|WORLD METEOROLOGICAL ORGANIZATION||
|Explanation of the criteria for classification and numbering of components||
|Explanation of the dates on the component's description|
GRAPHICAL METHOD FOR DETERMINING PEAK DISCHARGE (TR-55)
This is a quick procedure for estimating peak rates of discharge for use in designing soil and water conservation measures in agricultural areas, and storm water management practices in urban areas.
Graphs are used to estimate peak rates of discharge for times of concentration (Tc) less than 10 hours and for a range of rainfall amounts,
soil types, land use, and cover conditions. The graphs are for a variety of 24-hour rainfall distributions.
The required data are land use and hydrological soils group to calculate a runoff curve number, 24-hour rainfall amount, drainage area and an estimate of the time of concentration of the watershed.
Estimates of peak rate of discharge and runoff volume for time of concentrations less than 10 hours are read from the graphs.
5. Operational requirements and restrictions
a. An engineering technician who can calculate Tc can easily use this
b. One day of training or familiarization with the procedure may be
c. The data for the graphs were computed using procedures from the
d. Component K22.3.02 "Computer Program for Project Formulation
6. Form of presentation
Presented as Chapter 4, Urban Hydrology for Small Watersheds - Technical Release No. 55, Natural Resources Conservation Service, U.S. Department of Agriculture, June 1986.
7. Operational experience
The technique is used extensively by the U. S. Natural Resources Conservation Service with good results, and is used worldwide.
Water Science Technology Team
From the HOMS National Reference Centre for USA.
10. Conditions on use
| Reclassified from J20.1.09 MAR 1987
(First entered: 23 JAN 81
Last updated: APR 98)