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Voodoo Hydrology - The Pitfalls of Urban Hydrology Methods


Urban hydrology is stormwater management’s dirty little secret. It has been estimated that one out of every three design plan submittals has significant errors in hydrology estimates but only one in twenty is caught.

The truth is: urban hydrology—including newer Green Infrastructure sizing approaches and even detailed modeling approaches—as commonly practiced, is an inexact science at best. We can just now make the same mistakes at near light speed! One old, experienced stormwater professor once said, “I love urban stormwater hydrology. No one can prove you’re wrong, only that you’re inconsistent.”

As such, knowing the inner workings of the “black boxes,” unstated assumptions, and limitations inherent in the urban stormwater hydrologic design methodologies that we commonly use (even within modern computer packages) is essential to ensuring proper application—but there are few places to get such information. This webinar is one of them.

With his unique humor, prolific speaker Andy Reese (PE, LEED AP, D.WRE) will “lay bare” the most popular urban stormwater hydrologic design methodologies, detailing their key elements, assumptions, and very common misuses/misapplications. He will show the most common ways designers “cheat” the system and the most overlooked errors. He will help to expose basic assumptions within our models and methods.

If you are a stormwater plans reviewer, compliance officer, design engineer, consultant manager, professor, or attorney, this course is for you!

Ready to open these “black boxes” for a more comprehensive understanding of your design tools? Join Forester University and Andy for the 2021 edition of this fan-favorite, live, educational webinar!

Programming Note: The Voodoo never stops! This webinar was born out of Andy’s article by the same name in the July/August 2006 edition of Stormwater and has been an industry staple ever since. In other words, even if you have taken any previous iteration of this course, you can expect to learn something new from this most recent update covering the most current models.

Learning Objectives

By participating in this webinar, attendees will:

  • Discuss the most popular urban stormwater hydrologic design methodologies
  • Understand the basis for the most popular urban stormwater hydrologic design methodologies
  • Explore the key elements, assumptions, and common misuses/misapplications of the most popular urban stormwater hydrologic design methodologies
  • Know the limitations of the most popular urban stormwater hydrologic design methodologies and the keys to successful application

Train Your Team
Get the whole team trained! We offer additional savings if you register as a group. For group pricing information, contact us at

* Presentations are scheduled for approximately one hour with a 15-20 minute question and answer session to follow. Presentations may exceed scheduled time. * Each state and certification agency have different requirements; it is your responsibility to know what they are. Note that 1 PDH = 0.1 CEU. * Purchase of this course allows you access to the presentation(s) for 6 months from the order date.

On-Demand Webcast
Lectures: 1
Session: 1 H 30 M
Credits: 1 PDH / 0.1 CEU

On-Demand Webcasts > Stormwater ($79.00)


Special Group Pricing Available


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