The Hawkesbury Floods, March 2021

Some times it must feel like our community can't cop a trick. Devastating fires, pandemic and two floods, all within a 16 month period.

Yet again, out of the distress and destruction of property has arisen the real spirit of our local community, which has rallied magnificently. The response of our SES, Police and RFS have been truly heroic, and they deserve our respect, as do those who just help because it's the right thing to do. Neighbours help neighbours. It's the Hawkesbury way.

I tried to document the effects of and responses to flooding by visiting as many places and people as I could. These videos have apparently reached over 111,000 people on social media.

Since the waters have receded, I've been honoured to be present variously at the visits of the Governor General David Hurley, The Premier Gladys Berejiklian, Deputy Premier John Barilaro and Minister for Roads Andrew Constance.

It has also brought the need to raise Warragamba Dam back into focus.

The plan to raise the dam is about the safety of the community – the 134,000 people who live and trade on the Hawkesbury-Nepean floodplain. It isn't about development, or Sydney's drinking water supply. Nor should the debate be unduly focused on the temporary inundation of uninhabited bushland around lake Burragorang, for a week or two, once or twice a century.

The Resilient Valley, Resilient Community flood risk study released in 2017 explains 75% of our flood risk comes from the Warragamba catchment. It also points out that raising the dam would reduce the severity or frequency of bad floods by the same proportion – 75%.

Floods have already been averted or reduced by Warragamba, under certain circumstances. Severe rain events that began at the time of the early 1990s flood, when the dam was depleted to about 46% capacity, lowered the subsequent level of waters of on the floodplain by over three meters. This is the kind of 'accidental' mitigation that needs to be built into the dam permanently.

It really disappoints me that some of the commentary from people opposed to the project is so dishonest. This recent article in the Blue Mountains Gazette, and the comments of ex-Minister Bob Debus should anger everyone at risk of flooding, especially because he, like other opponents of the dam raising are usually high and dry and out of harms way. Our community in the Hawkesbury bears the brunt of this risk. I've pointed this out on many occasions.

Over the last fortnight I have stood with many people who have lost their homes and possessions because of Mr Debus' inaction in the 1990s, when there was a plan to raise the dam by 23m. The Labor government's decision not to treat this as a bipartisan issue and scotch those plans, which were shovel ready when Bob Carr was elected in 1995, is partly responsible for the damage this flood has caused.

Mr Debus says raising the dam won't prevent all floods. But wearing a seatbelt won't prevent all car accident fatalities. Backburning won't save every house in a bushfire. But only an idiot would argue against doing what we can.

Imagine if the present floods had been 3 meters lower as a result of being able to hold back 1000 gigalitres of that water for long enough to allow them to drain away.

When Mr Debus only notes the quarter of floods that result from rain in other tributaries, he's misleading you. And he's wrong to state that permanently lowering the dam levels by 10m is the same as raising them by 10m, because of the tapered shape of the dam. The bottom 2cm of a wine glass holds much less than the top 2cm.

And pre-emptively reducing water levels in the dam, which every armchair expert has advocated over the last fortnight would (literally) be a drop in the ocean.

The topical unit is the 'SydHarb' - A Sydney Harbour's worth of water, or about 500 gigalitres. Warragamba can hold 4 Sydharbs, and the dam raising project will add another 2. I was talking about this a decade ago. Lowering the dam to levels that would imperil Sydney's drinking water supply to create a buffer would have taken weeks, and would account for maybe 0.2-0.5 Sydharbs.

In comparison, the inflow of water resulted in a Sydharb *per day* topping the dam for 2-3 days. If we could have absorbed two days of that inflow and let it out over a week or fortnight, many of the grieving people who have lost their homes, goods or livelihoods would have been spared.

Lastly, Bob raises the debunked-a-thousand-times canard of development on the floodplain. The 1:100 flood height buildong controls will not change. Not a single square meter of land which is presently sterilised by these controls would be opened up for building in the event of raising Warragamba. And the only time any flood has exceeded the 1:100 level in the last 222 years was in 1867, showing this is a reasonable safety measure. The sad fact is that the 5,500 houses built below the 1:100 level were built before those flood height controls were implemented.

Damn you, Bob Debus, for your reckless conduct as a Minister - when you actually had a chance to do something about this, you sat on your hands.

I spoke to the media on several occasions to represent our at-risk community

Print stories: Central News (18-11-2020), ABC (27-3-2021), AAP (23-3-2021), and TV as below:

It concerns me that in each of these cases, the voice of the community at most risk is not emphasised in balancing the costs and benefits of flood mitigation.

An excellent book I have at home on the history of the construction of Warragamba Dam in the 1950s is subtitled "Thank God there were no greenies." I worry that an inability to soberly judge the necessity of flood mitigation will eventually cost lives, when a flood bigger than this one finally comes.

Nature has given us a warning. Are we wise enough to heed it?

 

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by Clr. Nathan Zamprogno