At a certain place, the transplantation of a crop takes 15 days, and the total depth of water required by the crop is 90 cm on the field. During the plantation rain falls and about 20 cm is utilised to fulfil the demand. Now determine the duty of irrigation water required during the plantation.

Correct Answer: 185.14hectares/cumec
Total depth of water required = 90 cm Useful rainfall = 20 cm Extra water depth needed after useful rainfall = 90 – 20 = 70 cm Period for which water is needed = 15 days Duty of irrigated water (∆) = (864B/d) = (864 x 15 / 70) = 185.14 hectares/cumec.