Modeling Hydrologic Performance of a Green Roof System with HYDRUS-2D
Publication: Journal of Environmental Engineering
Volume 141, Issue 11
Abstract
A green roof is an environmentally friendly best management practice for volume reduction, peak flow reduction, and peak delay of stormwater runoff from impervious rooftops. In this study, HYDRUS-2D was used to model the hydrologic response of a pilot green roof system. The root-mean-square deviation (RMSD) of growth media volumetric water content values between model and field measurements ranged between 0.38 and 1.74%. A method was developed to use the water content profile at three media depths to derive regression equations that predict hydrologic performance. These equations show that runoff volume reduction follows an inverse relationship between media field capacity and precipitation depth, that peak flow reduction obeys a second-order equation between media field capacity and precipitation depth, and that peak delay time can be approximated by a third-order equation that includes maximum capacity and precipitation depth. The values of the regressions range between 0.87 and 0.99. These derived equations can be used for performance evaluations or design work, including determining the necessary green roof media depth to meet Leadership in Energy and Environmental Design (LEED) runoff reduction requirements.
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References
Alfredo, K., Montalto, F., and Goldstein, A. (2010). “Observed and modeled performances of prototype green roof test plots subjected to simulated low- and high-intensity precipitations in a laboratory experiment.” J. Hydrol. Eng., 444–457.
Allen, R. G., Pereira, L. S., Raes, D., and Smith, M. (1998). “Crop evapotranspiration—Guidelines for computing crop water requirements.”, Food and Agriculture Organization.
ASTM. (2010). “Standard test methods for measurement of hydraulic conductivity of saturated porous materials using a flexible wall permeameter.”, West Conshohocken, PA.
Burszta-Adamiak, E., and Mrowiec, M. (2013). “Modelling of green roofs’ hydrologic performance using EPA’s SWMM.” Water Sci. Technol., 68(1), 36–42.
Carson, T. B., Marasco, D. E., Culligan, P. J., and McGillis, W. R. (2013). “Hydrological performance of extensive green roofs in New York City: Observations and multi-year modeling of three full-scale systems.” Environ. Res. Lett., 8(2), 024036.
Carter, T., and Jackson, C. R. (2007). “Vegetated roofs for stormwater management at multiple spatial scales.” Landscape Urban Plan, 80(1–2), 84–94.
Fassman-Beck, E., Voyde, E., Simcock, R., and Hong, Y. S. (2013). “4 living roofs in 3 locations: Does configuration affect runoff mitigation?” J. Hydrol., 68(1), 36–42.
Guo, Y. P., Liu, S. G., and Baetz, B. W. (2012). “Probabilistic rainfall-runoff transformation considering both infiltration and saturation excess runoff generation processes.” Water Resour. Res., 48(6), W0651.
Hilten, R. N., Lawrence, T. M., and Tollner, E. W. (2008). “Modeling stormwater runoff from green roofs with HYDRUS-1D.” J. Hydrol., 358(3–4), 288–293.
Li, Y., and Babcock, R. W. (2014). “Green roof hydrologic performance and modeling: A review.” Water Sci. Technol., 69(4), 727–738.
Londra, P. A. (2010). “Simultaneous determination of water retention curve and unsaturated hydraulic conductivity of substrates using a steady-state laboratory method.” Hortscience, 45(7), 1106–1112.
Metselaar, K. (2012). “Water retention and evapotranspiration of green roofs and possible natural vegetation types.” Resour. Conserv. Recyle, 64, 49–55.
Palla, A., Gnecco, I., and Lanza, L. G. (2009). “Unsaturated 2D modelling of subsurface water flow in the coarse-grained porous matrix of a green roof.” J. Hydrol., 379(1–2), 193–204.
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., 64(3), 766–773.
Radcliffe, D. E., and Simunek, J. (2010). Soil physics with HYDRUS—Modelling and applications, CRC Press, London.
She, N. A., and Pang, J. (2010). “Physically based green roof model.” J. Hydrol. Eng., 458–464.
Topp, G. C., and Ferre, P. A. (2002). “Thermogravimetric using convective oven-drying.” Methods of soil analysis: Part 4, physical methods, Soil Science Society of America (SSSA), Madison, WI, 422–424.
U.S. Department of Commerce, Weather Bureau. (1962). “Rainfall-frequency atlas of the hawaiian island.”, Washington, DC.
USEPA (U.S. Environmental Protection Agency). (2014). “Green roofs, national pollutant discharge elimination system (NPDES).” 〈http://cfpub.epa.gov/npdes/stormwater/menuofbmps/index.cfm?action=factsheet_results&view=specific&bmp=114〉 (Mar. 25, 2014).
van Genuchten, M. T. (1980). “A closed-form equation for predicting the hydraulic conductivity of unsaturated soils.” Soil Sci. Soc. Am. J., 44(5), 892–898.
van Genuchten, M. T. (1987). “A numerical model for water and solute movement in and below the rootzone.” U.S. Salinity Laboratory, U.S. Dept. of Agriculture (USDA), ARS, Riverside, CA.
Zhang, S. H., and Guo, Y. P. (2013). “Analytical probabilistic model for evaluating the hydrologic performance of green roofs.” J. Hydrol. Eng., 19–28.
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Information
Published In
Journal of Environmental Engineering
Volume 141 • Issue 11 • November 2015
Copyright
© 2015 American Society of Civil Engineers.
History
Received: Dec 14, 2014
Accepted: Apr 8, 2015
Published online: Jun 19, 2015
Published in print: Nov 1, 2015
Discussion open until: Nov 19, 2015
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