Why Engineers Can't Control Rivers - YouTube
发布时间 2023-04-03 16:00:00 来源
中英文字稿 
This is the old river control structure, a relatively innocuous complex of floodgates and levies off the Mississippi River in central Louisiana. It was built in the 1950s to solve a serious problem.
这是旧的河流控制结构，位于路易斯安那州中部的密西西比河附近，设有相对温和的防汛闸门和堤坝。它建于1950年代，旨在解决一个严重的问题。
Typically rivers only converge. Tributaries combine and coalesce as they move downstream, but the Mississippi River is not a typical river. It actually has one place where it diverges into a second channel, a district named the Achafalia.
通常情况下，河流只会汇聚，支流会随着流向下游合并。但密西西比河不是一条典型的河流。它实际上有一个分流成第二条河道的地方，那就是被称为阿夏法利亚的区域。
And in the early 1950s, more and more water from the Mississippi River was flowing not downstream to New Orleans in the main channel, but instead cutting over and into this alternate channel. The Army Corps of Engineers knew that if they didn't act fast, a huge portion of America's most significant river might change its path entirely.
在20世纪50年代初，越来越多来自密西西比河的水不再流向主要河道的新奥尔良，而是流向这个替代河道。工程兵团知道如果他们不采取行动，美国最重要的河流的一部分可能会完全改变它的流向。
So they build the old river control structure, which is basically a dam between the Mississippi and Achafalia rivers with gates that control how much water flows into each channel on the way to the Gulf of Mexico. It was certainly an impressive feat and now millions of people and billions of economic dollars rely on the stability created by the project. The now static nature of the Mississippi River that once meandered widely across the landscape.
因此，他们建造了古老的河流控制结构，基本上是一座水坝，控制密西西比河和阿查法利亚河之间的水流，并通过门控制流入墨西哥湾途中每个通道的水量。这无疑是一项令人印象深刻的壮举，现在数百万人和数十亿经济美元依赖于该项目所创造的稳定性。曾经广泛纵横于土地上的密西西比河现在已变得静止。
That's why Dr. Jeff Masters called it America's Achilles heel and his excellent three-part blog on the structure. You see, the Achafalia River is both a shorter distance to the Gulf and steeper too. That means if the structure were to fail and it nearly did during a flood in 1973, a major portion of the mighty Mississippi would be completely diverted, grinding freight traffic to a halt, robbing New Orleans and other populated areas of their water supply, and likely creating an economic crisis that would make the Suez Canal obstruction seem like a drop in the bucket.
这就是为什么Jeff Masters博士称之为美国的“跟腱”并在其结构上写了一篇优秀的三部曲博客。你看，阿卡弗利亚河既离海湾更近，也更陡峭。这意味着如果这个结构出了问题(在1973年的洪水中它几乎崩溃)，整个强大的密西西比河流将会被完全改道，使货运交通陷入困境、剥夺新奥尔良和其他人口密集地区的水源，并可能造成经济危机，使苏伊士运河的阻塞问题变得微不足道。
Our Twain famously said that 10,000 river commissions with all the minds of the world at their back cannot tame that lawless stream, cannot curb it or confine it, cannot say to it, go here or go there and make it obey. And engineers have spent the better part of the last 140 years trying to prove them wrong.
我们的特温（Mark Twain）曾经说过，即使有10000个河流委员会集思广益，也无法驯服这个无法无天的河流，无法控制或限制它，也无法命令它去哪里或到哪里，让它服从。而工程师们在过去的140年中，一直试图证明这句话是错误的。
In my previous video on rivers, we talked about the natural processes that caused them to shift and meander over time. Now I want to show you some examples of where humans try to control Mother Nature's rivers and why those attempts often fail or at least cause some unanticipated consequences.
