Jennifer Marohasy

a forum for the discussion of issues concerning the natural environment

Floods

Imposing Our Prejudices on the Value of Flood Waters: A Note from Cathy Green

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WHEN nutrient rich water flows into Lake Eyre it is considered good for the environment, but when nutrient rich water flows into the Great Barrier Reef lagoon it is considered bad for the environment. 

Indeed every time that Lake Eyre in central Australia floods, our oh-so-sensitive-to-nature journalists provide us with the sort of happy purple prose that we see on the front page of today’s The Australian, where Jamie Walker says:

“The torrents that swept down the swollen Georgina and Diamantina rivers, mixing in Goyder Lagoon before surging through Warburton Creek and into the lake proper, carry a bounty of new life: nutrient-rich sediments to feed the thirsty native vegetation that has erupted all around it, and in turn herbaceous native rodents; fish for the mass of birds tracking the flood; all the water the wild camels from the Simpson Desert can drink.”

Meanwhile, every time it rains hard enough in north Queensland for rivers to flood into the Great Barrier Reef lagoon, which represents precisely the same phenomenon as the Diamantina feeding Lake Eyre, journalists at The Australian provide us with much lamenting and concern like the following:

“A MASSIVE surge of polluted water has spewed onto the Great Barrier Reef following heavy rains that hit north Queensland last week, environmentalists say.

The WWF estimated up to one million megalitres – enough polluted water to twice fill Sydney Harbour – entered the reef after a monsoon brought drenching rain to north Queensland.

Mr Heath said satellite imagery confirmed water flows travelled to mid-shelf…”

Nature herself simply doesn’t care about the big environmental impacts and changes, no matter how much birthing, killing or (from our perspective) environmental degradation they may cause – it’s all just part and parcel of being a dynamic planet.

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Cathy has a PhD and lives in Far North Queensland.

The photograph of the pelicans was taken by Jennifer Marohasy below the Torrumbarry Weir, Central Murray Valley, in October 2007.  Pelicans (Pelecanus conspicillatus) can be found in coastal and inland Australia – where ever there are fish.  Some fishermen say that when there are floods on the land there is bounty in the sea.

Better Planning for Extreme Floods Possible: A Note from Stewart Franks

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DESPITE increased understanding of a number of different climate processes and their impact on a range of different timescales, this knowledge is not being used to inform planning and decision making. This is because long-term climate risk is often viewed only in statistical terms.

For instance, engineering techniques for estimating flood risk, where records exist, are largely based on simple statistics of their historic occurrence rather than on any real understanding of the processes that actually cause them.

In essence, if we have 100 years of flood record, then the largest flood measured represents, more or less, the hundred year flood level. This hundred year flood level is probably the most important of hydrological statistics in terms of its use in planning management. It is the yardstick by which decisions are made.

The problem with a simple statistical representation of risk is that it implies a static climate – the expected flood risk is equally likely in any year, irrespective of the actual climate processes that may or may not be dominating at that particular time. If this were the case, we would expect to see an equal spread of floods throughout our historical records. In Australia and in fact many other parts of the world, this is not so.

[Read more…] about Better Planning for Extreme Floods Possible: A Note from Stewart Franks

Weighing up protection – public versus environment

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The picturesque watercourse in the header on the main page of the Politics & Environment Blog, is Cooper Creek. It is a relatively short watercourse (∼8 km), running between Thornton Peak and its mouth, which drains an enormous catchment in one of the world’s highest rainfall areas.

Rainfall.jpg

Over these past three days, about 250 mm of rain has fallen and as expected the causeway crossing over the Cape Tribulation Road has flooded (please excuse the blurred photo).

CCcauseway.jpg

This is a regular occurrence in the wet season. Two years ago, students living north of Cooper Creek were unable to access 25% of their first term, because of flooding. It is also an almost annual occurrence that a driver will unsuccessfully attempt to cross, losing their vehicle to the power of the flood and being tumbled downstream into crocodile habitat.

