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Permeable Pavement (PP) models are valuable tools for studying the implementation of PPs in urban environments. However, the runoff simulated by traditional models such as the Curve Number (CN) is different from that created with PP models, as infiltration is computed differently. However, many investigations compare the runoff created by both models to extract broader conclusions without considering how the two models are related. Hence, this research explores the relation between runoff simulated by one general model, selecting the widespread CN model as a baseline, and the PP model provided in the Storm Water Management Model (SWMM). Correlation was set using the hydrograph created with the CN in a single event as a baseline and obtaining the best pavement permeability value from the PP model by calibration. The influence of storm depth, pavement slope, catchment shape, and PP type was also analysed. Calibration was conducted based on the Nash–Sutcliffe coefficient, but peak and volume performances were also studied. The results show that it is possible to link runoff hydrographs computed with the PP model to those created with the CN method, although that relation is not useful for the entire CN range. That relation is practical for CNs higher than 88 and shall be helpful for urban planners and researchers to compare several pervious/impervious scenarios in urban drainage models more robustly. One direct application is to compare the runoff computed by both models without changing the method that simulates runoff. It shall be enough to change a unique parameter that can be linked to a certain imperviousness by the CN.

Traditional urban development practices disrupt the natural water cycle, increasing surface runoff volume/velocity and reducing water quality, amongst other impacts. Those negative impacts can be reduced adopting sustainable urban drainage system (SUDS) techniques, such as pervious pavements. porous asphalt (PA) and permeable interlocking clay/concrete pavers (PICP) are two types of pervious pavements. Both are similar to traditional asphalt and pavers, but superficial layer has a high porosity for allowing infiltration of rain, and base/subbase layers contain a high void fraction to allow water retention. In order to analyse these types of pavements and assess how they affect the general urban stormwater network, the SWMM model has been widely used. Even so, more confidence in the selected parameters is needed, especially when modelling homogeneous areas by means of low impact development (LID) units. To do so, laboratory tests have been implemented using a rainfall simulator, testing PICP/PA materials under different slopes (1% and 6%) and rain conditions (35 mm/h and 70 mm/h), and infiltrated water was measured for each layer independently. This paper validates, using the aforementioned laboratory data, the parameters needed for modelling PA and PICP in SWMM, as well as differences between them, showing that SWMM is a convenient tool to model single events on permeable pavements for regular storms.

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