Where a creek begins

A pond in a tributary of Ithaca Creek, Mount Coot-tha. (February 2013)

A pond in a tributary of Ithaca Creek, Mount Coot-tha. (February 2013)

This is just a quick plug for a side-project of mine that has mostly sat on the back-burner since this website was conceived. Before I started mapping out Western Creek in my imagination, I had started to map out Ithaca Creek (a real creek!) photographically. My plan was (and still is) to photograph Ithaca creek from one end to the other, documenting its journey from the headwaters in Mount Coot-tha Forest through to the much more suburban surrounds of Red Hill where it joins its bigger brother, Enoggera Creek.

Ithaca Creek is a neighbour of Western Creek, sharing a catchment boundary along the ridge of Stuartholme Road, Simpson’s Road, Macgregor Terrace and much of Latrobe Terrace.

To see the Ithaca Creek photo-map, click here and then click on the small banner at the top of the page to go to the Picasa Web Album (Google appears to be phasing out Web Albums in favour of the happy-snap functionality of Google+, so I don’t know how long this will remain functional). Beneath the small map on the right-hand side of the album there is a link which takes you to a proper map view of the album.

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The Waters of Milton

I’ve expressed previously my enthusiasm for old maps. The older they are, the more they tend to reveal about the original landscape.

Until recently, the oldest map that I had found of the Milton area dated back to 1859. That map (‘Plan of Portions 203 to 257 in the Environs of Brisbane, Parish of Enoggera, County of Stanley, New South Wales) covers the area between Boundary Creek (which flowed between Cribb Street and Boomerang Street) and Toowong Creek. It depicts several features I had not seen on other maps, such as Red Jacket Swamp spilling over into Frew Park (later maps just show it covering Gregory Park) and a large lagoon between Cribb Street and Park Road.

But now I have an even older one, courtesy of Magnus, who writes the blog ‘A House in Auchenflower‘. Magnus went digging in the Queensland Museum of Lands, Mapping and Surveying and struck gold in the form of the map you see below.

Surveyor James Warner's plan of the Milton area in 1850, held by the Queensland Museum of Lands, Mapping and Surveying (B1234 14).

Surveyor James Warner’s plan of the Milton area in 1850, held by the Queensland Museum of Lands, Mapping and Surveying (B1234 14).

This map looks old enough to have fallen off a pirate ship. The various annotations on it show that it has been used and re-used for various purposes, and at different times, but the original drawing appears to date from 1850, when the assistant surveyor-general, James Warner, surveyed the area. Warner’s description of the map appears at the bottom-right corner: Continue reading

Are we learning yet?

A story in the Brisbane Times this morning, titled Buyers less fearful of flood zones, made me a little bit mad.

Though I try not to buy into the blame game around the 2011 flood, I suspect that the real estate industry is partly responsible for the false sense of security that set in after Wivenhoe Dam was built. I have no proof of this; it is just a hypothesis. But it stands to reason that someone whose job is to sell houses will downplay the risks of flooding any way they can. Buyer beware.

Whether or not real estate agents have done it in the past, they certainly seem to be doing it now.

According to agents working in river precinct suburbs, the percentage of buyers willing to consider properties previously flooded in 2011 has increased significantly because they feel assured that the Wivanhoe Dam did its job in mitigating another flood over the Australia Day weekend.

Granted, this boost in buyers’ confidence is not necessarily the doing of real estate agents. People make their own assessments of risk based on events, and make their own decisions accordingly. Whether those assessments and decisions are justified or wise is an open question, but it is one that needs to be answered with some understanding of the facts about the 2011 and 2013 flood events, what role the dam played in each, and how the two events are comparable. I won’t pretend to have all of those facts. But I humbly suggest that not many real estate agents do either.

The article continues, quoting Brad Robson of Brisbane Real Estate:

“They’re happy that the dam worked. There was a truckload of rain and nothing flooded so it’s given them the confidence to go ahead and make a purchase”

John Johnston, of Johnston Dixon, said the Brisbane River needed a proposed class action by residents to succeed in order to clear its name.

“These properties should never have experienced the flooding that they did in 2011 and the latest weather event last month supports that,” he said.

“The mitigation capacity of the Wivanhoe have now been proven. I’m confident that if this class action goes through, it will largely clear the Brisbane River’s name and buyers will no longer be afraid to purchase near the river.”

