Disappearing Delta — IELTS Reading Answers

Paragraph B

“Before the dams were built, the Nile flowed freely, carrying huge quantities of sediment north from Africa's interior to be deposited on the Nile delta. This continued for 7,000 years, eventually covering a region of over 22,000 square kilometres with layers of fertile silt.”

Paragraph B explains how Nile sediment built the delta over 7,000 years and how the Aswan dams now trap that sediment upstream — heading iv.

Paragraph D

“The water in the irrigation canals is still or very slow-moving and thus cannot carry sediment, Stanley explains. The sediment sinks to the bottom of the canals and then is added to fields by farmers or pumped with the water into the four large freshwater lagoons that are located near the outer edges of the delta”

Paragraph D explains that slow-moving irrigation canals cannot carry sediment, so it settles and is later dug out or pumped into lagoons — heading i.

Paragraph E

“The farms on the delta plains and fishing and aquaculture in the lagoons account for much of Egypt's food supply. But by the time the sediment has come to rest in the fields and lagoons it is laden with municipal, industrial and agricultural waste from the Cairo region,”

Paragraph E warns that sediment reaching fields and lagoons is 'laden with municipal, industrial and agricultural waste', poisoning the food chain — heading v.

Paragraph F

“According to Siegel, international environmental organisations are beginning to pay closer attention to the region, partly because of the problems of erosion and pollution of the Nile delta,”

Paragraph F reports growing international concern about erosion and pollution, plus Stanley's solutions of artificial floods or desalination — heading viii.

Coastal erosion occurred along Egypt's Mediterranean coast before the building of the Aswan dams.

“In the past, land scoured away from the coastline by the currents of the Mediterranean Sea used to be replaced by sediment brought down to the delta by the River Nile, but this is no longer happening”

Before the dams, land 'scoured away from the coastline' was replaced by Nile sediment; erosion therefore occurred even then, just balanced.

Some people predicted that the Aswan dams would cause land loss before they were built.

“Up to now, people have blamed this loss of delta land on the two large dams at Aswan in the south of Egypt, which hold back virtually all of the sediment that used to flow down the river”

The passage says people now blame the dams for land loss but never reports anyone predicting that outcome before construction.

The Aswan dams were built to increase the fertility of the Nile delta.

“But when the Aswan dams were constructed in the 20th century to provide electricity and irrigation, and to protect the huge population centre of Cairo and its surrounding areas from annual flooding and drought, most of the sediment with its natural fertilizer accumulated up above the dam in the southern,”

The dams were built 'to provide electricity and irrigation' and protect Cairo from flooding, not to increase the delta's fertility — they trap its fertilising silt.

Stanley found that the levels of sediment in the river water in Cairo were relatively high.

“Daniel Jean Stanley of the Smithsonian Institute noticed that water samples taken in Cairo, just before the river enters the delta, indicated that the river sometimes carries more than 850 grams of sediment per cubic metre of water - almost half of what it carried before the dams were built”

Stanley's Cairo samples showed the river carrying 'more than 850 grams of sediment per cubic metre', almost half its pre-dam load — a relatively high level.

Sediment in the irrigation canals on the Nile delta causes flooding.

“The water in the irrigation canals is still or very slow-moving and thus cannot carry sediment, Stanley explains. The sediment sinks to the bottom of the canals and then is added to fields by farmers or pumped with the water into the four large freshwater lagoons that are located near the outer edges of the delta”

Sediment settling in irrigation canals is discussed, but the passage never says this sediment causes flooding.

Water is pumped from the irrigation canals into the lagoons.

“The sediment sinks to the bottom of the canals and then is added to fields by farmers or pumped with the water into the four large freshwater lagoons that are located near the outer edges of the delta”

Sediment is 'pumped with the water into the four large freshwater lagoons', confirming that water from irrigation canals reaches the lagoons.

“'Pollutants are building up faster and faster,' says Stanley”

The summary needs the noun for contaminants: Stanley warns that 'pollutants are building up faster and faster', matching option F.

“In the immediate future, Stanley believes that one solution would be to make artificial floods to flush out the delta waterways, in the same way that natural floods did before the construction of the dams”

The short-term solution is 'to make artificial floods to flush out the delta waterways', matching option A.

“He says, however, that in the long term an alternative process such as desalination may have to be used to increase the amount of water available”

The long-term alternative is 'desalination ... to increase the amount of water available', matching option B.