Stand by for fresh Todd dam controversy

p2311-flood-Q100-town

p2311-Junction-Waterhole-3By ERWIN CHLANDA

 

The prelude for Todd Dam – Season Two is beginning to flicker across the screen with the appointment of a committee to advise the NT government on flood mitigation.

 

Season One ended with a 20 year moratorium imposed on a dam – or lake – by Federal Aboriginal Affairs Minister Robert Tickner in 1992 after ferocious arguments as construction had already started at Welatje Therre (pictured), a women’s sacred site upstream from the Telegraph Station.

 

Trouble was, engineering reports, whilst taking into account a string of alternate measures, such as levee banks along the river and removing the casino causeway, stressed that only a dam at that site would save the town from catastrophic damage and major loss of life in the event of a major flood. (Extensive coverage of the issues can be found buy googling our story archive.)

 

Today Chief Minister Adam Giles nominated Damien Ryan, Michael Sitzler, Rod Cramer, Russell Lynch, Ken Lechleitner and Jimmy Cocking as members of the Flood Mitigation Advisory Committee and he released updated flood mapping for the area (see images).

 

Mr Cocking, who heads up the Arid Lands Environment Centre, says a range of options should be looked at before considering violating a sacred site.

 

These options could include building a fly-over through The Gap for both the road and the rail to widen the bed of the Todd and allow a p2311-flood-Q100-Rangeviewgreater flow. (Although The Gap – Ntaripe – is also a sacred site for the Arrente.)

 

There should be fresh modelling of flows in stormwater drains, says Mr Cocking, and perhaps the casino causeway ought to be removed or modified while a dam should remain an option to be explored.

 

Mr Cocking also says that perhaps the population should be prepared for the inevitability of the town’s centre being obliterated in a flood.

 

Mr Cocking says a recommendation from the committee would depend on the information put before it, including details about the predicted major floods resulting from climate change.

 

Mr Cramer, the president of the Rural Areas Association, says he intends to represent the people in the farm areas, as well as bringing to the table his knowledge gained during the earlier discussions of the issues.

 

He says government flood modelling usually looks only at the consequences of a flowing Todd River, not the problems caused by run-off at Ilparpa from the southern flanks of the ranges.

 

He says there are precedents of the costs of major engineering works: Improvements of Henley Beach Road and Anzac Highway in Adelaide, for example, cost about $100m and $120m, respectively, and the simple railway overpass south of town cost $24m.

 

A flyover through the Gap had been suggested in the lead-up to the construction of Kilgariff to manage increased traffic.

 

Mr Cramer strikes a “you can’t win them all” note: “Nature is always capable of chucking at you something far worse than what you’ve prepared for.”

 

Mayor Damien Ryan said he will welcome the opportunity of making suggestions together with the other members: “We need a plan. Flood mitigation is an issue.”

 

(We have left messages for other members of the committee and will report their views as they come to hand.)

 

IMAGES: Parts of the town (top), Rangeview Estate (centre) and the Ross Highway area affected in a “Q100” flood – one that is likely to occure once in 100 years. Photo: The Junction Waterhole sacred site where a dam was proposed.

 

p2311-flood-Q100-Ross

 

 

CLARIFICATION. Mr Cramer provided the following notes: “If I did mention Ilparpa, I didn’t in terms of flooding caused in the rural area by rainfall off the back of the Heavitree Range.”

During the interview Mr Cramer and the reporter discussed the cost of the recently completed railway overpass near Alice Springs, in the context of what a flyover through the Gap would possibly cost. Mr Cramer mentioned Henley Beach Road and Anzac Highway in Adelaide, as well as that they cost about $100m and $120m, respectively.
Mr Cramer now advises: “None of the two examples I gave have anything to do with flood mitigation.”

 

 

Be Sociable, Share!

