This set of Irrigation Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Regulation Modules – Non Modular Outlet Types”.

1. Which type of non-modular outlet is used in South India?

a) Open Sluice

b) Pipe Outlet

c) Gibb’s Module

d) Open Flume

View Answer

Explanation: A non-modular may be in the form of a rectangular opening or open sluice or a simply submerged pipe. Pipe outlet is simple type of non-modular and therefore it is widely used in South India.

2. The discharge through the open sluice is given by suppressed weir formula.

a) True

b) False

View Answer

Explanation: Using suppressed weir formula the discharge through the opening is given when discharge consists of flow over upper part of section (H

_{L}may be considered as free discharge), then the discharge is given by q

_{1}= (2/3) x C

_{d1}x \(\sqrt{2g}\) x B x H

_{L}

^{3/2}and if the flow is through the remaining part (through submerged orifice) the discharge is given by q

_{2}= C

_{d2}x \(\sqrt{2gH_L}\) x B x d.

Total discharge is given by q = q

_{1}+ q

_{2}.

3. Why would a submerged pipe outlet be laid inclined?

a) To Provide Proper Exit Gradient

b) To Maintain Proper Hydraulic Jump

c) To Increase Silt Conductivity

d) To Increase the Discharge Capacity

View Answer

Explanation: Generally the diameter of the pipe varies from 10 to 30 cm. They are generally laid in concrete and fixed horizontally. They are also laid sloping upwards by depressing the upstream end of the pipe so as to increase the silt conductivity.

4. How many types of submerged pipe outlets can be laid?

a) 2

b) 3

c) 4

d) 5

View Answer

Explanation: The submerged pipe outlets can be laid either horizontally or sloping upwards. Generally, they are embedded in concrete and fixed horizontally at right angles to the direction of flow. They can also be laid sloping upwards to increase the silt conductivity.

5. What is the formula for velocity through the pipe?

a) Total loss of head = Entry loss + Frictional loss

b) Total loss of head = Frictional loss + Velocity head at exit

c) Total loss of head = Entry loss + Velocity head at exit

d) Total loss of head = Entry loss + Frictional loss + Velocity head at exit

View Answer

Explanation: If the difference in the water level of the distributary and the water course is known then by using the formula total loss of head = entry loss + frictional loss + velocity head at the exit. Mathematically it is represented as H

_{L}= 0.5V

^{2}/2g (1.5 + f’ l/d) where l = length of pipe, d = diameter of pipe and f’ = coefficient of friction.

6. What is the formula for discharge through the pipe?

a) Q = C_{d} x A

b) Q = C_{d} x A x \(\sqrt{2gH_L}\)

c) Q = C_{d} x \(\sqrt{2gH_L}\)

d) Q = A x \(\sqrt{2gH_L}\)

View Answer

Explanation: After knowing the velocity through the pipe, we can calculate discharge using the relation discharge = velocity x area. Mathematically q = V x A, therefore q = C

_{d}x A x \(\sqrt{2gH_L}\) where q = discharge, C

_{d}= coefficient of friction, A = area of pipe, H

_{L}= difference of head between FSL of distributary and FSL of water course.

7. To ensure equitable distribution of water flexible and rigid modules are preferred.

a) False

b) True

View Answer

Explanation: Flexible and rigid modules are preferred to non-modular outlets because to ensure the equitable distribution of water in the water courses irrespective of their being at high or low levels.

8. What is the range of modular outlet called?

a) Minimum Modular Head

b) Working Range

c) Minimum Loss of Head

d) Modular Ratio

View Answer

Explanation: Outlets are termed as modular outlets only when they work in certain range or say certain limits of water level in the distributary channel and the water course. The range over which each module acts as a modular outlet is called a working range or range of modularity.

9. To ensure the modularity of the modular outlet what should be maintained?

a) Minimum Modular Head

b) Efficiency of an Outlet

c) Drawing Ratio

d) Modular Range

View Answer

Explanation: A minimum difference of water levels on both sides of each module should always be present to ensure its modularity. This minimum difference of levels is known as minimum modular head or minimum loss of head of the modular outlet.

10. What is the value of H_{L}?

a) Water Level of Water course

b) Water Level of Distributary

c) The Water Level of Distributary – Water Level of Water Course

d) Discharge/Area

View Answer

Explanation: H

_{L}is defined as the difference in the water levels between distributary channel and the water course. H

_{L}in design is taken as equal to the average of head loss values observed once a fortnight throughout the season. Mathematically it is defined as (H – d).

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