# Determine the Discharge of the Channel for which it is to be Designed

## Determine the Discharge of the Channel for which it is to be Designed

Mathematical Problem

A channel is to be designed for irrigating 6000 hectares of Kharif crop and 5500 hectares of Rabi crop. The water requirement for the Kharif crop is 70 cm and the water requirement for Rabi is 35 cm. The Kor period for Kharif is 2 weeks and for Rabi is 3 weeks and 4 days. Determine the discharge of the channel for which it is to be designed.

Solution:

Using the relation

∇ = (8.64 × B)/ D

Discharge for Kharif crop

Here,

• ∇ = 70 cm = 0.70 m
• B = 2 weeks = 14 days

Duty (D) = (8.64 × 21)/ 0.70 = 259.2 hectares/cumec.

Area to be irrigated = 6000 hectares.

Required discharge of channel for Kharif crop = (6000/259.2) = 23.15 cumec.

Discharge for Rabi crop

Here,

• ∇ = 35 cm = 0.35 m.
• B = 3 weeks and 4 day = (21 + 4) = 25 days.

Duty (D) = (8.64 × 25)/ 0.35 = 617.14 hectares/cumec.

Area to be irrigated = 5500 hectares.

Required discharge of channel for Kharif crop = (5500/617.14) = 8.91 cumec.

Therefore, the channel is to be designed for the maximum discharge of 23.15 cumec, because this discharge capacity of the channel will be able to supply water to both seasons.