oncewasacreek: a words-eye view

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Time now for something completely different.

This site has reached a point where I am starting to look back, usually with some degree of bemusement, at all that I have written and done over the last two years. For a while now I’ve been meaning to overhaul the site’s structure to better serve the unexpected array of topics that I have ended up covering. But invariably, something more interesting captures my attention. This post is a case in point.

Recently I have been playing with network graphs as a way of visualising concepts and data. Networks are used as an analytical tool across many branches of science, because just about any phenomenon can be understood at some level as a system of discrete but inter-related entities (or nodes, in network-speak). Perhaps the most obvious examples are social groups and computer networks, but a myriad of other things, from gene sequences to ecosystems to economies, have been modelled and explored with the help of network theory. (Check out this page for a some examples of network visualisations.)

Networks are also useful for analysing text, because they can show relationships among words, such as which words occur together most frequently. And the best bit is that we can get computers to do all the counting. We still need to tell the computer which words to look out for, but thankfully there are dictionaries and word-recognition tools that do much of this work as well.

I wanted to have a go at analysing some text, so I found some software1 and fed it a collection of eleven of my own essays from this website.2 The result, shown below, is a kind of word-map of the topics covered by the eleven articles. In this case, the topics are limited to the names of people and locations, simply because these are much easier to identify than other kinds of topics. In the future, I hope to bring other topics (floods, maps, roads, etc.) into the mix.

The network of all people and places mentioned in the eleven articles. Node size reflects term frequency, and line thickness reflects the strength of co-occurrence. Hover over the image to see the network with the labels removed.

Continue reading

Notes:

  1. There are various packages out there, some free and some commercial, but the one that I used is called KNIME. It has an intuitive graphical interface, which means you don’t need to know any code.
  2. The essays were: A history of Gregory Park, John Olxey and the chain of ponds, Milton: Brisbane’s western frontier, The waters of Milton, Bottles and cans (an adventure in suburban archaeology), The broken lands of Toowong, Topography shock: postcards from the south, The history of the Coronation Drive Office Park, and the three installments of Uncovering Langsville Creek.

The history of the Coronation Drive Office Park

This post is all about the part of Milton bounded by the railway, Cribb Street, Coronation Drive and Boomerang Street. If you live in Brisbane, it’s a place that you have probably passed many times without really noticing. From Coronation Drive it presents as a row of office buildings and some Jacarandas; from the train, as a car park and some Moreton Bay figs. From within, the site feels like a secluded, shady village. Interspersed with the eight office buildings and fig trees are a tennis court, a childcare centre, a multi-level carpark, an open carpark, cafes, and various shops including a Flight Centre and a real estate office. This site is known (to those who know it as anything at all) as the Coronation Drive Office Park.

The Coronation Drive Office Park is bounded by Cribb Street, the railway line, Boomerang Street and Coronation Drive.

The Coronation Drive Office Park covers 4.5 hectares and is bounded by Cribb Street, the railway line, Boomerang Street and Coronation Drive.

AMP Capital, which manages of the majority of the site,1 are considering the next stage of its development. Before commencing this development, AMP Capital wanted to learn more about the site’s past. They asked me if I would like to do some research, and I jumped at the opportunity. After several weeks plumbing the depths of Trove, the Brisbane City Archives and various other sources, I produced a report documenting the history of the Coronation Drive Office Park.

You can download the report here (it’s about 13MB — apologies for the big download), but for a shorter, more web-friendly version of the story, read on below. Continue reading

Notes:

  1. Except for half a hectare at the corner of Coronation Drive and Cribb Street, the site is owned by AMP and Sunsuper.

The Duckbill Dimension

I wrote last week about the backflow prevention device — let’s call it a floodgate — that the council is installing at the end of the Milton Drain to protect the Western Creek drainage system from backflow flooding (that is, flooding from the river rather than from local stormwater). The Western Creek floodgate is the most recent — and probably the most ambitious — in a series of such works being done across Brisbane as part of the City Council’s Backflow Program.

Another place where a floodgate is presently being constructed is the outlet of the Leybourne Street drainage system in Chelmer. This system meets the river as a large open channel at Faulkner Park. There isn’t much of a creek left, and I don’t know what it used to be called. Evidently though, it flooded quite seriously in January 2011.

The end of the Leybourne Street drainage system in Chelmer, soon after the peak of the 2011 flood (note that a larger area was flooded — including the road — at the peak). Hover over the image (or tap it if you are using a tablet or smartphone) to see the normal landscape. Flood imagery from Queensland Globe.

Two large duckbill valves waiting to be installed near Leybourne Street, Chelmer.