在我之前的河流视频中，我们谈论了导致它们随着时间变化移动和弯曲的自然过程。现在我想给你展示一些人类试图控制大自然河流的例子，以及为什么这些尝试常常失败或至少会导致一些意想不到的后果。
We teamed up with Mripper, maker of these awesome stream tables to show you how this works in real life and we're here on location at their headquarters. I'm Grady and this is Practical Engineering. On today's episode, we're talking about the intersection between engineering and rivers.
我们与Mripper合作，他们制造了这些令人惊叹的流水实验平台，向大家展示如何将其应用于现实生活。我们正在他们的总部现场报道。我是格雷迪，欢迎收看Practical Engineering。在今天的节目中，我们将讨论工程技术与河流的交汇处。
One of the most disruptive things that humans do to rivers is build dams across them, creating reservoirs that can be kept empty in anticipation of a flood or be used to store water for irrigation and municipal supplies. But rivers don't just move water. They move sediment as well.
人类对河流最具破坏性的事情之一是在河流上建造水坝，形成可在洪水来临前保持空置的水库，或用于储存灌溉和市政用水。但河流不仅运输水，还运输沉积物。
And just like an impoundment across a river stores water, it also becomes a reservoir for the silt sand and gravel that a river carries along. That's pretty easy to see in this flume model of a dam. Fast-loving water can carry more sediment, suspended in it than slow water. The flow of water rapidly slows as it enters the pool, allowing sediment to fall out of suspension.
就像一道河上的拦河坝储存水一样，它也成为河流带来的淤泥沙和砾石的储存池。在这个大坝水槽模型中，这点很容易看出来。快速流动的水可以携带更多的悬浮沉积物，较慢的水则不能。当水流快速进入池中时，它的流速迅速下降，沉积物就会从悬浮状态中落下。
Over time, the sediment in a reservoir builds and builds. This causes some major issues. First, the reservoir loses capacity over time as it fills up a silt sand, making it less useful. Next, water leaving on the other side of the dam, whether through a spillway or out of the works, is mostly sediment-free, giving it more capability to cause erosion to the channel downstream. But there's a third impact, maybe more important than the other two that happens well away from the reservoir itself. Can you guess what it is?
随着时间的推移，水库中的沉积物会越来越多。这会引起很多问题。首先，水库会因为填满淤泥和沙子而逐渐失去容量，变得不那么有用。其次，通过坝另一侧流走的水，不论是通过泄洪道还是工程设施流出的水，大部分都是没有沉积物的，使得它具有更好的能力来引起下游河道的侵蚀。但是第三个影响，也许比前两个更重要，是远离水库本身的。你能猜到是什么吗？
In the previous video of this series, we talked about the framework that engineers and the scientists who study rivers called fluvial geomorphologists use to understand the relationship between the flow of water and sediment in rivers. This diagram, called Lane's Balance, simplifies the behavior of rivers into four parameters. Incident volume, sediment size, channel flow, and channel slope. You can see when we reduce the volume of sediment in a stream, like we would by building a dam, Lane's Balance tips out of equilibrium into an erosive condition.
在这个系列的之前的视频中，我们讨论了工程师和研究河流的地貌学家使用的框架，即被称为Lane平衡的图表，以理解水流和河流中沉积物的关系。该图表将河流的行为简化为四个参数：入射体积、沉积物大小、河道流量和河床坡度。我们可以看到，当我们减少河流中的沉积物体积，例如通过建造水坝，Lane平衡就会失去平衡而进入侵蚀状态。
In fact, according to Lane's Balance, anytime we change any of these four factors, it has a consequence on the rest of the river. As the other three factors adjust to bringing the stream back into equilibrium through erosion or deposition of sediments. And we humans make a lot of changes to rivers.
实际上，根据Lane平衡理论，我们改变了这四个因素中的任何一个，都会对河流的其他方面产生影响。因为其他三个因素会通过侵蚀或沉积物的沉积来调整，让河流重新恢复平衡。而我们人类对河流的改变很多。
We want them to stay in one place to allow for transportation and avoid encroaching unproperty. We want them to drain efficiently so we don't get floods. We want them to be straight so that the land on either side has a clean border. We want to cross over them with embankments, utilities, electrical lines, and bridges. We want to use them for power and for water supply. Oh, and rivers and streams also serve as critical habitats for wildlife that we both depend on and want to preserve.
