A New Coupled 2D/1D Surface Runoff and Infiltration Model for Permeable Pavements

Abstract Submission: Low-impact development techniques such as permeable pavements (PPs) can improve surface runoff water quality, reduce total volume, and alleviate peak flows. Several models of PP have been proposed in the literature with different levels of complexity: from lumped-parameter models based on level pooled routing schemes, vertical 1D models based on approximations or complete solutions of Richards equation (e.g., SWMM, HYDRUS-1D, and 2D). Simplified approaches such as level pool routing schemes can produce inaccurate results when the pavement is sloped, or rainfall is spatially variable (e.g., large parking areas). On the other hand, fully 2D Richards models often require prohibited computational times, especially for cases where Monte Carlo simulations, digital twin applications, or ensemble forecasting analysis are performed. To this end, we develop a surface 2D depth-average shallow-water equation model coupled with a 1D vertical Richards equation, capable of simulating excess infiltration and saturation and allowing testing cases with internal water storage or bottom exfiltration to be assessed. The model is rigorously tested in four pavement LID parking lots with equal area. Four events were carefully selected for calibration, and later, the model was validated against six observed events (with durations varying from 85 to 2080 minutes and rainfall volumes of 0.62 to 4.5 inches. The results indicate acceptable hydrological performance, instilling confidence in the model's reliability for future applications in physics-based digital twins for forecasting and analysis of PPs.

Learning Objectives/Expected Outcome (Optional) :