|WORLD METEOROLOGICAL ORGANIZATION||
|Explanation of the criteria for classification and numbering of components||
|Explanation of the dates on the component's description|
HYDROLOGICAL FREQUENCY ANALYSIS (HFA)
1. Purpose and objectives
Design of hydraulic structures, optimal operation of reservoirs, and flood forecasting are just some of the areas in which knowledge of the statistical properties of extreme floods or droughts are required. HFA is a technical tool for fitting statistical distributions to series of annual floods, and for estimating flood flows with a given return period and the corresponding confidence intervals.
HFA contains all the distributions belonging to the Gamma family.For each distribution several estimation methods are available:
Log-Gamma Moments, maximum likelihood, moments applied to the logarithms of the observations.
Gamma Moments, maximum likelihood.
Pearson Type 3 Moments with three different bias corrections for skewness, maximum likelihood.
Log Pearson Type 3 As for Pearson type 3 plus direct and indirect methods of moments, sundry averages method (SAM), mixed moments.
Generalised Gamma Moments, maximum likelihood, sundry averages method (SAM), mixed moments.
HFA offers the possibility to compare graphically several fittings and the confidence intervals associated with the estimation of quantiles.
To verify the basic assumptions of annual flood series analysis, several tests are available in HFA:
* test of homogeneity (Mann-Whitney);
HFA was conceived for the analysis of annual maximum flood series, but
the software can be used with any kind of data series that satisfy the basic assumptions of independence and stationarity.
Annual flood series, or other data to be analysed.
The results of frequency analyses are printed on the screen or on hard copy. Output includes:
* results of tests;
5. Operational requirements and restrictions
HFA must be used on an IBM (or 100% compatible) personal computer, with an EGA graphic card (or better), and a hard disk with a minimum of 1 megabyte free. It is designed for use with MS-DOS 3.x, or later.
6. Form of presentation
The HFA program is provided on 10 diskettes (5.25", 360K). The user guide is written in English and is also available on the installation
diskette. The modules of HFA are written in FORTRAN.
7. Operational experience
HFA is used by universities, companies, and governmental organizations in Canada (particularly in Quebec) and elsewhere in the world.
8. Originator and technical support
HFA was developed at INRS-Eau (National Institute of Scientific
Research - Water, Quebec, Canada). Theoretical and technical information can be obtained from the following persons: Dr B. Bobée (Tel: 418 654 2539) or Mr H. Perron (Tel: 418 654 3751, Fax: 418 654 2600).
10. Conditions on use
The software goes hand in hand with the book (written in English) "The Gamma Family and Derived Distributions Applied in Hydrology" (Bobée and Askhar, 1991), 203 pages. The package (software and book) can be obtained at the price of US$ 88.00 from the publisher (Water Resources Publications). The software and the book are also available separately at the price of US$ 60.00 and US$ 38.00, respectively.
|(First entered: 01 MAR 94||
Last updated: 15 DEC 1999)