xpswmm
is an economical hydrodynamic model and analysis software package that provides all the major hydrology methods.
xpstorm
is a tool based on xpswmm for design and analysis of stormwater projects including piped and channel flows.
xprafts is a robust runoff routing model that is used throughout Australia and the Asia Pacific region for hydrologic and hydraulic analysis of storm water drainage and conveyance systems.
Association of State Flood Plain Managers - Corporate Partner 2008.