Irrigation Engineering (Set-3)

Coefficient of discharge of an ogee spillway

• depends on depth of approach and upstream slope

• depends on downstream apron interference and downstream submergence

• remain constant

• both (a) and (b)

Which one of the following spillways is least suitable for an earthen dam?

• ogee spillway

• chute spillway

• side channel spillway

• shaft spillway

In a chute spillway, the flow is usually

• uniform

• subcritical

•  critical

• super critical

For the upstream face of an earthen dam, the most adverse condition for stability of slope is

• sudden drawdown

• steady seepage

• during construction

• sloughing of slope

Generally the weir is aligned at right angles to the direction of the main river current because

• it ensure less length of the weir

• it gives better discharging capacity

• it is economical

• all of the above

The main function of a divide wall is to

• control the silt entry in the canal

• prevent river floods from entering the canal

• separate the undersluices from weir proper

• provide smooth flow at sufficiency low velocity

As compared to crest of the normal portion of the weir, the crest of the undersluice  portion of weir is kept at

• lower level

• higher level

• same level

• any of the above depending on the design

Silt excluders are constructed on the

• river bed upstream of head regulator

• river bed downstream of head regulator

• canal bed upstream of head regulator

• canal bed downstream of head regulator

According to Khosla’s theory, the exit gradient in the absence of a downstream cutoff is

•  0

•  unity

• infinity

• very large

The ratio of average values of shear stresses produced on the bed and the banks of a channel due to flowing water is

• less than 1

• equal to 1

• greater than 1

• equal to zero