我们希望河流和小溪能够停留在一个地方，以便于运输和避免超越私人财产的限制。我们希望它们能够有效地排水，以避免洪水的发生。我们希望它们能够保持直线，以便两侧的土地有着干净的边缘。我们希望能够通过堤防、公用事业、电力线路和桥梁来跨越它们。我们还希望利用它们来提供电力和水源。同时，河流和小溪还是关键的野生动物栖息地，我们既依赖它们，也想要保护它们。
All those goals are important and worthwhile, but as we'll see with the help of this awesome demonstration that can simulate river responses, they often come at a cost. And sometimes that cost is borne by someone or someplace much further upstream or downstream than from where the changes actually take place.
所有这些目标都是重要和值得的，但通过这个可以模拟河流反应的真棒演示，我们会发现它们经常会付出代价。有时候这个代价是由更上游或下游的某个人或某个地方承担，而不是实际变化发生的地方。
One of the classic examples of this is channel straightening. In cities we often disentangle streams to get water out faster, reduce the impacts of floods, and force the curvy lines of natural rivers to be neater so that we can make better use of valuable space. I can show it in the stream table by cutting a straight line that bypasses the river's natural meanders. The impact of straightening a river is a reduction in the channel's length, necessarily creating an increase in its slope.
其中一个经典的例子是河道矫直。在城市中，我们经常将河流分开以更快地排放水，减轻洪水影响，并强制自然河流的弯曲线条变得更加整齐，以便更好地利用宝贵的空间。我可以在示教河流模型中通过切割绕过河流的自然弯曲线条来展示这点。河道矫直的影响是河道长度的缩短，必然会导致其坡度增加。
Water flows faster in a steeper channel, making it more erosion. So the practical result of straightening a channel is that it scours and cuts down over time. It's easy to see the results in the model. This is compounded by the fact that cities have lots of impermeable surfaces that send greater volumes of runoff, industries, and rivers.
水在更陡峭的河道中流动速度更快，从而更具侵蚀性。因此，使河道变直的实际结果是随着时间的推移，它会冲刷和切割。在模型中很容易看到结果。这还受到城市有许多不透水表面导致更大的径流量，工业和河流的影响的影响。
That's why you often see channels covered in concrete and urban areas to protect against the erosion brought on by faster flows. And this works in the short term, but making channels straight, steep, and concrete covered ruins the stream or river as a habitat for fish, amphibians, birds, mammals, and plants. It also has the potential to exacerbate flooding down the stream because instead of flood waters being stored and released slowly from the floodplain, it all comes rushing as a torrent at once instead.
因此，你经常会看到水道被混凝土覆盖在城市地区，以保护免受更快流动带来的侵蚀的影响。这在短期内是有效的，但是将水道变直、陡峭、覆盖混凝土会破坏流域或河流作为鱼类、两栖动物、鸟类、哺乳动物和植物栖息地的生态系统。它还有可能加剧河道下游的洪水，因为洪水不再在洪泛平原上缓慢蓄积和释放，而是一次性地涌入。
And it's not just cities. Channels are straightened in rural areas too to reduce flooding impacts to crops and make fields more contiguous and easy to farm. But over the long term, channelizing streams reduces the influx of nutrients to the soils in the floodplain by reducing the frequency of a stream coming out of its banks, slowly making the farmland less productive.
这不仅仅发生在城市里。在农村地区，沟渠也会被整修，以减少洪水对农作物的影响，并使田地更连续和易于耕种。但从长远来看，河流整治减少了洪水频繁泛滥入土地中带来的养分，使农田逐渐变得不再那么肥沃。
Farm restoration is big business right now as we've begun to recognize these long-term impacts that straightening and deepening natural channels has and reap the consequences of the mistakes of yesterday. In the U.S. alone, communities and governments spend billions of dollars per year undoing the damage that channelization projects have caused.
