This set of Irrigation Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Types of Canal Escapes”.
1. What is the main purpose of the canal escape?
a) To Maintain Uniform Flow in the Canal
b) To Remove Surplus Water
c) To Maintain Constant Velocity of the Flow
d) To Help for Proper Hydraulic Jump
Explanation: The canal escape is a side channel constructed to remove surplus amounts of water from an irrigation channel such as main canal, branch canal, distributary canal etc into the natural drain.
2. Which of the following is a reason for surplus water present in a canal?
a) No Fall
b) No Proper Hydraulic Jump
c) No Proper Uniform Velocity of Flow
d) Cultivators closing their outlets thinking their demand is over
Explanation: The presence of the surplus amount of water in canal can be due to difficulty in regulation at the head or due to heavy rainfall or due to cultivators closing their outlets suddenly thinking that the demand of water is over.
3. What is the other name for canal escape?
a) Canal Outlet
c) Surplus Water Escape
d) Canal Inlet
Explanation: Due to reasons for surplus amount of water to be present in the canal, the supplies shall be reduced or stopped from the head works. Therefore in order to avoid this damage immediate action is needed. This can be achieved by the means of an escape generally called surplus water escape.
4. In case of breaches in the canal, the escape present in the upstream of the breach is opened.
Explanation: In case if a breach occurs in a canal then immediate information is sent to the head to close the canal supplies immediately. But the water present from head to breach will cause damage if passed through the breach. So, therefore the escape existing on the upstream of the breach is opened to allow the water through the escape.
5. The canal escapes are safety valves that should be provided at regular intervals.
Explanation: To minimize the damage from a breach or any such leakages causing surplus of water to be present in the canal the canal escapes should be present at regular intervals depending upon the importance of the channel and it’s availability of a suitable drainage for the disposal of the escaped water.
Explanation: In this type of escape the crest of the weir wall is kept at RL equal to canal FSL. When the water level rises up FSL it gets escaped.
7. What type of escape is preferred these days?
a) Weir Type Escape
b) Venturi Flume
c) Regular Type Escape
d) Tail Escape
Explanation: In this type of escape the flow is controlled by gates and the sill of the escape is kept at bed level. These types of escape give better control and can be used for completely emptying the canal. Hence these types of escapes are preferred these days.
8. What is the other name given to weir type escape?
a) Surplus Water Escape
b) Venturi Flume
c) Tail Escape
d) Scouring Escape
Explanation: The weir type escape is generally provided at the tail end of the canal and is used to maintain the required FSL in the tail reaches of the canal. Hence the name tail escape.
9. What is the purpose of the regulator type escape?
a) To Remove Excess Silt
b) To Maintain Uniform Flow in the Canal
c) To Perform Proper Hydraulic Jump
d) For Distribution of Discharge for the Canals
Explanation: The purpose of the construction of a regulator type escape is to scour off excess bed silt deposited in the bed reaches from time to time. Therefore, it is also called as scouring escape.
10. Scouring escapes have become obsolete because of?
b) Weir Walls
d) Silt Ejectors
Explanation: When the deposited silt is to be scoured out, a discharge higher than the full supply discharge is let off into the canal from its head. To produce scouring velocities the gates are raised, to scour out the silt deposited. A cross regulator may also be provided for better efficiency just the downstream of scouring escape. Therefore, scouring escapes have become obsolete because silt ejectors are used nowadays for better efficiency.
Sanfoundry Global Education & Learning Series – Irrigation Engineering.
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