Invariably, the impassable floods cause stress to large numbers of travelers on unforgiving schedules. Hundreds of vehicles and pedestrians crowd either side of the water’s edge in a forlorn hope that the combined vigilance and force of will will somehow speed the recession.

Yesterday I witnessed a particularly ugly display of road rage as tensions rose, stopping just short of physical violence. Last time the causeway flooded, a frustrated traveler described the scene as a new order of official mayhem, “Working in Queensland Mental Health, I thought I knew administrative incompetence,” she remarked, “but this is in another order of ineptitude, entirely!”

So how is it that such a well-used and strategically important facet of transportation infrastructure is kept so inadequately low? Surely there is a duty of care to protect the public from such well-known vulnerabilities? Then again, there haven’t yet been any deaths; just a large number of very close calls.

In the lead-up to the Local Council elections (15th March ’08), one candidate has told of the ecological integrity of Cooper Creek as occupying the highest consideration – leaving the causeway incapable of being elevated. As absurd as this notion may sound, it was indeed the ecological values of the Cooper valley that justified unparalleled regulatory protection, under World Heritage and, downstream of the causeway, so that Queensland can compare all potential impacts on all other mangrove communities. So rigorous is this special provision that a person can be fined up to $225,000 if caught fishing, though such sensitivity would seem to fly in the face of the ecological damage of heavy machinery, recovering vehicles washed downstream.

Beyond Media Headlines: The Key Issues for the Macquarie Marshes

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Media reports yesterday** correctly drew attention to the fact that there are levy banks within the Macquarie Marshes and that they are depriving key wetland areas of water.

But the stories went on to lump upstream legal and planned irrigation development that makes allocations for environmental flows with legal and illegal levies on grazing land within the marshes. Some levies within the marshes are currently blocking designated environmental flow water from reaching the northern nature reserve.

Some of the media reports suggest a need for more studies, but the solution may simply be to bulldoze levies so that environmental flow can get through to the nature reserve.

Other issues within the marshes that require action, rather than more studies include:
1. Preventing the trampling of bird nesting sites by cattle, and
2. Addressing the general issues of overgrazing.

The Macquarie Marshes is a large non-termial wetland in central western New South Wales covering about 200,000 hectares. Most of this area (88 percent) is privately owned and grazed. There are two publicly-owned nature reserves where cattle are excluded and which are Ramsar-listed, meaning they are considered of international importance for migratory bird species.

The most definitive recent publication on the ecology of the Macquarie Marshes is:

The Macquarie Marshes: An Ecological History
by Gillian Hogendyk
IPA Occasional Papers
http://www.ipa.org.au/publications/publisting_detail.asp?pubid=683

You can see pictures of overgrazing at this blog post:

Cattle killing the Macquarie Marshes, 21October 2005
https://jennifermarohasy.com.dev.internet-thinking.com.au/blog/archives/000949.html

There are pictures of the illegal levies here:

More Water Won’t Save the Macquarie Marshes, 28 March 2006
https://jennifermarohasy.com.dev.internet-thinking.com.au/blog/archives/001282.html

And for more discussion read:

Three Pressing Issues for the Macquarie Marshes, 13 July 2006
https://jennifermarohasy.com.dev.internet-thinking.com.au/blog/archives/001481.html

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** Yesterday’s stories include:

Report reveals illegal Murray-Darling irrigation. By environment reporter Sarah Clarke
Scientists say the flood plains are being sucked dry and there is no legislation in place to stop further development.
A new report has exposed major flaws in the management of key rivers and flood plains along the Murray Darling Basin. Satellite images of a key wetland in north-western New South Wales reveal more than 2,000 kilometres of earthworks have carved up the waterway. While some of the channels and levees may have been authorised, others are considered illegal and are diverting water into irrigation and farming.
http://www.abc.net.au/news/stories/2008/02/25/2171517.htm