农田复原现在是一个非常大的生意，因为我们已经开始认识到挖深自然水道对长期影响，并收获昨天错误的后果。仅在美国，社区和政府每年花费数十亿美元来消除河道整治项目带来的损害。
Even the most famous of the concrete channels, the Los Angeles River, is in the process of being restored to something more like its original state. The LA River ecosystem restoration project plans to improve 11 miles or 18 kilometers of the well-known concrete behemoth featured in popular films like Grease and Dark Knight Rises. The project will involve removing concrete structures to establish a soft bottom channel, day lighting streams that currently run in underground culverts, terracing banks with native plants and restoring the floodplain areas, giving the river space to overbank during floods.
就连最著名的混凝土河道——洛杉矶河也正在恢复到更接近原始状态的过程中。洛杉矶河生态系统的恢复项目计划改善这条著名的混凝土巨兽的11英里（18公里），这条河曾经在流行电影《油脂》和《黑暗骑士崛起》中被广泛使用。该项目将涉及拆除混凝土结构，建立软底水道，照明目前在地下下水道中流动的水流，用本土植物修整河岸阶地，还原洪水平原区域，给予河流在洪水期间更大的空间。
Thanks to fluvial geomorphologists, projects like this are happening all around the world. But straightening channels isn't the only way humans impact rivers and streams. Another impactful place is at road crossings.
感谢河流地貌学家，在世界范围内实施类似的项目。然而，改变河道并不是人类影响河流和溪流的唯一方式。另一个重要的影响地点是在道路交叉口。
Bridges are often supported on intermediate piers or columns that extend up from a foundation in the riverbed. Water flows faster around the obstruction created by these piers, making them susceptible to erosion and scour. Peers have to estimate the magnitude of the scour to make sure the piers can handle it. You don't have to scour the internet very hard to find examples where bridges met their demise because of the erosion that they brought on themselves.
桥梁通常是建在河床基础上的中间墩或柱子上支撑的。水流会更快地绕过这些墩柱的障碍，使它们容易受到侵蚀和冲刷的影响。设计者必须估计冲刷的大小，以确保墩柱可以承受它。不必费力搜索互联网，就能找到桥梁因为自身的腐蚀而倒塌的例子。
In fact, the majority of bridges that fail in the United States don't collapse from structural problems or deterioration, they fail from scour and erosion of the river below. But it's not just piers that create erosion.
实际上，在美国大多数崩塌的桥梁并不是因为结构问题或老化，而是由于河流底部的冲刷和侵蚀导致的。但创造侵蚀的不仅仅是桥墩。
Both bridges and embankments equipped with culverts often create a constriction in the channel as well. Bridge abutments encroach on the channel, reducing the area through which water can float, especially during a flood, causing it to contract on the upstream side and expand on the downstream side. Changes in the velocity of water flow lead to changes in how much sediment it can carry. Often you'll see impacts on both sides of an improperly designed bridge or culvert. Settlement accumulates on the upstream side, just like for a dam, and the area downstream is eroded and scoured.
桥梁和堤坝上安装的涵洞常常在河道中产生狭窄的现象。桥墩侵占了河道，减少了水流通过的面积，尤其是在洪水期间，使它在上游收缩，下游扩大。水流速度的变化会导致其携带的沙土量发生变化。通常，您会看到不正确设计的桥梁或涵洞两侧都受到影响。像大坝一样，沉积物在上游侧积累，下游地区则受到侵蚀和冲刷。
Modern roadway designs consider the impacts that bridges and culverts might have on a stream to avoid disrupting the equilibrium of the sediment balance and reduce the negative effects on habitat too. Usually that means bridges with wider spans so that the abutments don't intrude into the channel and culverts that are larger and set further down into the stream bend.
