Papua New Guinea
Australia
• Fly (1)
• Aramia (2)
• Daly (3)
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Australasia
Papua New Guinea
Australia
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There are three main locations in Australasia where tidal bores occur. Several of the rivers on the north to north-west coast of Australia have bores. The rivers drain into the Timor Sea where tides are macrotidal though several of these bores are observational only, and it is also possible that there are several more that have not been reported. There is also a section of the east coast in Queensland where tides on the coast of the Coral Sea are macrotidal and bores have also been observed here
Papua New Guinea's south-west coast experiences a couple of bores in the Gulf of Papua. The tides are only mesotidal but bores of upto two metres have been observed on large spring tides.
We have also heard of a bore occuring in New Zealand but have had nothing to confirm this.
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Similar to the bores occuring on the Malaysian side of Borneo island, the tidal range of the Gulf is only mesotidal (2-4m) and the tidal oscillation is mixed. These conditions are generally rare for effective bore occurance, the best example being the now extinct Colorado River in Mexico.
The bores occur on the largest spring tides and these can only be expected once a day. The bores are probably most effective in the months from May to October when rainfall is less, so the river's do not break their banks. It is also likely that the south-east trade winds that blow through these months greatly increase tidal surge and hence the size of the bores.
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The Fly river drains into the Gulf of Papua in the Coral Sea. It is the largest river in New Guinea at a length of 1300km and travels through Western Province.
With mixed tide oscillation the bore occurs only once a day and probably is most effective when the south-east trade winds blow a surge into the Gulf through the summer months. |
The bore has been observed from Domori Island to Strickland River at a maximum of two metres.
Sadly, the resourceful Ok Tedi mine in the province pumps a large amount of residue and pollutant into the river!
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The Aramia bore was documented way back in 1914 in a report on The Western Province by Beaver. Other records of the bore are purely observational. The river is located about 50km east of the Fly river and also drains into the Gulf of Papua. |
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Bores have also been observed in the Joseph Bonaparte Gulf though there are no statistical records for these. The most effective are likely to be the Ord which flows into the Cambridge Gulf and the Victoria which flows into the Queens Channel.
Due to the large tidal range around this coast, bores may also occur on the rivers draining into Collier Bay and King Sound further west, especially the Fitzroy, but there are no records to confirm these.
A bore has also been observed on the Styx in Central Queensland which drains into the Coral Sea.
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The Daly river has the largest bore documented in Australia. Located 100km south-east of Darwin in the Northern Territory the river drains itno the Timor Sea and at the mouth experiences macrotides in excess of six metres. The bore forms 30km from the mouth of the river where the river width is only 15m. Records show that the depth of the river here is upto 5m. As a result the head wave which reaches upto 1.5m will not break at all in the center of the river but probably maintains a trochoidal form throughout its course. |