|WORLD METEOROLOGICAL ORGANIZATION||
|Explanation of the criteria for classification and numbering of components||
|Explanation of the dates on the component's description|
FLOOD FREQUENCY ANALYSIS, HEC-FFA
1. Purpose and objectives
The program computes annual peak discharge frequency curves that can be used to analyse flood damage potential.
Computational procedures are based on the "Guidelines for Determining
Flood Flow Frequency", Bulletin 17B, United States Water Resources Council,
June 1982. Frequency curves are computed for Weibull, median, or Hazen plotting positions and using the log-Pearson Type III distribution.
Card image input. Annual peak discharges are the only required data. The following data are optional: historic annual peak discharges, the
number of high outliers, the corresponding historic period, and the generalised skew coefficient.
Tabular results are provided for the annual peak discharges which correspond to both the plotting positions and to selected exceedance
frequency ordinates calculated using the log-Pearson Type III distribution. The calculated mean, standard deviation, skew coefficient, and number of events used in the analysis are printed. A printer plot of the frequency
curve can also be generated.
5. Operational requirements and restrictions
a. Persons with knowledge and experienced in frequency analysis and a
6. Form of presentation
Diskettes or download from www.hec.usace.army.mil. Support documentation consists of a Users' Manual and an addendum. Instructional videotapes are also available.
7. Operational experience
8. Originator and technical support
The program is a modification of the computer program FREQFLO written
by Leo R. Beard and David Ford (Center of Research in Water Resources, The
University of Texas at Austin) under contract to the Water Resources
10. Conditions on use
Internet download is free. A standard handling fee is charged for supplying the diskettes and documentation.
|(First entered: 3 FEB 81||
Last updated: 1 DEC 99)