现代道路设计考虑桥梁和涵洞可能对河流环境造成的影响，以避免破坏底泥平衡的平衡状态，并减少对栖息地的负面影响。通常意味着桥梁需要更宽的跨度，以便于墩台不会侵入河道，而涵洞需要更大的尺寸并且在河湾深处设定。
Just like bridges or culvert road crossings, dams slow down the flow of water upstream, allowing sediment to fall out of suspension as we saw in the flu merlier in the video. The consequences include sediment accumulation in the reservoir and potential erosion in the downstream channel, but there's one more consequence. All that silt sand and gravel that a dam rops from the river has a natural destination, the Delta. When a river terminates in an ocean, sea, estuary, or lake, it normally deposits all that sediment. Let's watch that process happen in the river tape.
像桥梁或涵洞路口一样，水坝可以减缓上游水流速度，让我们在视频中看到的，使泥沙从水中悬浮下落。这样做的后果包括水库中泥沙的积累和下游河道的潜在侵蚀，但还有一个后果。水坝从河流中截留下来的所有淤泥、沙子和砾石都有一个自然的去处——三角洲。当一条河流在海洋、海湾、河口或湖泊中终止时，通常会在那里沉积所有淤泥。让我们在河流录像中看这个过程发生。
River deltas are incredibly important landscape features because they enable agricultural production, provide habitat for essential species, and they feed the sand engines to create beaches that act as a defensive buffer for coastal areas. Wind and waves create nearly constant erosion along the coastlines, and if that erosion isn't balanced with a steady supply of sediment, beaches scour away, landscapes are claimed by the sea. Habitats degraded and coastal areas have less protection against storms. And hopefully you're seeing now why it's so difficult, and some might even say impossible to control rivers.
河口三角洲是极其重要的地貌特征，因为它们能够促进农业生产、为关键物种提供栖息地，并提供砂粒以创建海滩，作为沿海地区的防御屏障。风和海浪造成了沿海几乎不断的侵蚀，如果这种侵蚀不能与稳定的沉积物供应相平衡，海滩会被冲刷走，地貌被海洋夺去，栖息地遭受破坏，沿海地区对暴风雨的保护变得更加脆弱。希望现在你能看到为什么控制河流是如此困难，甚至有些人可能会说是不可能的了。
Because any change you make upsets the dynamic equilibrium between water and sediment. And even if you armor the areas subject to erosion and continually dredge out the areas subject to deposition, there's always a bigger flood around the corner, ready to unravel it all over again.
任何你做出的改变都会打破水和沉积物之间的动态平衡。即使你把易受侵蚀的区域防护起来并不断地疏浚易于沉积的区域，总有一次更大的洪水等着到来，准备重新打乱一切。
So many human activities disrupt the natural equilibrium of streams and rivers, causing them to either erode or agrate or both. And often the impacts extend far upstream or downstream. It's not just dams, bridges, and channel reallignment projects either. We build levees and revetments, dredge channels deeper, mine gravel from banks, clear cut watersheds, and more. Historically, we haven't fully grasped the impact that those activities will have on the river in 10, 50, or 100 years.
许多人类活动破坏了河流的自然平衡，导致它们发生侵蚀或淤积，有时候影响范围甚至可以延伸到河流的上游或下游。这不仅仅是指建筑水坝、桥梁和水道改建工程等，我们还修建防洪堤和石垛、挖深水道、从岸边矿石中开采砾石、砍伐流域内的树木等，历史上，我们并没有完全意识到这些活动将在未来10年、50年或100年对河流产生怎样的影响。
In fact, the first iteration of the stream tables we've been filming were built by in rivers late found or Steve Goff in the 1980s. At the time, he was working with the state of Missouri trying to teach minors, loggers, and farmers about the impacts they could have on rivers by removing sediment or straitening channels. These people who had observed the behavior of rivers their entire lives were understandably reluctant to accept new ideas. But seeing a model that could convey the complicated processes and responses of rivers was often enough to convince those landowners to be better stewards of the environment.
