Question

If the base period of 6-hour hydrograph of a basin is 84 hours, then a 12-hour unit hydrograph derived from this 6-hour unit hydrograph will have a base period of

• A. 72 hours
• B. 78 hours
• C. 84 hours
• D. 90 hours

Answer 1

The correct option is D 90 hours

A 12- hour unit hydrograph will be obtained by addling the ordinates of 6-hour UH and ordinates of 6-hours UH are lagged by 6 hours and then dividing the resulting ordinates by 2. So the base period for 12-hour UH will be
$=84+6=90hours$