|Authors: ||M.A. Monterusso, D.B. Rowe, C.L. Rugh, D.K. Russell|
|Keywords: ||native plants, Sedum, nitrogen, phosphorus, rainfall retention|
Use of green roof technology is becoming increasingly widespread throughout the world because of its environmental, economic, and aesthetic benefits.
The ability of a green roof to retain stormwater and limit the amount of fertilizer in the effluent flow are important characteristics of a properly installed green roof system.
However, scientific research quantifying these characteristics is limited – particularly in the United States.
Simulated rooftop platforms were constructed and runoff was analyzed from four commercially available green roof systems containing three distinct vegetation types.
Quantity of rainfall retained ranged from 38.6% for Xeroflor to 58.1% for Siplast.
Quantitatively, Xeroflor resulted in the greatest volume of runoff, but these volumes were only significant for the sections of Sedum plugs and seed during the fourth rainfall event.
Differences in water retention can likely be attributed to substrate depth, rather than drainage system or vegetation type.
Results demonstrate two important concepts that affect the amount of stormwater a green roof can retain – substrate thickness and substrate moisture content immediately prior to a rainfall event.
Nitrate concentrations in the runoff varied from 0.22 ppm in the Sarnafil native plant sections 314 days following fertilizer application to 22.7 ppm in Xeroflor Sedum seed sections 314 days following fertilizer application.
No significant differences were observed between any of the treatments with regard to phosphorus concentrations.
Download Adobe Acrobat Reader (free software to read PDF files)
URL www.actahort.org Hosted by KU Leuven