事实上，我们一直拍摄的溪流模型表格的首次迭代是在1980年代由发现于河流上的史蒂夫·戈夫或在的建造的。当时，他与密苏里州合作，试图教授未成年人、伐木工和农民有关去除沉积物或矫直河道对河流影响的知识。这些人一生观察河流的行为，自然不愿接受新的观念。但看到一个能够传达河流复杂的过程和反应的模型，往往足以说服这些土地所有者成为更好的环境管理者。
Huge thanks to Steve's wife, Catherine, and the whole team here at Imriver who continue his incredible legacy of using physical models to shrink down the enormous scale of river systems and the lengthy timescales over which they respond to changes, down to something anyone can understand to help people around the world learn more about the confluence of engineering and natural systems.
在此，特别感谢史蒂夫的妻子凯瑟琳以及Imriver团队的全体成员，他们继承了史蒂夫的卓越成就，利用物理模型将河流系统的巨大规模以及对变化做出反应所需的漫长时间尺度缩小到任何人都能理解的程度，帮助全球人民了解工程和自然系统的交融。
Historically, engineering and fluvial geomorphology have been entirely separate fields of study, which means if you were an engineer and wanted to learn more about the impacts engineering projects have on natural streams, you had to do some extra curricular learning.
历史上，工程学和河流地貌学一直是完全分离的研究领域，这意味着如果你是一名工程师，并想了解工程项目对自然河流的影响，你必须进行一些课外学习。
If you've done it, you know teaching yourself math and science is a hard thing to do. A problem that today's sponsor Brilliant.org takes on head first.
如果你尝试过自学数学和科学，你就知道这是一件难事。而今天的赞助商 Brilliant.org 正是直面这个问题。
There are a lot of things you learn in school that you don't end up needing in life, but if you're like me, there are just as many things you didn't learn in school that you need to know now to get ahead in your career, reach your personal goals, or just out of pure curiosity and the delight of learning something new.
在学校里，你学了很多在生活中并不需要的东西，但如果你和我一样，同样也有很多你没有在学校里学到但现在需要知道的东西，这些可以帮助你在职业上取得成功，达到个人目标，或者仅仅是因为好奇心和学习新知识的喜悦。
Brilliant is a platform where you learn by doing with thousands of lessons from math to AI, data science, and engineering.
Brilliant是一个平台，你可以通过数学、人工智能、数据科学和工程学等数千个课程来学以致用。
I've gone through a lot of these courses to freshen up on topics that are new to me, but my absolute favorite was this one on the Physics of Rockets and Tether Launchers by my friend Brian at Real Engineering. It's fun to hear about the engineering challenges of structures like this, but it's a different experience entirely to work through them yourself.
我参加了很多这样的课程，以便重新学习对我来说新的主题，但我最喜欢的是由我朋友Brian在真正的工程学上关于火箭和系留发射器的物理的课程。听到这样的结构工程方面的挑战很有趣，但亲自解决这些问题则完全是另一种体验。
It just gives you a new appreciation for the math and science and a feeling that you really understand the problems in a deep way. You should go try it yourself and see if you agree at Brilliant.org slash practical engineering. It's totally free to try for an entire month and you could get through a lot of courses in that time.
这种学习方式会让你对数学和科学有一种新的欣赏，并深刻地理解问题。你应该自己试试，看看你是否同意这种说法，可以在Brilliant.org/practicalengineering 上免费尝试一个月，你可以在这段时间内完成很多课程。
If you do find yourself coming back, like I did, the first 500 people that clicked the link below will get 20% off an annual premium subscription. They even have an app so you can try this on your phone.
如果你像我一样重新回来了，点击下面的链接的前500个人将享受年度高级订阅20%的折扣。他们还有一个应用程序，所以你可以在手机上尝试这个。
I really believe that we should never stop trying to learn new things and Brilliant makes that so easy to do. And it supports the channel too. Thank you for watching and let me know what you think.
我真诚地相信我们永远都不应该停止学习新事物，而Brilliant帮助我们轻松实现了这一点。同时，它还支持了这个渠道。感谢您的观看，请让我知道您的想法。