By KIERAN FINNANE
The ‘d’ word – a dam – isn’t mentioned in the recommendations of the Alice Springs flood mitigation draft report, though it may be hiding behind “structural mitigation” measures that include “detention basins in the upper catchments”. Is a dam excluded? On the basis of the draft report, it’s not possible to say.
The draft report has been prepared by an advisory committee, appointed in February by the Chief Minister and chaired by Mayor Damien Ryan. The main thrust is that work is yet to begin and there is plenty of it. The immediate priority is to undertake “preliminary investigations”.
Inexplicably, after almost a quarter of a century of angst about flooding – following the 1992 moratorium on construction of a dam at Junction Waterhole – topographical data in the upper catchment of the Todd has still not been collected. This should be done in year one, says the report, suggesting a $500,000 budget allocation for the work.
The other “preparatory” work is to assess the trunk drainage infrastructure that handles stormwater across the town, to reduce the impact and / or frequency of localised stormwater flooding. This should also happen in year one, with a $300,000 allocation.
Structural mitigation assessment should include a cost-benefit analysis and an order of priority in terms of effectiveness. This should inform a program of capital works over five to 10 years. A notional amount of $30m is suggested for the construction of three retention basins in the upper catchment.
However, “structural solutions have their limitations and no amount of intervention can stop flooding altogether”, warns the committee. “There will always be properties within the existing Alice Springs town boundaries that will be impacted upon by flooding.”
Given this, the town needs to be prepared and the committee recommends examination of all the obvious protective measures like an improved early warning system, sound evacuation plans and critical supplies storage in the event of the town being isolated for a period of time.
The impact of causeways crossing the Todd should be examined and a maintenance regime developed to reduce the build-up of sedimentation around them to maximise the “‘hydraulic efficiency’” of the river. This too should be done in year one, with a $100,000 budget suggested.
Flow-on effects should be considered for work that is already underway within the Department of Transport. The committee recommends that anything done as a result of a flood immunity study for the Mt John’s and Desert Springs areas does not make the situation worse elsewhere (amazing that this needs to spelled out).
Similarly, any duplication of the Stuart Highway south of the Tom Brown Roundabout – currently being investigated by the DoT – would have to ensure a positive impact on the existing flood profile of Alice Springs. In this part of the report, there is reference to a possible widening of the riverbed as it passes through Heavitree Gap.
After significant protest, construction of a dam at Junction Waterhole (at right) was prevented in 1992 by a 20 year moratorium under the Commonwealth’s Aboriginal and Torres Strait Islander Heritage Protection Act, with a view to protecting sacred sites in the area. The committee is obviously keen to head off the kind of confrontation seen at that time. Its report includes this statement:
“The committee is certain that a successful adoption and implementation of flood mitigation measures must accommodate the community’s needs which include the customs and beliefs of its traditional owners.
“The committee acknowledges the guidance of Lhere Artepe in developing its recommendations and strongly recommends continuous communication and participation from Lhere Artepe throughout any further progress of these recommendations.”
Lhere Artepe (wrongly identified as an association in the draft) is the Aboriginal Corporation of native title holders. It is represented on the committee by Ken Lechleitner.
Other committee members are Russell Lynch, a resident, Michael Sitzler, a business owner, Jimmy Cocking of the Arid lands Environment Centre, and Rod Cramer of the Rural Area Association. The absence of women from the committee is glaring.
The full draft report is available here. It is open for public comment until 2 July 2016.
PHOTOS of the 1988 flood (a ‘1 in 50’, where water depth at Anzac Oval measured 3.9m) by Hans Boessem.
By KIERAN FINNANE