Calculate the Base period of a crop if Duty of water is 1200 hectares/cumec and Delta is 50 cm

Answer: Option B

The base period for any crop is the total period of the plantation from the day of first irrigation provided to the field till the last watering before harvesting.
The formula to calculate Base period
$$\Delta =\frac{\text{B}\times 24\times 60\times 60}{\text{D}\times \text{104}}=\frac{8.64\text{B}}{\text{D}}\text{ metres}$$
Where, D = Duty in hectares/cumec = 1200 hectares/cumec
            $$\Delta$$ = Total depth of water supplied in metres (Delta) = 50 cm = 0.5 m
             B = Base period in days
Therefore, $$\text{B}=\frac{0.5\times 1200}{8.64}=69.44=70\text{ days approx}\text{..}$$