托福 托福 12 - Water in the Desert
题目
1 2 3 4 5 6 7 8 9 10 11 12 13
10.The word “immobile” in the passage is closest in meaning to
  • A.enclosed
  • B.permanent
  • C.motionless
  • D.intact
  • 正确答案:
    答案解析:
    答题统计
    答题统计

    登录 后才可以查看答案解析,还没有账号?

    还没有账号?马上 注册 >>

    阅读原文 中文译文

    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, have 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 humidities, 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 limestones when joints and cracks have been enlarged to form cavities. Most limestone and sandstone aquifers are deep and extensive but may contain groundwaters 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) groundwaters 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.

    沙漠中并不是完全没有降雨,只不过变数很大。通常年降水量100毫米以下是界定沙漠地区的条件。降水对沙漠地区地表和地下水资源的影响很大程度上取决于地貌。平原和洼地的共同特征是水源聚集,但是它们在地貌中所占比重很小。 令人惊奇的是,一些世界最大的河系都位于干旱地区,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。这些河流及河系因为源头位于干旱地区以外而被称为“外流河”。对世界上一些最干旱地区来说,它们哺育生命,意义重大。例如,几个世纪以来,尼罗河、底格里斯河和幼发拉底河每年都会泛滥洪水会为下游低洼地带的居民带来大量肥沃的泥沙和水源。现在,河水流量越来越多的受到人类的干预,因而有必要签署国际性的河流流域协议。阿塔图尔克大坝以及土耳其境内的其它大坝的蓄水极大地减少了幼发拉底河的径流量,可能会给叙利亚和伊拉克带来严重后果。 “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,以便洪峰可以出现在旱季。这虽然利于灌溉,但是高温度、低湿度,加上旱季独特的昼长,相比正常生长季节依然很难种植一些农作物。 通常发源于干旱地区的河流和溪水被称为“内陆河”。它们主要是由地下水泉补给,很多出口来自石灰岩断层,例如摩洛哥的阿特拉斯山脉。玄武岩同样可以提供地下水泉,最具代表性的是约旦和叙利亚边界的Jabal Al-Arab河.内陆河通常都不能流入大海而是注入内陆盆,蒸发掉或者消失在地表。大多数沙漠河床通常都是干涸的,但偶有较大径流和沉积物。 相比于湖泊和河流等地表水,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水循环——补给河流径流量,维持湖泊水位,并通过地表径流和降雨进行再次补给(再注入)。近些年来,地下水作为沙漠住民的淡水来源,重要性日益突显。美国国家环境总署和世界银行开始拨款着手调查干旱地区的地下水资源并开发合适的开采技术。这些项目非常有必要,因为在很多干旱地区对于地下水资源的程度概念非常模糊。然而可以确定的是,地下水资源分布非常不均匀,且大部分埋藏较深。 地下水一般贮存于岩石孔隙、节理、松散沉积物或者断裂和风化作用形成的孔洞。饱含水的岩石或沉积物被称为“蓄水层”。因为沉积岩多孔,比如砂岩和砾岩,都是地下水的重要潜在源头。只要节理和裂缝扩大形成容器,石灰岩中也能够储存大量水资源。大部分石灰岩和砂岩蓄水层深广,但是储存的水资源不可再生。大多数沙石中较浅的蓄水层贮水量少,但可以迅速再生。一些深层地下水被称作“化石水”。用“化石”来形容水,这就意味着这些水已经存在了千年之久。这些蓄水层注满水起码已经1万年以上了,而其无法再生。 贮存在蓄水层的水并非不流动,而是会通过泉眼渗出或是进入其他蓄水层,可以流动水的比例可能很低:在印度河平原,流动的含盐地下水在开采了70年之后依旧不能达到平衡。正常情况下,地下水的矿物含量随着深度的增加而增加,,但是即使很浅的蓄水层中可能含盐量也很高。 阿特拉斯山脉(阿尔卑斯山系的一部分) 节理:岩石中的裂隙,其两侧岩石没有明显的位移。地壳上部岩石中最广泛发育的一种断裂构造。

