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Coefficients de marée

 
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Tic
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PostPosted: 23.09.17 08:36    Post subject: Coefficients de marée Reply with quote
bonjour,


J ai une question bete!


J ai lu récemment sur un forum US, que certains avaient un lecture des coef particuliere.


J entends par la qu il interpretent cela de telle maniere que l important est d avoir un un gros coef en montante.


Dans mon esprit, il etait plus interressant d avoir un gros coef en descendante afin que cela decaisse un maximum de sable sur l estran...


Quel est votre point de vue sur le sujet?


Bonne journée 
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Nony
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PostPosted: 23.09.17 10:44    Post subject: Coefficients de marée Reply with quote
Salut,


Le coefficient reste le même, je vois pas vraiment ce qu'ils veulent dire. Il ne va pas être de 80 au montant et 40 au descendant !?
Perso je ne cours pas après un coefficient trop important mais plutôt de bonnes vagues, le bon vent et surtout pas de banc de sable de protection, sinon la houle ne rentrera pas détruire la plage.


L'idéal c'est que cela décaisse en bas mais pas en haut de plage, que la cuvette se fasse en bas et qu'une pente se forme. Enfin c'est l'idéal chez moi.
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Mike14
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PostPosted: 23.09.17 15:07    Post subject: Coefficients de marée Reply with quote
Hello quand ça monte haut, ça peut taper sur le zone ou se tiennent les touristes et creuser ou étaler les pertes. C'est ce qu'ils veulent dire.
Ensuite ça se retire loin et on peut aller la ou on sait.
A+++


Mika
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PostPosted: 23.09.17 15:46    Post subject: Coefficients de marée Reply with quote
Hello,
Beaucoup d articles sur la morphologie des plages existes sur ce forum quand tu aura le nombre de postes necessaire.En voila un qui donne toute l explication technique,ecrit par Alan Hassel en 1998:

"Understanding waves and how they work will give you clues where any objects on the beach might be carried or deposited. First it is generally accepted that waves are generated by the action of wind. It is the duration or frequency of the wave that determines whether a wave is either destructive or constructive.

When a wave breaks, the motion of its water instantly becomes turbulent, like that of a swift river. This broken water is known as surf. In turbulent surf, Each Wave finally washes up on a sloping beach until its energy is expended. This action of a wave racing up the beach is known as swash; when the swash drains back down the beach, it is called backwash. This returning water is mainly responsible for currents known to swimmers as undertow.

Most of the year, the swash is more powerful than the backwash because the wave is allowed to run it full course. When waves break at a rate of ten or less per minute, each wave can complete its natural action without interference from waves running behind. These waves are known as constructive waves.

They bring ashore material known as the load, which is deposited onto the beach. When a wave breaks with a frequency of more than fifteen a minute, the backwash runs into the swash of the wave behind. The force of the swash is reduced in strength and it is these waves that remove sand and pebbles from the beach.

This action is known as grading. These waves are known as destructive waves. During this grading process, coins and jewellery are sometimes left high and dry exposed for the eyes only beachcomber. Those of you who have not experienced this grading process may find it hard to believe.

Experienced beachcombers can tell of glory holes containing numerous coins exposed by this grading process. There is also another vital phenomenon known as long shore drift that you should understand to be successful yourself. When waves break onto the beach at an angle, the swash will also travel in the same direction.

However the backwash will run back at a right angle to the shore. When this happens materials such as coins are slowly carried along the coastline. During the summer months, materials bought ashore by constructive waves are graded and carried along the coast by the long shore drift.

This explains why in certain areas of beach one encounters sand piled up against backwaters and other man made constructions. Here too is a great place for finding modern coins, although obviously older coins will be buried beyond the reach of the metal detector. In cases such as this, it can sometimes pay to scoop and sieve the sand manually without using a detector. It is done quite a bit in the UK especially where groynes have been placed.

With a little thought and imagination you can turn a bad day into a better productive day. There's more to beach combing than you would imagine, once you start thinking about it. If sea walls have been made from individual stones, you should search for jewellery in the lowest part.

Quite often a ring may lodge between the crevices; once it's in the cracks its almost impossible for it to get out. Anyone can find the occasional coin every twenty metres or so, getting to know your beach and some of the things that go on when nature does its work will only enhance your chances and good fortune. For those interested in obtaining further good advice I suggest you read 'COASTS' and introduction to Coastal geomorphology by

Eric C.F.Bird published by Australian National University Press"

Ce que tu as lu est sans doute le coefficient de vagues par minutes qui est mentione dans cet article.
Va aussi voir magicseaweed dans le coin que tu veux detecter.

https://www.facebook.com/magicseaweed/
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Funam34
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PostPosted: 24.09.17 01:49    Post subject: Coefficients de marée Reply with quote
Intéressant tout ça ! Merci PY
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Tic
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PostPosted: 24.09.17 09:46    Post subject: Coefficients de marée Reply with quote
Wahou!

Merci PY! Ca a éclairé ma panterne. Je comprends bcp mieux l impact des coefficient. Et surtout l actuon mecanique!
Genial, je vais etudier tout ca.
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Raymond de Lyon
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PostPosted: 24.09.17 17:53    Post subject: Coefficients de marée Reply with quote
Bonjour @ tous,
Je ne sais pas si c'est une coïncidence, mais j'ai tendance à trouver plus et de plus belles choses aux coefficients montants et j'ai plutôt l'impression de trouver moins aux descendants...
J'ai aussi remarqué que quand les vagues ont creusé la plage, quand il y a une "marche" entre le sec et le mouillé,  le nombre de trouvailles augmente de façon considérable.
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Pierre-Yves
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PostPosted: 24.09.17 18:55    Post subject: Coefficients de marée Reply with quote
Hello,
Voila un resultat d erosion qui na rien a voir avec le coefficient de la maree.En suivant les indications de l article et celles de Magic seaweed les effets de mer etaient les suivants:
Vent fort du nord -est pendant 3 jours.
houle de 3 a 4 metres parallele a la plage.
vagues destructives toutes les 16 secondes




Voila un exemple de magicseaweed mais pourla date d aujourdhui.

http://magicseaweed.com/Fire-Island-Surf-Report/380/
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Tic
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PostPosted: 26.09.17 08:20    Post subject: Coefficients de marée Reply with quote
Je vois tout a fait! Il y avait une grande casssure comme celle smci cet ete sur la plage se moliets.
C est d ailleurs ce soir la que j ai fait le plus grand nombre de découverte!  CQFD
Merci PY!
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PostPosted: Today at 12:32    Post subject: Coefficients de marée
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