Calibration of a Physics-Based Hydrological Model of a Permeable Pavement using Data from a Laboratory Unscaled Physical Model

In the last two decades, green infrastructures have gradually been introduced in urban areas as a countermeasure for street flooding and pollutants wash-off to nearby water bodies. Among other solutions, permeable pavements (PP) are one of the most implemented one since they limit changes to the end of use of the urban space. However, due to the knowledge gap regarding the performance of the installed solutions and the efficiency over time of PPs, their adoption is often prevented. To overcome this problem, several modelling tools have been used to describe the hydraulic behaviour of PPs both at the short- and long-time scale. To accurately describe the physical processes occurring on the PPs surface, in the layers below and between PPs and nearby impermeable surfaces, the interaction between surface and subsurface flows must be considered. To this aim, Integrated Surface Subsurface Hydrological (ISSH) model (Camporese et al., 2010) can be fruitfully used to investigate the runoff vs infiltration processes along time in PPs. Here, the ISSH model reproduces an unscaled physical model of a section of permeable parking lot 6 m long, 2 m wide and with height varying between 0.9 and 1 m (surface slope of about 1.2%) realized inside a 6×2 m2 concrete box facility in the Laboratory of Hydraulics and Hydraulic construction of the University of Padova (Lora et al., 2016; Mazzarotto et al., 2024). No-flow boundary conditions are imposed on the bottom of the ISSH model as well as on the lateral sides, to reproduce the concrete walls surrounding the PP, except for the downstream side where a seepage face boundary condition is assumed to reproduce the porous wall built in the physical model that allows subsurface discharge quantification. A first set of experiments was performed on the physical model using a rainfall simulator. Data collected by the installed sensors is used to calibrate the parameters of the ISSH model, in particular the hydraulic characteristics of the blocks and of the aggregate materials, and reproduce the unsaturated hydraulic behaviour of the PP (e.g. Turco et al., 2017). The calibration results of the ISSH model based on a first set of experiments developed on the unscaled PP model are shown highlighting the major difficulties related in the assessment of parameters.