Cross Drainage Works – Short Question and Answers

Cross Drainage Works – Short Question and Answers Points : cross drainage works –short question and answers Q.1: Define the term cross drainage works. Ans : Cross drainage work to a structure carrying the discharge of a natural stream across canal intercepting the stream. Q.2: Write down the name of different types of cross drainage works carrying can over the drainage. Ans : Depending upon the relative levels and discharges, cross-drainage works may be of the following types:
In this type of C.D. work, the canal is carried over the natural drain. The advantage of such arrangement is that the canal, running perennially, is above the ground and is open to inspection. Also, the damage done by floods is rare. However, sometimes during heavy floods the foundation can be scoured, or the waterway of the drain may be chocked with trees etc. This is the usual type of work constructed when the drain ii very big in comparison to the section of the canal. The structures that fall under this type are:
1. Aqeduct
2. Syphon aqueduct. Q.3: Write down the difference between Aqueduct and siphon aqueduct. Ans : However, in the case of a syphon aqueduct the H.F.L of the drain is much higher above the canal bed, and the water runs under syphonic action through the aqueduct barrels. Q.4: Write down the difference between super passage and canal siphon. Ans : A super-passage is similar to an aqueduct, except that in this case the drain is over the canal. The F.S.L. of the canal is lower than the underside of the trough carrying drainage water. Q.5: Write down the disadvantages of CD work admitting the drainage water into the canal. Ans : in this type of work, the canal water and the drainage water are permitted to intermingle with each other. The only advantage of this type of work is its low initial cost. Such type of works have the following disadvantages:
(i) Regulation of such a work is difficult and requires additional staff.
(ii) The canal has to be designed to carry the increased flood discharge of the drain.
(iii)The faulty regulation of gates may damage the canal.
(iv)There is additional expenditure of silt clearance. Q.6 Write down the difference between level crossing and Inlet. Ans : Level crossings arc suitable for canals of all sizes. They arc, however, specially suited to crossings Os very large drains when the cost of other cross- drainage works would be very high. Q.7 What is canal escape? Ans : A canal escape is a structure constructed on an irrigation canal for the purpose of wasting some of its water Q.8 Write down the name of canal escape. Ans : (1). Canal scouring escape.
(2) Surplus escape, and
(3) Tail escape. Q.9 Define the tall escape. Ans : A tail escape is provided at the tail end of the canal, and is useful In maintaining the required F.S.L at the tail end.