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Brazil
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South America
Nearly all the documented bores in South America exist around the Amazon Basin in Brazil where macrotidal range is 4-6 meters. The only exception in Brazil is the Mearim located about 600km south near São Luís.
A bore has apparantly been observed on the Orinoco in Venezuala. However this seems very unlikely as the river drains into the Caribbean Sea where tide range is only microtidal (upto 2m).
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The Amazon Basin in Brazil is a major center for tidal-bores. A large number of the Basin's estauries and tributaries experience a bore on large spring tides. The Basin itself discharges more than 7 million square kilometres of water resulting in fresh water on the surface of the Atlantic upto 64km offshore!
The greatest volume of any tidal bore worldwide occurs at the mouth of the Amazon river on the Canal do Norte where the river is 16km wide.
The Amazon wave is known as the pororoca by the local people, meaning 'big roar'.
With around 48,280km of navigable waterways and located around the equator, the Basin is also home to a multitude of wildlife, including many dangerous species of snake, fish and crocodile! The whole concept of surfing the Amazon is a truly unique and formidable thought!
The only other recorded bore in Brazil is located on the Mearim about 650km south of the Basin, though this wave is considerably smaller than the pororoca's of the Amazon region.
The prevailing north-east trade winds and the Doldrums are likely to have a major affect on tidal surge through the monsoon months from November to April.
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The Moju is one of three major tributaries that flow into the vast Pará river, located south of Marajo Island - the largest marine fluvial island in the world.
Due to the dramatic change into tidal flow passing into the Moju from the Pará, the pororoca can form in the river more than 100km inland!
Boat cruises on the Pará and the tributaries can be organised in the town of Belem on the coast of Marajo Bay.
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The Mearim river has the only pororoca occuring outside the Amazon Basin. It is located about 600km west of the Basin near the town of São Luís (Maranhão).
The river drains directly into the Atlantic through a funnel shaped estuary.
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At the mouth of the Amazon, in the Canal do Norte, is the largest expanse of flowing water in the world where the estuary is upto 16km wide! The Amazon has numerous tributaries that flow into it on its course. Due to the variation in size between the main river and these, a bore wave can form on them - over 100km in land! On the Guajara tributary for example the pororoca can travel 150km in land. |
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The pororoca enters the Araguari estuary about 170km north-west of Macapa. However the topography of the Araguari delta extending into the Atlantic Ocean, the width of the Amazon Basin and the sheer volume of water that drains into the ocean (over 7 million sqkm) combine to cause a truly unique phenomenon. Upto 64km out to sea freshwater remains on the surface and this results in the formation of the pororoca as an undular wave upto 10km before the tide reaches the estuary mouth.
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As the wave travels into the river it spreads out over a width of about 2km (upto two thirds of the river's total width) and has been observed in the range 2 to 3 metres high.
Being relatively inaccessible by land, the wave is normally observed from the air, and a brief article was written in 1989 by Dr Ponce of San Diego State University. Probably not a surfable wave, but certainly a sight worth seeing!
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The Guamá flows into the vast Pará River south of Marajo Island. It was near the cofluence of the Guamá and Capim Rivers that the German explorer Martius sighted a 4.5 meter high bore spreading across the whole river! São Domingos do Capim at the Guamá River seems to have become the most popular spot for attempts at surfing and kayaking the pororoca. A wave ski/kayak competition, Pororoca Challenge, was held here for duration on the wave. The longest time was by kayaker Daniel Loreiro who rode for nearly four and a half minutes.
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In April 1998 a couple of Brazilian surfers rode the wave on shortboards - the first time it had been surfed. Potentially the wave may be surfable for upto an hour! Could put a whole new outlook on distance surfing considering the wave travels at upto 30mph.