The International Erosion Control Association (IECA) and Storm Water Solutions (SWS) is presenting a webinar on June 22, 2023 – From Bare Soil to Urbanization: Landcover and Runoff. Times for the one-hour webinar presented by Andrew Earles and Victoria Hennon are 2:00 PM ET / 1:00 PM CT / 11:00 AM PT / 7:00 PM GMT. More information is available here.
This webinar, sponsored by CleanWay, Presto Geosystems, Soil Moist, Stone Strong Systems, and United Storm Water Inc., will present recent work to update runoff coefficients in the metropolitan Denver area within the Mile High Flood District. Many of the runoff coefficients included in local, regional, and national guidance documents were developed decades ago and do not necessarily represent current types and densities of development. This work involved analysis of recent developments to compare measured imperviousness with guidance on imperviousness that is used to calculate runoff coefficients to assess current density of developments relative to imperviousness assumptions in current criteria. The presenters also searched the literature and performed analysis to develop criteria for runoff coefficients for different types of waterwise land cover from western desert rock mulch landscaping to landscaping with native grasses. In addition, they performed modeling analysis to evaluate the effects of disconnected impervious area and panel orientation on runoff coefficients for solar installations.
Dr. Andrew Earles is the vice president of water resources with Wright Water Engineers in Denver, Colo. He specializes in hydrology, hydraulics, and stormwater management and has worked across the United States on projects related to rainfall, runoff, and land cover. Earles is a professional engineer, professional hydrologist, CPESC, and member of the American Academy of Water Resources Engineers.
Victoria Hennon, EIT, is a water resources engineer at Wright Water Engineers. She has a master’s degree in civil and environmental engineering from the Colorado School of Mines and works on projects involving drainage criteria, hydrologic/hydraulic modeling, and watershed analyses.
The relationship between rainfall and runoff is fundamental to managing stormwater runoff from pre-project planning through construction and into operation of the permanent stormwater system. This relationship is defined by runoff coefficients that convert rainfall to runoff – runoff coefficients that are too low and under-represent real world conditions can lead to flooding, while runoff coefficients that are unrealistically high result in unnecessary expenditures on oversized infrastructure.
This webinar will also discuss construction phase runoff and how the lessons learned from updating runoff coefficients for post-construction land uses provide insight on how to effectively reduce runoff coefficients during construction through implementation of erosion control measures including mulching, temporary revegetation, and other similar practices. Attendees will come away from this webinar with a new appreciation for the subtleties of runoff coefficients and an understanding of how criteria for these important hydrologic parameters are derived for use in stormwater manuals.