Parametrization
The majority of the parameters characterizing the three green roof layers are determined by their intrinsic properties : geometry, substrate thickness, slope...
Only four parameters have been calibrated during the TVGEP project, essentially according the to substrate properties: porosity (f_sub), field capacity (FC), saturated hydraulic conductivity (Ksat) and roughness (R).
This model was calibrated and successfully validated for two types of green roof comprising an extensive vegetation (sedum), a substrate layer (thickness of 3 and 15 cm) and a drainage layer with expanded polystyrene.
The 3 cm green roof layer (ant its characteristics) has been integrated in the Multi-Hydro platform.
In order the validate this integration, Multi-Hydro was applied and run on the 35 m2 instrumented pilot site in Trappes (25 km from Paris). Observed and simulated discharges have been compared for the main rainfall events.
As we had no information on the initial saturation state of the substrate, several values have been used to match as well as possible with the observations.
