Irrigation Engineering Multiple Choice Questions on “Reservoirs”.
1. A dam reservoir which is not provided with gate controls on its spillway and other sluices is called ________________
a) detention dam
b) storage reservoir
c) retarding basin
d) flood control reservoir
Answer: c
Clarification: Storage reservoir is the one having gates and valves installed at its spillway and at its sluice outlets. The retarding basin is the one with uncontrolled and ungated outlets. The cost of gate installation is saved and there are no gates hence, the possibility of human error and negligence in their operation is eliminated.
2. A hydel power project has been envisaged to serve the water supply and irrigation needs of the area at its inception stage. The dam reservoir so constructed is known as __________________
a) multipurpose reservoir
b) single-purpose reservoir
c) distribution reservoir
d) retarding reservoir
Answer: a
Clarification: A reservoir planned and constructed to serve various purposes together is a multipurpose reservoir. It is designed to protect the downstream areas from floods, to conserve water, irrigation, industrial needs, hydroelectric purposes, etc. Bhakra dam and Nagarjuna Sagar dam are important multipurpose dams.
3. A dam reservoir catering to flood control, irrigation, and water supply basically designed for irrigation alone is a _______________-
a) multipurpose reservoir
b) single-purpose reservoir
c) distribution reservoir
d) retarding basins
Answer: b
Clarification: A reservoir planned, designed and constructed for one purpose is called a single purpose reservoir whereas a reservoir planned and constructed to serve various purposes together is a multipurpose reservoir. A small storage reservoir constructed within a city water supply system is called distribution reservoir
4. Which reservoir is also known as Mitigation reservoir?
a) Conservation reservoir
b) Flood control reservoir
c) Multipurpose dam
d) Storage reservoir
Answer: b
Clarification: A flood control reservoir protects the downstream areas by storing a portion of the flood flows to minimize the flood peaks. The entire inflow entering the reservoir is discharged or gradually released to recover the capacity for the next flood. It is also called as a mitigation reservoir.
5. A reservoir having gates and valves installation at its spillway and at its sluice outlets ___________
a) storage reservoir
b) retarding basin
c) both storage and retarding reservoir
d) distribution reservoir
Answer: a
Clarification: Storage reservoir is the one having gates and valves installed at its spillway and at its sluice outlets whereas retarding basin is the one with uncontrolled and ungated outlets. It provides more flexibility in operation and better control.
6. Which reservoir is helpful in permitting the pumps or the water treatment plants to work at a uniform rate?
a) Storage reservoir
b) Detention reservoir
c) Multipurpose reservoir
d) Distribution reservoir
Answer: d
Clarification: A small storage reservoir constructed within a city water supply system is called a distribution reservoir. It stores water during hours of no demand or less demand and supply water from their storage during the critical time of maximum demand.
7. In which of the following reservoir the flood crest downstream can be better controlled and regulated properly?
a) Distribution reservoir
b) Multipurpose reservoir
c) Storage reservoir
d) Retarding reservoir
Answer: c
Clarification: Storage reservoirs are preferred on large rivers and require better control. It is provided with gated spillway and sluiceways for more flexibility of operation, better control and to increase the usefulness of the reservoir.
8. What are the types of flood control reservoirs?
a) Multipurpose reservoir and Single purpose reservoir
b) Storage reservoir and retarding reservoirs
c) Distribution reservoir and Storage reservoir
d) Distribution reservoir and multipurpose reservoir
Answer: b
Clarification: There are two basic types of flood-mitigation reservoirs i.e. storage reservoir and retarding reservoirs. Storage reservoir is the one having gates and valves installed at its spillway and at its sluice outlets whereas the retarding basin is the one with uncontrolled and ungated outlets.
9. As the reservoir elevation increases, the outflow discharge increases.
a) True
b) False
Answer: a
Clarification: When floods occur the reservoir gets filled and discharges through sluiceways and the water level goes on rising until the flood has subsided. The inflow becomes equal or less than the outflow. The water gets completely withdrawn until the stored water is completely discharged.
10. The maximum discharging capacity of a retarding reservoir should not be equal to the maximum safe carrying capacity of the channel downstream.
a) True
b) False
Answer: b
Clarification: Since the retarding reservoir is not always filled much of the land below the maximum reservoir level will be submerged only temporarily and occasionally. The automatic regulation of outflow depends upon the availability of water. The maximum discharging capacity should be equal to the maximum safe capacity of the channel d/s.