Hydraulics and Hydrology
Tools and Models - TR-55

TR-55, Urban Hydrology for Small Watersheds

Technical Release 55 (TR-55) presents simplified procedures to calculate storm runoff volume, peak rate of discharge, hydrographs, and storage volumes required for floodwater reservoirs. These procedures are applicable in small watersheds, especially urbanizing watersheds, in the United States. Limits: NRCS type distributions, 24-hour duration rainfall, 10 subwatersheds, minimum 0.1 hour and maximum 10-hour time of concentration.

The Natural Resources Conservation Service used government funds to develop the Technical Release 55 (TR55) computer program. It may be downloaded for use and copying at no additional expense or license requirements.

downloads

DOS version of the TR-55 Program (Vers 2.1)  (320 kb)
TR-55 Documentation        (requires Adobe Acrobat.)