Green Roof Runoff Impact

Green roofs are stormwater management practices that capture and store rainfall in an engineered growing media that is designed to support plant growth.

Green roof runoff impact.

Because rooftops and streets in cities are hard surfaces the volume and velocity of stormwater runoff increases tremendously and is a major source of flooding and pollution worldwide. In summer a green roof can typically retain between 70 80 of the runoff green roofs can help to reduce the surface run off entering the drainage system. Green roofs can reduce and slow stormwater runoff in the urban environment and also filter pollutants from rainfall. Another important benefit of green roofs is their ability to reduce and slow stormwater runoff in urban environments.

The stormwater management benefit provided by green roofs lies in the ability of the soil media and plants to retain stormwater increase evapotranspiration and allow stormwater runoff to be released gradually to receiving waters at decreased flow rates. The current paper has focused on the analysis of the impact of green roof construction on stormwater production. A portion of the captured rainfall evaporates or is taken up by plants which helps reduce runoff volumes peak runoff rates and pollutant loads on development sites. Factors which affect influence of a green roof on runoff water quality are discussed in general terms followed by the review of data regarding concentrations of phosphorus nitrogen and heavy metals in green roof runoff its ph and first flush effect.

Green roof runoff does contain concentrations of some nutrients and other parameters but values are in line with other planted systems. Green roofs can retain nearly all storm related precipitation during the summer months with lower retention during the winter months 20. Green roof facilities act as a reduction of impervious surfaces where the largest or almost integrally the rainfall volumes produces runoff flowing into the urban drainage system. Green roof runoff does contain concentrations of some nutrients and other parameters but values are in line with other planted systems.

Due to the volume reduction actual nutrient loadings from green roofs are less than asphalt roofing runoff or otherwise manageable at the downspout. In summer a green roof can typically retain between 70 80 of the runoff. Enhanced stormwater management and water quality.