## 4 Stormwater Management in Permeable Pavements
Figure 10 shows the runoff movements in conventional AP, permeable AP, and ICBP structures for light traffic, such as pedestrian walkways. The materials used in each layer absorb part of the runoff, which depends on its saturation degree, porosity, and permeability coefficient. Table 7 lists studies conducted through field experiments to identify the impacts of AP and ICBP on stormwater management. The average permeability or hydraulic conductivity found by [PERSON] et al. [38] for the AP (B2 and B3) and ICBP (A2 and A3) sections is shown in Figure 11. According to the results, the ICBP sections had the highest permeabilities or infiltration rates, equal to approximately 0.62 cm/s. In contrast, AP showed the lowest hydraulic conductivity (\(\approx\)0.05 cm/s), but it was still sufficient to drain the rainwater without generating surface runoff during rain events. \begin{table}
\begin{tabular}{c c c c c} \hline
**Ref.** & **Authors** & **Types of pavements** & **Experimental Descriptions** & **Key Findings** \\ \hline \multirow{6}{*}{[38]} & & & - & Three AP (B1, B2, and B3) and three ICBP (A1, A2, and A3) sections with dimensions of & The permeable pavements could capture all & 4 m \(\times\) 4 m (length \(\times\) width). \\  & & & - & Surface pavement permeability was measured & surface ponding if well-designed. \\  & & & using the ASTM C1701 (2020) method, and the measurements were performed using six & Furthermore, a suggestion for additional & Investigation was field studies to verify the & hydraulic performance analysis and \\  & & & - & Approximately 3.5 m\({}^{3}\) was irrigated in each of & structural design performance under loading. \\ \hline \end{tabular}
\end{table} 
Table 7: Effects of asphalt and interlocking concrete block pavements on stormwater management. Figure 10: Mechanism of run-off infiltration in permeable pavement layers (adapted from [3,78]). The research by [PERSON] et al. [103] presented a regression analysis of the surface porosity, depending on the operation time for AP and ICBP in Figure 12. Types of regression were selected based on the R\({}^{2}\) values. As pressure washing was an effective way to recover the surface infiltration rates, a regression analysis was made before and after pressure washing. Then, the temporal variation of pavement performance was successfully captured by introducing functions to reflect the changes in the porosities in the pavement's surface layer from external factors such as traffic and maintenance activities. Based on the research by [PERSON] et al. [83], regression analysis were made on the relationship between the runoff reduction rate by the ICBP pedestrian walkway and the rainfall parameters, such as the total volume per specific period, intensity, and time variation. The runoff reduction rate versus the total amount of rainfall per hour had the highest correlation (R\({}^{2}\) = 0.9109), and Figure 13 shows this relation. The runoff reduction averaged 35% to 41%, according to stormwater management model (SWMM) simulations. However, the reduction rate decreased to approximately 10% when the hourly rainfall exceeded 100 mm. Then, low-impact development practices, mostly designed for 1-year to 2-year