First flush effect from vegetated roofs during simulated rain events
Author
Summary, in English
Abstract in Undetermined
Vegetated roofs are becoming increasingly popular in urban environments. Still, several aspects of their influence on various urban infrastructures are not sufficiently investigated, including the roofs' influence on runoff water quality. In this study a first flush effect in runoff water from vegetated roofs during simulated artificial rain events is investigated. Example extensive (Sweden) and intensive (Japan) vegetated roofs are studied. The first flush effect is typically occurring in urban runoff from hard surfaces and is not observed when the source of pollutants is unlimited (e.g. soil particles). Vegetated roofs would thus not be expected to exhibit a first flush effect. However, the results show that concentrations of the studied chemical compounds and elements were higher in first runoff samples than in samples taken at higher runoff depths. Analysis of the plots of normalized cumulative mass of studied runoff constituents as a function of normalized cumulative flow showed that, generally, the values are above the diagonal line with the exception of potassium (K) and dissolved organic carbon (DOC). This indicates that, with the exception of K and DOC, proportionally more mass is washed off in the earlier runoff than in the later, which can be interpreted as the occurrence of a first flush effect.
Vegetated roofs are becoming increasingly popular in urban environments. Still, several aspects of their influence on various urban infrastructures are not sufficiently investigated, including the roofs' influence on runoff water quality. In this study a first flush effect in runoff water from vegetated roofs during simulated artificial rain events is investigated. Example extensive (Sweden) and intensive (Japan) vegetated roofs are studied. The first flush effect is typically occurring in urban runoff from hard surfaces and is not observed when the source of pollutants is unlimited (e.g. soil particles). Vegetated roofs would thus not be expected to exhibit a first flush effect. However, the results show that concentrations of the studied chemical compounds and elements were higher in first runoff samples than in samples taken at higher runoff depths. Analysis of the plots of normalized cumulative mass of studied runoff constituents as a function of normalized cumulative flow showed that, generally, the values are above the diagonal line with the exception of potassium (K) and dissolved organic carbon (DOC). This indicates that, with the exception of K and DOC, proportionally more mass is washed off in the earlier runoff than in the later, which can be interpreted as the occurrence of a first flush effect.
Department/s
Publishing year
2008
Language
English
Pages
171-179
Publication/Series
Hydrology Research
Volume
39
Issue
3
Document type
Journal article
Publisher
IWA Publishing
Topic
- Water Engineering
Keywords
- vegetated roof
- first flush effect
- storm water quality
- green roof
Status
Published
ISBN/ISSN/Other
- ISSN: 1998-9563