Instructor: Harlan Bengtson

Credit Hours: 3.00

Approval Number: Not Required


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Course Description


The Calculation of peak storm water runoff rate from a drainage area is often done with the Rational Method equation (Q = CiA). Calculations with the Rational Method equation often involve determination of the design rainfall intensity and the time of concentration of the watershed as well. This course includes discussion of the equations and the variables for these types of calculations. Example calculations, including the use of a spreadsheet, for Rational Method equation calculations and for determination of the design rainfall intensity and the time of concentration of the drainage area, are presented and discussed in this course. The parameters in the equations are defined with typical units for both U.S. and S.I. units.



Course Objectives


Upon completion of this course, the participant will be able to:

  • Use a consistent set of units in either the U.S. or S.I. version of the Rational Method equation.
  • Calculate peak storm water runoff rate with the Rational Method equation, using either U.S. or S.I. units.
  • Place a given soil into one of the four SCS soil groups based on its measured minimum infiltration rate.
  • Place a given soil into one of the four SCS soil groups based on its description.
  • Calculate the overland sheet flow travel time for a watershed using the Manning Kinematic equation.
  • Calculate the shallow concentrated flow travel time for a watershed using the NRCS method.
  • Calculate the open channel flow travel time for a watershed using the Manning equation.
  • Use an Excel spreadsheet to make the types of calculations discussed in this course.


Instructor Bio


Dr. Bengtson is a graduate of Iowa State University with B.S. and M.S. degrees and of the University of Colorado with a PhD. He is a licensed Professional Engineer in Missouri. He has spent 30 years in engineering education in teaching and administrative positions, including six years as Dean of Engineering at Southern Illinois University Edwardsville. His areas of expertise are environmental engineering, hydrology and hydraulics, engineering science and renewable energy systems. He did consulting work while holding the academic positions. Prior to entering academia, Dr. Bengtson worked for Minnesota Mining & Manufacturing as a Product Development Engineer and for E. I. duPont deNemours as a Process Development Engineer. Dr. Bengtson has authored numerous publications, presentations and technical reports. He is currently active in providing continuing education opportunities for Professional Engineers and is the founder of www.engineeringexceltemplates.com and www.EngineeringExcelSpreadsheets.com, sites with the objective of providing inexpensive, easy to use Excel spreadsheets for a variety of engineering calculations.



Other Approvals


National Professional Engineer board: Not Required