TPO托福阅读真题：沙漠中的水源

　　Water in the Desert

　　Rainfall is not completely absent in desert areas, but it is highly variable. An annual rainfall of four inches is often used to define the limits of a desert. The impact of rainfall upon the surface water and groundwater resources of the desert is greatly influenced by landforms. Flats and depressions where water can collect are common features, but they make up only a small part of the landscape.

　　Arid lands, surprisingly, contain some of the world’s largest river systems, such as the Murray-Darling in Australia, the Rio Grande in North America, the Indus in Asia, and the Nile in Africa. These rivers and river systems are known as “exogenous” because their sources lie outside the arid zone. They are vital for sustaining life in some of the driest parts of the world. For centuries, the annual floods of the Nile, Tigris, and Euphrates, for example, has brought fertile silts and water to the inhabitants of their lower valleys. Today, river discharges are increasingly controlled by human intervention, creating a need for international river-basin agreements. The filling of the Ataturk and other dams in Turkey has drastically reduced flows in the Euphrates, with potentially serious consequences for Syria and Iraq.

　　The flow of exogenous rivers varies with the season. The desert sections of long rivers respond several months after rain has fallen outside the desert, so that peak flows may be in the dry season. This is useful for irrigation, but the high temperatures, low humidity, and different day lengths of the dry season, compared to the normal growing season, can present difficulties with some crops.

　　Regularly flowing rivers and streams that originate within arid lands are known as “endogenous.” These are generally fed by groundwater springs, and many issue from limestone massifs, such as the Atlas Mountains in Morocco. Basaltic rocks also support springs, notably at the Jabal Al-Arab on the Jordan-Syria border. Endogenous Rivers often do not reach the sea but drain into inland basins, where the water evaporates or is lost in the ground. Most desert streambeds are normally dry, but they occasionally receive large flows of water and sediment.

　　Deserts contain large amounts of groundwater when compared to the amounts they hold in surface stores such as lakes and rivers. But only a small fraction of groundwater enters the hydrological cycle-feeding the flows of streams, maintaining lake levels, and being recharged (or refilled) through surface flows and rainwater. In recent years, groundwater has become an increasingly important source of freshwater for desert dwellers. The United Nations Environment Programme and the World Bank have funded attempts to survey the groundwater resources of arid lands and to develop appropriate extraction techniques. Such programs are much needed because in many arid lands there is only a vague idea of the extent of groundwater resources. It is known, however, that the distribution of groundwater is uneven, and that much of it lies at great depths.

　　Groundwater is stored in the pore spaces and joints of rocks and unconsolidated (unsolidified) sediments or in the openings widened through fractures and weathering. The water-saturated rock or sediment is known as an “aquifer”. Because they are porous, sedimentary rocks, such as sandstones and conglomerates, are important potential sources of groundwater. Large quantities of water may also be stored in lime stones when joints and cracks have been enlarged to form cavities. Most limestone and sandstone aquifers are deep and extensive but may contain ground waters that are not being recharged. Most shallow aquifers in sand and gravel deposits produce lower yields, but they can be rapidly recharged. Some deep aquifers are known as “fossil waters. The term “fossil” describes water that has been present for several thousand years. These aquifers became saturated more than 10,000 years ago and are no longer being recharged.

　　Water does not remain immobile in an aquifer but can seep out at springs or leak into other aquifers. The rate of movement may be very slow: in the Indus plain, the movement of saline (salty) ground waters has still not reached equilibrium after 70 years of being tapped. The mineral content of groundwater normally increases with the depth, but even quite shallow aquifers can be highly saline.

　　Paragraph 1：Rainfall is not completely absent in desert areas, but it is highly variable. An annual rainfall of four inches is often used to define the limits of a desert. The impact of rainfall upon the surface water and groundwater resources of the desert is greatly influenced by landforms. Flats and depressions where water can collect are common features, but they make up only a small part of the landscape.

　　1. Which of the following statements about annual rainfall can be inferred from paragraph 1?

　　○ Flat desert areas receive more annual rainfall than desert areas with mountains

　　○ Areas that receive more than four inches of rain per year are not considered deserts.

　　○ Many areas receive less than four inches of annual rainfall, but only a few are deserts

　　○ Annual rainfall has no impact on the groundwater resources of desert areas.

　　Paragraph 2：Arid lands, surprisingly, contain some of the world’s largest river systems, such as the Murray-Darling in Australia, the Rio Grande in North America, the Indus in Asia, and the Nile in Africa. These rivers and river systems are known as “exogenous” because their sources lie outside the arid zone. They are vital for sustaining life in some of the driest parts of the world. For centuries, the annual floods of the Nile. Tigris, and Euphrates, for example, has brought fertile silts and water to the inhabitants of their lower valleys. Today, river discharges are increasingly controlled by human intervention, creating a need for international river-basin agreements. The filling of the Ataturk and other dams in Turkey has drastically reduced flows in the Euphrates, with potentially serious consequences for Syria and Iraq.

