The peak ordinate of 4 h unit hydrograph of a basin is 60 m3/s. An isolated storm of 4 hour duration in the basin was recorded to have a total rainfall of 8 cm. If it is assumed that the base flow and the ϕ−index are 30 m3/s and 0.25 cm/hr respectively, the peak of the flood discharge due to the storm could be estimated as.