Adding multiple design storms from 1987 Bureau of Meteorology data

In addition to adding single design storms, DRAINS can define multiple storms of various frequencies and durations from 1987 and 2019 data sources.  In almost all instances, the 2019 data is the most appropriate, but it may still be necessary to run DRAINS with the 1987 data to test older models.  This is done by downloading data from the Australian Bureau of Meteorology's website and pasting it into DRAINS.  The page on the BOM site that provides the 1987 information is http://reg.bom.gov.au/hydro/has/cdirswebx/cdirswebx.shtml, shown below:

(Note that there is another, 'non-flash' calculator that performs the same calculations, but has different outputs. - http://reg.bom.gov.au/cgi-bin/hydro/has/CDIRSWebBasic)

To apply the process in DRAINS, you must (a) have the Use ARR2019 procedures box unclicked in the Project Options property sheet, and (b) click the Add multiple ARR87 storms button in the Rainfall Data property sheet, which will open the dialog box shown below:

The zone of Australia, ARIs and durations required can be entered, as shown above.  Note that different antecedent moisture conditions (AMCs) can be provided for Horton (ILSAX) models.  When the option of using BOM format table is selected and the Next button is clicked, the following window opens:

You now need to go to the 'flash' BOM page at the top of this  page, and press the Create an IFD button.  The dialog box shown below will open:

Enter the latitude, longitude and name of the site, click the Conditions of Use box, and press the Submit button to produce the following web page:

Next, click the Coefficients button to open the following window:

Finally, click the Copy Table button, and then go back to DRAINS, to the Paste BOM format table dialog box, and click the  Paste Table button, to get:

The text shown is a set of polynomial coefficients in csv (comma separated variable) format.  You can now click the OK button, and you will find that the desired storms have been added to the rainfall pattern database.

As an alternative, you can select IFD Table rather than Coefficients in the BOM output that shows the IFD curves, giving:

There is a Paste Table button further down.  Clicking on this, and transferring the data on the Clipboard to DRAINS produces the following result:

Clicking on the OK button then produces the desired patterns if their durations are specified in the transferred table.  If a duration that you specified is not included, an error message will appear, and you will have to use the coordinates.

In the bottom right corner of the Add ARR87 Storms dialog box (the second window on this page) you can also select an option to calculate intensities using the 9 coefficients from ARR87. Choosing this option and pressing the Next button will open the following property sheet:

This is the same window used to enter single storms.  When the required numbers for the location are entered, and the OK button is clicked, the set of multiple storms will be created.

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