The table below represents the vertical coordinates of the hydrograph of a rainstorm over a mountainous area770 km² as a result of 6 rainstorm hours, derive the vertical coordinates of a standard hydrograph 6hour and then select:

1- The vertical coordinate value of the 6 hour standard hydrograph at the time of 18 hours.

2- The vertical coordinate value of 6 hours of standard hydrograph at a time of 36 hours.

3- The vertical coordinate value of 6 standard hydrographic hours at 66 hours.

 

the time. 72 66 60 54 48 42 36 30 24 18 12 60 (hour) 42 50 70 100 145 205 270 350 400 360 215 65 40 42 42 42 42 41 41 41 40 40 40 40 40 40 discharge (m3/s) flow baseband (m3/s)