A Q&A between Lionel Frost and Margaret Cook discussing Margaret’s book – A River with a City Problem: A History of Brisbane Floods. (UQP 2019.)
Margaret – congratulations on the book. Can you tell us what motivated you to do the research?
As I watched the events of the 2011 floods unfold and witnessed the response disintegrate from an outpouring of help and compassion to recrimination and blame, I noted that historical context was missing from the debate. Why were the residents of the floodplains in Brisbane and Ipswich surprised when their cities flooded as they had before? I felt the focus on management of the region’s dams suggested an underlying arrogance that humans think they can control nature, an idea that is prevalent in the current bushfire debates.
I wanted to research previous floods and explore how society had created the flood risk that exists today. This led to a PhD at the University of Queensland, that became this book. I hope that it will contribute to future discussions about adaptive approaches to living on a floodplain.
What are the key geographical features that make the Brisbane River catchment vulnerable to flooding?
The catchment itself is largely parallel to the coast in a subtropical environment. So, when it rains north of Brisbane, much of the water can drain west into the catchment. The sinuous Brisbane River, that winds through the capital city, has wide floodplains that are now highly developed.
What features of Brisbane’s initial planning and land sales made the city vulnerable to flooding?
Brisbane did not have a Town Plan until 1965 and developed without consideration of floods. Land sales were allowed right to the river’s edge offering prestigious real estate and low-lying areas were densely developed with cheap housing and industry.
Your title A River with a City Problem suggests that the urban landscape itself made a negative impact on natural waterways. Can you elaborate on this?
The title was chosen to acknowledge that the river came first; human behaviour has created the flood hazard. Floods are a natural part of a river’s hydrological cycle that rejuvenate the river system and deposit alluvial soil on the floodplains. Floods are an anthropogenic term: without humans, a flood is just a high-water event. It becomes a hazard when buildings are built in the floodwater’s path.
Since the 1860s British colonists have continually reshaped the Brisbane River and its tributaries. Channels have been widened, bars and navigational obstacles removed, and the riverbed dredged. More interventionalist approaches included building training walls, cutting river bends to straighten the river and reclaiming riverine land through infill. But it was the completion of Somerset Dam in 1959, followed by Wivenhoe Dam in 1984, that forever changed the river’s flow, especially at times of high rainfall.
What are the key features of the technological response to the floods of 1893?
The 1893 floods triggered a debate on engineering strategies to control floods that lasted for four decades. It was not until the 1930s when the need to find an unemployment relief project changed the economic equation, that it was agreed to build Somerset Dam.
Tell us about the Somerset Dam. What was it intended to do?
Somerset Dam was the first dual-purpose dam built in the southern hemisphere. Recognising southeast Queensland’s dual climatic concerns of drought and floods, the dam included a water supply compartment with additional storage space for retaining flood waters. A gated structure, it allows dam operators to manage floods through a prescribed release strategy.
What action was taken in response to the 1974 floods?
Unfortunately, not a lot. The State Government, under Joh Bjelke-Petersen, was already committed to a second dual purpose water supply/flood mitigation dam. Many people believed that Wivenhoe Dam, three times bigger than Somerset Dam, would prevent future floods.
A recurring theme throughout the book is the failure to take account of flood risk in city-building. Why do you think the historical lessons of building on a floodplain went largely unheeded?
I think part of the problem is the infrequent floods. That is not intended to blame the river! But it recognises that now that southeast Queensland’s dams withhold most floods, many city dwellers think floods have been prevented and complacency sets in. In the intervening years, when the other half of the hydrological cycle (drought) often occurs, the need to manage development on the floodplain is pushed far from mind.
Southeast Queensland has a development mentality, continuous growth is the goal. Restricting building on hazardous land is regarded as an economic impediment, and this has culminated in continuous expansion onto the floodplain.
The 2011 floods are fresh in our memory. Is there evidence that we have learnt from the history of flooding in the Brisbane River catchment?
While some planning measures were instigated in the 1970s to control development below recognised flood levels, compared to other Australian states these were slow to be implemented. They were also lenient and had loopholes. Floodplain development continued, making the increased flood damage in 2011 inevitable.
You argue that future floods in Brisbane are inevitable. Are we better prepared now than we were in the past?
I do think that there is a shift in the approach to floodplain management in the last few years, but there is much more to do. The fallacy of a largely myopic approach of relying on dams to manage floods needs to be recognised, the myth of flood security abandoned. The community must accept the inevitability of future flooding and policies need to become more proactive to restrict development areas and regulate building flood resilient houses. There are numerous examples of current building projects that are increasing the flood hazard. I am hoping my book can be a stimulus for change.
