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This is Eureka, Missouri, a city that floods repeatedly.
这里是密苏里州的尤里卡，一座洪灾频发的城市。
We're talking catastrophic floods, twice in less than two years.
我说的洪灾是特别严重而且不到两年就发了两次的那种洪灾。
"Yet more rain and dangerous flooding are affecting parts of the Midwest and South tonight."
“然而，中西部和南部的部分地区今晚还会出现更多的降雨及危险的洪水。”
"Take you across the Meramec River, notorious for flooding very quickly."
“大家现在看到的是梅拉梅克河，因为动不动就洪涝，这条河都已经出了名了。”
"Towns like Eureka, and others, well they're in for a rough few days."
“包括尤里卡在内的一些小镇接下来有苦头吃了。”
But, just 12 miles downstream is a town called "Valley Park".
问题是，下游12英里处就有一个小镇，小镇的名字叫“山谷公园”。
It stayed pretty dry thanks to a levee.
这里还挺干爽的，因为他们有堤坝。
A giant artificial embankment that surrounds the city, designed to keep water out.
为了将洪水挡在外面，他们修建了一座巨型的环城堤坝。
Valley Park got their levee largely because the city was willing and able to pay for it.
山谷公园之所以修了堤坝，很大程度上是因为这座城镇愿意也有能力为堤坝买单。
It kept their own town dry, but here's what flooding looked like in neighboring towns, including Eureka, that didn't have levees.
结果，他们自己的城镇倒是干爽了，但大家看看他们周边没有堤坝的小镇——尤里卡就是其中之一——看看这些地方都涝成什么样了。
"The valley Park levee withstood the water."
“山谷公园的堤坝顶住了洪水。”
"That levee holding could be part of the problem."
“堤坝的抵御可能恰好就是问题所在。”
"They suspected the same levee that protected Valley Park may have been to blame for devastating flooding in Fenton, Eureka, and Arnold."
“他们怀疑，芬顿、尤里卡和阿诺德等地摧枯拉朽的洪水可能就是山谷公园的那座堤坝造成的。”
Can a levee protect one town while making flooding worse for others -- especially towns that can't afford a levee?
堤坝保护一个城镇的同时也能加剧其他城镇，尤其是没钱修堤坝的城镇的洪灾吗？
A fluid mechanics lab, a 13-foot long model of a river, and some adorable tiny houses will help us find out.
一个流体力学实验室，一个13英尺长的河流模型加上一些可爱的小房子就能帮助我们找到答案。
People love levees.
大家其实是喜欢堤坝的。
There's about 100,000 miles of these embankments across the US.
整个美国已经修了将近10万英里这样的堤坝。
Sometimes concrete, sometimes earthen.
有的是混凝土的，有时是直接用土砌的。
For centuries, we've built them between humans and rivers.
几百年前，我们就已经开始在我们（的家园）和河流之间修筑堤坝了。
"Levee workers transported material by hand, by truck, by boat..."
“修坝工人运材料用的是他们的双手，卡车，还用到了船……”
We even write songs about them.
我们甚至还给堤坝写过歌。
But it turns out, even when levees are effective, they can still be devastating.
然而，事实证明，尽管堤坝有时候很管用，它们也能给人类带来毁灭性的打击。
As far back as 1852, levees came with a very important warning.
早在1852年，堤坝就向人类发出了一个非常重要的警告。
Charles Ellet Jr., a famed US civil engineer,
美国著名土木工程师小查尔斯·埃莱特就警告道，
cautioned that levees confine rivers and cause them to "rise higher and flow faster."
堤坝会限制河水的流动路径，会让河水“涨得更高，流得更快”。
And relying on levees "encourages a false security."
依赖堤坝会“让大家产生一种虚假的安全感”。
But he was largely ignored.
问题是，他的警告变成了耳旁风。
Levees became the default for flood control - mostly funded and constructed by local entities.
堤坝成为默认的防洪措施——负责出资和建设的大多是当地的一些实体单位。
Some riverside communities that could afford it, built taller levees for more protection,
河岸附近一些有钱的社区为了加强保护便抬高了堤坝的高度，
while less fortunate neighbors dealt with the devastating effects.
不那么好命的社区就只能收拾洪水留下的烂摊子了。
To show you what we mean, we went to the banks of the Mississippi River, to a fluid mechanics lab,
为了直观地给大家展示我们的意思，我们还去了一趟密西西比河附近，去参观了一个流体力学实验室，
where a team of engineers from the University of Minnesota built us this landscape model to test flood scenarios.
在那里，明尼苏达大学的工程师团队为我们搭建了这个测试洪水情景的景观模型。
Overhead, a scanner collects 3D data to measure exactly what's happening.
模型上方有一个收集3D数据，能够准确观测到正在发生的事情的扫描仪。
It's a generic model of a river with no levees.
这就是一个典型的没有堤坝的河流模型。
That means, when the water level increases, it overflows.
没有堤坝就意味着水位上升的时候，河水就会漫上河堤。
And spreads across the floodplain, often creating important wetland habitat that's home to a variety of species.
继而蔓延过整个漫滩，那些地方经常就变成了重要的湿地栖地，变成了各种飞鸟鱼虫的乐园。
Putting in levees cuts rivers off from this land, destroying floodplains and wetlands.
修筑堤坝就会切断河流与这片土地的联系，破坏漫滩和湿地的生态。
It allows people to convert these areas into farmland or build houses on them.
但也让人类有了在上面开垦农田，建造房屋的机会。
And while levees protect these communities from flooding,
堤坝能够保护这些社区免受洪水侵袭，
they constrict the river into a narrow channel, making the water flow faster and higher.
