Guest essay by Eric Worrall

Through causing panic by telling everyone climate change is making floods worse, Michael Man may have inadvertently triggered the destruction of hundreds of square miles of pristine protected NSW wilderness.

When the levee breaks

Some say the Warragamba Dam wall needs to be raised to help prevent the devastating floods seen in Sydney this week — but there is a cost upstream too.

By Michael Slezak and Penny Timms
Updated 27 Mar 2021, 9:44am
Published 27 Mar 2021, 4:53am

Almost 150 years ago, a torrent of water poured out of the Blue Mountains and filled western Sydney like a bathtub. 

Floodwaters rose to nearly 20 metres in some areas, with the high-water line still marked at some parts.

This week was one of the worst ever seen.

Almost 100 years later the Warragamba Dam was built. 

It was never intended to be a flood mitigation dam. Its purpose to provide 80 per cent of Sydney’s drinking supply.

When not full, it can mitigate floods by catching some of the rainwater that would otherwise flow into parts of western Sydney.

So the NSW government is charging ahead with a radical plan — an idea which, in some form or another, dates back at least to the 1990s — to raise the wall of the dam bybetween 14 and 17 metres.

It says the move will protect lives and property and would haveslowed the peak of the floods this week, likely saving some homes and businesses. Some experts disagree.

But to protect those living on the floodplain there is a cost upstream.

With a higher dam wall, thousands of hectares of unique World Heritage bushland will be flooded, and according to government documents obtained by the ABC much of that will be severely damaged. 

Read more: https://www.abc.net.au/news/2021-03-27/warragamba-dam-raising-to-save-flooding-cost-others/13226472

I don’t know if a higher wall on the dam will help prevent floods. More likely dam managers will use the greater capacity to improve the stability and resilience of Sydney’s stretched water supply. But it was absurd for greens like Michael Mann to think that all their rhetoric about climate change and flooding would not have consequences.

Normal people act to address perceived threats, and most people would prefer to protect their homes from flooding, even if that means destroying a few hundred square miles of protected wilderness.

via Watts Up With That?

2021March27