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One ofAfrica’s Biggest Dams Is Falling Apart file:///C:/Users/lenovo/AppData/Local/Temp/msohtmlclip1/01/clip_image002.jpg Despiteefforts to slow the facility’s decline and correct structural problems, KaribaDam is crumbling; a dam collapse at the site would prove disastrous for theentire region.CREDITPHOTOGRAPHBY JEKESAI NJIKIZANA / AFP / GETTY 尽管对卡里巴水库中的设施老化和结构问题进行了各种延缓、修正措施，这座水坝还是处于崩塌边缘；水坝的倒塌将对这整个地区造成毁灭性伤害。贾克赛·尼吉克扎那 /法新社/华盖图片社 供图
Thenew year has not been kind to the hydroelectric-dam industry. On January 11th,the New York Times reported that Mosul Dam, the largest suchstructure in Iraq, urgently requires maintenance to prevent its collapse, adisaster that could drown as many as five hundred thousand people downstreamand leave a million homeless. Four days earlier, the energy minister of Zambiadeclared that Kariba Dam, which straddles the border between his country andZimbabwe, holding back the world’s largest reservoir, was in “dire” condition.An unprecedented drought threatens to shut down thedam’s power production, which supplies nearly half the nation’s electricity. 水力发电工业在今年状况不佳。今年1月11日，《纽约时报》报道了伊拉克境内的最大工程，摩苏尔大坝，亟需紧急维护，否则将面临50万人溺亡、100万人流离失所的灾难。四年前，赞比亚国家能源部长就宣称跨越本国与津巴布韦边界的卡里巴大坝，正阻碍着这世界上最大蓄水量的蓄水池，它已处于“干涸”的边缘。近期，一场空前的干旱袭击赞比亚全国，导致大坝水位低于发电所需的最低水位。如果情况短期内没有好转，供应一半国家电力的卡里巴湖电站可能将被迫关闭。
Thenews comes as more and more of the biggest hydroelectric-dam projects aroundthe world are being cancelled or postponed. In 2014, researchers at OxfordUniversity reviewed the financial performance of two hundred and forty-fivedams and concluded that the “construction costs of large dams are too high toyield a positive return.” Other forms of energy generation—wind, solar, andminiature hydropower units that can be installed inside irrigation canals—arebecoming competitive, and they cause far less social and environmental damage.And dams are particularly ill-suitedto climate change, which simultaneously requires that they belarger (to accommodate the anticipated floods) and smaller (to becost-effective during the anticipated droughts). 类似这种世界范围内最大水利工程取消或推迟的新闻屡见报端。2014年，牛津大学的研究人员检查了245座大坝的财政状况，总结道“大型水电站建造成本太高，难以回本。”其他能源生成的方式——风、太阳光和小型水利发电设施可以安装在灌溉渠里——它们更有竞争力，对社会和环境危害更小。大坝对气候变化适应性特别差，需要同时具备扩张（适应即将到来的洪水）和收缩（在预期到来的干旱中减少开支）的功效。
Mosul Dam’s predicament is partly a result of the ongoing war;many maintenance workers have not returned there since August of 2014,when ISIS fighters brieflytook control. (Iraqi and Kurdish forces soon regained it.) But the main issueis that, like many such dams, the project shouldn’t exist in the first place.Opened in 1986, it was built on unstable gypsum bedrock, requiring grout to beconstantly injected into the foundation to prevent the dam’s collapse. That work has ceased. In 2006, long before ISIS began making headlines, theU.S. Army Corps of Engineers called Mosul Dam “the most dangerous dam in the world.造成摩苏尔大坝困境的原因之一是不间断的战争；但是更重要的是，很多维修工人自从ISIS2014年8月份控制这里就再也没返回工作过。（尽管伊拉克库尔德人不久又夺回了这里。）但最大的问题在于，有些工程从一开始就不应该存在。建立在不稳定的膏岩基层上的摩苏尔大坝于1986年投入使用，期间不断灌浆填补防止大坝坍塌。现在这项工作已经停止了。早在ISIS成为头版头条之前，美国陆军工程兵团就在2006年称这座大坝为“世界上最危险的大坝”。