NSW vows crackdown on Murray-Darling earthworks
The New South Wales Government says it will crack down on unauthorised earthworks in the Macquarie Marshes in the state’s north-west. A report by the University of NSW found that more than 2,000 kilometres of channels, levees and dams are carving up the Macquarie Marshes and diverting water into irrigation and grazing areas.
http://www.abc.net.au/news/stories/2008/02/25/2171663.htm

Wetlands in a flap after the rains
February 25, 2008
Birds are winning the battle of the marshes, writes Daniel Lewis.
Wading through Monkeygar Swamp, with magpie geese honking in the sky above, even a vicious bite from the odd leech can’t wipe the smile off Ray Jones’s face.
There’s enough water for significant bird breeding in his beloved Macquarie Marshes for the first time since 2000, and the National Parks field officer is on a high after depressingly dry years.
“When you see these geese taking off you can’t help but smile,” Jones says. A fellow parks employee recently told him: “This is the first time I have seen you smiling for years.”
http://www.smh.com.au/news/environment/wetlands-in-a-flap-after-the-rains/2008/02/24/1203788147733.html

‘Water theft’ threatens Murray-Darling
By DANIEL LEWIS & MARIAN WILKINSON – Australia
Monday, 25 February 2008
A MAZE of levee banks, channels and dams is stealing water from the state’s flood plains and threaten to undermine the $10 billion Murray-Darling Basin rescue plan.
A year-long study by a leading wetlands expert also says environmental water stolen on the flood plain that is home to the iconic Macquarie Marshes has already caused enormous environmental damage.
The report says inappropriate development has continued for decades…
http://www.smh.com.au/news/environment/river-rescue-under-threat/2008/02/24/1203788147679.html

Flood plain development ‘stealing water’
February 25, 2008 – 6:35AM
Levee banks, channels and dams are stealing water from NSW flood plains and threatening to undermine the $10-billion Murray-Darling Basin rescue plan.
The authors of a report on flood plain development on the lower Macquarie River say state and federal governments have turned a blind eye to water theft through flood plain harvesting, Fairfax reported on Monday.
http://news.smh.com.au/flood-plain-development-stealing-water/20080225-1ugc.html

‘Water theft’ threatens Murray-Darling
By DANIEL LEWIS & MARIAN WILKINSON – Australia
Monday, 25 February 2008
A maze of levee banks, channels and dams is stealing water from NSW’s flood plains and threaten to undermine the $10 billion Murray-Darling Basin rescue plan.
A year-long study by a leading wetlands expert also says environmental water stolen on the flood plain that is home to the iconic Macquarie Marshes has already caused enormous environmental damage.
…. SOURCE: Sydney Morning Herald.
http://www.farmonline.com.au/news_daily.asp?ag_id=48948

Exceptional rainfall produces exceptionally clean waterways

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CooperCk.jpg

I recently reported that the wet season had well and truly arrived in the Daintree, with over 700 mm of rain in five days.

More recently, Jennifer published the Australian mean rainfall total for 2007 at 497 mm, slightly more than the long-term average of 472 mm.

So, there is no question; the Daintree Cape Tribulation rainforest occupies a very wet part of Australia. Last year we recorded a total rainfall of 4,757 mm and the year before; 6,240 mm.

The most recent deluge, though, was of an intensity not seen for many years. In March of 1996, I recall that 1,219 mm fell in 48 hours. Flooding was so powerful that the Daintree River Ferry was deposited upon its pylons and the road across the heights of the Alexandra section, collapsed.

It must be said, that here in the Daintree rainforest, we brace ourselves in the face of extreme weather events, but they also remind us unequivocally of our subordinance to nature.

If I were to conservatively estimate that only one direct cyclone was to have hit every fifty years, the ancient rainforests of the Daintree would have bore the brunt of 2.7million cyclones over its 135-million year existence. On this basis, it becomes a very regular and recurring event.

In the aftermath, perhaps half the canopy is dislodged to the forest floor and as much as twice the sunlight is able to penetrate to these leafy depths of nutrient abundance. There can be no doubt that the extent of flowering and fruiting is maximised after cyclonic events. All other populations seem to multiply.

