|WORLD METEOROLOGICAL ORGANIZATION||
|Explanation of the criteria for classification and numbering of components||
|Explanation of the dates on the component's description|
ENGINEERING FIELD MANUAL FOR SOIL AND WATER CONSERVATION PRACTICES
This chapter establishes procedures for estimating depth and peak
rates of runoff from small watersheds for use in designing soil and water
Tables and graphs are included for a quick and reliable way to estimate peak rates of discharge, and associated runoff volumes for a range of rainfall amounts, soil types, land use, cover conditions. The procedures for determining peak rates are applicable to drainage areas of 5 to 200 acres.
The graphs were prepared for the solution of general relationships,
and are based on 24 hour rain distributions. The data for the peak rate
discharge were computed using procedures from the NRCS National Engineering Handbook, Section 4 Hydrology (NEH-4).
The required data are land use and hydrologic soils group to calculate
a runoff curve number, 24 hour rainfall amount, drainage area and an
estimate of average watershed slope.
Estimates of peak rate of discharge and runoff volume for drainage areas from 5 to 2000 acres are read from the graphs.
5. Operational requirements and restrictions
a. An engineering technician who can calculate time of concentration
b. One day of training or familiarization with the procedure may be
6. Form of presentation
Presented as Chapter 2, National Engineering Field Manual for Soil and Water Conservation, Natural Resources Conservation Service, U.S. Department of Agriculture, August 1989.
7. Operational experience
The technique is used extensively by the U. S. Natural Resources Conservation Service with good results, and is used worldwide.
8. Originator and technical support
Water Science Technology Team
From the HOMS National Reference Centre for USA.
10. Conditions on use
| Reclassified from J20.1.08 MAR 1987
(First entered: 22 JAN 81
Last updated: APR 98)