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AThe history of human civilisation is entwined with the history of the ways we have learned to manipulate water resources. As towns gradually expanded, water was brought from increasingly remote sources, leading to sophisticated engineering efforts such as dams and aqueducts. At the height of the Roman Empire, nine major systems, with an innovative layout of pipes and well-built sewers, supplied the occupants of Rome with as much water per person as is provided in many parts of the industrial world today.
[p:a]人类文明的历史与我们如何利用水资源的历史密不可分。随着城镇逐渐扩张，人们从越来越遥远的水源取水，由此催生了诸如大坝和引水渠等复杂的工程设施。在罗马帝国鼎盛时期，九个大型供水系统通过创新的管道布局和完善的下水道，为罗马居民提供的用水量相当于当今许多工业化国家的人均用水水平。
BDuring the industrial revolution and population explosion of the 19th and 20th centuries, the demand for water rose dramatically. Unprecedented construction of tens of thousands of monumental engineering projects designed to control floods, protect clean water supplies, and provide water for irrigation and hydropower brought great benefits to hundreds of millions of people. Food production has kept pace with soaring populations mainly because of the expansion of artificial irrigation systems that make possible the growth of 40 % of the world's food. Nearly one fifth of all the electricity generated worldwide is produced by turbines spun by the power of falling water.
[p:b]在19至20世纪的工业革命和人口爆炸期间，对水的需求急剧上升。为控制洪水、保障清洁水源以及提供灌溉和水电而兴建的数以万计的大型工程项目，前所未有地造福了数十亿人。由于人工灌溉系统的不断扩展，粮食生产得以跟上人口增长的步伐，全球约40%的食物产量正是依靠这些系统实现的。全世界产生的电力中，近五分之一由水流下落驱动的涡轮机发电。
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CYet there is a dark side to this picture: despite our progress, half of the world's population still suffers, with water services inferior to those available to the ancient Greeks and Romans. As the United Nations report on access to water reiterated in November 2001, more than one billion people lack access to clean drinking water some two and a half billion do not have adequate sanitation services. Preventable water-related diseases kill an estimated 10,000 to 20,000 children every day, and the latest evidence suggests that we are falling behind in efforts to solve these problems.
[p:c]然而，这一图景中也暗藏阴霾：尽管我们取得了进步，全球仍有半数人口饱受苦难，其用水条件甚至不如古希腊和古罗马时期。正如联合国2001年11月发布的关于水资源获取的报告所重申的那样，超过十亿人无法获得清洁饮用水，约两亿五千万人缺乏基本的卫生设施。据估计，每天有1万至2万名儿童死于可预防的水相关疾病，而最新证据表明，我们在解决这些问题方面正逐渐落后。
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DThe consequences of our water policies extend beyond jeopardising human health. Tens of millions of people have been forced to move from their homes - often with little warning or compensation - to make way for the reservoirs behind dams. More than 20 % of all freshwater fish species are now threatened or endangered because dams and water withdrawals have destroyed the free-flowing river ecosystems where they thrive. Certain irrigation practices degrade soil quality and reduce agricultural productivity. Groundwater aquifers* are being pumped down faster than they are naturally replenished in parts of India, China, the USA and elsewhere. And disputes over shared water resources have led to violence and continue to raise local, national and even international tensions.
[p:d]我们的水资源政策带来的后果不仅危及人类健康。数以千万计的人被迫离开家园——往往毫无预警或补偿——为大坝后方的水库让出空间。如今，超过20%的淡水鱼类物种因大坝和取水导致其赖以生存的自由流动河流生态系统遭到破坏而面临威胁或濒危。某些灌溉方式损害了土壤质量，并降低了农业生产力。在印度、中国、美国等部分地区，地下水含水层的开采速度已超过自然补给速度。此外，对共享水资源的争端引发了暴力冲突，并持续加剧了地方、国家乃至国际层面的紧张关系。
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EAt the outset of the new millennium, however, the way resource planners think about water is beginning to change. The focus is slowly shifting back to the provision of basic human and environmental needs as top priority - ensuring 'some for all,' instead of 'more for some'. Some water experts are now demanding that existing infrastructure be used in smarter ways rather than building new facilities, which is increasingly considered the option of last, not first, resort. This shift in philosophy has not been universally accepted, and it comes with strong opposition from some established water organisations. Nevertheless, it may be the only way to address successfully the pressing problems of providing everyone with clean water to drink, adequate water to grow food and a life free from preventable water-related illness.
