Fairfax Media Network

Weather News

The story behind Adelaide's unique dodge tides

Brett Williamson, Friday February 17, 2017 - 14:00 EDT
ABC image
Dodge tides are only experienced in a few locations around the world, including Adelaide. - ABC

Dodge tides are a well-known phenomenon among Adelaide's ocean lovers but reportedly happen in only a few other places around the world.

The term dodge tide dates back to when Matthew Flinders first mapped the coast of South Australia, according to James Chittleborough of the National Tidal Unit at the Bureau of Meteorology.

It refers to tides with little or no height variance.

"[Flinders] noticed the tides missed the usual timing several times a year and coined that the tide was dodging," Mr Chittleborough told Afternoons.

He said the phenomena was only reported as happening in one other place in the world, the Gulf of Mexico, and possibly at a gulf near Nova Scotia and in the Gulf of Carpentaria.

Mr Chittleborough said dodge tides were different to neap tides, when water movements were at their smallest change.

"Tides are essentially driven by the Moon and the Sun, with the Moon having twice of the effect of the Sun.

"In a few places in the world, due to the symmetry of the oceans and how the tidal waves respond, the effects of the Sun and Moon are about equal.

"The effects actually cancel each other out so that we get no tidal movement whatsoever for a day or two.

"It's quite a unique phenomenon.



"Other places have what we call a spring neap cycle, but in Adelaide the neap tides are quite weak and several times a year the tide [movement] almost disappears."

Mr Chittleborough said other locations around the world had similar water height changes as a dodge tide but their natural variations were not as high as in the Gulf St Vincent.

"In Adelaide, we have quite substantial tides of several metres [normally]," he said.

"Normally we are used to [around] two metres of tide going up and down each day.

"It's quite noticeable here and has effects on shipping and so forth."


- ABC

© ABC 2017

More breaking news

Sydney Morning Herald
ABC News
National Nine News
News Limited

Display Your Local Weather

Weather News

Severe and 'unusual' summer weather forces cancellation of music and Christmas events

22:38 EDT

Major Perth events, including Carols by Candlelight and A Day on the Green, have been cancelled as a severe and unseasonal storm approaches the city.

A week of two halves for Tasmania

16:29 EDT

It will be one of those weeks where Tasmanians will need sunnies and a hat, followed by a jumper and umbrella.

Extreme heatwave heads to outback towns in Queensland, NSW

11:37 EDT

There will be extreme heatwave conditions in south-west Queensland and north-west New South Wales over the next three days, the Bureau of Meteorology (BOM) says, with several outback towns expecting sweltering daytime temperatures of at least 43 degrees Celsius.