Tuesday 8 December 2009

Vulnerable owls slowed flood mitigation works at Saltwater creek

Originally planned flood mitigation works for Saltwater Creek will be completed by the end of the week.

Cairns Regional Council works are now continuing to work on the remaining section of clearing between the Greenslopes Street bridge and the Centenary Lakes footbridge.

"The flood mitigation efforts were stopped due to the position of the work site," chair of Works and Services Councillor Paul Gregory says. "This was situated near a breeding site of owls considered a vulnerable species."

“Negotiations with Queensland Parks and Wildlife Services have been underway for some time. The agency has granted approval for a management program to be put in place that will prevent the disturbance of the bird’s breeding place and set conditions that will help the birds to successfully breed into the future,” Paul Gregory said.

"This work is designed to improve flood immunity for residents in Edge Hill, Manunda and Manoora and involves the clearing of mangroves and sediment from some banks of the creek."

What a hoot.


Alison Alloway said...

Damn! I didn't know this and I adore owls. Anyone got a photo of this "vulnerable" breed of owls?

hooter said...

There are breeding sites of Rufous Owls and resident owls living along the creeklines in the Cairns northern beaches - and yet development and vegetation clearance there has been rife, and Council has never given any consideration to this vulnerable species in their assessments of development applications or during Council works. Why is that?

Denis Walls said...

Most people who visit Centenary Lakes regularly have been appalled at the mangrove destruction ostensibly as a flood mitigation measure. Eric Wolanski from JCU wrote a paper entitled ‘Hydrodynamics of a Tidal Creek – Mangrove Swamp System’ which demonstrated that the outgoing tide is always of greater head pressure than the incoming provided the mangrove banks are intact.

Therefore, when mangroves are removed the outgoing water becomes sluggish and causes silting up of the channel. (See upstream of the Greenslopes St bridge as an example of this after clearing was done there a few years back.)

Thus, the net profit of removing the mangroves may be very small because of the sluggish outgoing current created. We will never know for sure because no council engineer so far has done any research in light of Wolanski’s work. His paper was published in 1980 and the hydrology report on which the 1994 Master Flood Plan was based has not been updated since 1972. Mangroves have been removed completely from one side of the creek system from Greenslopes to Collins in a protected Fish Habitat area without any recent hydrological study by council! And during the bird nesting season to boot.

By the way, these so-called ‘minor’ works were carried out without any public consultation apart from a last minute chat on site with CRC staff about what was intended. This occurred only because Brian Venables insisted on it.

When the young Rufous Owl chick was found dead in its nearly hatched but very thin shell two weeks ago council were informed (and mangrove clearing resumed). The chick was sent to CSIRO in Canberra to find out what had caused its demise and the thinness of the shell.

Rufous Owls are uncommon, classified as vulnerable, are Australia’s second largest owl (after the Powerful Owl down south) and are probably our top most predator taking possums, lorikeets and even kookaburras. If something is remiss right at the top of our food chain then it is a serious concern. As is the wanton clearing of mangroves right on our doorstep.

Blue Chaffinch said...

Blue Chaffinch said...
I've just been fortunate enough to spend some time in and around Cairns and saw for myself the vegetation clearance undertaken on Saltwater Creek. Here in the UK this kind of work would absolutely have to be preceded by a full ecological survey and assessment, ideally a full calendar year's worth. This would then allow a robust mitigation strategy to be devised and implemented.

I'm not at all au fait with the legislative framework in Queensland but I can't believe that the local authority can get away without protecting the environment, even when the work is deemed essential and/or 'minor'. Maybe they simply don't give a damn? The reasons given for the clearance are highly dubious it seems to me - how can mangrove removal be an acceptable method for conserving fish stocks or flood defence?

Aren't mangroves and other wetland habitats a natural defence against flooding as well as spawning grounds for fish? Basic ecology. Anyway, my advice is to gather as much detailed information on these unprotected sites as you can - species lists, breeding territories, population estimates etc - as it is only hard evidence that will ever stop this kind of pointless destruction of valuable habitat. What's the local university doing for goodness/ sake? Ideal project for students as well as local birders... OK, best of luck.
Tristan Norton, Winchester, Hampshire, UK

Denis Walls said...

Go to
Cairns Birding for more info on the rufous owl saga as well as photos of the breeding pair and of the dead chick.

Alison Alloway said...

Thanks everyone for your comments, and thanks especially to Denis Walls for the website, "Cairns Birding." I've added it to my "favourites"!!

Factman said...

Does anyone care about the dozens of homes that became flooded and had to have carpet removed?

And does anyone care when the insurance companies say "no more insurance cover until the drains are cleared of obstructing mangroves"?

And further, does anyone care about the stress caused to the families that reside in these homes?

No, of course not - life revolves around a bloody owl.

Why doesn't the owl pack up and move to the Cattana Wetlands where$3million dollars has just been spent providing such a suitable environment?

Did you know that there were no Mangroves in this area before the gate holding back the salty sea was removed because it rusted up many years ago.

The storm water run off from the Whitfield Range needs to have an unobstructed passage to the sea.

That's what Saltwater Creek is ... a drain ... and that's a fact!

Denis Walls said...

Mr Factman certainly doesn't let the facts get in the way of some high end emoting.

Insurance companies don't block coverage on account of mangrove presence and he knows it.

The mangroves have grown up largely since the area became a fish sanctuary. Fingerlings like mangroves Mr F.

Re-the water run off issue Mr F needs to read what I wrote above on the basis of Eric Wolansky's research.

Factman said...

Mr Walls.

Please take the time to google "Mannings N Values".

You will see that mangroves do indeed add considerable friction to the water path.

The best hydraulic solution would be to concrete line the whole length of Saltwater Creek.

And by the way Mr Walls, Mannings formula has been used by hydraulic engineers all over the world and has been proven to stand the test of time.

Eric Wolansky's research states the bleedin' obvious - of course there is more pressure from outflow.

That's because of another little bit of science called "gravity".

And that's a fact !

concerned said...

Honestly, Factman is playing devil's advocate for a laugh on this blog isn't he? He cannot truly believe half the **** he comes out with. Let's concrete all the creeks, easements, any waterway, I say!!

Mike said...

If they do concrete the waterways, can we use 'know all' Factman as fill?