1.   Purpose and Objectives

     To interactively estimate individual and an average unit hydrograph from a number of flood events.

2.   Description

     The program works through each flood event enabling the user to interactively adjust parameters to obtain the best fit unit hydrograph. The use of graphical displays allows the selection of individual unit 
hydrographs to be included in the calculation of an average unit hydrograph. The average unit hydrograph is obtained using a simple arithmetic average which is then smoothed and adjusted to ensure unit runoff volume. Unit hydrographs are estimated using Snyder's Least Squares algorithm using various smoothing techniques (based on Kuchment's method of regularisation).  

3.   Input

     For each flood event; station rainfall data, rainfall station weights (eg. Thiessen weights) and a discharge hydrograph.

4.   Output

     Screen based graphical output displaying unit hydrograph, hyetograph and observed and calculated hydrographs to guide the interactive estimation of the best fit unit hydrograph and the selection of unit hydrographs for averaging. An output file is created containing the final average unit hydrograph and for each flood event; rainfall data, observed outflow hydrograph, unit hydrograph and calculated outflow hydrograph.

5.   Operational requirements and restrictions

     The software operates on IBM compatible microcomputers. A Intel 486 processor, VGA screen and 2.4 MB of disk space is adequate to run the package. The software does not require specialised installation and no additional software is required. Specialised hydrological knowledge is required to apply the software effectively.

6.   Form of presentation

     The software is provided as a PC-DOS executable program, sample data file and brief user instructions.

7.   Operational experience

     The software has been used successfully in Australia for the calculation of unit hydrographs for both engineering design and flood forecasting. The algorithms included are general and should be applicable 
in other parts of the world.

8.   Originator and technical support

     The software was developed by Don Carroll and has been placed in the Public Domain. Formal support for its use is not available. The interface is intuitive and with the brief instructions is sufficient for program use. Some guidance on the use of the software within the Australian Bureau of  Meteorology is available from the HNRC for Australia.

9.   Availability

     From the HOMS National Reference Centre for Australia.

10.  Conditions on use

     The use of DCUH in any studies should be acknowledged in any reports or papers resulting from the studies.