　　2. The word drastically in the passage is closest in meaning to

　　○ obviously

　　○ unfortunately

　　○ rapidly

　　○ severely

　　3. In paragraph 2. Why does the author mention the Ataturk and other dams in Turkey?

　　○ To contrast the Euphrates River with other exogenous rivers

　　○ To illustrate the technological advances in dam building

　　○ To argue that dams should not be built on the Euphrates River

　　○ To support the idea that international river-basin agreements are needed

　　4. According to paragraph 2. Which of the following is true of the Nile River?

　　○ The Nile‘s flow in its desert sections is at its lowest during the dry season

　　○ The Nile’s sources are located in one of the most arid zones of the world

　　○ The Nile‘s annual floods bring fertile silts and water to its lower valley

　　○ The Nile’s periodic flooding hinders the growth of some crops

　　Paragraph 5：Deserts contain large amounts of groundwater when compared to the amounts they hold in surface stores such as lakes and rivers. But only a small fraction of groundwater enters the hydrological cycle-feeding the flows of streams, maintaining lake levels, and being recharged (or refilled) through surface flows and rainwater. In recent years, groundwater has become an increasingly important source of freshwater for desert dwellers. The United Nations Environment Program me and the World Bank have funded attempts to survey the groundwater resources of arid lands and to develop appropriate extraction techniques. Such programs are much needed because in many arid lands there is only a vague idea of the extent of groundwater resources. It is known, however, that the distribution of groundwater is uneven, and that much of it lies at great depths.

　　5. The word dwellers in the passage is closest in meaning to

　　○ settlements

　　○ farmers

　　○ tribes

　　○ inhabitants

　　6. Paragraph 5 supports all of the following statements about the groundwater In deserts EXCEPT:

　　○ The groundwater is consistently found just below the surface

　　○ A small part of the groundwater helps maintain lake levels

　　○ Most of the groundwater is not recharged through surface water

　　○ The groundwater is increasingly used as a source of freshwater

　　Paragraph 6：Groundwater is stored in the pore spaces and joints of rocks and unconsolidated (unsolidified) sediments or in the openings widened through fractures and weathering. The water-saturated rock or sediment is known as an “aquifer”. Because they are porous, sedimentary rocks, such as sandstones and conglomerates, are important potential sources of groundwater. Large quantities of water may also be stored in lime stones when joints and cracks have been enlarged to form cavities. Most limestone and sandstone aquifers are deep and extensive but may contain ground waters that are not being recharged. Most shallow aquifers in sand and gravel deposits produce lower yields, but they can be rapidly recharged. Some deep aquifers are known as “fossil waters. The term “fossil” describes water that has been present for several thousand years. These aquifers became saturated more than 10,000 years ago and are no longer being recharged.

　　7. The word fractures in the passage is closest in meaning to

　　○ streams

　　○ cracks

　　○ storms

　　○ earthquakes

　　8. According to paragraph 6. Which of the following statements about aquifers in deserts is true?

　　○ Water from limestone and sandstone aquifers is generally better to drink than water from sand and gravel aquifers

　　○ Sand and gravel aquifers tend to contain less groundwater than limestone or sandstone aquifers

　　○ Groundwater in deep aquifers is more likely to be recharged than groundwater in shallow aquifers

　　○ Sedimentary rocks, because they are porous, are not capable of storing large amounts of groundwater

　　9. According to paragraph 6. the aquifers called fossil“ waters

　　○ contain fossils that are thousands of years old

　　○ took more than 10.000 years to become saturated with water

　　○ have not gained or lost any water for thousands of years

　　○ have been collecting water for the past 10,000 years

　　Paragraph 7：Water does not remain immobile in an aquifer but can seep out at springs or leak into other aquifers. The rate of movement may be very slow: in the Indus plain, the movement of saline (salty) ground waters has still not reached equilibrium after 70 years of being tapped. The mineral content of groundwater normally increases with the depth, but even quite shallow aquifers can be highly saline.

　　10. The word immobile in the passage is closest in meaning to

　　○ enclosed

　　○ permanent

　　○ motionless

　　○ intact

　　11. The passage supports which of the following statements about water in the desert?

　　○ The most visible forms of water are not the most widespread forms of water in the desert.

　　○ Groundwater in the desert cannot become a source of drinking water but can be used for irrigation.

　　○ Most of the water in the desert is contained in shallow aquifers that are being rapidly recharged.

　　○ Desert areas that lack endogenous or exogenous rivers and streams cannot support life.

