Dirty River But Clean Water Reading Answer
IELTS Academic Reading PassageA
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.
D
This lack of flooding has harmed local wildlife. The humpback chub,for example, thrived in the rust-redwaters of the Colorado. Recently, though, its population has crashed. At first sight, it looked as if the reason was that the chub were being eaten by trout introduced for sport fishing in the mid-20th century. But trout and chub co-existed until the Glen Canyon dam was built, so something else is going on. Steve Gloss, of the United States’ Geological Survey (USGS), reckons that the chub’s decline is the result of their losing their most valuable natural defense, the Colorado’s rusty sediment. The chub were well adapted to the poor visibility created by the thick, red water which gave the river its name, and depended on it to hide from predators. Without the cloudy water the chub became vulnerable.
E
And the chub are not alone. In the years since the Glen Canyon dam was built, several species have vanished altogether. These include the Colorado pike-minnow, the razorback sucker and the round-tail chub. Meanwhile, aliens including fathead minnows, channel catfish and common carp, which would have been hard, put to survive in the savage waters of the undammed canyon, have move din.
F
So flooding is the obvious answer. Unfortunately, it is easier said than done. Floods were sent down the Grand Canyon in 1996 and 2004 and the results were mixed. In 1996 the flood was allowed to go on too long. To start with,all seemed well. The floodwaters built up sandbanks and infused the river with sediment. Eventually, however, the continued flow washed most of the sediment out of the canyon. This problem was avoided in 2004, but unfortunately, on that occasion, the volume of sand available behind the dam was too low to rebuild the sandbanks. This time, the USGS is convinced that things will be better. The amount of sediment available is three times greater than it was in 2004. So if a flood is going to do some good, this is the time to unleash one.
G
Even so, it may turn out to be an empty gesture. At less than 1,200 cubic metres a second, this flood is smaller than even an average spring flood, let alone one of the mightier deluges of the past. Those glorious inundations moved massive quantities of sediment through the Grand Canyon,wiping the slate dirty, and making a muddy mess of silt and muck that would make modern river rafters cringe.
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.
Questions 8-13
Complete the summary below.
Choose NO MORE THAN TWO WORDS from the passage for each answer.
Write your answers in boxes 8-13 on your answer sheet.
The eco-impact of the Canyon Dam
Floods are people’s nightmare. In the past, canyon was raged by flood every year. The snow from far Wyoming would melt in the season of 8…………………. and caused a flood flow peak in Colorado river. In the four decades after people built the Glen Canyon dam, it only could gather 9…………………. together from tiny, undammed tributaries.
Humpback chub population on reduced, why?
Then, several species disappeared including Colorado pike-minnow, 10…………………. and the round-tail chub. Meanwhile, some moved in such as fathead minnows, channel catfish and 11…………………. The non-stopped flow leaded to the washing away of the sediment out of the canyon, which poses great threat to the chubs because it has poor 12………………… away from predators. In addition, the volume of 13………………… available behind the dam was too low to rebuild the bars and flooding became more serious.
Solution for: Dirty River But Clean Water Reading Answer
1. NOT GIVEN | 8. spring |
2. FALSE | 9. sediment |
3. TRUE | 10. razorback sucker |
4. FALSE | 11. common carp |
5. TRUE | 12. visibility |
6. TRUE | 13. sand |
7. NOT GIVEN |
Latest Academic Reading Passages
The Bridge That Swayed Reading Answer
1. When the London Millennium footbridge was opened in June 2000, it swayed alarmingly. This generated huge public interest and the bridge became known as London's "wobbly bridge". 2. The Millennium Bridge is the first new bridge to...
The Bite That Heat Reading Answer
Scientists are unlocking the medical potential of venom. A Michael decided to go for a swim. He was on vacation with his family in Guerrero, Mexico, and it was hotter than blazes. He grabbed his swimming trunks from where they’d been drying on...
The Birth Of Scientific English Reading Answer
World science is dominated today by a small number of languages, including Japanese, German and French, but it is English which is probably the most popular global language of science. This is not just because of the importance of English-...
The Birds Of London Reading Answer
There are more than two hundred different species and sub-species of birds in the London area, ranging from the magpie to the greenfinch, but perhaps the most ubiquitous is the pigeon. It has been suggested that the swarms of feral pigeons are...
The Benefits Of Being Bilingual Reading Answer
A According to the latest figures, the majority of the world’s population is now bilingual or multilingual, having grown up speaking two or more languages. In the past, such children were considered to be at a disadvantage compared with their...
No Results Found
The page you requested could not be found. Try refining your search, or use the navigation above to locate the post.