Hydrologic Restoration in the Urban Environment Using Green Roofs

Abstract

Loss of natural soil and vegetation within the urban environment can significantly affect the hydrologic cycle by increasing storm water runoff rates and volumes. In order to mitigate these modifications in urban areas engineered systems are developed, such as green roofs, to mimic and replace functions (evapo-transpiration, infiltration, percolation) which have been altered due to the impact of human development. Green roofs, also known as vegetated roof covers, eco-roofs or nature roofs, are composite complex layered structures with specific environmental benefits. They are increasingly being used as a source control measure for urban storm water management. Indeed, they are able to re-establish the natural water cycle processes and to operate hydrologic control over storm water runoff with a derived peak flow attenuation, runoff volume reduction and increase of the time of concentration. Furthermore green roofs exhibit the capacity to reduce storm water pollution; they generally act as a storage device, consequently pollutants are accumulated in the substrate layer and released when intensive rainwater washes them out. In order to investigate the hydrologic response of a green roof, the University of Genova recently developed a joint laboratory and full-scale monitoring programme by installing a "controlled" laboratory test-bed with known rainfall input and a companion green roof experimental site (40 cm depth) in the town of Genoa. In the paper, data collected during the monitoring programme are presented and compared with literature data.

The Influence of Hydrologic Parameters on the Hydraulic Efficiency of an Extensive Green Roof in Mediterranean Area

“…Palla et al [34] explored the performance of a green roof installed at the University of Genoa, Italy, under Mediterranean climate conditions. The retained volumes, calculated as the percentage difference between the volume of rain and the discharged volume, ranged between 0% and 100%, with an average value of 51.5%.…”

“…[34] Mediterranean-Genova (IT) 0.48 Voyde et al (2010) [15] Sub-tropical-Auckland (NZ) 0.34 Stovin et al (2012) [16] Temperate-Sheffield (UK) 0.48 Gromaire et al (2013) [19] Temperate-Trappes (F) 0.36-0.50 Locatelli et al (2014) [20] Ocean-Odense and Copenaghen (DK) 0.43-0.68 Wong and Jim (2014) [35] Humid sub-tropical-Hong Kong (CN) 0.86-0.89…”

A modelling study of long term green roof retention performance

“…Miller, 2003;Bengtsson et al, 2005;Jarrett and Berghage, 2008;Palla et al, 2010;. Furthermore, Jarrett and Berghage (2008) and Kasmin et al (2010) attention is paid to the ET rate, which is considered to by the key parameter in green roof retention performance modelling.…”

“…Green roofs have received a particularly high level of interest in recent years, and the literature includes many reports on the hydrological performance of both test beds and full scale roof installations; see Palla et al (2010) and Stovin et al (2012) for an overview.…”

İstanbul’un Yağmur Suyu Taşkınlarına Karşı Yeşil Teras Çatıların Önleyici Rolü

“…Bu veri çoğu zaman yıllık yağmura göre verilir ve yeşil teras çatı sistemlerinde değişik yağmur suyu tutma kapasiteleri ölçülür. Yapılan araştırma ve değerlendirmelere göre bu değer, Almanya'da %27 ile %81 arasında değişirken [9], Amerika'nın Chicago, Philadelphia ve Portland şehirlerinde %65 [19], Fransa'nın Nantes şehrinde %72,8 ile %80,2 arasında [20], İtalya'da Genova kenti için ise %51 olarak bulunmuştur [21]. İstanbul için yapılan bir araştırmada ise yeşil çatının standart bir çatıya göre %43 daha fazla yağmur suyu tuttuğu tespit edilmiştir [22].…”