In this article (and video above), I solve a new surface water resources and hydrology question by calculating the runoff volume, similar to what you may encounter on the FE exam.
Question:
A 53-acre watershed (curve number = 79) receives 122 mm of precipitation. The runoff volume (ac-ft) is most nearly:
- 4.11
- 11.62
- 18.15
- 4,615
Solution:
Calculate the mazimim basin retention (S) and the runoff (Q) which can be calculated using the NRCS (SCS) Rainfall-Runoff equations:
Substituting the given parameters in the equation shown above yields:
Therefore, the runoff volume (ac-ft)
Answer:

I hope you found this week’s surface water resources and hydrology question helpful. In upcoming articles, I will answer more FE Exam questions and run through more practice problems. We publish videos bi-weekly on our Pass the FE Exam YouTube Channel. Be sure to visit our page here and click the subscribe button as you’ll get expert tips and tricks – to ensure your best success – that you can’t get anywhere else. Believe me, you won’t want to miss a single video.
Lastly, I encourage you to ask questions in the comments of the videos or here on this page and I’ll read and respond to them in future videos. So, if there’s a specific topic you want me to cover or answer, we have you covered.
I’ll see you next week.
Anthony Fasano, P.E.
Engineering Management Institute
Author of Engineer Your Own Success





