|WORLD METEOROLOGICAL ORGANIZATION||
|Explanation of the criteria for classification and numbering of components||
|Explanation of the dates on the component's description|
ESTIMATION OF THE PROBABILITY OF OCCURRENCE OF N-MONTH DROUGHTS
1. Purpose and objectives
Information on the frequency of occurrence of multi-year drought
sequences is fundamental to the formulation of effective strategies for
managing droughts. However, the analyses required to estimate the
probability of occurrence of multi-year droughts are quite complex and this
program assists in these analyses.
DROUGHT is a user-friendly PC-based program, which allows the estimation of the probability of occurrence of droughts of any duration,
including multi-year droughts. It performs partial duration frequency analyses of overlapping and non-overlapping n-month low flow sequences.
Details of the methodology used in these analyses can be found in Section 3-7 of the publication River and Reservoir Yield by T. A. Mc Mahon & R. G.
Mein, Water Resources Publications, 1986. The cumulative probability
distribution of low flows is obtained from the steady-state solution of the class transition probability matrix. The results of this program may be
used to calculate other statistics such as the average recurrence interval
The name of a monthly streamflow data file; the start year and month of the streamflow sequence; whether overlapping or non-overlapping sums are
to be used to construct the transition probability matrix; and the length
of the n-month drought sequence to be processed.
A low flow frequency plot is displayed on the graphics screen and may be saved as a plot file. The on-screen results are written to a user-specified output file.
5. Operational requirements and restrictions
The system hardware requirements for operation of the software are as follows:
* an 80386-, 80486- or Pentium-based IBM compatible personal computer;
6. Form of presentation
IBM PC-based computer program on disc with users guide.
7. Operational experience
Program has been used within Australia, primarily by Government
Departments and water authorities in the State of Victoria to assist in the
development of Drought Management Plans.
8. Originator and technical support
The program was developed by Mr R. Nathan (now of Sinclair Knight Merz
(SKM)) for the Water Bureau, Department of Natural Resources and
Environment (NRE), Victoria. Questions about the program should be
directed to the Water Bureau.
The program is only available to government departments/agencies and water authorities and educational institutions and must not be used for commercial gain.
10. Conditions on use
Users of the program are required to complete, sign and return to the Water Bureau, a "Terms and Conditions of Supply" form acknowledging that:
* the performance of the DROUGHT software is not guaranteed;
|(First entered: 02 AUG 96||
Last updated: 23 APR 99)