Hydropower Engineering MCQ: Dams, Tunnels, Penstock, Turbines (NEC Chapter 8)

Chapter 8: Hydropower Engineering MCQ

192 questions with answers. Practise by sub-section or take a timed test.

Chapter

Sub-section

Level

Number of questions

Question navigator:

Free practice by EngineeringNepal.com.np. Questions are written and checked by our team; always confirm the current exam format in the official notice.

Hydropower Engineering MCQ: what this set covers

Hydropower is a big part of civil engineering work in Nepal and of NEA and IPP recruitment. These questions follow a project from planning and power calculation through dams, intakes, settling basins, tunnels, surge tanks and penstocks to turbines and the powerhouse.

There are 192 questions in this chapter, each with the answer and a short explanation. Choose a sub-section, pick how many questions you want, and either see the answer straight away or take it as a timed test. Your mistakes are saved in your browser, so you can come back and practise only those.

Code	Sub-section	Questions here
8.1	Hydropower planning and development in Nepal	32
8.2	Power and energy potential	32
8.3	Storage plant headworks	32
8.4	Run-of-river headworks	32
8.5	Water conveyance structures	32
8.6	Turbines and powerhouse	32

Sample questions with answers

A few questions from each sub-section are shown below. Tap a question to see the answer. Use the practice tool above for the full set.

8.1 Hydropower planning and development in Nepal

Nepal's first hydropower plant, commissioned in 1911 AD, is:

Sundarijal
Pharping
Panauti
Trishuli

Answer: B. Pharping hydropower plant, near Kathmandu, was commissioned in 1911 AD (1968 BS) and is the first hydropower plant of Nepal.

The installed capacity of the Pharping hydropower plant was about:

50 kW
5 MW
500 kW
60 MW

Answer: C. Pharping was built with an installed capacity of about 500 kW, mainly to supply electricity to the palaces and the Kathmandu area.

8.2 Power and energy potential

The power output (in kW) of a hydropower plant with discharge Q (m³/s), net head H (m) and overall efficiency η is:

1000 QHη
9.81 QHη
QHη/9.81
QHη/75

Answer: B. P = ρgQHη watts = 1000 × 9.81 × QHη W = 9.81 QHη kW.

A plant uses 10 m³/s under a net head of 50 m with an overall efficiency of 80%. Its power output is:

4905 kW
3924 kW
400 kW
39.24 MW

Answer: B. P = 9.81 × 10 × 50 × 0.8 = 9.81 × 400 = 3924 kW.

8.3 Storage plant headworks

A gravity dam resists the external forces acting on it mainly by:

Arch action transferring load to the abutments
Its own weight
Tension in steel anchors
Buttresses supporting a sloping slab

Answer: B. A gravity dam is a massive concrete or masonry structure whose self weight provides the resisting moment and the friction needed against overturning and sliding.

An arch dam is most suitable for a site having:

A wide valley with deep soft soil
A flat plain with no rock
A narrow gorge with strong rock abutments
A river with a very low head

Answer: C. An arch dam carries much of the water load horizontally to the valley sides by arch action, so it needs a narrow gorge with sound rock abutments.

8.4 Run-of-river headworks

The main function of the headworks of a run-of-river hydropower scheme is to:

Store the monsoon flow for use in the dry season
Divert the design flow into the waterway while limiting sediment entry and passing floods safely
Generate electricity directly
Reduce the tailwater level at the powerhouse

Answer: B. ROR headworks (weir, intake, undersluice, gravel trap, settling basin) divert the required discharge, keep out bed load and debris, and pass floods with little or no storage.

On a curved river reach, the intake of a run-of-river scheme is best located on the:

Inner (convex) bank
Middle of the river bed
Outer (concave) bank
Point bar on the inner bank

Answer: C. Secondary currents at a bend sweep bed load towards the inner bank, while the outer bank has deeper, cleaner water, so an intake on the outer bank draws less sediment.

8.5 Water conveyance structures

In a diversion type hydropower scheme, the low-pressure conduit that carries water from the intake to the forebay or surge tank is the:

Penstock
Headrace
Tailrace
Draft tube

Answer: B. The headrace (canal, pipe or tunnel) runs at a gentle slope under low pressure; the steep high-pressure pipe below the forebay or surge tank is the penstock.

A forebay at the end of a headrace canal mainly serves to:

Provide a smooth transition into the penstock with a small storage, trash rack and spill arrangement
Store water for seasonal regulation
Convert pressure head into velocity head
Release water back to the river below the powerhouse

Answer: A. The forebay is a small pond at the head of the penstock; it supplies short-term demand changes, holds the trash rack and penstock gate, and spills excess water.

8.6 Turbines and powerhouse

A Pelton wheel is classified as:

An axial flow reaction turbine
A mixed flow reaction turbine
A tangential flow impulse turbine
A radial outward flow reaction turbine

Answer: C. In a Pelton wheel a free jet at atmospheric pressure strikes the buckets tangentially; all the available head is converted to velocity in the nozzle, so it is an impulse turbine.

A modern Francis turbine is a:

Mixed flow (radial inward to axial) reaction turbine
Tangential flow impulse turbine
Axial flow impulse turbine
Double-pass cross-flow turbine

Answer: A. Water enters the Francis runner radially inward and leaves axially, and part of the pressure energy is converted in the runner, so it is a mixed flow reaction turbine.

Full mock tests

When you have covered every chapter, take a full NEC licence mock test or Lok Sewa model test. The NEC mock follows the real pattern of 80 questions and 100 marks in 2 hours.