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Tuesday, February 16, 2010

More about the South Coast rains and damage

Mick from "Sandy Straits and Beyond" asked me today if the rains I had talked about was what had been now declared a Natural Disaster.
In short, yes.

I did make a somewhat flippant comment that the local Member is also the Minister for Emergency Services. In fact. the Minister, Steve Whan MLA, is the Member for Monaro, not the Member for Bega. His father Bob Whan,was the former Federal Member for Eden-Monaro. But Steve Whan is not responsible for this area. That should be clarified.

The Canberra Times had a story today on a road collapse at Tilba, just south from Narooma, caused by this storm event.
Floodwaters washed out the Tilba-Punkalla road yesterday

I acknowledge that this is a dramatic road collapse, and I recall a similar event near Gosford that resulted in the death of five members of a family caught up in floodwaters. In no way do I wish to minimise the risk of such an event, but the danger lies in the sudden and unpredictable event of the road collapse, not the magnitude of the storm event. See Footnote below.

The main point I was trying to make in the comments earlier was that the ABC radio today reported that the Minister's declaration was made on the basis that there was some $4 million worth of road and other infrastructure damage.

Do you realise how $4 million worth of road repairs would buy? It would barely amount to the rebuilding of a single road bridge. No doubt the true costs of this storm will far exceed the original estimates. But I keep repeating, this is a small flood event, relative to large floods.

What the Bureau of Meteorology was at pains to explain today was that the large rivers in the region (Deua River - at Merimbula, Tuross River - at Tuross Lake and Bega River - at Bega) have been "swollen", but not in full flood. So it is actually the little creeks and rivers which have risen and blocked roads and done some minor damage. I include the road washaway above in this category, even though it is potentially fatal for motorists. It is just a little stream, grown large, briefly.

This storm event needs to be put in context. In 1971 the Bega River (which has a large*** catchment) flooded, and it took out a relatively new bridge near the River mouth. It took about 2 years to replace. People at Tathra had to drive an extra 40 Kms around the river for about two years. Today there is a very large, high clearance bridge across the Bega River, just near the mouth - and the locals are very proud of it. For good reason.

This flooding event is nothing like that.

Tyto Tony at Ingham lived through worse than this three times a year ago.

"The highest flood on record occurred in February 1971. Up to 900 mm of rain fell in 15 days over the catchments of the Bega and Bemboka Rivers. ...
"An anecdotal record of flooding in the Bega Valley has been compiled by Smith (1978) who recorded a total of 39 floods in the valley during the period 1851 to 1978."
Source: Bega River Estuary - Data Review

*** The Bega Valley is a "large catchment" relative to most other NSW coastal catchments. Of course, the inland catchments are far, far greater in area. The coastal catchments however, trap large amounts of rain because of the presence of the Great Dividing Range, relatively close to the Pacific Ocean, especially when triggered by post-cyclonic storms, such as this one. That means they are prone to sudden and quite dramatic flood events. The Hunter River (at Maitland), the Clarence (at Grafton and below) and the Wilsons River (at Lismore) are probably the most flood prone of these coastal NSW rivers.


Flabmeister said...

ABC Canberra Radio included a comment yesterday (16/2) afternoon explaining that the designation "natural disaster" was primarily about triggering funding mechanisms. This means that the local council doesn't have to fund all the repairs themselves, but can draw on State and Commonwealth funds.

Their report also had its share of hyperbole in that they talked about the Moruya River being cut at the Bridge. I suspect the 'cut' was actually the 2kms of flood plain immediately to the North of the bridge. This would be little more than a few of the creeks in the area flexing their muscles. That happened at least once in the 1980s when we had a weekender at Congo.

mick said...

Thanks Denis, very interesting. I hope they can get the roads and bridges fixed soon. In my experience the smaller local roads are the slowest to be fixed since it often means depending on local council funds and timetables!

Denis Wilson said...

Hi Martin
You are exactly right - which is what triggered my previous flippant response, that the "local member" was well placed to fix it. Turns out I was wrong about the local member bit - but only just. He grew up as the son of the Federal Local Member, so it is in his blood, so to speak.
Yes, the ABC has had a fair bit of hyperbole about most of their reports.

Denis Wilson said...

Hi Mick
My brother has sent photos of further damage to a local bike path, and other minor structures. Now the issue will be getting Council's attention ot fix them.
So, you have hit the nail on the head.

Anonymous said...

Hi Denis, I happened to be in Tathra, Bemboka, Bega and Narooma last week, driving back through them all on Monday. End of the world atmosphere, although my farmer uncle seemed happy.

Denis Wilson said...

Hi Jill
Thanks for that bit of "local knowledge" - it greatly strengthens reports such as mine.
Love the "End of the World atmosphere".
Ironically, my brother was to have been here, helping me, but we cancelled because of the weather forecast.
As it turned out, the weather here has eased, and working here would have been fine, but he would have been as nervous as a kitten, with reports on the radio. So just as well we cancelled out.