Answer:
The change in storage in the reach that occurred, during the hour = 43200 m3
The storage at the end of the hour = 129600 m3
Explanation:
Given
Storage = 3 hectare-meters
Inflow volume = 15 m3/s
Outflow volume = 20 m3/s
Storage in one hour of change
Inflow volume = 20 m3/s
Outflow volume = 20.5 m3/s
Outflow volume - Inflow volume = 0.5 m3/s = 0.5 * 24*60 * 60 = 43200 m3
Storage at the end of one hour
43200 m3 + (20-15) * 24*60 * 60 = 129600 m3