（剑5 Test3 Reading Passage2）Disappearing Delta 翻译谁有啊

（剑5 Test3 Reading Passage2）Disappearing Delta 翻译谁有啊
A The fertile land of the Nile delta is being eroded along Egypt's Mediterranean coast at an astounding rate, in some parts estimated at 100 metres per year. In the past, land scoured away from the coastline by the currents of the Mediterranean Sea used to be replaced by sediment brought dawn to the delta by the River Nile, but this is no longer happening.
B 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. 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. Annual flooding brought in new, nutrient-rich soil to the delta region, replacing what had been washed away by the sea, and dispensing with the need for fertilizers in Egypt's richest food-growing area. 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, upstream half of Lake Nasser, instead of passing down to the delta.
C Now, however, there turns out to be more to the story. It appears that the sediment-free water emerging from the Aswan dams picks up silt and sand as it erodes the river bed and banks on the 800-kilometre trip to Cairo. 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 mare than 850 grams of sediment per cubic metre of water — almost half of what it carried before the dams were built. I'm ashamed to say that the significance of this didn't strike me until after I had read 50 or 60 studies,' says Stanley in Marine Geology. There is still a lot of sediment coming into the delta, but virtually no sediment comes out into the Mediterranean to replenish the Coastline. So this sediment must be trapped on the delta itself. '
D Once north of Cairo, most of the Nile water is diverted into more than 10,000 kilometres of irrigation canals and only a small proportion reaches the sea directly through the rivers in the delta. 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. So very little of it actually reaches the coastline to replace what is being washed away by the Mediterranean currents.

尼罗三角洲的肥沃土地沿埃及的地中海海岸被腐蚀以令人惊奇率,在有些零件估计在每年100米.以前,土地走遍远离海岸线由地中海的潮流曾经被沉积被带来的黎明替换到由河尼罗的三角洲,但是这不再发生.
B到现在,人们在二个大水坝责备了三角洲土地这损失在埃及的南部的阿斯旺,SED的阻止实际上全部