Question: Derive relation between duty and delta.
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Mumbai University > Civil Engineering > Sem 7 > Irrigation Engineering

Marks: 6M

Year: Dec 2015, May 2016

 modified 2.0 years ago  • written 2.0 years ago by Juilee ♦ 2.1k
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D = duty in hectares/cumec

∆ = total depth of water supplied in metres

B = base period in days

If we take a field of area D hectares, water supplied to the field corresponding to the water depth ∆ metres will be = ∆ x D hectares-metres.

$= D \times ∆ \times 10^4$ cubic-metres. .... (1)

Again for the same field of D hectares, one cumec of water is required to flow during the entire base period. Hence, water supplied to this field.

$= (1) \times (B \times 24 \times 60 \times 60) m^3$ .... (2)

Equating Equations (1) and (2), we get

$D \times ∆ \times 10^4 = B \times 24 \times 60 \times 60$

$∆ = (B \times 24 \times 60 \times 60)/(D \times 10 4) = 8.64 B/D metres.$