Smart Stormwater Management in Urban Areas by Roofs Greening

Abstract

By 2050 the world population will grow to about 9 billion contributing to deep changes in urban areas structure. This would increase the effect of water deficiency and along with projected climate changes the impact of urban floodings, urban heat islands or drought. Smart cities could be key part of the solution contributing to improve the quality life of citizen in urban areas with the adoption of smart, intelligent technologies and infrastructure for energy, water, mobility, buildings, and government. The concept of smart water refers to the ability to provide and manage this primary resource in quantitative and qualitative terms in order to satisfy the future needs of population. The green roof (GR) is a technique belonging to the sectors of smart energy and smart water. It could provide several benefits: sound and thermal insulation of the buildings, mitigation of the urban heat island effects, reduction of air pollution, additionally, GR induces important hydraulic advantages acting as an effective tool for reducing flood risk in urban area with runoff reduction, attenuation and delay of the peak flow. In this paper, the retention capacity of two green roof test beds located in the campus of University of Salerno has been investigated. The analysis has referred to measures of runoff and rainfall conducted in 2017 during the months of February and March. The two roofs substantially differ in the composition of the water storage layer made up of expanded clay in GR1 and of commercial drainage panels in GR2. The retention capacity of the two test beds has been compared. The results confirm that both green roofs, although to a different extent, are effective for the reduction of total runoff volume of rainwater falling on their area.