The parameters of the SWMM are presented in Table 2. The average values of the recommended ranges of the void ratio of the pavement and storage layers are selected from the SWMM manual (Rossman 2015), following the work of Zhang & Guo (2015). The berm height of the surface layer was selected as zero to allow for surface runoff to occur if the pavement is full while the pavement slope was selected as 1% (Zhang & Guo 2015). The impervious surface fraction parameter is selected arbitrarily as 0.9. This parameter, together with the void ratio of the pavement layer, is only used by the SWMM in clogging conditions (Rossman 2015). In this study, however, we assumed no clogging conditions during the pavement lifetime through frequent maintenance. Randall et al. (2020) found the void ratio of the pavement layer to be an insensitive parameter for the SWMM with no clogging condition. The permeability of the pavement was set as 3,600 mm/h, which is a typical value for permeable pavement that is designed with permeable materials (Zhang & Guo 2015; Vaillancourt et al. 2019).

Table 2

SWMM parameters used in the study

ParameterLayerSelected value(s)Unit
Manning Surface 0.1 –
Berm height mm
Slope
The thickness of the pavement layer Pavement 80 mm
Void ratio 0.17 –
Impervious surface fraction 0.9 –
Permeability 3,600 mm/h
Void ratio Storage 0.63 –
Depth of the storage layer (D10, 20, 50, 100, 300, 400 mm
Infiltration to the native soil 0.1, 0.5, 1, 3, 5, 10, 20 mm/h
ParameterLayerSelected value(s)Unit
Manning Surface 0.1 –
Berm height mm
Slope
The thickness of the pavement layer Pavement 80 mm
Void ratio 0.17 –
Impervious surface fraction 0.9 –
Permeability 3,600 mm/h
Void ratio Storage 0.63 –
Depth of the storage layer (D10, 20, 50, 100, 300, 400 mm
Infiltration to the native soil 0.1, 0.5, 1, 3, 5, 10, 20 mm/h

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