Tuesday, 25 October 2011

Calculating New Zealand IDF data for Autodesk Storm and Sanitary Analysis

The main source of rainfall design for areas in New Zealand is the NIWA Hirds website . However the first thing you will notice on getting data from the Hirds website is that the you do not get the rainfall intensity data for the 5 and 15 minute duration storm and the 1,2,3 and 25 ARI event that SSA asks for.

Figure 1.0 Raw Hirds Data


Figure 2.0 Autodesk Storm and Sanitary Analysis IDF input screen


Thanks to the help of Graeme Mackay at NIWA who explained the equations behind the Hirds data. Detailed on pages 19 and 20 of the Hirds method help file available for download at the bottom of this page.

I have developed the attached spreadsheet to calculate the alternative duration rainfall data.


Here is a short video of the process you need to go though with the spreadsheet and SSA to get up and running
Unable to display content. Adobe Flash is required.

Update thanks to Matt Anderson

SSA allows editing of the Storm Duration and the Return Period. Note the 10 and 20 minute Duration added below.


When you right-click on the durations, you get:


No spreadsheet is needed.

Sunday, 16 October 2011

Had to have a Monday morning Rant


Please add a comment of support for these changes to the Autodesk forum. We have only been waiting 5 years for updates in these areas.

Thursday, 6 October 2011

Upgrade Issues

Just spend the last couple of days upgrading my PC from XP to windows 7 and Civil 3d from 2011 to 2012, as usually I have seem to have stuck a number of issues the most noticeable being that may user profile from Civil3d 2011 completely screws up 2012.
I thought that it would be seamless to import the 2011 profile and I would be away. But whenever I use the old profile 2012 crashes on editing label styles and on opening it brings up the vanilla Autocad 2012 splash screen.
To get round the issues I have decided I am just going to have to rebuild my user profile in 2012 what a pain.  
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