Disappearing Delta Reading Passage
Disappearing Delta Reading Passage
Paragraph A
The Nile delta’s fertile land eroded along the Mediterranean coast of Egypt is highly increased, 100 metres per year is eroded in some parts. In the past, sediment brought to the delta by River Nile was replaced in the place where the land was scoured away from the coastline by the Mediterranean sea currents. But this is no longer the case.
Paragraph B
All the sediment which used to flow down the river is virtually blocked by the two large dams at Aswan in the south of Egypt. So, the people have blamed the delta for the loss of the delta land. The Nile flowed freely before the dams were built, which carried a large amount of sediment north from the interior of Africa that was to be deposited on the Nile delta. This happened for 7000 years. At least it covered a region of over 22,000 square kilometres with the fertile slit’s layer. In the Delta Region, new, nutrient-rich soil is brought down by the Annual flooding. It replaces what had been scoured away by the sea and provides the fertilisers for Egypt’s richest food-growing area. The problem occurred when the Aswan dam was built in the 20th Century for the purpose of providing electricity and irrigation protecting the large population centre of Cairo, and preventing floods from the surrounding areas. Most of the sediments with its natural fertilisers, instead of passing down to the delta, accumulated up above the dam in the southern, upstream half of Lake Nasser.
Paragraph C
However, the story is not finished. The silt and sand were picked up by the sediment-free water which emerged from the Aswan Dams and eroded the river bed as well as banks on the 800-kilometre trip to Cairo. The water samples are taken in Cairo before the river enters the delta by Daniel Jean Stanley of the Smithsonian Institute, which indicates that sometimes rivers pick up more than eight fifty grams of sediment per cubic metre of water. About half of what it carried before the dams were constructed. Stanley in Marine Geology says that “I'm ashamed to say that the significance of this didn't strike me until after I had read 50 or 60 studies”. A lot of sediment is still entering into the delta. But, no sediments come out into the Mediterranean to restore the coastline. Therefore, the sediment must be stuck on the delta itself.
Paragraph D
Most of the Nile water is bypassed into more than 10,000 kilometres of irrigation canals and what directly reaches the sea through the rivers in the delts is only a small proportion. Stanley explains that water in the irrigation canals is either still or moves slowly, so it cannot carry the sediment. The sediment went down to the bottom of the canal, and the farmers added it to the fields or expelled it with the water into the four large freshwater lagoons, which are situated near the outer edges of the delta. So, what reaches the coastline is very little to replace what Mediterranean currents wash away.
Paragraph E
Most of Egypt's food supply depended on the farms located on the delta plains, as well as fishing and aquaculture in the lagoons. Stanley said that Pollutants are building up faster and faster. It is because the sediments which come to rest in the fields and lagoons are combined with industrial, municipal and agricultural waste from the region of Cairo, which is considered the home to more than 40 million people.
Paragraph F
Fredric Siegal of George Washington University says, “In Manzalah Lagoon, for example, the increase in mercury, lead, copper and zinc coincided with the building of the High Dam at Aswan, the availability of cheap electricity, and the development of major power-based industries”. He agreed to it based on his investigations of sediment from the delta lagoons. From that time, a significant increase in the concentration of mercury is noted. With that, leaded fuels and other industrial sources were also found to be dramatically increased. It can badly affect the productivity of fishing and farming as it enters into the food chain. One more problem is that agricultural wastes include fertilisers, which increase plant growth in the lagoons and disturb the ecology of the area, with serious consequences for the fishing industry.
Paragraph G
According to Siegel, international environmental organisations are starting to invest closer to the region, the partial reason being the erosion problems and pollution of the Nile. However, they mainly fear the effect this situation will have on the whole Mediterranean coastal ecosystem. It cannot be solved easily. As an immediate solution, Stanley believes that creating artificial floods to drive out the delta waterways is similar to natural floods before the dams were built. He says that long-term alternative processes, such as desalination, could increase the amount of water available. Stanley said that, in his view, Egypt should devise a way to have more water running through the river and the delta”. It is difficult to accomplish in a desert region with a rapidly growing population.
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