HEC-HMS
FreeVerified
The US Army Corps standard for rainfall-runoff modelling — event and continuous simulation, free to use.
Hydrology & Catchment AnalysisActiveHEC-HMSSCS Curve Number
4 tools · Topic
SCS Curve Number (NRCS CN) Tools
The SCS/NRCS Curve Number method converts rainfall depth to runoff depth using land cover and soil group, and it underpins TR-55, HEC-HMS loss models and countless drainage manuals worldwide. These tools compute CN-based abstractions, composite curve numbers and runoff hydrographs — from full models to single-purpose calculators.
HydroCAD
Commercial
The US land-development standard for TR-55/TR-20 hydrographs and detention pond design.
Urban Stormwater & InfrastructureActiveDetention DesignTR-55
SWAT+
Open Source
The USDA watershed model for land use, sediment and nutrients — continuous simulation at catchment scale.
Hydrology & Catchment AnalysisActiveWater Quality ModellingSCS Curve Number
WinTR-55
Gov-Public
NRCS's official implementation of TR-55 small-watershed hydrology: peaks, hydrographs and storage.
Hydrology & Catchment AnalysisStableTR-55SCS Curve Number