IELTS Reading Summary Completion Topic 5

Dirty River But Clean Water

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. These floods infused the river with sediment, carved its beaches and built its sandbars. 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. This lack of flooding has harmed local wildlife. 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 to survive in the savage waters of the undammed canyon, have moved in. 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. 

Questions 1-4

Complete the summary below.

Choose No More Than Two Words from the passage for each answer. Write your answers in the blank spaces next to 1-4 on your answer sheet.

The snow from far Wyoming would melt in the season of 1…………………… and caused a flood flow peak in the Colorado river. In the four decades after people built the Glen Canyon Dam, it only could gather 2…………………… together from tiny, undammed tributaries. Then, several species disappeared including Colorado pike-minnow, 3…………………… and the round-tail chub. Meanwhile, some moved in such as fathead minnows, channel catfish, and 4……………………..

Explanation

Now, could you guess the reason behind the answers?