2017 ASHS Annual Conference

Green roofs have been shown to have many environmental benefits. Of these benefits, stormwater management has received a great deal of attention in both policy and incentive programs, which require green roofs to meet certain criteria. It is unclear at this time if agricultural green roofs meet these requirements or have the same stormwater benefits as conventional green roofs. This study was designed to monitor the stromwater retention of a full scale rooftop farm and compare retention rates to conventional extensive sedum green roofs. V-notch weirs with acoustic distance sensors were installed in one drainage basin on the roof to measure runoff. A weather station was also installed to measure ambient weather conditions and rainfall. Rainfall retention rates were then compared to the results of a previous study on an extensive sedum green roof (referred to as USPS). Overall stomrwater retention on the Brooklyn Grange was 50%. The Brooklyn Grange roof exhibited greater retention for smaller storms and during the summer months, a similar pattern to the USPS roof and patterns of retention reported in the green roof literature. In most cases, retention on the Brooklyn Grange was no significantly different from that of the USPS roof. It was also similar to retention values reported in the green roof literature. There was no difference between peak flow reduction on the Brooklyn Grange and USPS green roofs and peak flow reductions from the Brooklyn Grange resembled those reported in the green roof literature. Differences in retention on the Brooklyn Grange and USPS rooftops can most likely be attributed to the use of irrigation on the Brooklyn Grange.