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 driest continents is______
The driest continents is______
admin
2014-02-25
72
问题
The driest continents is______
LECTURER
Good morning. This morning we are continuing our look at Australia and its natural problems. Actually dryness, or aridity, as it is generally called by geographers, is probably the most challenging of Australia’s natural problems and so it is very important in this course for you to have a good understanding of the subject. For Australia, water is a precious resource and its wise management is of the greatest importance.
As I have said, Australia is a dry continent, second only to Antarctica in its lack of rainfall. Long hours of hot sunshine and searing winds give Australia an extremely high rate of evaporation, far more than in most other countries. It is estimated that approximately 87% of Australia’s rainfall is lost through evaporation, compared with just over 60% in Europe and Africa and 48% in North America. You generally think of Africa as being a very hot and dry place, but it is not in comparison with Australia. In many parts of Australia standing water, that is dams, puddles and so forth, dry up rapidly and some rainfall barely penetrates the soil. The reason for this is that the moisture is absorbed by thirsty plants.
Some parts of Australia are dry because rainwater seeps quickly through sandy soils and into the rock below. In parts of Australia this water which seeps through the sandy soil collects underground to form underground lakes. Water from these subterranean lakes can be pumped to the surface and tapped and so used for various purposes above the ground. In fact, extensive underground water resources are available over more than half of Australia’s land area, but most of the water is too salty to be used for human consumption or for the irrigation of crops. However, most inland farmers do rely on this water for watering their animals and, where possible, to a lesser extent for irrigation.
Underground water can flow very large distances and can be kept in underground reservoirs for a very long time. Water from these underground reservoirs bubbles to the surface as springs in some parts of the country, and these rare sources of permanent water were vital to early explorers of inland Australia, and to other pioneers last century, who used the springs for survival. But in many places levels have fallen drastically through continuous use over the years. This has necessitated the pumping of the water to the surface. Remarkably, underground water sources in Australia supply about 18% of total water consumption. So you can see it is quite an important source of water in this dry land.
So most of the consumption of water in Australia comes from water which is kept above ground. More than 300 dams regulate river flows around the country. The dams store water for a variety of functions, the rural irrigation of crops, without which many productive areas of the country would not be able to be farmed; the regulation of flooding, a serious problem which will be dealt with later in the course; and last but not least, the harnessing of the force of gravity for the generation of electricity.
That is all we have time for this morning, but you will be able to do further study on this important area in the library. I have a handout here with references on the subject, so if you are interested, please come up to the desk and take a copy.
Next week’s lecture is a case study of an outback farm and it will be going into detail about some of the problems we discussed here...
选项
A、evaporate quickly.
B、seep down to rock.
C、wash the soil away.
答案
B
解析
转载请注明原文地址:https://www.kaotiyun.com/show/SyAO777K
本试题收录于:
雅思听力题库雅思(IELTS)分类
0
雅思听力
雅思(IELTS)
相关试题推荐
Withinthenextdecade,sophisticatedtelescopesnoworbitingtheEarthwilldeterminewhetherthecontinentsreallyaremoving,
Thedriestcontinentsis______
Thedriestcontinentsis______
Thedriestcontinentsis______
AUSTRALIAGeographyThedriestcontinentis【L31】________Australiaisabout【L32】________timeslargerthanBritain.Threemains
AUSTRALIAGeographyThedriestcontinentis【L31】________Australiaisabout【L32】________timeslargerthanBritain.Threemains
AUSTRALIAGeographyThedriestcontinentis【L31】________Australiaisabout【L32】________timeslargerthanBritain.Threemains
AUSTRALIAGeographyThedriestcontinentis【L31】________Australiaisabout【L32】________timeslargerthanBritain.Threemains
随机试题
患者,男,64岁。主诉“食物嵌塞五年”,口腔检查发现:前牙深覆,双侧后牙牙尖低平,面几乎为平面,牙本质暴露,咬合紧密;邻接呈平面状接触,近远中径减小;牙龈退缩,牙根暴露。自述有长期夜磨牙习惯影响患者的咀嚼效率降低的原因不包括
药品临床评价的意义()。
金融机构对于房地产抵押物的情况要按()等要求进行审查确定。
根据要求,证券指数的编制遵循的原则是()。
在利率体系中起主导作用、能带动和影响其他各种利率的利率是指()。
2017年3月4日,甲公司为履行与乙公司的货物买卖合同,签发一张商业汇票交付乙公司。汇票收款人为乙公司,由Q银行承兑,到期日为9月4日。7月9日,乙公司财务人员不慎将该汇票丢失,于当日同时申请挂失止付和公示催告。7月10日,法院通知Q银行停止支付并发出公告
注册会计师在确定是否有必要实施函证以获取认定层次充分、适当的审计证据时,应当考虑()因素。
诱导训练法是指运动员有意识地、积极地利用头脑中已经形成的运动表象或充分利用表象进行训练的方法。()
中共十五大把同马克思列宁主义、毛泽东思想一道确立为中国共产党的指导思想的是
Manyteachersbelievethattheresponsibilitiesforlearningliewiththestudent.【21】______alongreadingassignmentisgiv
最新回复
(
0
)