An agricultural land of 437 ha is to be irrigated for a particular crop. The base period of the crop is 90 days and the total depth of water required by the crop is 105 cm. If a rainfall of 15 cm occurs during the base period, the duty of irrigation water is
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437 ha/cumec
-
486 ha/cumec
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741 ha/cumec
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864 ha/cumec
D
Correct answer
Explanation
Duty is defined as the area irrigated per unit discharge. Net water required = 105 cm - 15 cm = 90 cm = 0.9 m. Total volume = 437 ha * 0.9 m = 393.3 ha-m. Base period = 90 days = 90 * 24 * 3600 seconds. Discharge = Volume / Time = (393.3 * 10000 m^3) / (90 * 86400 s) = 0.5057 cumec. Duty = 437 / 0.5057 = 864 ha/cumec.