The river bed of the Todd is more stable than many assume. I have two photos taken from exactly the same vantage point on Meyers Hill (originally called Nannygoat Hill). The first was by John Flynn in 1926. I took the second this year. In my photo there is a prominent "island" covered in buffel grass on the eastern side of the riverbed. This island is also observable in Flynn's photograph, although it was devoid of vegetation at the time. ALEX NELSON comments.
At left: John Flynn's photograph, held by the National Library of Australia.
It is remarkable how little comment there has been to mark the recent expiry of the 20 year moratorium that had prevented the construction of a flood mitigation dam on the Todd River north of Alice Springs, says letter-writer ALEX NELSON. He summarises what is known about the town's susceptibility to flooding and notes that the Imparja headquarters (pictured above) would be inundated by more than a metre of water above ground level in a 100 year flood. The Civic Centre and the Alice Springs Public Library are equally at risk.
The popular misconception about sand being taken out of the Todd River is that this is done as a flood mitigation measure, deepening the channel to allow a greater volume of water to flow within the banks. In truth, it would take major works to achieve this, including the removal of causeways and the re-location or re-laying of services that are under the river.
The works that are undertaken are better described as "channel improvement" to prevent channel migration and bank scouring.
The Town Council's Director of Technical Services, Greg Buxton explains that this is done "to ensure the river doesn't change course and endanger the properties close to the existing river banks."
However, works at Heavitree Gap are seen as a priority and would contribute to reducing the threat of flooding. "Silt, fines and sand" deposited at the gap by flows have "grassed up" with couch and kikuya, matted into a solid mound (pictured) that now stands well above the Bloomfield drainage line. These conditions could lead to the river breaking its banks in a Q20, let alone a Q100.
Extensive works removing sand and weeds were done to address this very same problem at the start of the decade, so why hasn't there been regular maintenance? KIERAN FINNANE reports.