    留言区中有很多我们对问题的解答喔, 登录后可以查看

    还没有账号?马上 注册 >>

    最新提问
    • wx_6697
      觉得B C 意思一样,不知道选哪个
    • wx_5576
      这道题C为什么对,E为什么不对?
    • wx_5576
      B为什么不能选啊?
    • wx_6697
      TPO30 passage 2 Q5我选的 D,不明白为啥不对?
    • wx_6697
      鑫哥,TPO6passage3Q5 答案是给错了吗?好多人都选A
    • wx_6697
      这题也很容易选错选成了D
    • wx_6697
      这道题A为什么错了
    • 芊儿
      为什么这道题不选c??a中的variety不是应该对应文中的differentiating 吗??求解!
    • wx_1000
      这道题不选E是因为太细节了吗
    • 王金阁
      这个题为什么不选C啊。。。
    • 芊儿
      这道题的D选项不是和文中的better able to reproduce in open settings相对应么??
    • 风荨火
      有大佬解释一下这个为啥选D嘛?
    • 以沫
      请问这个D 在哪里提现?为什么D错?
    • 芊儿
      第六题 的C选择为什么不对,感觉A是明显驳斥啊...
    • wx_6697
      鑫哥,这道题D是从哪里看出来的
    • wx_6697
      这题选的A,根据是Joly’s calculations clearly supported those geologists who insisted on an age for Earth far in excess of a few million years.想问鑫哥为啥不选A
    • wx_6697
      这题我选的是C依据是into a new habitat outside of its natural range, it may adapt to the new environment and leave its enemies behind.C为啥错了呢?鑫哥
    • wx_8861
      F选项的weather-related destruction在哪里体现了呢?原文最后一段的开头Among the costs里的costs是不是打错了?应该是coast?
    • wx_6697
      求问这道题B为啥不选,原文依据:viable seeds of pioneer species can be found in large numbers on some forest floors.
    • 与托福的斗争史
      与托福的斗争史 去解答 去解答
      这题为什么选C?
    • 小雨淅沥哗啦的下
      小雨淅沥哗啦的下 去解答 去解答
      B哪里错了
    • 小雨淅沥哗啦的下
      小雨淅沥哗啦的下 去解答 去解答
      B为啥不对
    • 李浩然
      B选项错误,是因为残缺么?
    • wx_100
      请问在做题的时候如何排除c呢。看了答案,感觉是该选a的,但是当时做题脑子一热,就特别钟爱c,也没看其他选项。。求敲醒。。
    • wx xxxxx
      请问鑫哥,这段开头有写As one pesticide replaces another为什么不是对应a new pesticide is developed?
    • wx_7695
      鑫哥,从哪里看出来这个masks 不是use呀,原文说了wear呀
    • haiyuqiao
      @鑫哥,这题the damage will continue 不应该对应前面的 the target species evolves resistance to it,然后As one pesticide replaces another,不应该是结束了time cycle 吗
    • wx_2065
      鑫哥,想知道E错在哪里?
    • wx_7695
      鑫哥,B选项 cannot extended to earlier geological periods. 原文说的意思是后来的进化无法估计吧
    • wx_2163
      B为什么不选
    • wx_7780
      鑫哥,这个哪里看不use了。BD是修饰错,C是无中生有,怎么能直接选出A?
    • 100
      看到第一句话,以为是中心句就选了A... 为什么不能选A呢
    • 100
      为什么选b?
    • gu33
      请问下 这里选D的原因是 因为 evolutionary approach 对应着 原文的 Rates of evolution 嘛? 这里我选了C。。不是很懂 插入句和 D的关系 求解答
    • 我是啦啦啦
      我是啦啦啦 去解答 去解答
      这个题A哪里错了?是因为主语不对吗?这个C比A多一步推理啊
    • haiyuqiao
      鑫哥,D选项里的19世纪出现了很多假设,原文中并没有提到啊
    • wx_7060
      为什么选a 呢。我觉得a是细节。F哪错了?
    • wx_1105
      我想问一下,这道题为什么不能选A呢?
    • wx_8122
      D为什么不选
    • wx_1655
      f选项哪里说了
    • chaulaw
      鑫哥,原文是below经济损害水平,D是一触发经济损害就用,这也对吗?
    • chaulaw
      interclan婚姻是对的吗?不是只在自己的family结婚扩大家族吗?
    • wx_6697
      鑫哥,这道题答案是不是错了,好多人选D 我也选的D求解答
    • wx_6697
      这道题应该是一道易错题,每个选项的都有,然而我选的A错了,求解
    • wx_6697
      鑫哥,这题的C是怎么得到的?B也没有找到啊?难道不是应该选B
    • wx_6697
      鑫哥,还有这个,好多人选A答案是不是错了
    • wx_6697
      求问D是从哪里得出来的,我选的B呀哎呀
    • wx_4185
      it is difficult to say how far they were intended to be portraits rather than generalized images 这句话怎么理解呢
    • 此楠楠
      请问下这个插入题怎么选的呢?
    • 此楠楠
      求鑫哥讲解下A选项。。。 Even though in error, Joly’s calculations clearly supported those geologists who insisted on an age for Earth far in excess of a few million years.