June 9, 2022

AAWRE Board member David T. Williams, Ph.D., P.E., P.H., D.WRE, F.ASCE will present a two-part webinar series on HEC-RAS Culverts Modeling (Part 1) on Wednesday, June 15 at 1pm EDT and Part 2 on July 12 at 1pm EDT.  This is part of the free AAWRE webinar series provided only to AAWRE Diplomates. 


HEC-RAS is a rather complicated 1-D and 2-D hydraulics program that can be easily put together but also easily—and unknowingly—misused. The most common hydraulic structures modeled are related to culvert modeling.

Join Dr. David T. Williams (who has taught HEC-RAS and bridge and culvert hydraulics to the Federal Highway Administration as well as state and local departments of transportation) present examples of common geometric mistakes and misunderstandings of culvert parameters using HEC-RAS that could have potentially significant effects on a culvert project’s hydraulic results.  Note: Since most HEC-RAS models are still performed in 1-D, this course will concentrate on only 1-D culvert applications; however, most of the presentation is applicable to 2-D HEC-RAS modeling.

Part I will discuss common 1-D geometric misrepresentations, the proper placement of cross sections within an HEC-RAS model, and initial coefficients to use to properly simulate the hydraulic effects of a culvert.

Part II will detail how some of the input parameters should be refined, where within the 1-D model they should be placed, and a step-by-step creation of an HEC-RAS culvert model with a real culvert.

Course material will be based upon Dr. Williams’ review of submitted models, his discussions with experienced users, his blogs on hydraulic and culvert modeling topics, and his HEC-RAS Steady and Unsteady course lecture notes.

Learning outcomes:

Learn the types of flow through culverts.
Understand common culvert terminology and relation to HEC-RAS modeling.
Recognize the reason for initial placement of the four cross sections to model a culvert.
Determine initial expansion and contraction coefficients.
Know the proper placement and elevations of ineffective flow areas.
Understand culvert flow computations in HEC-RAS.


Dr. David T. Williams, a registered Professional Civil Engineer in eight states, brings a variety of experience, including: National Technical Director for Water Resources for PBS&J (now Atkins), National Technical Director for Hydrology and Hydraulics for HDR, co-founder and President of WEST Consultants (a nationally recognized water resources engineering firm), the U.S. Army Corps of Engineers, and adjunct professor at San Diego State University. Dr. Williams’ 45 years of professional experience includes more than 20 years as a hydraulic engineer with the U.S. Army Corps of Engineers at the Waterways Experiment Station (WES) in Vicksburg, MS, both the Nashville and Baltimore Districts, and the Hydrologic Engineering Center (HEC) in Davis, CA. While at WES, Dr. Williams worked on research applications of sediment transport in rivers and reservoirs and the solution of unusual hydraulic and sediment related problems using computer models and other state-of-the-art techniques. During the mid-1970's, Dr. Williams worked at HEC, helping in the development of spatial data management techniques, evaluation of the economic benefits of flood control projects, and sedimentation in rivers and reservoirs.

Dr. Williams has been a frequent short course instructor for ASCE and other professional and public organizations on computer training using HEC-2, HEC-RAS, HEC-HMS and HEC-6. Dr. Williams has taught short courses on hydrologic and hydraulic modeling, risk and uncertainty, channel bed scour for toe protection design, sediment transport, stream restoration, fluvial geomorphology and streambank protection, as well preparing for becoming an expert witness. Dr. Williams’ professional society activities have included past chair of the ASCE/EWRI Committees on Sedimentation, Computational Hydraulics, RUPA (Risk, Uncertainty and Probabilistic Approaches), and Stream Restoration as well as 2 time past President of the International Erosion Control Association. He currently serves on the AAWRE Board of Trustees.

>To contact David