Thread: The Channel Country, from drought to a one in forty year flood.

When a meteorological event is categorised as "one in forty years" (or any other time period), this is simply the average time interval between these event, predicted on the basis of existing meteorological records.

Since the oldest continuous records in Australia go back less than 200 years (Sydney), and for most parts of the country little more than 100 years, when you are talking about events that, on average, only occur every forty years, the "average", is the average of not many data points.

And it needs to be pointed out that something that is "one in forty years" does not mean it will happen every forty years - that is only one data point. For a reasonable number of data points, it would be more reasonable to say it would occur five times in two hundred years - but the occurrences do not have to be forty years apart.

Floods: Recurrence intervals and 100-year floods

Originally Posted by JDNSW

When a meteorological event is categorised as "one in forty years" (or any other time period), this is simply the average time interval between these event, predicted on the basis of existing meteorological records.

Since the oldest continuous records in Australia go back less than 200 years (Sydney), and for most parts of the country little more than 100 years, when you are talking about events that, on average, only occur every forty years, the "average", is the average of not many data points.

And it needs to be pointed out that something that is "one in forty years" does not mean it will happen every forty years - that is only one data point. For a reasonable number of data points, it would be more reasonable to say it would occur five times in two hundred years - but the occurrences do not have to be forty years apart.

Exactly. Data points are only one method of measurement or knowledge generation. It would make more sense to listen to those who’ve been here the longest. Using a Land Rover to drive there and ask would make the experience even better.

I have, yesterday, just driven back to Doomadgee from Cairns.
All the plains land North of Bang Bang Jump Up is pretty much stuffed.
The pasture is all covered in mud & debris, the Mustard Weed etc is sprouting & taking the pastures over.
I don't know how long the land will take to recover but I reckon it will be years.

On flat plains there was debry in the top of the trees, 3 or so meters up.
Just, so sad. Who would be a bloody farmer?

Incidentally, we are 200k or so West of there & have dry river & no rain.

Jonesfam

Originally Posted by Zeros

Exactly. Data points are only one method of measurement or knowledge generation. It would make more sense to listen to those who’ve been here the longest. Using a Land Rover to drive there and ask would make the experience even better.

While oral history can provide some additional information, it is misleading to consider it to be data. Archaeological/geological studies can provide additional information as well - detailed stratigraphic sampling, with analysis of spores and pollens can provide significant pre-modern weather data, but there is very little of this work been done in Australia, except on a very broad scale over long time intervals. One of the issues is dating events that have been identified in the stratigraphic column. C14 dating is well understood and fairly reliable up to about 10,000 years, but there is always the issue of whether the sample you dated really represents the event you are trying to date - and the precision is often less than 100 years or so, hardly useful for talking about "40 year" events.

Older than that thermoluminescence dating can be used, but this is much less accurate, and has even more sources of error. And is expensive.

Lake Eyre begins filling with Queensland floodwaters as Birdsville roads reopen - ABC News (Australian Broadcasting Corporation)

I didn't have time to go and visit Lake Eyre South when I picked the Disco up two years ago so reckon I need to make the time this time around and go see it.

Originally Posted by rick130

..... so reckon I need to make the time this time around and go see it.

Yeah, same here.
My last trip was '13.
Damn! just realised 6 years between visits .. far too long.
Wonder if there's enough water for the south lake to get some too(doesn't always).