And the creeks become magnificent!

Queensland Tsunami Warning

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TOP PRIORITY FOR IMMEDIATE BROADCASTQUEENSLAND TSUNAMI WARNING
Issued at 8:57am on Monday the 2nd of April 2007, by the Bureau of Meteorology

For people in coastal areas of Queensland.

TOP PRIORITY FOR IMMEDIATE BROADCAST

TSUNAMI BULLETIN

TSUNAMI THREAT TO EASTERN AUSTRALIA and Willis and Barrier Reef Islands, Lord Howe and Norfolk Islands.

The Pacific Tsunami Warning Centre in Hawaii has detected an undersea earthquake near Solomon Islands and has issued a Tsunami Bulletin.

The earthquake has also been detected by Geoscience Australia.

FOR ALL OTHER PACIFIC AREAS, THIS MESSAGE IS AN ADVISORY ONLY.

AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS ORIGIN TIME – 6:40 am EST 02 APR 2007 COORDINATES – 8.6 SOUTH 157.2 EAST LOCATION – SOLOMON ISLANDS MAGNITUDE – 8.1

MEASUREMENTS OR REPORTS OF TSUNAMI WAVE ACTIVITY HONIARA 15CM ZERO-TO-PEAK OBSERVED AT 7:31 am EST EVALUATION

SEA LEVEL READINGS INDICATE A TSUNAMI WAS GENERATED. IT MAY HAVE BEEN DESTRUCTIVE ALONG COASTS NEAR THE EARTHQUAKE EPICENTER AND COULD ALSO BE A THREAT TO MORE DISTANT COASTS. AUTHORITIES SHOULD TAKE APPROPRIATE ACTION IN RESPONSE TO THIS POSSIBILITY. THIS CENTER WILL CONTINUE TO MONITOR SEA LEVEL DATA TO DETERMINE THE EXTENT AND SEVERITY OF THE THREAT.

FOR ALL AREAS – WHEN NO MAJOR WAVES ARE OBSERVED FOR TWO HOURS AFTER THE ESTIMATED TIME OF ARRIVAL OR DAMAGING WAVES HAVE NOT OCCURRED FOR AT LEAST TWO HOURS THEN LOCAL AUTHORITIES CAN ASSUME THE THREAT IS PASSED. DANGER TO BOATS AND COASTAL STRUCTURES CAN
CONTINUE FOR SEVERAL HOURS DUE TO RAPID CURRENTS. AS LOCAL CONDITIONS CAN CAUSE A WIDE VARIATION IN TSUNAMI WAVE ACTION THE ALL CLEAR DETERMINATION MUST BE MADE BY LOCAL AUTHORITIES.

ESTIMATED INITIAL TSUNAMI WAVE ARRIVAL TIMES. ACTUAL ARRIVAL TIMES

MAY DIFFER AND THE INITIAL WAVE MAY NOT BE THE LARGEST. THE TIME BETWEEN SUCCESSIVE TSUNAMI WAVES CAN BE FIVE MINUTES TO ONE HOUR.

Based on the magnitude and location of the earthquake, tsunami could start affecting these locations at the following local time:

Cooktown from 0931am 02/04/2007
Cairns from 0949am
Brisbane 1033am
Gladstone 1139am
Mackay 1144am

This bulletin is also available through TV and Radio broadcasts and the Bureau’s website at www.bom.gov.au/tsunami/

Dangerous waves and currents may affect beaches, harbours and rivers for several hours from the time of impact and low- lying coastal areas could be flooded.

The waves can be separated in time by between ten to sixty minutes and the first wave of the series may not be the largest.

The Queensland State Emergency Service advises that people should stay away from low lying coastal areas.

This warning will be updated by this morning.

This warning is also available through TV and Radio broadcasts; the Bureau’s website at www.bom.gov.au or call 1300 659 218