strip the city --Dubai
四年级 记叙文 3122字 52人浏览 光棍两个3

40 years ago, most of this was desert. Now there is a glittering metropolis, the fastest growing desert city on the planet, Dubai. When I first came here, none of these existed. It was one huge big desert. Building a city like this in one of the hottest inhospitable place on earth seems impossible. So how did engineers do it? To find out, we will strip the city to reveal its secret inner workings and expose the ingenious technology that allowed engineers to build this jewel in the desert.

8am in Dubai, temperature will soon reach over 100 degree Fahrenheit. But Dubai’s 2 million citizens don’t have to worry about the scorching heat or know much about the technology that keeps them alive. The city’s most visible techno marvel is the burj Khalifa. Half a mile high, almost twice as tall as the empire state building. It ’s the tallest skyscraper in the world. Tearing away its glass skin reveals a hive of activity. Up to 35000 people can live and work in this gigantic greenhouse. What stop them from being roasted alive? The short answer —water, 200000 gallons a day for this building alone. Finding this much water in one of the driest places on earth was a huge challenge when the building boom began 40 years ago. There are no rivers in the city and hardly any rain. Yet Dubai is awash with water. How is this possible? The answer lies 50

miles to the east in the Hajar Mountains. Geologist Kathryn Goodenough knows this area like the back of her hand. She is part of the team that is producing an extremely detailed geological map for the United Arab Emirates. We ’ve covered pretty much the whole of the U.A.E. We’ve done sth like 30000 observations points. We have to drive every tract, we have to try and drive over most of the desert. We have to climb mountain ridges and walk up wadis, basically have to cover the whole country. On her mapping mission, Kathryn discovered signs that the emirates weren ’t always as dry as today. Here in this deep mountain valley, this wadi, we got evidence of water everywhere that we look. The wadi itself is v-shaped. That pretty much tells you that the valley is being caved out by flowing water, and then we can see all the rocks around here have been smoothed off, just planed off and eroded by the action of water. Two millions years ago, Dubai was a really wet place, where the skyscrapers stand today, mighty river flowed through a lush, fertile flood plain. But over time, temperature rose, and rivers ran dry. As the desert swallowed the area, the water seeped away. But it didn ’t all vanish. Some of them moved underground. And today it is still flowing through the rocks deep under the city. When the water is flowing through the wadis, of

course it’s flowing really quickly, but once it gets underground, id starts flow around between sand grains and pebbles and so on and move much more slowly. And, also of course, it can ’t evaporate easily because it ’s not on the surface, so that water can stay there in the ground for thousands of years and that provided the original source of water for Dubai. The ancient water kick-started Dubai’s explosive growth.