　　Paragraph 4：Regularly flowing rivers and streams that originate within arid lands are known as “endogenous.” These are generally fed by groundwater springs, and many issue from limestone massifs, such as the Atlas Mountains in Morocco. Basaltic rocks also support springs, notably at the Jabal Al-Arab on the Jordan-Syria border. ■Endogenous Rivers often do not reach the sea but drain into inland basins, where the water evaporates or is lost in the ground. ■Most desert streambeds are normally dry, but they occasionally receive large flows of water and sediment.■

　　Paragraph 5：Deserts contain large amounts of groundwater when compared to the amounts they hold in surface stores such as lakes and rivers. ■But only a small fraction of groundwater enters the hydrological cycle-feeding the flows of streams, maintaining lake levels, and being recharged (or refilled) through surface flows and rainwater. In recent years, groundwater has become an increasingly important source of freshwater for desert dwellers. The United Nations Environment Program me and the World Bank have funded attempts to survey the groundwater resources of arid lands and to develop appropriate extraction techniques. Such programs are much needed because in many arid lands there is only a vague idea of the extent of groundwater resources. It is known, however, that the distribution of groundwater is uneven, and that much of it lies at great depths.

　　12. Look at the four squares [■] that indicate where the following sentence could be added to the passage

　　These sudden floods provide important water supplies but can also be highly destructive.

　　Where would the sentence best fit?

　　13. Directions: Select from the seven sentences below, the two sentences that correctly characterize endogenous rivers and the three sentences that correctly characterize exogenous rivers. Drag each sentence you select into the appropriate column of the table. Two of the sentences will NOT be used. This question is worth 3 points.

　　Endogenous Rivers

　　●

　　●

　　Exogenous Rivers

　　●

　　●

　　●

　　Answer Choices

　　○ Their water generally comes from groundwater springs.

　　○ Their water is saltier than the water of most other rivers.

　　○ They include some of the world‘s largest rivers.

　　○ They originate outside the desert.

　　○ They often drain into inland basins and do not reach the sea.

　　○ They contain too much silt to be useful for irrigation

　　○ Their water flow generally varies with the season of the year.

　　参考答案：

　　1. ○2

　　2. ○4

　　3. ○4

　　4. ○3

　　5. ○4

　　6. ○1

　　7. ○2

　　8.○2

　　9. ○3

　　10. ○3

　　11. ○1

　　12. ○3

　　13. ○Endogenous Rivers 1 5

　　○Exogenous Rivers 3 4 7

　　沙漠中的水源

　　沙漠中并不是完全没有降雨，只不过是变数很大。通常一年以内降雨次数少于4次是定义沙漠的限定条件。降水对沙漠地表和地底的水资源的影响很大程度上取决于地貌。平原和洼地是水源聚集的共同地貌特征，不过他们只占地表的很小一部分。

　　令人惊奇的是，干旱地区往往都存在着世界上最大的河流流域，例如澳大利亚的墨累-达令河，北美洲的格兰德河，亚洲的印度河，以及非洲的尼罗河。这些河流被称作和所在的流域因为河的源头在干旱地区以外而被称为“外流河”。他们对于全世界沙漠地区的生命的存活至关重要。几个世纪以来，尼罗河每年都会定期泛滥。举个例子，幼发拉底河和底格里斯河都会把大量的肥沃的泥沙和水源带给下游低洼地带的居民。现在，河水的流量越来越多的受到人类的干涉，产生了国际性的河流流域的协议。阿卡杜克水坝以及其他一些建在土耳其境内的大坝就极大的减少了幼发拉底河的径流量，潜移默化的给叙利亚河和伊拉克造成了严重的后果。

　　外流河的径流量通常受季节影响。雨季过后，从外部流入沙漠区域的长河可以持续好几个月，以便保持干旱时节的相对较少的径流量。这虽然有助于灌溉，但是高温，低湿，以及干旱时节与众不同的日照时长，相比正常的生长季节也很难栽种一些作物。

　　通常发源地在干旱地区的河流和溪水被称为“内流河”。它们通常是又地下水的泉眼供给，也一些石灰岩断层中流出的水源供给，例如摩洛哥的阿特拉斯山。Basaltic岩石也提供源头水，比较著名的就是约旦和叙利亚交接的Jabal Al-Arab.内流河通常都不会到达大海而是注入内陆的低地的同时蒸发或者消失在地表。大多数沙漠的河床通常都是干枯的，偶有比较大的径流和沉积物。

　　相比于地表所的湖泊和河流含有的水量，沙漠中地下水的贮藏量要大得多。不过只有一小部分地下水参与了河流的水循环，保持湖泊的水位，并通过地表径流和降雨进行再造（再注入）。近些年来，地下水作为沙漠住民的活水来源的重要性日益加重。美国国家环境总署和世界银行开始拨款尝试调查统计干旱地区的地下水资源并发展合适的开采技术。像这样的工程非常必要因为在干旱地区对于地下水资源的保有量的概念非常模糊。然而可以确定的是，地下水资源的分布非常不均匀，且大多埋藏在很深的地底。

