Abstract
Both deterministic and probabilistic models have been developed to study the hydrologic operation of green roofs. Previously developed probabilistic models provide only approximate solutions because of simplifying assumptions. Exact analytical solutions are derived here for not only those variables that are solved for already but also some additional ones of interest. Analysis of the additional variables reveals that, depending on local climates, the average moisture level of a green roof may either always increase or increase first but reach a maximum and then even gradually decrease as the growing medium depth increases. Example results of analysis also demonstrate that with shallow growing medium depths, water required for irrigation may be greater than the runoff that can be reduced by green roofs. Taking advantage of the solution’s analytical tractability, similar insights can be easily obtained for locations of interest and used for the better design and operation of green roofs.
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Acknowledgments
This work was supported partly by the Natural Sciences and Engineering Research Council (NSERC) of Canada. Dr. Shouhong Zhang assisted in SWMM simulations and analysis of some of the SWMM results. This work was also partially completed within the framework of the Panta Rhei Research Initiative of the International Association of Hydrological Sciences.
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Journal of Hydrologic Engineering
Volume 21 • Issue 7 • July 2016
Copyright
© 2016 American Society of Civil Engineers.
History
Received: Feb 18, 2015
Accepted: Dec 29, 2015
Published online: Mar 18, 2016
Published in print: Jul 1, 2016
Discussion open until: Aug 18, 2016
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