WRRC/Ike Wai Seminar
March 20, 12:00pm - 1:00pmMānoa Campus, HIG 210
Stormwater Management Using Green Roofs: Predicting Runoff Volume Reduction, Peak Flow Reduction and Peak Delay
by
Dr. Roger Babcock
Urban areas typically consist of 50 percent impervious rooftop surfaces. Green roofs hold the potential to reduce urban runoff by allowing for onsite retention / detention / evapotranspiration of stormwater. A recent review found that green roofs can reduce stormwater runoff volume by 30 to 86 percent, reduce peak flow rate by 22 to 93 percent, and delay the peak flow by 0 to 30 min. Consequently, green roofs can help decrease pollution, flooding, and erosion during precipitation events.
We have created a pilot green roof and used it to calibrate different models to extrapolate green roof performance and create a design tool type model.
First, a HYDRUS—ZD model was developed for a modular green roof system. Physical hydraulic properties of the media were acquired through laboratory testing of cores extracted from a pilot modular green roof and then the model was calibrated with field measurement data. The model was then used to simulate performance of a full—scale green roof in response to a range of statistical recurrence interval storms from 1 to 100 years and durations from 30 min to 24 hr. The resulting simulated media water content profiles were used to develop regression equations to predict system performance for any combination of future design and precipitation event. The HYDRUS-ZD model numerically solves the Richards equation for unsaturated flow and is computationally dense.
Second, a simplified MATLAB—based model was created that incorporates the VanGenuchten equation for predicting water content, the Mualem equation for predicting unsaturated hydraulic conductivity, and the Penman—Monteith equation for evapotranspiration. This model was also calibrated using the field and lab data and used to simulate green roof performance for extrapolated scenarios.
Third, an Excel-based VBA model was created that performs similarly to the MATLAB model and is user friendly for engineer-designers to use for design or predicting the performance of existing green roofs, and is available online. Additional pilot green roof experiments and simulation development are currently underway and will be described here.
Roger is a Professor with the Department of Civil and Environmental Engineering and Water Resources Research Center at the University of Hawai‘i at Manoa. He received his PhD in Civil Engineering from the University of California at Los Angeles.
For more information contact:
Niels Grobbe, ngrobbe@hawaii.edu, 808-956-5857
Event Sponsor
Water Resources Research Center/Ike Wai, Mānoa Campus
More Information
Niels Grobbe, (808) 956-5857, ngrobbe@hawaii.edu
Tuesday, March 20 |
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8:30am |
Spring 2018 Childrens Nature Camp Mānoa Campus, Lyon Arboretum, 3860 Manoa Road, Honolulu, HI 96822
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9:00am |
MÄlama MÄnoa Mānoa Campus, Sherman courtyard, Moore Hall
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10:30am |
Qualify for SNAP with SP@M Mānoa Campus, Campus Center
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11:00am |
International Pacific Research Center Seminar Mānoa Campus, POST 414
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12:00pm |
WRRC/Ike Wai Seminar Mānoa Campus, HIG 210
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12:00pm |
Increasing Student Engagement in Class with iClicker: Overview and Q&A Mānoa Campus, Kuykendall 106 Events Room
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12:00pm |
Political Science Final Oral Mānoa Campus, Kuykendall 410
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12:00pm |
WRRC/Ike Wai Seminar Mānoa Campus, HIG 210
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12:30pm |
Study Abroad Meeting - Semester in Seville, Spain Mānoa Campus, Moore 224
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1:00pm |
East-West Toastmasters Leadership/Public Speaking Club Meeting Mānoa Campus, Campus Center 309
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1:30pm |
Study Abroad Meeting - Semester in 3 Cities in Italy Mānoa Campus, Moore 205
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1:30pm |
English Final Oral Mānoa Campus, Kuykendall 203
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1:30pm |
Resume & Cover Letter: Market Yourself on Paper Mānoa Campus, Queen Liliuokalani Center for Student Services Rm. 212
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2:30pm |
Education Final Oral Mānoa Campus, Wist 128
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3:00pm |
Padma Viswanathan Mānoa Campus, Kuykendall 410
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4:00pm |
Q&A with Admissions at Richardson Mānoa Campus, William S. Richardson School of Law- Seminar Room 2
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