Soil-Water-Plant Relationship

A crop has a base period of $B = 120\text{ days}$ and a total depth of water required during the base period (delta) of $\Delta = 60\text{ cm}$ ($0.60\text{ m}$). Using the standard duty formula $D = \frac{8.64 B}{\Delta}$, calculate the duty of irrigation water in $\text{ha/cumec}$.