Hydrology Manual

Project Highlight: ADOT Hydrology Manual Update




Arizona Department of Transportation

Project Leads

Jon Fuller
Brian Fry
Ted Lehman

The Arizona Department of Transportation (ADOT) issued its Highway Drainage Design Manual- Hydrology (1993 Manual) in 1993.  At that time it represented a significant advancement in the practice of hydrology for highway drainage design in Arizona.  The 1993 Manual was the result of an extensive research and validation effort.  The methods and procedures within the manual represented the state of the practice at that time.  The 1993 Manual has been used extensively since then with no significant updates.  ADOT has updated the 1993 Manual to incorporate advances in the state of the practice that have been developed since 1993.  The 2012 edition of the Manual updates, refine, and improves the methods for estimating storm water runoff, cognizant of the diverse nature of hydrologic conditions in Arizona.  Four general areas of updates are recommended:

  • Update Rainfall from NOAA Atlas 2 to NOAA Atlas 14.
  • Update the Manual document to be more user-friendly by providing an electronic version suitable for online use and/or distribution
  • Migrate from HEC-1 to HEC-HMS
  • Provide guidance for application of two-dimensional modeling (FLO-2D) where appropriate.