HEC-HMS
FreeVerified
The US Army Corps standard for rainfall-runoff modelling — event and continuous simulation, free to use.
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HEC-ResSim
ActiveReservoir system simulation from HEC — operating rules, flood control and multi-reservoir networks, free.
by US Army Corps of Engineers (HEC)
- Pricing
- Free
- License
- US Government (public domain)
- Commercial use
- Permitted
- Ecosystem
- Standalone, Jython scripting
- Platform
- Windows
About HEC-ResSim
HEC-ResSim simulates reservoir operations: pool zones, rule-based releases, hydropower, flood-control constraints and multi-reservoir system coordination. It is the tool USACE itself uses to model its reservoir systems, and it is free for anyone to use.
ResSim's rule-based operation logic is its differentiator — releases respond to pool elevation, downstream control points, tandem reservoir balancing and scripted state variables, which lets it represent real operating policies rather than idealised ones. For planning studies, dam-safety assessments and yield analyses it remains the reference free tool.
Where it fits in the workflow
TerrainCatchmentRainfallRunoffRoutingHydraulicsMappingReporting
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