首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
"The Hydrologic Cycle" →The hydrologic cycle is the transfer of water from the oceans to the atmosphere to the land and back
"The Hydrologic Cycle" →The hydrologic cycle is the transfer of water from the oceans to the atmosphere to the land and back
admin
2012-01-14
35
问题
"The Hydrologic Cycle"
→The hydrologic cycle is the transfer of water from the oceans to the atmosphere to the land and back to the oceans. The processes involved include evaporation of water from the oceans; precipitation on land; evaporation from land; and runoff from streams, rivers, and subsurface groundwater.
The hydrologic cycle is driven by solar energy, which evaporates water from oceans, freshwater bodies, soils, and vegetation.
Of the total 1.3 billion km water on Earth, about 97% is in oceans, and about 2% is in glaciers and ice caps. The rest is in freshwater on land and in the atmosphere. Although it represents only a small fraction of the water on Earth, the water on land is important in moving chemicals, sculpturing landscape, weathering rocks, transporting sediments, and providing our water resources. The water in the atmosphere-only 0.001% of the total on Earth-cycles quickly to produce rain and runoff for our water resources.
Especially important from an environmental perspective is that rates of transfer on land are small relative to what’s happening in the ocean. For example, most of the water that evaporates from the ocean falls again as precipitation into the ocean. On land, most of the water that falls as precipitation comes from evaporation of water from land. This means that regional land-use changes, such as the building of large dams and reservoirs, can change the amount of water evaporated into the atmosphere and change the location and amount of precipitation on land-water we depend on to raise our crops and supply water for our urban environments. Furthermore, as we pave over large areas of land in cities, storm water runs off quicker and in greater volume, thereby increasing flood hazards. Bringing water into semi-arid cities by pumping groundwater or transporting water from distant mountains through aqueducts may increase evaporation, thereby increasing humidity and precipitation in a region.
Approximately 60% of water that falls by precipitation on land each year evaporates to the atmosphere. A smaller
component
(about 40%) returns to the ocean surface and subsurface runoff. A This small annual transfer of water supplies resources for rivers and urban and agricultural lands. B Unfortunately, distribution of water on land is far from uniform. C As human population increases, water shortages will become more frequent in arid and semi-arid regions, where water is naturally nonabundant. D
→At the regional and local level, the
fundamental
hydrological unit of the landscape is the drainage basin (also called a watershed or catchment). A drainage basin is the area that contributes surface runoff to a particular stream or river. The term drainage basin is usually used in evaluating the hydrology of an area, such as the stream flow or runoff from hill slopes. Drainage basins vary greatly in size, from less than a hectare (2.5 acres) to millions of square kilometers. A drainage basin is usually named for its main stream or river, such as the Mississippi River drainage basin.
→The main process in the cycle is the global transfer of water from the atmosphere to the land and oceans and back to the atmosphere. Together, the oceans, ice caps and glaciers account for more than 99% of the total water, and both are generally unsuitable for human use because of salinity (seawater) and location (ice caps and glaciers). Only about 0.001% of the total water on Earth is in the atmosphere at any one time. However, this relatively small amount of water in the global water cycle, with an average atmospheric residence time of only about 9 days, produces all our freshwater resources through the process of precipitation.
→ On a global scale, then, total water abundance is not the problem; the problem is water’s availability in the right place at the right time in the right form. Water can be found in either liquid, solid, or gaseous form at a number of locations at or near Earth’s surface. Depending on the specific location, the residence time may vary from a few days to many thousands of years. However, as mentioned, more than 99% of Earth’s water in its natural state is unavailable or unsuitable for beneficial human use. Thus, the amount of water for which all the people, plants, and animals on Earth compete is much less than 1% of the total.
As the world’s population and industrial production of goods increase, the use of water will also accelerate. The world per capita use of water in 1975 was about 185,000 gal/yr. And the total human use of water was about 1015 gal/yr. Today, world use of water is about 6,000, which is a
significant
fraction of the naturally available freshwater.
The word significant in the passage is closest in meaning to
选项
A、rare
B、small
C、important
D、regular
答案
C
解析
In this passage, important is a synonym for "significant." Context comes from the numbers in the fraction.
转载请注明原文地址:https://jikaoti.com/ti/zNlYFFFM
0
托福(TOEFL)
相关试题推荐
Arestaurantmay______foritsdeliveryservice.ThespeakerdescribestheatmosphereatBritishpubsas______.
Harborsare(protected)areas(ofwater)thatcanbe(usedthe)transferofpassengersandcargo(between)shipsshore.
Thewaterof(the)Atlantic,Pacific,andIndianOceans(makeup)70.8percent(to)theEarth’s(surface).
NarratorListentoapartofalectureinanecologyclass.Whatcanbeinferredaboutplantsinthehydrologiccycle?
"TheHydrologicCycle"→Thehydrologiccycleisthetransferofwaterfromtheoceanstotheatmospheretothelandandback
"TheHydrologicCycle"→Thehydrologiccycleisthetransferofwaterfromtheoceanstotheatmospheretothelandandback
"TheHydrologicCycle"→Thehydrologiccycleisthetransferofwaterfromtheoceanstotheatmospheretothelandandback
随机试题
传统的行政科学认为进行行政改革的关键是说服掌握政府机器的_________。
A.鳞状上皮被柱状上皮取代B.发生消化性溃疡C.二者均是D.二者均非(2002年)Barrett食管是指
腹泻时的护理措施包括()
某非法吸收公众存款刑事案件,因涉及人数众多,影响面广,当地领导私下曾有“必须重判”的说法。①主审李法官听此说法即向院长汇报。②开庭时,李法官对律师提出的非法证据排除的请求不予理睬。③李法官对刘检察官当庭反驳律师无罪辩护意见、严斥该律师立场有问题的做法不予制
业主委托房地产估价机构评估该宾馆的抵押价值。下列关于房地产抵押贷款风险的表述中,正确的是()。如果该宾馆的财务数据能客观反映同类宾馆的客观经营状况和经营收益,则在运用收益法评估该宾馆的价值时()。
下列各项中,应计入增值税应税销售额的有()。
输入学生的学习成绩,如果成绩大于等于90,输出A;如果成绩在60和89之间,输出B;如果成绩小于60,输出C。利用条件运算符编写程序完成以上判断。
下列描述中正确的是
[A]park[B]music[C]library[D]taxi[E]worker[F]subjects[G]hotelManypersonslikelisteningtoit.
Forthispartyouareallowed30minutestowriteacompositionofnolessthan100wordsonHowtoGetaBetterJob.Remembery
最新回复
(
0
)