71. For efficient working of a control meter, its throat length is approximately kept

A. equal to the critical depth

B. twice the critical depth

C. three times the critical depth

D. four times the critical depth.

72. A control meter is preferred to a weir because

A. it measures the discharge even in silt laiden streams

B. the velocity of approach of the channel increases above the control, and thus removes the silt completely

C. it is not damaged by floating debris

D. all the above.

73. A river is said to be of uniform section if in its section

A. a segment of a circle can be fitted

B. a parabolic section can be fitted

C. a rectangular section can be fitted

D. all the above.

74. Discharge curve may be extended by logarithmic method if

A. cross section of river is uniform

B. river is broader and shallower

C. river is of any type

D. none of these.

75. Prof. Kunning suggested the method for extending the discharge curve. It is known as

A. Logarithmic method

B. iy method

C.. General method

D. None .of these

76. The best instrument for measuring the velocity of a stream flow is

A. pitot tube

B. Price's current meter

C. surface float

D. sub-surface float

77. If y is the depth of water at any section, then the mean velocity is

A. 0.1y

B. 0.2 y

C. 0.3 y

D. 0.5 y

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