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Almost anywhere arid, the water underground, once largely ignored, has come to be seen as especially valuable as the demands of farmers have outgrown their supplies of rain and surface water. Groundwater has come to the rescue, and for a while it seemed a miraculous solution: drill a borehole, pump the stuff up from below and in due course it will be replaced. In many places, however, from the United States to India and China, the quantities being withdrawn exceed the annual recharge. This is serious for millions of people not just in the country but also in many of the world's biggest cities, which often depend on aquifers for their drinking water.
几乎在所有的干旱地区，过去基本被忽视的地下水，如今因为农民对水的需求超过了雨水和地表水的供应而显得尤其珍贵。地下水成了救命水，一时间，有了它，缺水问题似乎有了一个奇迹般的解决方法：钻个洞，把水从地底下抽上来，到时候地下水自然又能得到补充。不过在许多地方，从美国到印度和中国，抽出的水量已经超过每年能补充的水量。这对千百万的人来说已经是非常严重的问题，不仅在农村如此，世界上许多大城市也是如此，这些城市里，人们的饮用水往往依靠地下的蓄水层。
The 20 million inhabitants of Mexico City and its surrounding area, for example, draw over 70% of their water from an aquifer that will run dry within 200 years, maybe sooner. Already the city is sinking as a result. In the Hai river basin in China, deep-groundwater tables have dropped by up to 90 meters.
比如，居住在墨西哥城及周边地区的两千万人，70%的用水要从地下蓄水层抽取，而这个蓄水层将会在200年内枯竭，或许比这更快。这个城市因地下水面的降低已经在下沉。在中国的海河流域，地下深水层水位已经下降了90米。
