Correct Answer - Option 3 : in alluvial rivers and canal
Concept:
Lacey followed Lindley’s hypothesis, which states that “dimensions and slope of a channel to carry a given discharge and silt load in easily erodible soil are uniquely determined by nature”.
Lacey’s theory is applicable to flow in alluvial rivers and canal
According to Lacey:
“Silt is kept in suspension by the vertical component of eddies generated at all points of forces normal to the wetted perimeter”.
So the eddies are generated from the bottom as well as the side of the channel.
Regime Channel: “A channel is said to in regime if there is neither silting nor scouring”.
According to Lacey, there may be three regime conditions:
(i) True regime; (ii) Initial regime; and (iii) Final regime.
According to Kennedy’s theory Silt carried by the flowing water is kept in suspension by the vertical
component of eddies which are generated from the bed of the channel.
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Kennedy’s theory
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Lacey’s Theory
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Kutter’s equation is used for finding velocity.
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He has given an equation for finding the velocity.
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It gives no equation for the bed slope.
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It gives an equation for bed slope.
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The design is based on a trial and error method.
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The design does not involve any trial and error
method.
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