Irrigation Engineering
If Δ is the depth of water in metres, B is the number of days of base period and D is the duty in hectare/cumec, the relationship which holds good, is

D = Δ (8.64 D/B)
D = (8.6 Δ/B)
Δ = (8.6 B/D)
B = Δ (8.64 B/D)

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Irrigation Engineering
For designing the venturi head,

All listed here
Length of the throat should be 2.5 times the depth measured to F.S.L. in the main canal
Width of the throat should not be less than one-third of the bed width of main canal
Minimum throat width should not be less than 60 cm

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