(Solved): A 3-hr storm unit hydrograph is given in the following table. Find the runoff in ft3/s at t=9 hours ...
A 3-hr storm unit hydrograph is given in the following table. Find the runoff in ft3/s at t=9 hours from two 3 -hour storms. Given: (a) the first 3 -hr storm has an average precipitation of 1.5 inches and starts at t=3 hour the second 3 -hr storm has an average precipitation of 2 inches and starts at t=6 hour 
To find the runoff at t=9 hours from two 3-hour storms, we need to calculate the total runoff for both storms individually and then sum them up.
For the first storm (t=3 to t=6), the average precipitation is 1.5 inches. We can use the given unit hydrograph to calculate the runoff during this period.
Runoff for the first storm = Average precipitation (in inches) * Runoff factor for the corresponding time period (from the unit hydrograph)
Using the unit hydrograph, the runoff factors for the time periods are as follows:(((