Independent Validation of the SWMM Green Roof Module
Publication: Journal of Hydrologic Engineering
Volume 22, Issue 9
Abstract
Green roofs are a popular sustainable drainage systems technology. They provide multiple benefits, amongst which the retention of rainfall and detention of runoff are of particular interest to stormwater engineers. The hydrological performance of green roofs has been represented in various models, including the Storm Water Management Model (SWMM). The latest version of SWMM includes a new low-impact development green roof module, which makes it possible to model the hydrological performance of a green roof by directly defining the physical parameters of a green roof’s three layers. However, to date, no study has validated the capability of this module for representing the hydrological performance of an extensive green roof in response to actual rainfall events. In this study, data from a previously monitored extensive green roof test bed have been used to validate the SWMM green roof module for both long-term (173 events over a year) and short-term (per-event) simulations. With only 0.357% difference between measured and modeled annual retention, the uncalibrated model provided good estimates of total annual retention, but the modeled runoff depths deviated significantly from the measured data at certain times (particularly during summer) in the year. Retention results improved [with the difference between modeled and measured annual retention decreasing to 0.169% and the Nash–Sutcliffe model efficiency (NSME) coefficient for per-event rainfall depth reaching 0.948] when reductions in actual evapotranspiration (ET) due to reduced substrate moisture availability during prolonged dry conditions were used to provide revised estimates of monthly ET. However, this aspect of the model’s performance is ultimately limited by the failure to account for the influence of substrate moisture on actual ET rates. With significant differences existing between measured and simulated runoff and NSME coefficients below 0.5, the uncalibrated model failed to provide reasonable predictions of the green roof’s detention performance, although this was significantly improved through calibration. To precisely model the hydrological behavior of an extensive green roof with a plastic board drainage layer, some of the modeling structures in SWMM green roof module require further refinement.
Get full access to this article
View all available purchase options and get full access to this article.
References
Alfredo, K., Montalto, F., and Goldstein, A. (2010). “Observed and modelled performances of prototype green roof test plots subjected to simulated low-and high-intensity precipitations in a laboratory experiment.” J. Hydrol. Eng., 444–457.
Berretta, C., Poë, S., and Stovin, V. (2014). “Moisture content behavior in extensive green roof during dry periods: The influence of vegetation and substrate characteristics.” J. Hydrol. (Amsterdam, Neth.), 511, 374–386.
Burszta-Adamiak, E. A., and Mrowiec, M. (2013). “Modelling of green roofs’ hydrologic performance using EPA’s SWMM.” Water Sci. Technol., 68(1), 36–42.
Carter, T., and Jackson, C. R. (2007). “Vegetated roofs for stormwater management at multiple spatial scales.” Landscape Urban Plann., 80(1–2), 84–94.
Cipolla, S. S., Maglionico, M., and Stojkov, I. (2016). “A long-term hydrological modelling of an extensive green roof by means of SWMM.” Ecol. Eng., 95, 876–887.
Fassman-Beck, E. A., and Simcock, R. (2012). “Moisture measurements as performance criteria for extensive living roof substrates.” J. Environ. Eng., 841–851.
Fassman-Beck, E. A., Simcock, R., Voyde, E., and Hong, Y. S. (2013). “4 Living roofs in 3 locations: Does configuration affect runoff mitigation?” J. Hydrol. (Amsterdam, Neth.), 490, 11–20.
Feng, Y., and Burian, S. (2016). “Improving evapotranspiration mechanisms in the U.S. environmental protection agency’s Storm Water Management Model.” J. Hydrol. Eng., 06016007.
Fioretti, R., Palla, A., Lanza, L., and Principi, P. (2010). “Green roof energy and water related performance in the Mediterranean climate.” Build. Environ., 45(8), 1890–1904.
Getter, K. L., Rowe, D. E., and Andresen, J. A. (2007). “Quantifying the effect of slope on extensive green roof stormwater retention.” Ecol. Eng., 31(4), 225–231.
Hilten, R. N., Lawrence, T. M., and Tollner, E. W. (2008). “Modeling stormwater runoff from green roofs with HYDRUS-1D.” J. Hydrol. (Amsterdam, Neth.), 358 (3–4), 288–293.
Hydrus-1D version 3.0 [Computer software]. Dept. of Environmental Sciences, Univ. of California Riverside, Riverside, CA.
Jewell, T. K., Adrian, D. D., and Nunno, T. J. (1978). “Methodology for calibrating stormwater models.” J. Environ. Eng. Div., 104(3), 485–501.
Kasmin, H., Stovin, V., and Hathway, E. (2010). “Towards a generic rainfall-runoff model for green roofs.” Water Sci. Technol., 62(4), 898–905.