Kariba’s difficulties are more complicated. It has beennearly incapacitated by ongoing drought, which has lowered the reservoir’svolume to twelve per cent of its usual capacity. But if the reservoir isrefilled, the dam faces the possibility of collapse. It was built in the latenineteen-fifties, and in the years since water flowing through the dam’s six floodgates has carved a three-hundred-foot-deep pit, or plunge pool,at its base. The plunge pool extends to within a hundred and thirty feet of thedam’s foundation; if it reaches the foundation, the dam will collapse. Thatseems hard to imagine now, with the reservoir at a record-low level. But theZambezi River Basin, on which the dam sits, is the most susceptible of Africa’sthirteen basins to exceptional droughts and floods, and climate change isintensifying both. 卡里巴水电站的情况更加复杂。因为持续干旱，水库蓄水仅达平日的12%，几无效用。但是如果水库蓄足水，大坝又会面临崩塌的可能。大坝建立于五十年代后期，自从水流穿越大坝的6个水闸后，便在地基切开了一个300英尺的深坑，或者叫水垫塘。这个水垫塘距离地基不到130英尺，一旦到达地基，大坝便不复存在。不过现在水库蓄水处于低水位状态，这种情况暂时还无法想象。但是大坝坐落的赞比西河流域，是非洲13个流域中最易受干旱和洪水影响的流域，而目前气候变化同时加剧了这两个因素。
Kariba’s collapse, like Mosul’s, would constitute an epochal eventin the history of energy development—the dam industry’s Chernobyl. The ensuingtorrent would be four times bigger than the Zambezi’s biggest recorded flood,in 1958, and would release enough water to knock over another major dam threehundred miles downstream, in Mozambique. At least three million people live inthe flood’s path; most would die or lose their crops or possessions. Aboutforty per cent of the electricity-generating capacity of twelve southernAfrican nations would be eliminated. 若卡里巴大坝发生类似摩苏尔大坝的坍塌，必将成为大坝行业的切尔诺比利，在能源发展史上记下浓重的一笔。赞比亚史上最大洪水发生在1958年。卡里巴大坝倒塌后会释放四倍于1958年洪水的水流，奔袭三百英里，冲垮莫桑比克境内的另一座大坝。至少300万人生活在洪水流经区域，会被洪水夺去农作物和财产，乃至生命。南非十二国家总发电能力将因此降低百分之四十。 卡里巴或摩苏尔大坝若崩塌，将成为能源发展史上划时代的大事件——无异于水坝工程中的“切尔诺贝利”。接下来发生的洪水会比赞比西记录的1958年最大洪水大4倍，届时将会释放足够的水流冲垮300英里以外莫桑比克国境内的一座水坝。而洪水流经的地方至少有300万人定居，他们大部分人会死亡、丢失庄稼和财产。另外，12个南非洲国家40%的电力将会难以为继。
The dam,four hundred and twenty feet tall and nearly two thousand feet wide, was builtwith financing from the World Bank to provide power for the copper mines ofwhat was then Northern Rhodesia. The designersintended to make the dam impervious to a one-in-ten-thousand-year flood, buttheir calculations were based on only three decades of Zambezi flow data—aperiod too short to permit credible forecasting. This flaw became apparent in1957, when the site, still under construction, was hit with a flood bigger thanthe designers’ worst-case projection. The planners hurriedly enlarged thespillway, but in 1958 the project was hit by another flood, twice as big as theprevious one, so the spillway was expanded again. Morerecent projections, cited by the Intergovernmental Panel on Climate Change,indicate that the Zambezi River Basin will experience still drier and moreprolonged droughts and even bigger floods in years to come. 卡里巴大坝高420英尺，近200英尺宽，当时由世界银行筹资贷款建造，为当时还称作北罗得西亚①的铜矿提供电力。大坝设计师们有志想要使大坝能经受住千年一遇的洪水侵袭，但是他们的计算仅基于赞比西河30年的流量数据上——在这么短的时期内根本不可能作出可靠预测。1957年，这种缺陷变得更加明显，此时还在建设中的大坝就被超出设计师最大预期的洪水侵袭了。设计师据此立即扩宽了泄洪道，可没想1958年又迎来了一场较之前两倍的凶猛洪水，所以泄洪道只得再次拓宽。引用自政府间气候变化专门委员会的推测，赞比西河流域将在未来迎接更剧烈、更持久的干旱和更猛烈的洪水。
