Poor infill design contributes to increased Canberra flood risk

Poor infill design contributes to increased Canberra flood risk

The Canberra Times February 27 report on flooding makes for thought-provoking reading, particularly for anyone with a knowledge of the planning history of Canberra.

We read that the Auditor-General's report into the stormwater system found many areas had not been reassessed for flood risk mitigation despite known risks. The report specifically refers to "[infill] development such as multi-unit high rise developments … reduce the amount of open space to help absorb stormwater so leading to more concentrated flows". Transport Canberra and City Services indicates some parts of the system are unable to cope with major events already.

Northbourne Ave blocked off due to intense flooding.

Northbourne Ave blocked off due to intense flooding. Credit:Dion Georgopoulos

In an attempt to diminish the report findings and comments, a spokesperson for Minister Meagan Fitzharris opines the events were extreme and the kind that would place pressure on any stormwater network no matter how much infrastructure is in place. This is meaningless commentary. Apart from anything else, it's the increased infrastructure without any care or thought for stormwater runoff that is the problem: a problem exacerbated by decreased landscape space and increased hard surfaces leading to enlarged flow of water into existing drains and stormwater systems.

A number of us who know something about planning in Canberra and the history of the open space and stormwater management system integral to Canberra's National Capital Open Space System (NCOSS), including Sullivan's Creek, have warned in the past of the danger of flood events following significant rainfall as took place on the weekend. Most of us, of course, are in the older age groups and who in the Labor government wants to listen to advice based on experience and long-held informed knowledge?


Some years ago a report from the then research centre at University of Canberra led by the late Professor Peter Cullen focused on the flood control system (including Sullivan's Creek) of North Canberra with particular reference to future risks. It warned that, with increasing infill, diminishing landscape space and burgeoning hard surfaces, the system would be unable to cope with runoff from a significant rainfall event, for example the equivalent to a one-in-100-years flood. My recollection of the report is that it linked the heightened flood risk to the design of infill developments, not, will the Chief Minister please note, infill per se. It is the poor spatial design within such development projects generally where landscape space is minimised as far as possible whist maximising on hard surfaces, ie roofs and ground surfaces. The result is inevitable, more runoff to the point at which some time, some place, flooding will occur because the stormwater system is overloaded.

Add to this set of circumstances that of climate change, with increasing associated risks of rapid deluges of rain, there will be more flooding more frequently.

The floodways of Canberra designed and built as part of the city's distinctive open space system by the NCDC were at the time regarded as cutting-edge thinking and practice. Planners and government officials came to Canberra to learn how to do it and why. Now we have our planning minister and party jetting (business class of course) around the world to see how other cities plan. What do we get in return? We get what some of us call the Authorised International Planning Discourse where in the end every city looks the same the world over. Canberra's once proud mantra of the city in the landscape, a city not like any other, is trashed.

Again the Chief Minister should note that people like me are not against infill, higher densities or tall buildings (in their place), but what dismays us is the poor urban design outcomes that we see in infill projects with little thought or care given to spaces between buildings. If anyone doubts this take a trip along Flemington Road in Gungahlin and remember we have to have the tram to justify this sort of development. Do we? Still, it has given me and a PhD student the opportunity in writing a chapter on Canberra for a forthcoming international publication on cities to illustrate what I mean with poor urban design.

Professor Ken Taylor, Centre for Heritage and Museum Studies, The Australian National University

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