Building dams to protect Lismore from flooding would cost billions. Could nature do it better?

The Conversation (Australia) reports that Australia's national science agency, CSIRO, has modelled ten large detention dams upstream of Lismore, in New South Wales, which could lower flood heights in the town by about two metres. Governments have already committed several million dollars to a detailed study of the proposal, but the piece, published on Sunday, urges caution: the dams would likely cost billions of dollars, would only partly reduce damage from a flood on the scale of the twenty twenty-two disaster that killed thirteen people across the state, and large water projects in Australia have a track record of cost blowouts. Researchers at the Australian National University, Southern Cross University and the Richmond Landcare Network are instead investigating nature-based options — revegetating hill slopes, wetlands and riparian zones to hold water upstream — alongside older ideas like a diversion channel around the town, first floated after the nineteen seventy-four floods and rejected by the council in nineteen eighty-one. The author argues a combination of engineered and natural systems could make Lismore Australia's first so-called sponge city.

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