23 Comments (starting with the most recent)

NB: If you want to reply to a previous comment, start your comment with this notation: @n where n is the number of the comment you want to reply to.
  1. Ian Sharp
    Posted March 8, 2016 at 3:03 pm

    Climate report issued this week by UNSW Climate Change Centre indicates desert areas may become wetter, but certainly likely to have more extreme events which would include heavy rains and therefore floods.
    So the “mythical” 1:100 flood event may be on its way, it would be devastating for the town. The biggest flood that I can recall was the Easter ’88 one, both the Stott Tcce bridge and the Wills Tcce walkway were closed, helo rescue attempts to save river campers, lots of local flooding including up our driveway in lower Mistetoe.
    I towed out a few sedans conked out around the Undoolya – Grevillea roundabout. And the 88 flood was not a 1:100 event, smaller.
    Time to get thinking on a workable strategy. Levees are possible, but complicated by site factors and the need for closable gates in some locations where ramps not practicable eg Wills Tce.
    I think a flood mitigation dam at Junction waterhole is a good option, the 1990s head works still there.
    The earlier proposal for a dam at the Telegraph station needed a long containment berm as well as the actual dam across the river.
    A properly engineered and maintained flood mitigation dam should merely spread the flood peak over a few days instead of a few hours, and not unduly disrupt the ecology of the river anymore than it is already.
    Note: By Flood Mitigation dam I mean one designed just for that purpose, not one that doubles as a potential recreation lake … we should learn from past mistakes.

    View Comment
  2. Byjingalo
    Posted March 6, 2016 at 5:45 pm

    @ Michael La Flamme: I agree with your words, the problem in your message is we humans. I actually do not think there is a solution to that conundrum because the majority don’t see the issue.

    View Comment
  3. Michael LaFlamme
    Posted March 5, 2016 at 11:49 am

    We humans need to think beyond our own interests, and consider the long-term ecological impacts of changing the Todd River flow. Regular flooding brings nutrients to the trees along the river, and the temporary rise in the water table triggers germination and growth of young trees and helps them grow deeper roots. Native trees are adapted to those flood regimes.
    Building mitigation dams to reduce common flooding will slow or stop that natural regeneration process, and eventually the existing trees will get old and die.
    Flooding also maintains healthy fish and inverts in the surface-groundwater systems fed by the Todd catchment (as shown in a recent Alice Springs News Online photo).
    Most desert streams are intermittent like the Todd. I lived in a desert city that built mitigation dams. It first wiped out the native fauna, and then the native riverside trees got old and died, leaving only invasive species.
    At the same time, we need to consider the ecological impact of holding all of that water and sediment on the land behind the dam. Most sacred sites are also ecologically significant, so what will be the impact of gradually filling that place with sand?
    We need to take the long view, and not fall back into short-term “Buffel Grass Thinking.”
    Free-flowing rivers are an endangered species worldwide. We humans have many more options than do our plant, fish and insect relatives. (Those options include a much less expensive emergency plan for flood plain residents, which I certainly had in my years as a South Terrace business manager!)
    And finally, degradation of the Todd will affect future generations’ wellbeing. How many of us are joyful when we see our relatively healthy river, especially when it floods? The Todd River is a sacred site for Arrernte … and for many more of us.

    View Comment
  4. Gender Balance
    Posted March 3, 2016 at 9:11 pm

    Funny, all men talking about destroying a women’s sacred site.

    View Comment
  5. Penangke
    Posted March 3, 2016 at 9:10 pm

    Lowering the causeways to improve flow is a good idea. Using the natural retardation basins like Coolibah Swamp is a good idea.

    View Comment
  6. Peter Driscoll
    Posted February 29, 2016 at 7:00 pm

    Let’s hope we get a flood levee in place before we need to turn it on.
    Small business is already struggling in Alice.
    This is a preventable disaster. Thanks the Alice Springs News Online for keeping this story on the front page, for Alice Springs’ sake!

