Reposted from NOT A LOT OF PEOPLE KNOW THAT
APRIL 6, 2021tags: Australia
By Paul Homewood
Floods in Australia made big news last month, (Click on link to watch video):
The floods mainly affected NSW and SE Queensland. The video talks of “less than 1%” chance of this amount of rainfall occurring. But the BOM figures don’t support this claim.
In NSW, although it was the second wettest March, it was considerably wetter in 1956. Moreover it was not particularly wet in February, so the ground would not have been saturated.
March of course is only one month. Last month 136mm fell in NSW, but this amount is not unusual when all months are taken into account. Indeed it would appear that extreme rainfall months were more common in the past:
The BOM published a summary last week, which highlights various daily and monthly records set at some locations, but again these are only for March. None of this supports the allegation of a 1 in 100 year event. Instead it was just an unusual and localised occurrence for the month of March.
http://www.bom.gov.au/climate/current/month/nsw/summary.shtml
As the video points out, Australia is a land of flood and drought:
I mentioned March 1956, but that year it barely stopped raining from February to May, which led to the worst flooding in NSW, Victoria and South Australia since 1870. This truly was an epic event, and was accurately described as a 1 in 100 year occurrence. This year’s floods don’t go anywhere near approaching 1956, as the following video vividly shows.
It is 16 minutes long, but I would thoroughly recommend watching it. It not only gives an idea just how bad the flooding was, but also offers an insight into life in those days. Below it is a short film, which also shows how widespread the flooding was.
Towards the end, you will see a reference to the floods of 1870, which by all accounts were even worse.
The term 1 in 100 year event is regularly abused nowadays, and is invariably used to describe what are no more than common weather events. Scientists doing this belittle the truly epic events of the past.
Using data for Centennial Park in Sydney, the recent rains were not exceptional. The highest daily rainfall was for March 28 1943 of 302 mm. 484 mm fell for the month, or nearly 20 inches. For some reason, data stops on the 23rd this year at 315 mm, but likely another 100 mm fell, still well short of 1942.
Another nearby station with a record going back to the early 20th C is the Botanical Gardens. It only had 277 mm that day but 520 mm for the month. This March only had 457 mm.
10 % less rain for the two despite claims that the rains were worse because of simple physics. I’m not pointing out that global warming definitely didn’t make it worse, just that you can’t tell. Now the two sites are also 4 km apart and almost 10% different.
August 1986 shows even a bigger difference. 532 and 408 for the former, over 20% difference. A broken record is meaningless unless shattered by over a fifth because of the huge variability even over 4 km.
Not all months in Sydney are equally likely of having a big dump of rain but close enough that a one in 100 year event for a month happens one in 10 years.
It’s really impossible to claim this was unusual due to climate change.
Just visited Gundagai.
original township built on Murrumbidgee flood plain flooded to a meter depth 1846?
Rebuilt, in 1852? it flooded to a depth of over 4 meters and was completely destroyed with 78 registered deaths.
The next years flood was apparently larger but no town to destroy.
It was rebuilt higher up out of the flood plain and both parts of the township [feuding a little at the moment] exist today.
This was the largest natural disaster in Australia in terms of deaths for over a hundred and fifty years.
Technically a 1 in 75 year event?