SWMHYMO (Stormwater Management Hydrologic Model)


SWMHYMO has been updated to version 5.5; check out  some of the features that changed in the new release.

Better Compatibility with Windows

Recompiled in a 64 bit environment to work with Windows 7 and above with faster run times. 

Now allows use of longer file names and file paths.

Larger Data Sets

Data file width increased from 80 characters to 256, allowing users to copy/paste input data prepared in spreadsheets directly into SWMHYMO input files.  The ADD HYD and ROUTE RESERVOIR commands now allow a greater number of input hydrographs or points, respectively. 

LID Commands

BMP and LID commands (RAIN BARRELS, PERMEABLE PAVEMENT, INFILTRATION TRENCH, WATER CISTERN) have been added to the model. Additionally, a new SWM POND command can be used to account for losses due to infiltration in ponds and reservoirs.

No ID Numbers

Users can now create data files with or without using ID numbers. The alphanumeric NHYD values (up to 10 characters in length) are used to track hydrographs.

Larger Simulations

The number of computational time steps is increased to 105,408 points (from 15,000 points), allowing for 366 days of simulation with a 5 minute time step.  

Backwards Compatible 

Can run all SWMHYMO version 4.02 formatted input files without modification.

SWMHYMO, as with many HYMO successors, is a complex hydrologic model used for the simulation and management of stormwater runoff in either small or large rural and urban areas.

Using easily acquired watershed or sewershed information, SWMHYMO processes rainfall records to simulate the transformation of rainfall into surface runoff. Computed hydrographs can be routed through pipes, channels or stormwater control ponds and reservoirs. In urban areas, the effective capture rates of catch basins and the effects of storage in street low points can also be simulated.

Though the application of SWMHYMO is not limited to any particular type of hydrological analysis, the model will typically be used in studies for the following:

  • Master Drainage Plans for entire watersheds
  • Floodplain mapping studies
  • SWM studies for new developments
  • Design of dual drainage systems
  • Design and analysis of storm sewer systems
  • Design of stormwater control facilities
  • Erosion and flood control studies
  • Design and evaluation of SWM ponds
  • Hydrologic budget analysis
  • System failure analysis and evaluation of alternatives

Download SWMHYMO 5.5: Software Downloads

To purchase SWMHYMO you can purchase by email us at SWMHYMO@JFSA.com



 is a “single user license” and therefore will require one license per computer.


/Year + Taxes