Not so long ago, the hydraulic modelling world dreamed of seamlessly integrating pipeline and 2D overland flow modelling. Whilst commercial developers managed to combine existing modules to meet this need, The Hydrologic Engineering Centre (HEC) is now stepping into this arena.
Two major developments occurred recently. First, HEC-RAS 6.6 introduces integrated stormwater pipe networks, finally bringing network modelling capabilities to urban environments enabling users to analyse the adequacy of stormwater systems and assess pluvial flood risks more effectively., albeit in beta version. This latest addition should worry commercial competitors, given how rapidly HEC-RAS developed 2D and sediment transport capabilities that often outperform paid alternatives.
The familiar (some might say dated) GUI is finally getting an overhaul. HEC-RAS 2025 represents more than just a facelift – it’s a complete rebuild. The team is consolidating nearly 3 million lines of code from five programming languages into C#.NET, addressing architectural limitations that have restricted new features.
Development Timeline
A quick overview of the key milestone planned for HEC-RAS 2025, currently in alpha version, is presented in the Table below.
| FY25 | FY26 | FY27 |
|---|---|---|
| Mesh generation advancements | Advanced Terrain Modifications | Geometry & Boundary Condition clipping: import and export |
| Precipitation, wind, atmospheric pressure | Advanced Structures (Bridges/Gates/Pumps) | Sensitivity analysis framework |
| Basic Structures | Advanced Mesh Post-Processor tooling | Project management features (model delta charts, summary reports) |
| Basic Terrain Modifications | Advanced 1D Solver and Mesh enhancements | Improved inundation mapping, particularly with precipitation and shallow flow |
| Improved v6 Model Importer | Improved Boundary Conditions (Rating Curve, Multi-Variate) | Implicit 2D solver |
Out of all the updates so far, advanced meshing abilities using quadrilateral, cartesian, and triangular meshes is the most interesting. So useful that you can generate a mesh in HEC 2025 and export it for use in HEC 6.6. Days of re-meshing and optimizing ad nauseam may be gone – or at least shorter.
Community and Transparency
HEC-RAS’s strength extends beyond its free availability. Veteran modellers will recall the Manning’s coefficient issue in early HEC-RAS 5 and the team’s swift response – no corporate liability concerns to hide behind, just straightforward problem-solving. This transparency, combined with comprehensive documentation and an active user community sharing real-world solutions, sets it apart from commercial alternatives where liability often dictates the level of disclosure.
The eventual merger of HEC-RAS 6.6 and 2025 will create an integrated platform for 1D, 2D, sediment transport, and pipeline modelling – all freely available.
We can’t wait!
Links:
https://www.hec.usace.army.mil/confluence/hecnews/fall-2024/stormwater-pipes-in-hec-ras
