2020年9月17日雅思阅读真题+题目+答案：Dirty River But Clean Water

2020年9月17日雅思阅读真题+题目+答案：Dirty River But Clean Water

Floods can occur in rivers when the flow rate exceeds the capacity of the river channel, particularly at bends or meanders in the waterway. Floods often cause damage to homes and businesses if they are in the natural flood plains of rivers. While riverine flood damage can be eliminated by moving away from rivers and other bodies of water, people have traditionally lived and worked by rivers because the land is usually flat and fertile and because rivers provide easy travel and access to commerce and industry.

A   Fire and flood are two of humanity’s worst nightmares. People have,therefore,always sought to control them. Forest fires are snuffed out quickly. The flow of rivers is regulated by weirs and dams. At least, that is how it used to be. But foresters have learned that forests need fires to clear out the brash and even to get seeds to germinate. And a similar revelation is now – dawning on hydrologists. Rivers – and the ecosystems they support – need floods. That is why a man-made torrent has been surging down the Grand Canyon. By Thursday March 6th it was running at full throttle, which was expected to be sustained for 60 hours.

B   Floods once raged through the canyon every year. Spring Snow from as far away as Wyoming would melt and swell the Colorado river to a flow that averaged around 1,500 cubic metres (50,000 cubic feet) a second. Every eight years or so, that figure rose to almost 3,000 cubic metres. These floods infused the river with sediment, carved its beaches and built its sandbars.

C   However, in the four decades since the building of the Glen Canyon dam, just upstream of the Grand Canyon, the only sediment that it has collected has come from tiny, undammed tributaries. Even that has not been much use as those tributaries are not powerful enough to distribute the sediment in an ecologically valuable way.

。。。。。余下雅思阅读真题原文省略！

Questions 1-7

Do the following statements agree with the information given in Reading Passage?

In boxes 1-7 on your answer sheet, write

TRUE             if the statement agrees with the information

FALSE            if the statement contradicts the information

NOT GIVEN   if there is no information on this

1 Damage caused by fire is worse than that caused by flood.

2 The flood peaks at almost 1500 cubic meters every eight years.

3 Contribution of sediments delivered by tributaries has little impact.

4 Decreasing number of chubs is always caused by introducing of trout since mid 20th century.

5 It seemed that the artificial flood in 1996 had achieved success partly at the very beginning.

6 In fact, the yield of artificial flood water is smaller than an average natural flood at present.

7 Mighty floods drove fast moving flows with clean and high quality water.

。。。。。余下雅思阅读真题题目及答案省略！

2020年9月17日雅思阅读真题+题目+答案：Dirty River But Clean Water，10元有偿下载完整版！