Torwood Street during the January 2011 flood

Torwood Street during the January 2011 flood

There you have it: the smallness of the 2013 flood proves that the 2011 flood did not need to happen. It was all the fault of the dam operators. They are guilty, and the river is innocent — we just need to ‘clear its name’!

I’ll stress again that I do not know all of the relevant facts. But in case someone else has the inclination to go do some homework, I suggest that the following questions would be a good place to start:

  • Could it be that the 2013 flood was smaller than the 2011 flood because there was less rain?
  • Where did the “truckload of rain” that fell in 2013 actually fall? According to our Premier and the Bureau of Meteorology, the flooding in 2013 was caused by rain that fell in catchments that discharge to the Brisbane River downstream of Wivenhoe Dam. Suppose that even more rain (a shipload?) fell in those catchments: would the dam save us then?
  • Could there be any truth in the Flood Commission’s finding, stated on page 524 of the Commission’s final report, “that, allowing for the limits of the strategies in the Wivenhoe manual, the flood engineers achieved close to the best possible flood mitigation result for the January 2011 flood event”?

I’m not presuming that the dam manual is perfect, that the dam operators did a perfect job, or that there are not lessons to be learned from the way the 2011 flood was managed. And I’m not offering an opinion on whether a class action against the government’s management of the flood is warranted. But I do think that comments such as those above from the real estate industry are grossly irresponsible, and are the absolute last thing we need if we are to to learn from past events and become better informed about the nature of flood risks in Brisbane.

Buyer beware.

Here we go again . . .

I don’t know about you, but I didn’t expect to be seeing scenes like these just a couple of years after January 2011. (See the new Gallery page for more pictures of today’s flooding.)

Gregory Park, 28 January 2013. The tide was still rising, and water was gushing into the park through this drain.

Gregory Park, 28 January 2013. The tide was still rising, and water was gushing into the park through this drain.

Milton Drain, from the mystery building on Milton Park, 28 January 2013.

Milton Drain, from the mystery building on Milton Park, 28 January 2013.

Then again, we shouldn’t be surprised: there’s no reason why floods should be spaced out evenly over time. Indeed, the historical record of Brisbane’s floods suggests that they often come in twos or threes.

Flood events greater than 1.7m in the Brisbane River since 1841. Also shown are the estimated mitigating impacts of river works and the two dams. All data sourced from the Brisbane River Flood Study except the effect of the two dams, which is indicative only and has been inferred from an analysis on page 523 of the final report of the Flood Commission of Inquiry.

Flood events greater than 1.7m in the Brisbane River since 1841. Also shown are the estimated mitigating impacts of river works and the two dams. All data sourced from the Brisbane River Flood Study except the effect of the two dams, which is indicative only and has been inferred from an analysis on page 523 of the final report of the Flood Commission of Inquiry.

Meanwhile, just downstream . . .

A duckbill valve on the riverbank at Milton

A duckbill valve on the riverbank at Milton

I’m also guessing that the Brisbane City Council wasn’t expecting their new backflow prevention devices to be put to use so soon. As explained in my essay Backflow to the Future, the Council has recently installed duckbill valves and flap-gates to prevent flooding in several locations, including the Cribb Street drainage system in Milton. This area spans between Cribb Street and Park Road.

After my little adventure this morning I took a walk around this area and could see no evidence of flooding. Unless this whole area is higher up than the Western Creek area (which I do not believe to be the case), this means that the duckbills and flap-gates are doing their job.

If this is the case then the Council can give itself a pat on the back. And if it has any sense, the Council will look for ways to tell everyone how many properties these devices saved from being flooded. Then again, the Council may not want to create too much work for itself. Before long, every suburb in Brisbane will be wanting one of these duckbill thingies . . .

When waters collide

Just over a week ago I posted about the ‘tidal limits’ of Milton Drain, noting that at a very high tide, the drain is pretty much full to the brim.

Today, I braved weather that ranged between miserable and awful in order to see how the drain held up when it had more than just a high tide to contend with. With the remnants of Cyclone Oswald looming over South East Queensland, Seqwater began releasing water from Wivenhoe Dam on Friday evening, and according to the Seqwater website, the releases are expected to continue for several days. So we have the tides coming in from downstream, the dam releases coming from upstream, and the stormwater from the Western Creek catchment racing through the drains towards the river. What happens when the waters collide?
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