Two large duckbill valves waiting to be installed near Leybourne Street, Chelmer.

I see this place several times a week because I ride past it on my way to work. For some weeks now there has been excavation work going on in the channel on both sides of the road. There have been tractors, trucks, fences, signs, portaloos, the whole works. In this last week, the stars of the show have arrived: two enormous duckbill valves.

Duckbill valves seem to be the City Council’s favoured backflow prevention device, as they are popping up everywhere. There are two already at Milton just downstream from the Western Creek system, and just last weekend I noticed one at Merthyr Park at Newfarm. But the specimens I have seen so far are all modestly sized — certainly less than a metre across. The two at Leybourne Street are of another scale altogether. Each of them must be nearly two metres wide, and in their current position on the grass they stand more than two metres tall (even at full stretch I could not reach their tops). They are made of some sort of very hard rubber-like material — so hard that I have trouble imagining it yielding even to a torrent of stormwater. But this is exactly what these devices have been designed to to, or else they would cause local flooding every time there is a downpour.

A temporary dam at the outlet of the Leybourne Street drainage system, where the duckbill valves will be installed.

A temporary dam at the outlet of the Leybourne Street drainage system, where the duckbill valves will be installed.

Looking over the embankment towards the river, you can see the new concrete structure into which these duckbills will be fixed. Curiously, the area in front of it has been made into a small temporary dam. I’m not sure why.

These devices will bring some comfort to residents in this area who were flooded in 2011. But it is worth being aware of their limitations. If you look closely at the Queensland Globe flood imagery (best done via Google Earth rather than the image above), you will notice that there is mud all over the road at Leybourne Street. This is a telltale sign that the river broke its banks here, flooding the area directly rather than just through the drains. Indeed, the river spilled over the banks for much of the length of the Chelmer Reach. This means that the two duckbill valves, as big as they are, will not protect this drainage system from a flood as high as 2011 unless the bank itself is raised. Even so, they will hold off the flood until the riverbank is breached, and should stop most floods that are below the 2011 mark.

These are not the sort of devices that I expect to see installed at Western Creek, where to have any real impact a floodgate will need to fill up the large space around the footbridge under Coronation Drive. But as the Backflow Program proceeds, I will be curious to see if any duckbills appear that are bigger than these two.

A sticker showing the manufacturer of the two big duckbill valves.

A sticker showing the manufacturer of the two big duckbill valves.

The tip of the duckbill valve.

The tip of the duckbill valve. The rubber is thick and hard, but will open up when there is enough water pressure behind it. We hope.

A floodgate for Western Creek

A sign announcing the construction of a backflow valve at the mouth of Western Creek.

A sign announcing the construction of a backflow valve at the mouth of Western Creek. It is erected on the gate to the footbridge under Coronation Drive. (Photo: S. Cowley)

So, it’s really happening. If this sign is to be believed, then Western Creek is finally going to have its floodgate. The photo was snapped at the entrance to the footbridge under Coronation Drive at the mouth of Western Creek (otherwise known as the Milton Drain) a few weeks ago by Steven Cowley, who has been my eyes on the ground at Western Creek ever since I moved to the southside last year.

The sign doesn’t mention a floodgate, but that is essentially what the ‘devices to be installed’ as part of the ‘Backflow Program’ are. They are contraptions of varying designs that ‘mitigate river water from flowing back up stormwater pipes when the river is in flood’. Such devices have already been installed just downstream near Cribb Street and the Go-Between Bridge. The City Council’s website has a page listing all of the places where backflow devices have been, or might soon be, installed. The page also provides links to the technical reports about these devices that the council commissioned in the wake of the 2011 flood. Continue reading

Email problems

UPDATE (15th January) — The contact form is now working, so please feel free to use it. Please note, though, that I cannot retrieve any messages that were sent while it was not working.

If you have tried to email me recently via the contact page, the chances are that I have not received your email.

I have just discovered that the site’s email feature is not working. I’m not sure how long this has been the case: a week at the least, but probably longer — possibly several weeks.

I will update this post when I have managed to resolve the problem. Until then, please to NOT use the contact form to contact me. Instead, you can:

  • post a comment at the end of a post or article
  • post a comment in The Forum
  • email me directly at angus-at-oncewasacreek-dot-org (replacing ‘-at-’ with ‘@’ and ‘-dot-’ with ‘.’).

I sincerely apologise if you have sent me something and received no reply. I have no way of retrieving the lost emails, so I’m afraid you will need to contact me again using one of the methods above.

Fingers crossed, normal service will resume shortly.
-Angus