Irrigation Engineering Multiple Choice Questions on “Various Types of Dams”.
1. Gravity dam is most suitable when the foundation is _______________
a) weak
b) strong
c) with heavy overburden
d) rocky but cracked
Answer: b
Clarification: A gravity dam is the one in which the stability against external load is achieved by the weight of the dam itself. This type of dam requires minimum maintenance. It can be constructed on any site where the natural foundation is strong enough to bear the weight of the dam.
2. Which of the following type of dam is built in areas where the foundation is not strong enough to bear the weight of concrete?
a) Rock-fill dam
b) Earth dam
c) Gravity dam
d) Arch dam
Answer: b
Clarification: An earth dam is built up by compacting successive layers of the earth with vibrating or heavy machinery. It is built in areas where the earth is more easily available as compared to concrete or stone or rock.
3. Which of the following dam is partly earthen and partly rockfill?
a) Tehri dam
b) Koyna dam
c) Sardar Sarovar dam
d) Bhakra dam
Answer: a
Clarification: The Koyna dam is a rubble-concrete dam which is built on Koyna River near Satara district in Maharashtra. The Sardar Sarovar Dam is a gravity dam on the Narmada River, Gujrat and Bhakra dam is also a concrete gravity dam.
4. Idukki dam is a type of ________________
a) rockfill dam
b) a hollow masonry gravity dam
c) arch dam
d) steel dam
Answer: c
Clarification: The Idukki dam is a double curvature arch dam constructed across the Periyar River and has a height of about 170 m. It is one of the highest arch dams in Asia and it was constructed and owned by Kerala State Electricity Board.
5. In which of the following dam the weight of water is carried by a deck of RCC or by arches that share the weight burden?
a) Earth dams
b) Rockfill dams
c) A hollow masonry gravity dam
d) Timber dam
Answer: c
Clarification: The Hollow Masonry Gravity dam contains less concrete or masonry (about 35 to 40%) than solid masonry gravity dam. They are difficult to build and the labor cost is too high to build its complex structure.
6. It is possible to construct steel dam only up to a height of ____________
a) 5 m
b) 10 m
c) 20 m
d) 50 m
Answer: c
Clarification: Steel dams are not in common use and it is possible to build the dam up to a height of 18 to 20 m. They are used as coffer dams for the construction of permanent dams.
7. The temporary structures that are built to enclose certain worksite is ______________
a) storage dam
b) coffer dam
c) timber dam
d) steel dam
Answer: b
Clarification: Coffer dams are temporary structures that are used to divert the flow to enable construction activity in the main river channel. It is also used to enclose certain work site. Steel and timber dams are also used as coffer dams.
8. Which of the following dam is suitable for narrow valleys?
a) Arch dam
b) Steel dam
c) Coffer dam
d) Timber dam
Answer: a
Clarification: An arch dam is that dam in which stability of the dam against external forces is obtained partly due to the weight of the dam and partly due to transferring horizontal pressure to the abutments. The presence of sound abutments is an important requirement and is suitable for narrow valleys.
9. When sand and gravel foundation strata are available at a proposed dam site of moderate height, the dam may be of the type ________________
a) earthen or rockfill dam
b) masonry gravity dam
c) concrete gravity dam
d) double arch dam
Answer: a
Clarification: The piles of loose rocks and boulders in the river bed are nothing but rockfill. On the upstream face of the dam, a slab of reinforced concrete is often laid to make it watertight.
10. According to the Hydraulic design, the dams are classified as _________
a) diversion and detention Dams
b) storage and diversion dams
c) overflow and non-overflow dam
d) arch and buttress dam
Answer: c
Clarification: The dams are classified as Over-flow dam and Non-over flow dam according to the hydraulic design. When water flows over the crest of the dam it is known as the overflow dam. The dams which do not allow water to flow over the crest of the dam is called non-overflow dam.