Particle-Tracking within an Ultra-High-Resolution Urban Domain Integrated with Best Management Practices

Abstract:

Best management practices (BMPs) are used to offset the impacts of urban developments known to decrease aquifer recharge, alter drainage networks, change feedbacks to the atmosphere and enhance contaminant transport. To evaluate the effectiveness of BMPs (i.e. engineered wetlands, grass swales, permeable pavements, etc.), a high-resolution study of these processes can be performed in the field using timely monitored instruments, or conceptually-based hydrologic models. However, this approach requires advancing stormwater modeling techniques using high performance computing. The goal of this work is to develop a novel approach to evaluate BMP implementation using an ultra-high-resolution domain and ParFlow, a physically-based hydrologic model that simulates surface and subsurface water interactions. This study domain is located in Aurora, CO, an area that experienced over 200% urban growth over the last 30 years. The ultra-high-resolution domain was constructed using LIDAR imagery and consisted of 1m x 1m horizontal resolution over a ~7.7 km by 2.1 km lateral extent up to 2 m in the subsurface, with a domain totaling more than 3x10⁶unknowns. Three storm events (wet, dry and normal) were simulated with two pavement types, permeable (K=0.18 mhr^-1,Φ=0.1) and impermeable (K=0.0018 mhr^-1, Φ=0.06), amounting to 6 simulation scenarios. We investigated changes to stormwater routing and infiltration with and without BMP implementation. Contaminant transport was performed using SLIM-FAST, a Lagrangian, particle tracking approach that allows for complex, contaminant-loading scenarios common in the urban environment. Preliminary results show delayed particle movement within impermeable pavement scenarios and particle trapping along the gutters and rooftop locations. This approach is useful for evaluating the effectiveness of BMPs in trapping and reducing concentrations of emerging contaminants of concern within urban environments.