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
48
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、the soil is too hard.
B、the soil is too hot.
C、plants use it up.
答案
C
解析
转载请注明原文地址:https://kaotiyun.com/show/vyAO777K
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
Thedriestcontinentsis______
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
根据《水利水电工程设计工程量计算规定》,永久建筑物初步设计阶段模板工程量系数为()。
宣传招牌安置在门店所在建筑物的正面,用以表示店名。()
路面上的菱形块虚线是何含义?
患者,男,55岁。自觉饱胀,食少,乏力,神疲气短,面黄肌瘦,久泻不止。医生诊断后开处方:薏苡仁(炒)240g,山药180g,白术、莲子、扁豆、当归、砂仁、陈皮、青皮、神曲、山楂、麦芽(炒)各20g,人参、茯苓、木香各90g,枳壳、甘草各60g。煎煮此方
用药后能在较长时间内持续释放药物以达到延长药效目的制剂是药物能在设定的时间内自动地以设定的速度释放的制剂是
某项目建筑工程费5500万元,设备及工器具购置费12000万元,安装工程费3500万元,工程建设其他费用9600万元,建设期各年价格上涨指数均为5%,项目建设期2年,各项费用的第一年和第二年的分年投入比例为4:6,该项目的涨价预备费为()万元。
假设甲公司的固定成本占总成本比例高于乙公司固定成本占总成本比例,且两家公司的周期性、资本结构相似,下列正确的是()。
总经理:我主张小王和小孙两人中至少提拔1人。董事长:我不同意。以下哪项最为准确地表述了董事长实际上同意的意思?
HowlonghadPopeJohnPaulbeenleadingtheRomanCatholicChurch?
Shesawtheadvertisementandwrotealetterloapplyforthe______.
最新回复
(
0
)