Sul coefficiente di deflusso delle coperture a verde pensile

A numerical simulation model of the hydrologic response of suitable substrates for greenroof systems has been developed, calibrated and validated. During the first part of the work an experimental data set was obtained from the operation of a laboratory test-bed aimed at evaluating the hydrologic performance of green roof substrates. The experimental campaign has been carried out with a system configuration consisting of a granular drainage layer and growing medium, this being the same green-roof configuration employed on the roof of the Laboratory of Hydraulic “E. Marchi” (University of Genova). In this stage of the work three reference rain intensities were generated and tests were carried out with different test-bed slopes; the detention capability of the system was obtained by calculating the runoff coefficient referring to the whole duration of the rain event. The second part of the paper reports about calibration and validation of a numerical model of green-roof performance obtained by simulating the same system configuration tested in the experimental campaign. A physically based model was implemented, which describes infiltration in a partially saturated medium, addressing the hydrologic response of the system within a continuous approach. These achievements allow the interpretation of the substrate behaviour under different conditions than those imposed during the laboratory campaign, therefore extending the study to a wide range of high intensity/short duration rain events.