    View Comment
  7. Hal Duell
    Posted February 29, 2016 at 2:17 pm

    @ Penangke, Posted February 29, 2016 at 2:02 pm: If we get rid of the drains and causeways, urban Alice Springs as we now know it would become uninhabitable. Is that your agenda?
    A bridge replacing the Taffy Pick causeway is a good idea.
    Keeping the Todd River’s floor where it flows through the Gap clear to the depth of the entry from Chinaman’s Creek is a good idea.
    A mitigation dam upstream from the Telegraph Station is a good idea.
    A recreation dam anywhere in Alice is not a good idea.
    Doing away with the drains and causeways is not just not a good idea, it is a bad idea.

    View Comment
  8. Penangke
    Posted February 29, 2016 at 2:02 pm

    Water from the east side of town used to flow into a natural retardation zone called ankerre ankerre coolibah swamp
    Now it flows straight into the river adding to the probability of flooding.
    Yes uncle, get rid of the drains and causeways. Let it mitigate itself.

    View Comment
  9. Ian Sharp
    Posted February 29, 2016 at 1:26 pm

    “Cleaning” the river useless against a big flood. A 1:100 plus flood would scour the bed all by itself, no assistance required from us, as well as ripping a channel through to the coolabah swamp and flooding that to depth of at least 3 metres.
    As for it being “mythical” – a 1:100 flood is a certainty, we just don’t know when.
    And there is nothing magical about that 1:100 figure, it’s not an upper limit to the size of possible flood events, it was just selected as a reasonable design criteria for the proposed flood mitigation dam.
    It would be next to useless against a 1:200 year event.
    The only long term solution is to gradually shift the built up area off the flood plain.
    Or accept the risk and live with it as best we can. A 1:100 dam at Junction Waterhole would be very useful protection against the most common flood events.

    View Comment
  10. Sean
    Posted February 29, 2016 at 6:07 am

    This whole topic is just a diversion tactic by Giles and his so called Government to get Alice Springs talking away from the real issues of the town: Dead economy, crime and population decline.
    The focus should be on: Improving infrastructure, creating and developing trade apprenticeships, lobbying against handouts and sit down money and reinstating a decent first home buyers scheme.

    View Comment
  11. Mpetyane
    Posted February 28, 2016 at 7:47 pm

    Groundhog Day: Ditto Penangke, lives were lost over this ludicrous proposal the first time (and one of them was a child).
    Have we not invaded enough? Remove the causeways and storm water drains and let country mitigate itself the way it did forever.

    View Comment
  12. Fred the Phillestine
    Posted February 28, 2016 at 6:26 pm

    @ Charlie Carter: If the river was well maintained, there would be no need for flood insurance.
    But if you decide to live in flood prone area, that is your problem, we do have choices.
    No insurance company is going to carry that risk without a premium.
    The indigenous people I have spoken to want the river cleaned.

    View Comment
  13. Charlie Carter
    Posted February 28, 2016 at 1:53 pm

    @ 1: Fred read post 5. TIO was and could still have been used as a public policy instrument, and still balanced the books.

    View Comment
  14. Fred the Philistine
    Posted February 28, 2016 at 6:46 am

    @ Bob Durnan: I agree, it is time that the talk to the traditional owners and their thoughts.
    Cleaning out the river by bulldozing the saplings out and making sure the river flows properly would be a start and get rid of some of the causeways. They are building up with sand.
    As for the insurance premiums being high, town planning, should be more responsible. Insurance companies are there to make money!

    View Comment
  15. Jocelyn Davies
    Posted February 28, 2016 at 6:36 am

    Love the gender balance in the committee!

    View Comment
  16. R Henry
    Posted February 27, 2016 at 3:42 pm

    What I would really like to know is when will this mythical 100 year flood happen.

