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本文題目：高中英語課外閱讀：經(jīng)濟學防止河水泛濫的絕妙新方法

經(jīng)濟學：防止河水泛濫的絕妙新方法

Science and Technology Flood defences Dambusterbusters

科技 防洪減災 堤壩除險，以水御水

Some clever, new ways of stopping rivers flooding

防止河水泛濫的絕妙新方法

THE destruction of New Orleans by Hurricane Katrina in 2005 showed the importance of keeping levees—the artificial banks that contain the flow of partly canalised rivers—in tip-top condition.

2005年的卡特利娜颶風摧毀了新奧爾良。這場慘劇提示我們部分渠化的河流其人造大壩即使在洪峰到來，河水漫壩的情況下也要挺住而不出現(xiàn)垮塌是多么重要。

In practice, though, that is hard.

然而，實際上這很難做到。

Levees fail for many reasons, not all of them associated with violent storms, and there are so many of them (100,000 miles-worth in America alone) that keeping an eye on all of them is an almost impossible task.

導致堤壩垮塌的原因很多，并非全都是狂風暴雨所致。而且堤壩數(shù)量眾多(僅在美國就有十萬英里的在用堤壩)，難以對所有的堤壩狀況都進行密切監(jiān)視。

It is good, therefore, to have a backup plan to block up unexpected holes before they can cause too much damage.

因此，事先儲備預案極為重要，一旦堤壩出現(xiàn)未曾預料的缺口時能夠及時予以封堵，以防造成更大災難。

The traditional approach is to throw bags filled with sand or rocks into a breach.

一旦堤壩出現(xiàn)裂口，傳統(tǒng)的做法是向缺口拋擲沙袋和石塊。

Such bags, though, are heavy and unwieldy—particularly if they have to be filled far from the breach and then carried there.

然而這些沙袋死沉，難以搬運。如果不得不在離裂口較遠的地方灌裝沙袋再運過去的話，這項工作就難上加難。

William Laska of the Science and Technology Directorate at America's Department of Homeland Security has therefore sought out alternatives.

威廉?拉斯卡在美國國土安全部所屬的工程科技處工作。

He has found several technologies that have a common theme: they all use water itself to help stem the flood.

他找到了解決這一難題的辦法,這些方案有一個共同點：以水御水。

The largest of the new devices is designed to block deep breaches.

這些新發(fā)明的裝置中體積最大是設計用來堵塞寬深堤壩裂口的。

The Portable Lightweight Ubiquitous Gasket (PLUG) is a sausage-shaped balloon made of polyester and PVC, and fitted with motorised pumps.

這種裝置叫做"便攜式通用輕型堵漏包"(其英文縮略語為PLUG，正好有塞子的意思)。

When dropped into a river (usually by helicopter), PLUG's pumps switch on automatically and begin forcing water into the balloon through a valve.

它是由聚酯纖維和聚氯乙烯制作的圓柱形氣球，并安裝了發(fā)動機帶動的水泵。把這個裝置投入河中(一般使用直升機)，水泵就自動開始工作，通過一個閥門把河水注入氣球。

The air thus displaced is expelled through a second valve until the device is 80% full, at which point the pumps shut themselves down.

河水不斷注入，球內(nèi)的空氣通過另一組閥門被擠出。就這樣直到水充滿了80%的球體后水泵就自動停了下來。

Filled thus far, PLUG is still buoyant and will float wherever the current carries it.

灌了這么些水PLUG仍然可以浮于水面，隨河水任意漂流。

If it has been dropped in the right place, that will be towards the breach it is designed to fill.

如果投放的位置恰當，它就會漂到堤壩的裂口處。

And there, if all goes well, it will stick—blocking the hole in a manner suitable to its rather contrived acronym.

在這里如果一切順利的話，就像這個裝置有點蹩腳的的英文首字母縮略語道出的，它就會像一個塞子一樣堵住裂口。

Prevention, however, is always better than cure, and the second of Mr Laska's devices is designed to stop levees being breached in the first place.

