現在是夏天，每個人都在瀑布裡游泳，我開始看到一連串的留言警告，警告人們不要在瀑布中形成隱藏的，看不見的水流下游泳。這是一個非常常見的留言，用來嚇唬沒有經驗的游泳者或不熟悉瀑布的人，以免他們掉入水中。它常出現在FB和YT的留言中，並在新聞文章中發表，甚至溯溪教練有時也會重複（即使他們知道這是錯誤的）。在每個深瀑布池中，水下的水流比表面的流得慢。
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這是深水池的物理屬性，沒有例外。頂部放快水，底部放慢水。發生這種情況是因為水在水池的頂部進入和流出，所以水流在整個表面上做移動，而且還因為更深的水與其他水分子和水池底部之間的摩擦更大，從而減慢了水的速度（動能為轉化為熱量）。告訴人們深水池中存在隱性水流，這不僅不準確，而且很危險。
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向人們提供有關安全的虛假信息是危險的。試圖通過散佈煽動性的恐懼心理來恐嚇某人遠離水域，這只會適得其反。如果您了解水流的工作原理，那麼您應該在教這些知識，而不是虛構知識。
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知道不是看不見的水下水流非常重要，原因有兩個：
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1）當水流過大而您不能逆流游泳時，最好的措施是在水底下游泳。沒錯！您可以簡單地更深入地潛水並在水流底下游泳，而完全避開它。在下面的影片中，表面水流過強而無法游泳抵抗。在水底下游泳卻很容易。在1-2公尺深處，水幾乎沒有移動。 （觀看我們輕鬆逆流游泳）
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2）告訴人們水下存在看不見的水流，而忽略了表面上存在非常可見且可預測的水流這一事實。只要通過查看水池，我們就可以對水池的流體動力學有很多了解。通過視覺觀察，我們可以輕鬆地看到流動的速度和方向。如果要使水流方向更清晰，也可以拋出棍子或樹葉之類的物體。
因此，你無法看到水中有什麼時，請不要告訴別人那裡很危險。這不是事實。您只需看一下就可以看到發生了什麼。在您看到它之後，它不再是未知的危險。一旦知道了，您就可以進行研究並製定相應的計劃。水流可能會成為繞行的障礙，或者是幫助您到達目的地的工具。這不是一個令人恐懼的隱藏妖怪惡靈，而是河中自然而可預測的一部分。知道自己的極限，學習如何閱讀河流，並做好相應的準備。這樣，您每次都會安全。教育永遠比嚇阻來的有效！
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EDIT:一些評論認為這對不懂游泳的人沒有幫助。 這是不正確的。 如果您不知道如何游泳，那麼此信息對您而言甚至更為重要。 因為您需要潛水才能在強流下游泳，所以這意味著，如果您穿著救生衣，將會被卡住而無法返回。 這意味著，如果您不會潛水或不會游泳，那麼在這種情況下您不應入水。 即使有救生衣。 知識總是使您更安全。Some comments suggest this is not helpful for people that don't know how to swim. This is incorrect. If you don't know how to swim, this information is even more important for you. Because you need to dive to swim against a strong current, it means that if you are wearing a life jacket, you will be stuck and unable to return. What this means is that if you can't dive, or can't swim, you should not go in the water in that situation. Even with a life jacket. Knowledge always makes you safer.
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Wutan Waterfal (Dongxi Waterfall)
Pingtung County, Taiwu Township
武潭瀑布 (東西瀑布)
屏東縣泰武鄉
Waterfall and Parking: 22.585093, 120.641308
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Now that it's summer and everyone is out swimming in waterfalls, I'm starting to see a string of comments warning people against hidden, unseen underwater currents that can form in waterfalls. It's a very common phrase which is used to scare away inexperienced swimmers or people unfamiliar with waterfalls, so that they don't go in the water. It shows up in comments all over FB and YT, it's published in news articles, and even river tracing coaches repeat it sometimes (even though they know it's false). In every single deep waterfall pool, the current is slower under the water than it is on the surface.
This is the physical property of a deep pool, there are no exceptions to it. Fast water on top, slow water on the bottom. This happens because water is entering and exiting at the top of the pool, so the flow is moving across the surface, and also because deeper water has more friction against other water molecules and the pool bottom, which slows down the water (kinetic energy is converted to heat). Telling people that there are hidden currents in deep pools is not only inaccurate, but it's also dangerous.
Giving people false information regarding safety is dangerous. Trying to scare someone into staying out of the water by spreading sensationalist fear-mongering is counter productive. If you have knowledge about how currents work, you should be teaching that knowledge instead of making stuff up.
It's so important to know that aren't invisible underwater currents for two reasons:
1) When the current is too strong, and you can't swim against it, the best action to take is to swim under it. That's right. You can simply dive deeper and swim under the current, avoiding it entirely. In the video below the surface current is too powerful to swim against. It's very easy to swim under. At 1-2 meters depth, the water is practically unmoving. (Watch Nicky swim directly against the current with ease)
2) Telling people that there are invisible currents underwater ignores the fact that there are very visible and predictable currents on the surface. We can understand a lot about the fluid dynamics of a pool just by looking at it. We can easily see the speed and direction of the flow by visual observation. Objects such as sticks or leaves can also be thrown if to make it more clear.
So stop telling people that there is a danger you can't see in the water. It's not true. You can see what happens just by looking at it. And after you see it, it's not an unknown danger anymore. Once it's known to you, you can study it and plan accordingly. The current can be an obstacle to get around, or a tool to help you get where you are going. It's not a hidden boogie man to be feared, but a natural and predictable part of the river. Know your limits and learn how to read the river, and prepare accordingly. Then you will be safe, every single time.
water property 在 Properties of water - Wikipedia 的相關結果
This unique property of water is due to hydrogen bonding. The molecules of water are constantly moving concerning each other, and the hydrogen bonds are ... ... <看更多>