Pororoca

The voice pororoca is an onomatopoeia from the Tupi-Guarani language pororó-ká, which means "great roar", and is used to designate a phenomenon similar to what is known as bore in the delta of the Orinoco river, which manifests itself as a kind of noisy waves that travel the great rivers of the north of the country, especially the Amazon river, from its mouth for tens of kilometers. It is a much more powerful phenomenon than the one that occurs in the Orinoco delta, due to the difference in flow between the two rivers.

Dynamics of the phenomenon

It is produced by the action of the tides when the marine waters penetrate the fluvial waters during the high tide or flow. The pororoca is more intense when the width of the river narrows, so that the oceanic waters of the Atlantic can penetrate more easily and with greater speed and length in the channels of the delta of this river, which gives rise to a true flood that fills saltwater many riparian areas.

Even the youngest children are taught in schools how devastating this phenomenon can be. This natural phenomenon has been mythologized as a killer or monster that floods the lowlands of the shores with salt water. Its sound, up to half an hour before arriving, is that of an intense and continuous wave.

Causes and characteristics

The fact that this swell lasts so long to advance is a consequence of the enormous flow of the Amazon River: the waters of this river (more than 100,000 cubic meters per second) cause the seawater to break, forming waves on them, but these waves they get very close to each other due to the lower displacement of the fluvial waters in the opposite direction, which translates into a strong opposition between the two, an opposition that is the cause of the noise. For this natural phenomenon to occur, several factors must concur: the phases of the full moon or new moon, which give way to the rise of the most intense tides (syzygy tides, which are those that occur when the three stars are that is, the Earth, the Moon and the Sun are aligned), the marine currents and the opposition of the ocean on the river.

The successive waves of brown color, which go tens of kilometers upstream and sometimes reach up to four meters in height in some narrow and enclosed points on the banks and in the very central part of the channel (where the speed of the waves fluvial waters is greater), they form with some frequency throughout the year, although the occurrence of exceptionally "spring" or intense is much less frequent. The maximum height of the wave is reached at the moment of breaking when the upper sea waters accumulate on the fluvial ones that slow them down below.

Consequences

The riverside inhabitants are usually prepared to try to minimize the undesirable effects of the phenomenon, although it also has positive effects, since due to this fight between the river and the ocean, fishing on the riverbanks is much more important, with species both marine as fluvial.

One of the detrimental effects is the temporary flooding with salt water in some marshes on both sides of the channels in this atypical Amazon delta, although this is unavoidable and which also has positive effects, since many species of fish can take advantage of these hydraulic mechanisms for their reproduction and growth processes. It could also have detrimental effects by flooding cultivated land, but this should not be attributed to the phenomenon itself, but rather to the agricultural use of those potentially floodable areas. The problem is due to the fact that not all the most intense tides always break the channel in the same places, which can give rise to farmers planting in areas that they believe are safer but are not. And this delta is somewhat atypical, for the same reasons that the Orinoco delta is: the mouth of the Amazon is more of an estuary, with the large island of Marajó at its mouth and some smaller islands, similar to the southern part of the Orinoco delta, as explained in the article on the bore phenomenon.

The phenomenon has been used by surfers who come from all over the world to ride these waves when they enter the river: they are not very high, but they can penetrate one of them and rise upstream from the mouth for almost one hour. hour. So it is not a surfing record in terms of the height of the waves, but in terms of duration on a single wave. The first world record for duration on a surfboard (a very light special "longboard") was obtained in the Amazon in 1999 by Picuruta Salazar, a 43-year-old Brazilian surfer at the time, with more than average hour long on the breaking wave. This record was subsequently broken.

In 2009 Eugenio and Sebastián "Culini" Weinbaum known in Latin America for their program MDQ Para todo el Mundo They were the first Argentines to surf the Pororoca. All this feat was broadcast in the cycle of that same year with a program lasting almost an hour completely dedicated to this natural phenomenon.

Similar terms in other languages

In French there is the term 'mascaret' where the term macareo comes from -rising tide in the form of a wave(s) that goes up(n) a river-, which derives from the Gascony word 'masquaret' which means 'galloping ox' (Little Robert, 1996). In Japanese there is the term 'shio-tsunami', and a tsunami-induced bore is known as 'kaisho'. or just 'tsunami' (seaquake). In China, the 'Silver Dragon' is the name of the bore of the Qiantang River. Other local tidal names include 'le montant'; (Garonne river, France/Spain), 'la barre' (Seine River, France), 'le mascarin' (river Vilaine, France) and the 'donkey' (from Colorado River, Mexico/United States).