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
Scientists say there has been a severe decrease in the amount of water in Lake Chad in northern Africa in the last thirty years.
Scientists say there has been a severe decrease in the amount of water in Lake Chad in northern Africa in the last thirty years.
admin
2007-01-12
104
问题
Scientists say there has been a severe decrease in the amount of water in Lake Chad in northern Africa in the last thirty years. They reported that nature and humans share equal blame for this loss.
In 1963, the fresh-water lake covered 25, 000 square kilometers. Now the lake is only about five percent of that size. It measures only about 1, 300 square kilometers in the dry season.
Four nations surround Lake Chad. People in Niger, Nigeria, Chad, and Cameroon use it for water, fish and plant life.
Michael Coe and Jonathan Foley, water experts at the University of Wisconsin in Madison, reported on Lake Chad in a science journal. They say the area has suffered from a lack of heavy rain for more than thirty years. This has forced people to build systems to carry water to dry land. These irrigation systems further decrease the amount of lake water.
Mr. Coe says Lake Chad will be only a small body of water in the future. He says people still can get water from the lake to drink and for crops. But he says the lake will no longer provide a healthy environment for fish and plant life.
The researchers used a computer to study what caused the water loss. Their computer study estimated the climate and amount of water in the area. The estimate started with written records from the early 1960s. Then the researchers compared the estimates with the area’s recorded climate and water supply for the same period.
The computer study showed results similar to the recorded ones for the first twenty years. But there was a big change in the 1980s. At the time, the lake got smaller much faster than the computer research had estimated.
The researchers say that major irrigation systems were built in the 1980s. The systems took water from two rivers that flow into Lake Chad. The Chari and Logone rivers carry most of the water that enters the lake. The study showed that the increased irrigation reduced the flow in the two rivers. Climate changes also were responsible for the reduction. The flow of the two rivers was reduced by almost seventy-five percent.
Scientists say the problem is expected to worsen in the coming years as the population and demand for water continued to increase.
When did the scientists find that Lake Chad got smaller much faster?
选项
答案
In the 1980s
解析
(文章倒数第三段指出The computer study showed results similar to the recorded ones for the first twenty years.But there was a big change in the 1980s.“此次利用计算机进行研究的结果与二十年前第一次记录的结果相似,但是有一个很大的变化。”因而可知第一次对乍得湖进行研究的时间是19世纪80年代。)
转载请注明原文地址:https://kaotiyun.com/show/yukK777K
本试题收录于:
D类竞赛(专科)题库大学生英语竞赛(NECCS)分类
0
D类竞赛(专科)
大学生英语竞赛(NECCS)
相关试题推荐
Whichofthefollowingphrasesindicatesasubject-predicaterelationship?
Thescientistshaveabsolutefreedomastowhatresearchtheythinkisbestto______.
Thestudents_______busilywhenMissBrownwenttogetabookshe_______intheoffice.
Itisannouncedthatawallethasbeenfoundandcanbe______atthemanager’soffice.
Shouldyoungpeoplecontinuetolivewiththeirparentsafterfindingajob?Thisissuehasbeenintenselydiscussedforyears.
Sleep1.Howmuchsleepdoweneed■Recommendedamountforadults:【T1】______hours【T1】______2.Waysforabetterni
Inthesentence"LettingahundredflowersblossomandahundredWschoolsofthoughtcontendisthepolicyforpromotingthepro
PASSAGEONEWhatcan"theconceptofartimposedbythetriumphofModernism"(Para2)bebestdescribedas?
A.dataB.getaccustomedC.effectD.sparedE.solveF.associatedG.details
InwhichsubjectdidJaneWestmacottgetthebestGCSEGrade?
随机试题
简述副交感神经到达盆腔脏器的途径。
有关舒张试验的描述,不正确的是
应增加摄影管电压值的病理因素有
前腭杆的前缘应
某铁路工程A标段长度为30km,包括路基土石方50000m3,大桥1座,小桥涵10座。铺轨架梁由建设单位单独发包。路基工程中,里程DK0+000~DK9+000主要为路基挖方,DK9+000~DK11+000段为1座特大桥,DK11+000~DK18+00
某公司人群3天的膳食调查中,能量供给量为2100kcal的有10人,2400kcal的有12人,2600kcal的有18人,该人群蛋白质平均摄入量为72g/人.日。计算该人群的混合系数。
APowerfulInfluenceTherecanbenodoubtatallthattheInternethasmadeahugedifferencetoourlives.Parentsareworr
把下面的六个图形分为两类,使每一类图形都有各自的共同特征或规律,分类正确的一项是:
有关系R、S和T,如下图所示,关系T是由关系R和S通过运算得出,则所使用的操作是
France
最新回复
(
0
)