Integration of SWMM and TELEMAC for Coupled 1D/2D Modeling

Urban flood modeling increasingly requires the integration of one-dimensional hydraulic networks with high-resolution two-dimensional surface flow simulations. This paper presents a robust 1D/2D coupling framework that integrates the EPA SWMM engine with the TELEMAC hydrodynamic modeling system.

The framework enables dynamic, two-way exchange between 1D networks and 2D surface domains using physically based hydraulic relationships. SWMM junctions, storage units, and outfalls are connected to designated TELEMAC source points through configurable structures, including orifices, weirs, pumps, outlets, outfalls, and direct runoff transfer. Exchange flows are governed by standard head-based discharge equations and embedded within the TELEMAC time-stepping loop.

A custom C-based bridge provides native access to the official 64-bit EPA SWMM dynamic link library without recompilation, ensuring numerical consistency and long-term maintainability. More than 35 Fortran modules were developed or enhanced to implement flow exchange, and companion Python scripts were updated to preserve existing TELEMAC subroutine customizability.

The integrated platform supports flexible network-to-surface mapping and high-performance parallel MPI computation. Visualization and workflow support are provided through PCSWMM, enabling efficient model development and management.

The framework is demonstrated through real-world applications, showing stable and accurate representation of surface–surface and surface–network interactions. This work provides a practical and extensible solution for advanced flood modeling and supports future community-driven development.

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