An average rainfall of 16 cm occurs over a catchment during a period of 12 hours with uniform intensity. The unit hydrograph (unit depth = 1 cm, duration = 6 hours) of the catchment rises linearly from 0 to 30 cumecs in six hours and then falls linearly from 30 to 0 cumecs in the next 12 hours. ^$\psi$index of the catchment is known to be 0.5 cm/hr. Base flow in the river is known to be 5 cumecs.

Area of the catchment in hectares is