常言說治病不如防病，對待堤壩亦然。拉斯卡先生發(fā)明的第二種裝置就是用于事先防止堤壩出現(xiàn)垮塌。

In this case the acronym of choice is REPEL (Rapidly Emplaced Protection for Earthen Levees).

這種裝置的全稱是"泥土壩便置保護裝置"，其英文首字母的縮略語REPEL也正好有"防御"的意思。

REPEL is made of the same material as PLUG, but instead of being thrown into the water and carried to its destination by the current, it is laid out flat on a levee that is in danger of being overtopped and thus eroded by the river it is supposed to contain.

它與第一種裝置使用同樣材料制作，但不是要把它投入河中由水流帶到裂口處。一旦河水猛漲漫過堤壩就會對泥土壩造成沖蝕，危及堤壩的安全。此時可以把REPEL鋪在堤壩頂上保護堤壩。

In normal circumstances merely placing a layer of protective material on top of a levee in this way would not do much good.

一般來說如果只是這樣在堤壩頂部鋪一層類似的保護材料在漫壩時不會起到什么作用。

The force of the water would quickly wash it away.

水流的力量會很快將它們沖掉。

However, REPEL has a series of tubes that sit on top of it and can be pumped full of water in a manner similar to that employed by PLUG.

而ERPEL在其上部裝上了一系列的粗管，可以如第一種裝置一樣往這些粗管里灌水。

The weight of these tubes holds the protective layer in place, while the gaps between the tubes permit the overspill to escape.

這些裝滿水的管子的重量足以固定住這些保護層，漫出堤壩的河水可以在粗管間溢過。

Some flooding from that overspill results—but not as much as if the spill were allowed to erode and destroy the levee itself.

這樣雖然有一些河水漫出堤壩，但造成的損失會遠遠小于由于土壩在水流侵蝕下而垮塌產(chǎn)生的后果。

Yet simply halting floodwaters and preventing short-term damage is not enough.

然而只是堵住了洪水防止了眼前的災難并不完美。

Neither PLUG nor REPEL can be used permanently.

PLUG與REPEL都是應急設施。

It is the third of Mr Laska's acronyms, REHAB, that allows engineers to make permanent repairs.

拉斯卡先生還有第三套裝置，其首字母縮略語是REHAB，又正好有"重建"之意。工程師們可以用它對堤壩進行永久性的修復。

The Rapidly Emplaced Hydraulic Arch Barrier, made of the same material as the other two devices, can be put in place around a plugged breach to keep it sealed and dry once the PLUG has been removed.

該裝置的全稱叫做"便置式拱形折流壩"。它與前兩種裝置采用相同材料制作，可以圍住一個被暫時封堵住的堤壩裂口，使之與河水隔開。此時就可以將PLUG這個塞子撤掉，晾干堤壩裂口處的泥土。

First, the arch is filled with air and floated to the desired location.

首先將這個拱壩注入空氣使它能夠漂到指定的位置。

Then, once it is in place, it is partly flooded and allowed to sink to the riverbed around the breach, making a tight seal.

一旦到位，就向拱壩內(nèi)灌水使它沉到裂口周圍的河床上，形成了一道嚴密的圍堰。

That done, a second set of pumps evacuates the gap between the arch and the PLUG, allowing workers access to the site.

這些工作完成后，再調(diào)用一組水泵將拱壩與堵塞間的水全部抽干，堤壩搶修工人們就可以進入現(xiàn)場進行堤壩的修復作業(yè)了。

Not only is installing REHAB easier and faster than building a conventional temporary dam, it is also less wasteful.

設置一道"重建"拱壩與常規(guī)的方法建臨時圍堰相比不僅省時、省工，而且還省錢。

A conventional temporary structure is demolished after use.

常規(guī)的臨時圍堰在完工后還需要拆除。

REHAB can simply be floated away and reused-it will have rehabilitated itself, in other words.

這種"重建"拱壩用完后只需充氣排水就可浮起拖走重新使用，這也就是說，這種拱壩是可重復使用的。

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