DBPapers
DOI: 10.5593/SGEM2014/B31/S12.061

MODELING OF HYDRAULIC BEHAVIOUR OF GREEN ROOF IN CATCHMENT SCALE

M. Carbone, M. Turco, G. Nigro, . P. Piro
Wednesday 1 October 2014 by Libadmin2014

References: 14th International Multidisciplinary Scientific GeoConference SGEM 2014, www.sgem.org, SGEM2014 Conference Proceedings, ISBN 978-619-7105-13-1 / ISSN 1314-2704, June 19-25, 2014, Book 3, Vol. 1, 471-478 pp

ABSTRACT
In the last decades the increase of urbanization has drastically modified the hydrological cycle; in particular, while the extension of impervious surface has increased the runoff and hence, the potential for flooding, the reduction of green areas has caused the formation of urban heat island and consequently, the increase of the energy demand. Another negative effect of urbanization has been a severe decline of biodiversity. In this context a comprehensive land planning and engineering design approach with a goal of maintaining are needed to restore pre-development hydrologic regime of urban and developing watersheds. At the University of Calabria GIs were designed and built to develop a sustainable approach example of university campus; the project is called “Urban Water Park”. The park consists of a green roof, a permeable pavement and a biofiltration system. From the hydraulic point of view the parameters retrieved are rainfall, influent and effluent flow rates, humidity and water content in the soil substrate. For each facility the main pollutant (eg. TSS, heavy metal, PAH, COD) are monitored. From a thermo-physical point of view temperature and solar parameters are measured. Green roof techniques are increasingly becoming popular among the Low Impact Developments (LIDs) techniques for urban runoff management. Of particular interest is the rooftop runoff management on large time scales (eg. annual). Several studies have shown that green roofs allow to effectively control the generation of surface runoff, significantly reducing the overall discharged volumes (40% to 80%) as well as slowing the contribution to the urban drainage network. This study proposes a conceptual model based on the SWMM model to predict the hydrological benefit of a green roof in a large watershed for daily simulation. The model idealizes the green roof as a system consisting of three individual components in series, each characterized by a specific process hydrological and hydraulic. A mass balance equation is applied to each block, taking into account the specific physical phenomena occurring in each module, and the flow is governed by Richards equations. The model is validated with the data observed from the monitoring campaign (climatic, thermal-hydraulic parameters) of a full-scale green roof characterized by different drainage layers and vegetation species. This study aims to provide quantitative information about the hydraulic performance of green roofs in large watershed for daily series of rainfall, and to identify the most sensitive parameters, such as retained volume, runoff delay for modeling the hydraulic behaviour. The results show that the ability of water regulation is a function of weatherclimatic conditions, plant species and green roof design characteristics.

Keywords: SUDs, stormwater, green roofs, runoff, conceptual model, monitoring, water storage.