PE Exam Practice Problem #33: Water Resources | Rainfall Hyetograph - Hydrologic Budget

Update to this problem - one of the comments below correctly pointed out a mistake I made when setting this problem up. My method of solving for each water gain/water loss term all at once only works if the rainfall rate is always greater than the rate of the infiltration plus the rate of the evaporation/transpiration. Since it is not, we would have to solve this problem a little differently and make sure we are not double-counting and water losses at certain 10 min intervals.
Welcome to SolvedIn6: Free practice problems for the Professional Engineering Exam! Each question is styled after those created by the NCEES, and is usually solved in under 6 minutes, which is the average time you will have to solve each question on the Professional Engineering Exam.
Today's problem covers rainfall hyetographs. The reference manual isn't very helpful for this problem. However, there is a section listed in the video which will give you all possible terms that you might need to add or subtract. Otherwise, just read the problem carefully and don't mix up the terms that you are adding and subtracting. This is a long problem full of unit conversions.
Step 1: Sum the values in the hyetograph and multiply by the area (converting units as needed) to get total rainfall volume.
Step 2: Calculate and subtract the volume of infiltration.
Step 3: Calculate and subtract the transpiration volume.
Step 4: Calculate and subtract the depression storage.
Step 5: Divide the remaining volume by the depth limitation to find the area.
If you would like more Water Resources practice problems, please check out the rest of the playlist which this video is part of.
Please note that newer versions of the reference manual may have been released since this video was recorded. The search terms are usually still correct, but the page numbers listed in the video will be different.

[@emilezankoul]

For infiltration, shouldn't the amount be (0.01 + 0.03 + 0.02) in * 10 min? Because how can you infiltrate more precipitation than you're getting? So infiltration should be the lower of the infiltration rate or of the precipitation. In this problem, precipitation is lower.

[@SolvedIn6]

You're absolutely right. My lumped math would only work if the rainfall rates were always greater than the sum of the infiltration and transpiration at each minute. I made a mistake here, thank you for pointing it out. This problem would need to be solved in 10 minute increments like you suggested.