Li, Y., and Babcock, R. (2014). “Green roof hydrologic performance and modeling: A review.” Water Sci. Technol., 69(4), 727–738.
Locatelli, L., Mark, O., Mikkelsen, P. S., Arnberg-Nielsen, K., Jensen, M. B., and Binning, P. J. (2014). “Modelling of green roof hydrological performance for urban drainage applications.” J. Hydrol. (Amsterdam, Neth.), 519, 3237–3248.
Mualem, Y. (1976). “A new model for predicting the hydraulic conductivity of unsaturated porous media.” Water Resour. Res., 12(3), 513–522.
Nash, J. E., and Sutcliffe, J. V. (1970). “River flow forecasting through conceptual models. Part I: A discussion of principles.” J. Hydrol. (Amsterdam, Neth.), 10(3), 282–290.
Nawaz, R., McDonald, A., and Postoyko, S. (2015). “Hydrological performance of a full-scale extensive green roof located in a temperate climate.” Ecol. Eng., 82, 66–80.
Palla, A., and Gnecco, I. (2015). “Hydrologic modeling of low impact development systems at the urban catchment scale.” J. Hydrol. (Amsterdam, Neth.), 528, 361–368.
Palla, A., Sansalone, J. J., Gnecco, I., and Lanza, L. G. (2011). “Storm water infiltration in a monitored green roof for hydrologic restoration.” Water Sci. Technol., 62(3), 766–773.
Poë, S., Stovin, V., and Berretta, C. (2015). “Parameters influencing the regeneration of a green roof’s retention capacity via evapotranspiration.” J. Hydrol. (Amsterdam, Neth.), 523, 356–367.
Rosa, D. J., Clausen, J. C., and Dietz, M. E. (2015). “Calibration and verification of SWMM for low impact development.” J. Am. Water Res. Assoc., 51(3), 746–757.
Rossman, L. A. (2008). Storm water management model; version 5.0.19, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Cincinnati.
Rossman, L. A. (2010). Storm water management model; version 5.0.022, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Cincinnati.
Rossman, L. A. (2015). Storm water management model user's manual version 5.1, U.S. Environmental Protection Agency, Cincinnati.
Rossman, L. A. (2016). Storm water management model; version 5.1.011, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Cincinnati.
She, N., and Pang, J. (2010). “Physically based green roof model.” J. Hydrol. Eng., 458–464.
Stovin, V., Poë, S., and Berretta, C. (2013). “A modelling study of long term green roof retention performance.” J. Environ. Manage., 131, 206–215.
Stovin, V., Poë, S., De-Ville, S., and Berretta, C. (2015a). “The influence of substrate and vegetation configuration on green roof hydrological performance.” Ecol. Eng., 85, 159–172.
Stovin, V., Vesuviano, G., and De-Ville, S. (2015b). “Defining green roof detention performance.” Urban Water J., 14(6), 574–588.
Stovin, V., Vesuviano, G., and Kasmin, H. (2012). “The hydrological performance of a green roof test bed under UK climatic conditions.” J. Hydrol. (Amsterdam, Neth.), 414–415, 148–161.
SWMM5 [Computer software]. U.S. Environmental Protection Agency, Cincinnati.
Vesuviano, G., Sonnenwald, F., and Stovin, V. (2014). “A two-stage storage routing model for green roof runoff detention.” Water Sci. Technol., 69(6), 1191–1197.
Vesuviano, G., and Stovin, V. (2013). “A generic hydrological model for a green roof drainage layer.” Water Sci. Technol., 68(4), 769–775.
Villarreal, E. L., and Bengtsson, L. (2005). “Response of a sedum green-roof to individual rain events.” Ecol. Eng., 25(1), 1–7.
Woods Ballard, B. (2015). The suds manual, CIRIA, London.
Yang, W., Li, D., Sun, T., and Ni, G. (2015). “Saturation-excess and infiltration-excess runoff on green roofs.” Ecol. Eng., 74, 327–336.
Zhao, D., Chen, J., Wang, H., Tong, Q., Cao, S., and Sheng, Z. (2009). “GIS-based urban rainfall-runoff modeling using an automatic catchment-discretization approach: A case study in Macau.” Environ. Earth Sci., 59(2), 465–472.
Information & Authors
Information
Published In
Copyright
©2017 American Society of Civil Engineers.
History
Received: Dec 9, 2016
Accepted: Apr 5, 2017
Published online: Jul 12, 2017
Published in print: Sep 1, 2017
Discussion open until: Dec 12, 2017
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.