If the news I saw was of the fire you're talking about, a ditch is only going to help if you want to sit in it while the fire passes overhead. Those flames were tens of metres high. You'd need to buldoze a strip hundreds of meters wide for many kilometres.
There were horrific bushfires in New South Wales at the start of this year. We even rented a helicopter from the US to help put it out. They caught a volunteer firefighter who was supposed to have started many of the fires too.
Hope you all stay safe.
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Murray
I What part of 'no' don't you understand?
Is it the 'N', or the 'Zero'?