Category Archives: Water

2011 Grantham floods – how significant were breaches in the sand quarry wall

I saw the 60 Minutes segment on the 2011 Grantham floods last Sunday where they
raised again the issue that a wall at a local sand quarry breached which they say caused the loss of life at Grantham. This issue has been discussed for years – just google “quarry wall near grantham”. I have not read earlier reports but it surprises me that a matter involving simply ascertainable engineering matters such as volume of trapped water – height of the wall and nature of the breaches – would not have been reported on with some certainty in terms of flood effects on Grantham.
I posted on this in 2011 – Toowoomba flash flood shambles – and reading comments which ran for over a month – there is no mention of this sand quarry.
I have found a map of the quarry – exhibit 359 at the Queensland Floods Commission of Inquiry 2011 – The copy I took needed lightening – the pdf has rather a dark image – the map goes with exhibit 358. More recent map I just obtained from GoogleEarth – the flooded quarry is obvious inside that loop in Lockyer Creek just north of the end of the word Carpendale.
So this sand quarry is slap bang in the path of the Lockyer-Toowoomba-Helidon-Grantham flood and I would be pretty sure the waters would have surged around any earthworks with little problem – would have flowed north, south and over any quarry wall – no surprise there were multiple breaks in this wall. The abrupt natural bends in the creek around the quarry and the earth walls would tend to slow the flow and could have been the sites of debris, logs etc accumulating and obstructing the flood for periods until they were in turn swept on.
In months to come we will see what the new inquiry brings.
Recent flooding in the Hunter with loss of life at Dungog shows that although the BoM get rain telemetry in real time – and allied with historic hydrology data should be able to highlight areas of danger – our modern and technology rich society at times can not produce useful warnings against effects of flash flooding.

Example where the Australian Bureau of Meteorology is told about a fault in rain recording but in two years fail to correct their data

I was told by a reader about a loss of ~18mm rain recorded at Montague Island Lighthouse 69017 (NSW south coast near Narooma) on 6/7th April 2013. I checked this out and sure enough the 30 minute data shows 20.6mm at 2.30am on the 7th which at 3am is reset to 2.2mm – so 18.4mm of rain was lost in what must have been an electrical/electronic fault. I kept the www page of 30 minute data.

I sent the following fax to BoM Sydney on 9 May 2013 and never got a reply.
[MONTAGUE ISLAND LIGHTHOUSE ID: 069017 Rainfall 7 April 2013
Dear Manager,
Your webpage “Latest Weather Observations for Montague Island”
www.bom.gov.au/products/IDN60801/IDN60801.94939.shtml
records around 18.8mm rain ~10.30am to 11am on Saturday 6th April.
There was another 1.6mm recorded ~9.30-10pm that evening making 20.4mm.
A further 0.2mm made the total 20.6mm around midnight.
Then at 3am on the 7th the rain total reset to 2.2mm which was the 9am total recorded.
You can check the Canberra radar archive at –
www.oscilmet.com.au
and there were rain signatures at “~10.30am to 11am on Saturday 6th April” and
“~9.30-10pm that evening”.
So perhaps your Montague Island telemetry has lost 18.4mm of rain in the signal somewhere.
All the best,]
Checking daily rain for station 069017 at Climate Data Online we see that 2.2mm is recorded for the 7th April 2013 –

What would it take to get the BoM to correct an error ?

As early as 1985 the Australian Government was spreading harmful Green propaganda about water

Rummaging through some ancient boxes I found this 1985 stamp which I had never noticed – carrying the slogan “Water is Precious”.

A slogan unworthy of a rational Govt – a slogan that has assisted to take us on the policy road where dams have been forbidden and $Billions have been wasted on unnecessary seawater desalination factories – mostly now in mothballs and we have to put up with a constant Green inspired push for inflated water prices. Reality is water is a common compound and falls free from the sky in huge quantities if you have the brains to store it. Cheap clean water from municipal supplies piped to homes has been an important contributor to increased life expectancy over the last 150 years. If we allow Green policies to interfere with this we risk turning the clock back healthwise.

Dubious BoM claim about Brisbane rainfall – “Wettest May day in 175 years” – thats the 2nd of May 2015

Fairfax are running this story Brisbane weather: Wettest May day in 175 years
The claim that 182.6mm on the 2nd May represents the “Wettest May day in 175 years” is not even technically clean because many early years had no data – so the 175 years is shonky. But let’s ignore that. Facts are that rain data are so noisy that any claims based on one station need examining. In this case on 2nd May 2015 for the BoM’s own rain district 40 South Coast Moreton & Brisbane.
These stations exceeded the 182.6mm figure. I have tried to avoid the higher altitude stations which have heavier falls.
ALDERLEY (040224) 252.4mm
BEERBURRUM FOREST STATION (040284) 233.2mm
BOONDALL (040531) 213.6mm
CALAMVALE ALERT (040784) 186mm
DECEPTION BAY ALERT (040980) 278mm
HILLTOP GARDENS (040911) 209mm
MORAYFIELD ALERT (040979) 296mm
PEACHESTER (040169) 269mm
TOMEWIN TALLOWOOD (040899) 187.4mm
WATERFORD ALERT (040878) 193mm

Let’s look at a four day period 2nd to 5th May 1996 – there may be others but my time is limited –

I think by any standards the 2nd to 5th May 1996 swamps any record claimed from 2nd May 2015. Count some of the 4 day totals.

Media spreads fairy story that Caboolture and north Brisbane floods were a once in 2000 year event

More likely a once in two years event. Queensland storm: Five dead in storm called ‘one-in-2000-year event’
I saw this headline – Thats why our homes flooded

Queensland storm: Residents of Deception Bay claim Moreton Bay Rail Link works contributed to homes being flooded
Interesting to read the comments in both articles – most seen realistic.
I was surprised to see on TV news video of quite modern houses built along what became a raging watercourse. Looks like Qld town planners need to learn basics about flood prone areas.

Australian Bureau of Meteorology claims Caboolture rainfall is “off the scale” – yet their own maps show higher daily totals in May 2009

Fairfax media reports – Brisbane weather: ‘An extreme weather event’ takes five lives – The ABC reports – Queensland weather: Five people killed after three cars swept away by floodwaters; storm moves into northern NSW
A BoM contour map shows the rainfall to 9am on 2nd May – this map is for 20 May 2009 – note the higher rain contouring into the purple zone.
The 7th, 8th and 9th of May 1980 had heavy rain in the Brisbane region too. Note I have only scanned for May rain – there would be many more floods if I looked at all months.
I have not yet seen numbers convincing me that the last couple of days was worse than 2009 – and daily data is very poor for the earlier in the 20th Century.
There are many more rain gauges now but data is not easy to access. This AWN site is useful for eyeballing daily rain at the many Brisbane region stations. Here are the rain maps from above BoM links to compare for yourself –

Purple is above 200mm per day
Dark blue is 150-200
Light blue 100-150.
Obviously the station data is more spotty than the contour maps – and BoM computing has to somehow average to get the contour positions.