2. 考研
  3. [A] There is also concern about falling water tables in the US, one of the world’s three largest food-producing countries. "In t

[A] There is also concern about falling water tables in the US, one of the world’s three largest food-producing countries. "In t

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问题 [A] There is also concern about falling water tables in the US, one of the world’s three largest food-producing countries. "In the United States the irrigated area is shrinking in leading farm states with rapid population growth, such as California and Texas, as aquifers are depleted and irrigation water is diverted to cities."
[B] The situation is most serious in the Middle East. According to Brown: "Among the countries whose water supply has peaked and begun to decline are Saudi Arabia, Syria, Iraq and Yemen." By 2016 Saudi Arabia projects it will be importing some 15m tonnes of wheat, rice, corn and barley to feed its population of 30 million people. It is the first country to publicly project how aquifer depletion will shrink its grain harvest.
[C] Brown warns that Syria’s grain production peaked in 2002 and since then has dropped 30%; Iraq has dropped its grain production 33% since 2004; and production in Iran dropped 10% between 2007 and 2012 as its irrigation wells started to go dry.
[D] Wells are drying up and underwater tables falling so fast in the Middle East and the US that food supplies are seriously threatened, one of the world’s leading resource analysts has warned. In a major new essay Lester Brown, head of the Earth Policy Institute in Washington, claims that 18 countries, together containing half the world’s people, are now overpumping their underground water tables to the point — known as "peak water" — where they are not replenishing and where harvests are getting smaller each year.
[E] The situation in India may be even worse, given that well drillers are now using modified oil-drilling technology to reach water half a mile or more deep. "The harvest has been expanding rapidly in recent years, but only because of massive overpumping from the water table. The margin between food consumption and survival is precarious in India, whose population is growing by 18 million per year and where irrigation depends almost entirely on underground water. Farmers have drilled some 21 m irrigation wells and are pumping vast amounts of underground water, and water tables are declining at an accelerating rate in Punjab, Haryana, Rajasthan, Gujarat and Tamil Nadu. "
[F] In the US, farmers are overpumping in the Western Great Plains, including in several leading grain-producing states such as Texas, Oklahoma, Kansas and Nebraska. Irrigated agriculture has thrived in these states, but the water is drawn from the Ogallala aquifer, a huge underground water body that stretches from Nebraska southwards to the Texas Panhandle. "It is, unfortunately, a fossil aquifer, one that does not recharge. Once it is depleted, the wells go dry and farmers either go back to dryland farming or abandon farming altogether, depending on local conditions," says Brown. "In Texas, located on the shallow end of the aquifer, the irrigated area peaked in 1975 and has dropped 37% since then. In Oklahoma irrigation peaked in 1982 and has dropped by 25%. In Kansas the peak did not come until 2009, but during the three years since then it has dropped precipitously, falling nearly 30%. Nebraska saw its irrigated area peak in 2007. Since then its grain harvest has shrunk by 15%. "
[G] "Iran is already in deep trouble. It is feeling the effects of shrinking water supplies from overpumping. Yemen is fast becoming a hydrological basket case. Grain production has fallen there by half over the last 35 years. By 2015 irrigated fields will be a rarity and the country will be importing virtually all of its grain. "

【C5】
选项
答案F
解析 上一段是题目已给出的段落[A]，提到美国地下水位的下降令人担忧，并指出“由于蓄水层被耗尽，并且灌溉用水被引至城市，人口迅速增长的美国农业大州灌溉面积在缩小。”本段则讲的是美国农民正过度开采主要产粮州的地下水，这些州(德州、俄克拉何马州、堪萨斯州和内布拉斯加州)的灌溉用水水源是奥加拉拉蓄水层，这个蓄水层一旦耗尽，水井会干涸，农民要么退回到旱地耕作，要么完全放弃耕作，然后指出四个州的灌溉面积在下降。本段的内容明显是对上一段内容的具体说明，故[F]为答案。
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