GATE Civil Engineering (CE) 2023 Shift 1 Solved Paper

The ordinates of a one-hour unit hydrograph for a catchment are given below: 

Using the principle of superposition, a D-hour unit hydrograph for the catchment was derived from this one-hour unit hydrograph. The ordinates of the D-hour unit hydrograph were obtained as 3 m3/s at t = 1 hour and 10 m3/s at t = 2 hour. The value of D (in integer) is _____________.