The CSIRO report on flood mitigation in the Richmond River was released in June to enthusiastic proclamations from Lismore business leaders. ‘We must act without delay!’ they urged. ‘The science has spoken!’
I understand the urge to grasp what looks like a miracle cure for Australia’s most flood-prone town. The trouble with miracle cures is that they often fail to match the promise. Sometimes they have awful side effects – in this case, flooding communities who live upstream. But we should not describe this as a ‘side effect’ since the goal of the project is engineered flooding of these localities.
CSIRO modelled several engineering interventions, the most aggressive of which involves ten detention dams in the upper catchment. Huge walls would be built across valleys. When floods threaten, sluice gates in these walls would close to hold phenomenally large volumes of water for up to two weeks.
When CSIRO released the report, they did not consider it important to include inundation maps so that families in these valleys could see what was planned for them.
Without an understanding of the huge extent and depth of these ‘detention dam floods’, few rural people knew why they should participate in consultations. Even more extraordinary was the callous disregard of the National Emergency Management Agency (NEMA) which oversaw the CSIRO project and ‘consultations’ in which the targets of intentional flooding were kept in the dark. Although NEMA has done excellent work in disaster preparedness and recovery, they did not think about the impact on people who had lived through the flood and landscape collapse event of 2022. National guidelines on post-disaster mental health were forgotten as they progressed a project to flood communities. Questions should be asked about how this project was allowed to proceed without proper ethics oversight.
Flooding our homes
But then something happened which shone a light into the void created by CSIRO/NEMA neglect. A skilled community volunteer produced an interactive map which shows indicative extents and depths of the detention dam floods. To say that people are shocked when they examine the map is an understatement. It can be accessed using the QR code shown.
CSIRO/NEMA have not ‘approved’ the interactive map. However, the map was built using coordinates for the dam walls obtained from CSIRO. The height of the dam walls is given in the CSIRO report. Inundation is determined by the contours.
NEMA, which commissioned the CSIRO report, and was present at the Lismore consultations, announced that they would produce maps within two weeks of the Lismore event – but these have not materialised, months later.
The interactive map reveals the astonishing scale of engineered flooding at Nashua, Booyong, Corndale, Bentley, Nimbin, Rock Valley, Larnook, Dunoon/The Channon and Collins, Fawcetts, Eden and Barlings creeks.
No meaningful flood reduction
By placing a finger on the map, we can see the indicative depth at that location: 10m over Pearce’s Creek Road, Booyong Road, and Corndale Road. That’s more than the height of a two-storey building. The map reveals the extents – stretching 10km up Rock Valley, mostly 20m deep. That’s the height of a six-storey building. The CSIRO report reveals that the Booyong detention holds 82GL – that’s nearly six times the volume of Rocky Creek Dam. Corndale is equally huge. Despite the enormous size of the ten detention dams, they don’t even eliminate flooding of Lismore. A February 2022 flood would be 2m lower but still go over the levee.
Cut off from help
The proposed detention dams flood roads essential for emergency services and for communities coming to each other’s aid during floods, cyclones, and landslides. This is not temporary water-over-road. This is not gentle rain collected in a pond. It is high-velocity creeks hitting a wall, bearing logs, rocks, soil, dead cows, and occasional shipping containers. After the detained water is released, councils will have to scrape all this off the roads before they can even assess what is left of the road surface. It is likely that engineers will find extensive damage, with sections requiring intensive remedial work before they are safe. After drawdown, it is unlikely that these roads will be functional. Roads essential for emergency capability would be disabled.
Valleys unite
CSIRO’s modelling of interventions to reduce flooding in the Richmond River was theoretical. The NSW Reconstruction Authority will now coordinate a feasibility study covering geotechnical, engineering, dam safety, cost-benefit, and Indigenous heritage, ecology, agriculture, communities, and emergency capability. This is a big task as the proposals include some downstream engineering as well as ten detention dams. The targeted communities are organising within their valleys so they can have a voice in this study. An alliance of these communities has emerged called Valleys United.
Upstream communities know the 2022 flood brought immense suffering and loss on the Wilson and Richmond Rivers. Many volunteered to help in Lismore, for weeks. What is not so well known is that upstream people also suffered loss and trauma in that flood. In the upper catchment, rain intensity was extreme. Houses and roads were demolished by landslides, and farms and livestock destroyed. These were life-threatening conditions and the communities self-organised their own emergency response, clearing roads with farm machinery so they could reach each other. They are now experiencing another shock – the plan to subject them to flooding. Given the disregard with which they have been treated, it would be in their interests to examine the interactive map and organise.
♦ Annie Kia is an advocate for rural flood safety.
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