A catchment of 720 ha area has 25 -year mean rainfall intensity of $100 \mathrm{~mm} \mathrm{~h}^{-1}$ occurring for a duration equal to its time of concentration. During a storm event, the catchment received a total of $7.5 \mathrm{~cm}$ design rainfall for 6 hours. Assuming $\phi$ -index of $0.25 \mathrm{~cm} \mathrm{~h}^{-1}$ and runoff coefficient of 0.6 , the peak ordinate of the 6 -h unit hydrograph in $\mathrm{m}^{3} \mathrm{~s}^{-1}$ will be______________

A catchment of 720 ha area has 25 -year mean rainfall intensity of $100 \mathrm{~mm} \mathrm{~h}^{-1}$ occurring for a duration equal to its time of concentration. During a storm event, the catchment received a total of $7.5 \mathrm{~cm}$ design rainfall for 6 hours. Assuming $\phi$ -index of $0.25 \mathrm{~cm} \mathrm{~h}^{-1}$ and runoff coefficient of 0.6 , the peak ordinate of the 6 -h unit hydrograph in $\mathrm{m}^{3} \mathrm{~s}^{-1}$ will be______________

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