[p:e]然而，在新千年的开端，水资源规划者对水的看法正开始发生变化。重点正逐步回归于优先满足人类基本需求和环境保护——确保“人人有水”，而非“为部分人提供更多”。一些水专家现在主张，应以更智能的方式利用现有基础设施，而不是新建设施，因为后者日益被视为最后的、而非首要的解决手段。这种理念转变尚未得到普遍认同，并且受到一些传统水利组织的强烈反对。尽管如此，这或许才是成功应对当前紧迫问题的唯一途径：为每个人提供安全饮用水、充足的用水以种植粮食，以及摆脱可预防的与水相关的疾病生活。
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FFortunately - and unexpectedly - the demand for water is not rising as rapidly as some predicted. As a result, the pressure to build new water infrastructures has diminished over the past two decades. Although population, industrial output and economic productivity have continued to soar in developed nations, the rate at which people withdraw water from aquifers, rivers and lakes has slowed. And in a few parts of the world, demand has actually fallen.
[p:f]幸运的是——也出乎意料地——对水资源的需求增长速度并未如一些人所预测的那样迅速。因此，过去二十年来，建设新水基础设施的压力已有所减缓。尽管发达国家的人口、工业产出和经济生产力持续攀升，但人们从含水层、河流和湖泊中取水的速度却有所放缓。在世界某些地区，甚至出现了需求下降的情况。
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GWhat explains this remarkable turn of events? Two factors: people have figured out how to use water more efficiently, and communities are rethinking their priorities for water use. Throughout the first three-quarters of the 20th century, the quantity of freshwater consumed per person doubled on average; in the USA, water withdrawals increased tenfold while the population quadrupled. But since 1980, the amount of water consumed per person has actually decreased, thanks to a range of new technologies that help to conserve water in homes and industry. In 1965, for instance, Japan used approximately 13 million gallons* of water to produce $1 million of commercial output; by 1989 this had dropped to 3.5 million gallons (even accounting for inflation) - almost a quadrupling of water productivity. In the USA, water withdrawals have fallen by more than 20 % from their peak in 1980.
[p:g]是什么导致了这一惊人变化？有两个因素：人们已经学会了更高效地使用水资源，同时各社区也在重新思考其用水优先事项。在20世纪的前三个季度中，人均淡水消耗量平均翻了一番；在美国，尽管人口增长四倍，取水量却增加了十倍。但自1980年以来，由于一系列新技术的应用，家庭和工业领域实现了节水，人均用水量实际上有所下降。例如，1965年，日本生产100万美元商业产值所使用的水约为1300万加仑*；到1989年，这一数字已降至350万加仑（即使考虑通货膨胀），几乎提高了四倍的用水效率。在美国，自1980年峰值以来，取水量已下降超过20%。
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HOn the other hand, dams, aqueducts and other kinds of infrastructure will still have to be built, particularly in developing countries where basic human needs have not been met. But such projects must be built to higher specifications and with more accountability to local people and their environment than in the past. And even in regions where new projects seem warranted, we must find ways to meet demands with fewer resources, respecting ecological criteria and to a smaller budget.
[p:h]另一方面，大坝、引水渠及其他各类基础设施仍需建设，尤其是在那些基本生活需求尚未得到满足的发展中国家。但这些项目必须按照更高的标准建造，并比过去更加重视当地民众及其环境的权益与问责。即使在一些看似需要新建项目的地区，我们也必须找到方法，在资源更少的情况下满足需求，同时尊重生态准则并控制预算。
* underground stores of water
* 地下储水层