The area, on which crops are grown in a particular season, is called
Cuiturable area is the cultivable part of the gross command area, and includes all land of GCA on which cultivation is possible. At any given time, all the cultivable land may not be actually, under cultivation.
The canal, which can irrigate only on one side, is a
A contour canal irrigates only on one side because the area on the other sides is higher.
The capacity of an irrigation canal is usually controlled by
The canal which is not supposed to do any irrigation is called
The following structure serves the purpose of a ‘safety valve’ for a canal
Canal escapes are the safety valves of canal and must be provided at regular intervals depending upon the importance of the canal and availability of suitable drainage. Minimum capacity of escape is generally kept as half of the channel capacity at the point of escape.
The following data pertain to a natural drain crossing an irrigation canal
Which one of the following types of cross-drainage should be recommended in this case?
The difference in bed level of the canal and drainage is 4 m while the flow depth in drainage is 10 m. Thus HFL of drain at 126 m is higher than the canal bed at 120 m. Therefore syphon aqueduct is most suitable.
What type of cross drainage work is provided when the canal runs below the drain, with FSL of canal well below the bed of the drain?
If bed level of canal is sufficiently above the HFL of the drain, an aqueduct is the right choice. Sometimes bed level of canal may be little below the HFL of drain so that water flows under syphonic action. This structure is known as aqueduct syphon.If bed level of the drain is sufficiently above the canal FSL, a super passage may be constructed. If the canal FSL is little above bed level of drain to allow syphonic action, the structure is called Canal Syphon. Aqueduct or superpassage type of drainage works are used when high flood discharge is large and continues for a sufficient time.
A level crossing is used when the canal water and drain water are allowed to intermingle with each other. This is adopted when high flood drainage discharge is short lived.
Consider the following statements: An aqueduct is a cross drainage work in which
1. a canal is carried over the drainage channel.
2. a drainage channel is carried over the canal.
3. both drainage channel and canal are at the same level.
Which of these statements is/are correct?
An aqueduct and syphon aqueduct are cross drainage works in which the canal is taken over the natural drain, such that the drainage water runs below the canal either freely or under syphoning pressure. Super passage and syphon are cross drainage works in which the drain is taken over the canal such that the canal water runs below the drain either freely or under syphoning pressure. Level crossing is a cross drainage work in which the canal water and drain water are allowed to intermingle with each other. A level crossing is generally provided when a large canal and a huge drainage (such as a stream or a river) approach each other practically at the same level.
Consider the following statements:
1. In a super-passage, the drain runs over the canal.
2. In a siphon, the drain runs below the canal.
3. In a siphon aqueduct, type-II, the canal banks are made of RCC walls.
Which of these statements are correct?
A super passage is just like a bridge in which the natural drain is carried over the canal. A super passage is constructed where the bed of the drain is well above the canal F.S.L.
A syphon serves the same purpose as superpassage and is constructed where the F.S.L.