英语听力：自然百科 神奇水世界 Water-8

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So where did they find it, here in the middle of the desert? Now, this is the key to the Garamantians' incredible success. It's vertical¹ holes that are sunk deep into the ground. 40 to 50 meter. That's 150 feet. And the purpose of them was pretty simple - it was to bring water up from below ground. In this environment, it must have seemed that it was almost magic. In fact, the Garamantians had discovered ground water.

 

Beneath the surface of the Sahara, is a surprising part of the great water cycle, a massive store of ground water.

 

This is water that has seeped² into the ground and has collected in the poorest layers of rock. The water came from the period thousands of years before when the Sahara was lush and wet. Some of that water percolated³ into the rocks below and remained there, despite the dramatic drying above until the Garamantes found it.

 

You can dig them down until hit the water table and then you just keep doing the same thing. And there's one after another after another, all in a whole line. But these holes aren't wells that maintain and shaft⁴. They reach down to tunnels which carry the water. The point is right up there at the end. It’s where the water source is. So the water flows naturally from the escarpment up there, underground, down to the kind of oasis⁵ over there and that's where the Garamantians’ city was. What they could have done is they could have dug wells down, they lifted the water up but that's a, that's a lot of work for very little return. Much better to use gravity to channel the water in an underground tunnel straight to where they needed. That was the Garamantians’ real ingenuity⁶.

 

The Garamantes had managed to tap the same water that the early Saharans had enjoyed thousands of years earlier. By mining ground water, the Garamantians managed to turn the clock back on the Sahara. They made the desert bloom again.

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