Since the nineteen-nineties, Kariba’soperators have been allowed to open only three of the dam’s six floodgates at atime, for fear of enlarging the plunge pool. If the reservoir fills to adangerous level, the operators face two options: allow water to flow over thetop of the dam and tumble down its face, threatening the foundation, or, morelikely, open more than three floodgates, causing the plunge pool to expand. Tohead off a catastrophe, the World Bank and other international lenders agreedin November of 2014 to provide a loan of nearly three hundred million dollarsto repair it, stating that the project requires “immediate attention.” 九十年代以来，卡里巴大坝的经营者一次只能打开大坝6个水闸中的3个，就是担忧泄洪道需要再次扩宽。如果水库蓄水超过危险水平线，经营者就面临两个选择：一是眼看水漫过大坝，造成崩塌，威胁地基，或者更可能的是，打开超过3个水闸，水垫塘不得不被扩大。为了阻止灾难发生，世界银行和其他的国际贷方在2014年11月同意提供近3亿美元的贷款去修补大坝，宣称这项工程需要受到“即刻关注”。
But “immediate” means decades, notyears. “It takes a long time to carry out the necessary due diligence andsecure the financin for a complex project like this,” Munyaradzi Munodawafa,the chief executive of the Zambezi River Authority, which operates Kariba, toldme in an e-mail. “We‘re looking at a fifteen-to twenty-year process, in which weare five years under way.” To repair the dam, workers will enlarge the plungepool downstream, to reduce erosion near the foundation. But it’s not certain towork, and major flooding could occur before the repairs are completed. 但是“即刻”也是意味着数十年，而不是短短几年的关注。“这需要长时间谨慎的实施和安全的财政保障才能支撑如此复杂的工程。”管理赞比西河的当局行政长官穆尼亚拉齐·穆诺达瓦法就卡里巴大坝事件给我发了邮件。“我们对它的修缮需要15到20年的过程，目前已经进行了5年了。”为此，工人们会顺着水流拓宽水垫塘，以减少对地基进一步的侵蚀。不过这种修补不一定有用，主汛期可能会在修补完成之前就到来。
The World Bank and otherinternational financiers like dams because they seem to offer large-scalesolutions to energy and water shortages. Kariba is just one of more than twothousand large dams in Africa; Zimbabwe, one of the world’s poorest nations,has at least two hundred and fifty-four. But maintaining a dam is expensive—andmuch less popular than building one. Even in affluent countries such as theUnited States—whose dam infrastructure is in sufficient disrepair to haveearned a “D” rating from the American Society of Civil Engineers, in 2013—maintenanceis often neglected; it’s not likely to fare better in impoverished,corruption-ridden countries such as Zimbabwe or Iraq. Dams can’t be drained, and dismantling them can be as costly asbuilding them. It’s the trap of Industrial Age technology: once mechanizedsystems supplant natural ones, they must be managed in perpetuity, or else theybreak down. 世界银行和其他国际金融家钟爱投资大坝，原因是大坝项目看起来是在为能源和水短缺提供大型解决方案。卡里巴大坝只是非洲2000多座大型水坝中的一座；津巴布韦，世界上最贫穷的国家之一，就至少有254座。但是维持一座大坝的运作是很费钱的——远比建造一座更昂贵。即使是在像美国一样富裕的国家——大坝基础设施也是年久失修，在2013年，整个大坝工程基础设施被美国土木工程师协会评为质量D级——它的日常维护常被忽视；所以像津巴布韦或者伊拉克这种贫穷且腐败的国家经营更是糟糕。大坝也无法完全排尽水，拆除它们的费用跟建造一样高昂。这就是工业技术时代的困境：机械系统需要维修才能维持运作，在其取替自然界中对应的功能结构后，人类就需要时刻维护它，否则就会发生故障。
注释： ①北罗得西亚：赞比亚的旧称。
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发表于 2016-4-30 14:18:48
