Climate, soil moisture and drainage layer properties impact on green roofs in a Mediterranean environment

In the last few years, due to an increasingly invasive urbanization the scientific community has had to face technologies for hydrogeological risks management in urban environments. GRs are considered, in this context, a promising solution able to reduce the risks deriving from the inability of drainage urban systems to collect stormwater. They act as filters that reduce the stromwater production based on the specific retention capacity. Green roof retention capacity depends on numerous factors such as the characteristics of the rain event, the moisture content, the depth and characteristics of the substrate, the vegetation, the slope and the research in this area is still challenging and affected by large uncertainties . In particular, in the Mediterranean regions, characterized by long periods of drought, high temperatures and heavy rainfall, the substrate layer moisture content, which is not routinely measured, is considered the key element that influences the performance of green roofs and is mainly affected by substrate depth and composition of the soil. In the reported paper, the importance of observed substrate soil moisture measurements is shown to improve the prediction of hydrological performances of two extensive green roofs test beds, located in the University of Salerno campus, Southern Italy , highlighing the dependence of rainfall depth and duration and on the construction technology.