    View Comment
  17. Charlie Carter
    Posted February 27, 2016 at 1:27 pm

    G’Day Ian Sharp,
    To answer your question, no, not really.
    The Giles Government in its stupidity sold off TIO, and my house insurance premium has more than doubled because I am in the 1/100 flood area.
    Thus, the most cost effective flood mitigation measure (much better than a dam) as identified by the Floodplain Management Plan (1996) has been destroyed.
    The concept of across-the-board flood insurance cover is actuarially efficient (I am told) because if people don’t have flood insurance the “flood relief” provided by the various relief bodies comes from the taxpayer in the long run.
    It is paying for the flood damage in advance.
    Of course Giles assured us that flood insurance would not change and everything would be “more efficient”. Ha bloody ha.

    View Comment
  18. Charlie Carter
    Posted February 27, 2016 at 1:09 pm

    The following is an extract from a longer letter I wrote in 2012, when the issues were again in the news.
    The Alice Springs Flood Plain management plan (1996) is the primary document in this issue. I was a member of a Steering / Advisory Committee that oversaw the development of this plan.
    The plan looks at the effect of the causeways, and concludes that the “bed-level” causeways (Schwarz and Tuncks) have no effect on the river flow.
    The obvious conclusion from this is that these causeways are on the “natural” bed level. It also follows from this that deepening the river bed by sand removal would do nothing for the river flow capacity unless the causeways were also removed and deepened, or replaced by bridges. Even if this were done, the sand would settle to its natural level after he next flow, and cover the below “bed level” causeways.
    My information comes from The Alice Springs Flood Plain Management Plan 1996. It is available in the Alice Collection in the Library.

    View Comment
  19. Damn it
    Posted February 27, 2016 at 12:35 pm

    What is the role the causeways play in slowing the flow of water? Anyone who has floated down on a lilo will know that the river slows before the causeways and picks up speed after.
    When you drive across you can see the river bed is several feet lower on the south side than the north. The causeways appear to be damming up the sediment and impeding the flow of water thus increasing the likelihood of a flood.
    Surely an important option would be to lower the causeways (cheaper) or build bridges (expensive) allowing the sediment to wash thru and so deepening the river. Seems pretty obvious.

    View Comment
  20. Penangke
    Posted February 27, 2016 at 12:05 pm

    Is Lhere Artepe the right place to go Bob, when they themselves seem happy to bypass the senior custodians and make decisions without consulting?
    There are a lot of people connected to Lhere Artepe but there are only a few people who have the right to speak for country for Mparntwe.
    Do they get consulted? Do they get the final say? Are the rights of apmereke-artweye and kwetungurle respected by Lhere Artepe?

    View Comment
  21. Bob Durnan
    Posted February 26, 2016 at 9:51 pm

    The flood mitigation studies in the late 80s and early 90s at times included more options, such as some smaller “dry dam” walls arrayed at less problematic points on the streams that fed into the Todd before the Junction site and Charles Creek.
    One small point: the Werlatye-Therre site, which was the first location proposed for a recreation dam, in the late 70s and early 80s, is further downstream than the Junction site.

    View Comment
  22. Bob Durnan
    Posted February 26, 2016 at 9:38 pm

    A good starting point would be to begin with respect, and seek advice from the senior traditional owners and custodians, through the Lhere Artepe Aboriginal Corporation, about their views and suggestions.

    View Comment
  23. Ian Sharp
    Posted February 26, 2016 at 8:05 pm

    A dam at Junction Waterhole would have some merit as a flood mitigation measure. But as we saw in 91-2 it is unlikely to get the nod from the TOs unless it is purely for flood mitigation, not a recreation lake in disguise.
    That dam was designed to mitigate a 1:100 flood event, which is pretty big, but as Rod Cramer points out Nature doesn’t always limit itself to our designs. The Todd inland delta floodout sand sheets near the airport indicate that there have been much bigger flows over the centuries … but you can’t build a dam for 1:1000 flood.
    Perhaps at some point in the future our town will suffer huge flood damage, despite our best efforts now. Locating the town centre on the flood plain was a good idea in the 1890s, to access the water table with shallow wells, but we are stuck with it now. TIO still offering flood insurance to those on the flood plain?

    View Comment

Post a Comment

Your email is never shared. Required fields are marked *

*
*