Watershed Surface and Channel Runoff Coefficient Assessment with Unified Runoff Time Implications

Date: July 15, 2025 | 2:00 PM EST/1:00 PM CST
Speakers: Kenneth Kagy, P.E., CFM, CPSWQ, CPESC
Credits: 1.0 PDH | 0.1 CEU | Approved for all Envirocert International, Inc. (ECI) Certifications: Approval #PDH-0151

Join us for this live in-depth exploration of a fundamental technique used across hydrologic evaluations: assessing how rainfall runoff travels through a watershed. This webinar will focus on estimating the time of concentration—an essential factor in stormwater modeling—based on key watershed characteristics.

Attendees will examine standard methods for calculating travel time, including comparisons between Manning’s sheet flow coefficients, watershed percent impervious surface, rational method runoff coefficients, and NRCS soil curve numbers. The session will also explore how these variables influence the time of concentration and the reliability of various empirical equations when compared to traditional estimation methods.

Learning Objectives

Upon completion of this presentation, attendees should be able to:

• Improve the development of rainfall’s runoff time for the modeling hydrographs for stormwater hydrology
• Explain normalization in watershed runoff coefficients applied among other time of concentration equations
• Demonstrate additional methods to estimate rainfall runoff time with small watersheds for runoff hydrographs

About the Presenter

Kenneth Kagy, P.E., CFM, CPSWQ, CPESC
Ken has worked in engineering for private consulting and local governments during the past 40 years.  He has made presentations on storm water management to national technical organizations, local universities, and several conferences.  He has experience in site development design, site storm water management, storm water infrastructure design and construction, floodplain management, and community floodplain outreach programs.  Ken is licensed as a Professional Engineer, Certified Floodplain Manager, Certified Professional in Storm Water Quality, Certified Professional in Erosion & Sediment Control, and state certified instructor for erosion control certifications.