Correct Answer - Option 4 : None of the above
Concept:
Emergency spillways:
The spillway crest is the uppermost part of the spillway over which water discharge
Different zone of storage of water:
Minimum pool level: The minimum pool level is the lowest level up to which the water is withdrawn from the reservoir under ordinary conditions.
Dead Storage: The volume of water held below the minimum pool level is called dead storage.
Full Reservoir Level (FRL): The FRL is the highest water level to which the water surface will rise during the normal operating conditions.
Maximum Water Level (MWL): The MWL is the maximum level to which the water surface will rise when the design flood passes over the spillway.
Normal Pool Level: For a reservoir with a fixed overflow it is a maximum water level to which water may rise under normal conditions.
The essential requirement of spillway:
1. It must have sufficient capacity
2. Must be hydraulically & structurally adequate
3. Must be so located that it provides safe disposal of water.
4. A spillway is a waterway provided in a dam for carrying the surplus floodwater from a reservoir safely to a downstream river.
Hence spillway crest is located at normal pool level.
