question 6

A pump is installed in a pipeline to move water from a lower reservoir to a higher reservoir. Which of the following best describes the effect of the pump on the Energy Grade Line (EGL) and Hydraulic Grade Line (HGL)?

Accepted Answer

An abrupt vertical rise in both the EGL and HGL at the pump's location.

Answer

A gradual, steady rise in both the EGL and HGL over the length of the pump.

Answer

An abrupt vertical drop in both the EGL and HGL at the pump's location.

Answer

A rise in the EGL but a drop in the HGL at the pump's location.