却也将河道压缩成了一条窄窄的水渠，河水就会流得更急，水面也会变得更高。
That creates a bottleneck, leading to additional flooding upstream.
这样一来，河流的某个位置就会变成一个瓶颈，河流的上游就开始出现洪涝了。
If all the levees are the same height, both sides should be about equally protected from the average flood.
如果堤坝每个位置都一样高，那河道两岸免于普通洪水侵袭的几率应该是一样的。
And if the river rises so much that the water overtops the levee, then both sides should flood pretty equally.
如果河水涨得太高，高到漫过了堤坝，那么河道两岸受洪水侵袭的程度也应该是差不多的。
But let's say, people on one side of the river lobby for higher levees.
打个比方，如果只有一边的人支持加高堤坝，
Now, instead of both sides flooding, only one floods.
那被洪水侵袭的就不再是两边的居民了，而是一边的居民。
The side with the lower levees is at a clear disadvantage.
显然，堤坝较低的那边劣势一些。
So what can people in flood zones do?
那么问题来了，洪泛区的人能做些什么呢？
We can't just pick up and move major cities.
我们没办法直接把那些大城市搬走。
We need levees to protect places like these.
我们需要用堤坝来保护这些地方。
There is an alternative.
办法也不是没有。
We could build levees farther back, so rivers could still expand and create wetlands.
我们可以在离河岸远一些的地方修建堤坝，这样河流还是可以扩张，可以形成湿地。
These "setback levees" ease flooding on both sides, rather than protecting one city at the expense of another.
这些“后退堤坝”不仅没搞拆了东墙补西墙那一套，还能一举缓解两岸的洪涝问题。
This approach is common in other parts of the world - like Holland for example-but not in the U.S.
这种做法在世界其他地方，比如荷兰已经很常见了，只是在美国还没有那么常见。
Here, we tend to build levees right next to rivers.
在美国，我们习惯直接在河岸上修筑堤坝。
Some communities that can afford to build higher levees do so at the risk of others with little oversight.
有资本修建高堤坝的社区以牺牲其他社区为代价修筑了高高的堤坝，也没什么人监督他们，
We do have the Army Corps of Engineers -- a federal agency tasked with regulating a fraction of all levees.
虽然我们确实也有陆军工兵部队——一个负责监管小部分堤坝的联邦机构——这样的单位。
They have to ensure -- at least on paper -- that federal levees won't dramatically raise local flood levels.
他们的工作就是确保——至少书面规定是这样——联邦的堤坝不会大幅提高当地的洪水水位。
But those engineering predictions don't always match reality.
问题是，现实和这类工程预测往往都是不相符的。
For instance, the Army Corps designed Valley Park's levee in the early 90s with data and software from that era.
举个例子，山谷公园的堤坝是陆军工兵部队在90年代初用那个时代的数据和软件设计的。
Engineers estimated the levee's impact on neighboring areas would be minimal.
据工程师们估计，这一堤坝几乎不会影响到邻近的地区。
But by the time it was completed in 2005, the region had grown significantly.
然而，到了2005年堤坝完工的时候，这个地区就已经明显扩张了。
More people had built alongside the river, increasing the risk of flooding - which wasn't considered in the original plan.
在河边建房的人多了，这样一来，发生洪灾的风险也就高了——原来的方案并没有考虑到这一点。
While we don't know the precise impact of Valley Park's levee on neighboring towns just yet,
尽管目前我们还不知道山谷公园的堤坝对邻近城镇的确切影响，
since the levee was built, the region outside Valley Park has suffered two of the worst floods in its history.
但我们知道的是，自从他们的堤坝修好以后，周边的地区就已经遭受了当地历史上最为严重的两次洪灾。
The Army Corps says they've done nothing wrong, and that the levee meets all state and federal laws.
陆军部队表示他们没有错，他们修筑的堤坝也符合所有州和联邦的法律规定。
But there's a growing body of research that shows levees push flooding onto surrounding communities that have lower levees or no levees at all.
问题是，越来越多的研究都表明，堤坝是会将洪水推向堤坝较低或根本没有堤坝的周边社区的。
Researchers measured water levels around 13 levees in the Midwest and found they all increased flooding -- some by over five feet.
研究人员测量了中西部13个堤坝附近的水位，发现它们都加剧了洪灾的严重性——有些甚至导致洪水水位上涨了5英尺(1.5m)以上。
As the climate changes and cities push for higher levees, flooding is only expected to get worse.
随着气候变化，随着城市修筑的堤坝越来越高，洪水问题估计只会变得更糟。
Especially along the Mississippi River, which is almost entirely lined with levees.
尤其是在密西西比河沿岸地区，因为这里几乎沿河全线都修筑了堤坝。
Some of these embankments have been substantially raised since their completion, against federal rules,
其中一些堤坝是完工后被大幅抬高的，尽管这一做法并不符合联邦的规定，
making flooding worse across the river and upstream.
结果就是，整个河流沿岸地区和上游的洪灾问题都变得更加严重了。
So, yes, we need some levees.
总而言之，是的，我们确实需要一些堤坝。
But the system for regulating them is broken.
但问题是，监管它们的体系已经被打破了。
Even though the science overwhelmingly shows that constructing higher levees makes flooding worse in the long-term.
尽管绝大多数科学研究都表明，从长远来看，修建更高的堤坝会加剧洪涝灾害。
We keep building them taller, passing our problems upstream.
但我们依然没有停止加高堤坝的脚步，停止把后果甩给上游的脚步。