　　地下水一般储存在多孔道的地区和连接岩层的未凝固沉积层或者是通过风华和断裂形成的宽阔的孔洞。饱含水的岩石或沉积物被称为“蓄水层”。因为沉积岩的多孔性，比如砂岩和砾岩，都是地下水的重要潜在源头。大量的水资源也可能储存在石灰岩中，只要联结和裂口足够大到形成容器。大多数石灰岩和砂岩蓄水层很深且广大，但是保有的水资源是不能再生的。大多数沙石中的较浅的蓄水层只有较小的保有量，但是他们可以迅速的再生。一些深层的蓄水曾被称为“化石水”。“化石”的意思是说这里的水已经被保存了几千年之久。这些蓄水层充满水起码已经1万年以上了，而其他们在短期之内是无法再生的。

　　水在贮存在蓄水层中不是保持不流动的，而是通过泉眼或是渗漏进入其他的蓄水层，可以流动的比例可能很低；在印度平原，流动的含盐地下水在开发了70年以后依旧不能达到平静。矿石中保有的地下水通常会增加蓄水层的深度，但是较浅的安静蓄水层会饱含盐分。

　　1下列哪项推断符合第一段中年度降水的观点

　　沙漠的平原地区的年度降雨要比山地地区的多

　　每年降雨次数多于4次的地区不能被定义为沙漠

　　很多地区的降雨都小于四次，但是已有几个是沙漠

　　年度降雨对沙漠地区的地下水资源没有影响

　　2与文中“drastically”的意思最接近的是

　　明显的

　　迅速的

　　不幸的

　　急剧的

　　3文中第二段中，为啥作者要提到土耳其的包括阿卡图科水坝在内的大坝？

　　为了将幼发拉底河与其他外流河作对比

　　举例说明建大坝的技术优势

　　讨论大坝不应该建在幼发拉底河上

　　为了证明国际河流条例存在的必要性

　　4根据文章第二段，下列关于尼罗河的叙述正确的是？

　　尼罗河在沙漠地区的径流干旱季节是最低

　　尼罗河的源头位于世界上最干旱的地区

　　尼罗河的年度洪水给谷地带来肥沃的泥土

　　尼罗河的季节性泛滥妨碍了作物的生长

　　5与文中“dwellers”中意思最接近的是

　　稳定

　　老农

　　部落

　　居民

　　6下列对文中地下水的观点的支持哪一个是不对的？

　　地下水始终只在地下形成

　　地下水的一小部分用于保持河流水位

　　绝大多数地下无法通过地表水再生

　　地下水越来越多的被当作活水的来源

　　7于文中“fractures”意思最接近的是

　　溪流

　　裂口

　　风暴

　　地震

　　8根据文中第六段，下列关于沙漠中蓄水层的观点哪一个是正确的？

　　石灰岩和砂岩的蓄水层中的水通常比砂石蓄水曾中的水更好喝

　　沙石蓄水层保有的地下水比石灰岩和砂岩所保有的地下水少

　　深层地下水要比浅层地下水更容易再生

　　由于沉积岩的多孔性，所以他们不能作为保有大量地下水的容器

　　9根据文中第六段，被称为“化石水”的蓄水层

　　保存了好几千年的化石

　　注满水资源要用掉1万年

　　好几千年不再获取水分，也不在丢失水分

　　在过去的1万年里不断的蓄水

　　10与文中所指“immobile”意思相近的是

　　包围

　　固定

　　不动

　　完整无缺的

　　11下列选项中哪项支持了文章关于沙漠中水源的观点

　　视线可见的地表水只是沙漠中蕴含的水量的一小部分

　　沙漠中的地下水不能喝但是能用于灌溉

　　沙漠中的绝大部分浅层地下水可以迅速再生

　　沙漠地区由于缺少外流河喝内流河而没有生命

　　12看见文中抠出的四个[■]，指出下面这句话最应该搁在哪？

　　这种突如其来的洪水带来了重要的水源供应同时也造成很大的破坏

　　小朋友们，哪个坑最合适？

　　13提示：从下面的7个备选答案中选出两个正确的对内流河特点的描述以及3个对外流河特点的描述。把你选的拖到紧邻的空里。7句话中，有两句是没有意义的。这题3分

　　内流河

　　外流河

　　备选答案

　　这些水通常来自地下水的喷涌

　　这些水要比其他河流的水含盐量高

　　它们包括很多世界上最大的河流

　　它们的源头都在沙漠以外

　　它们通常流入低地而到不了海洋

　　它们携带大量的可以用于灌溉的泥沙

　　它们的径流量随季节不同而变化