Why did the stream dry up?

泉为什么干了呢？

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Groundwater commonly collects in stream drainages but may remain entirely beneath the surface of dry stream-beds in arid regions.

地下水通常聚集在河流流域，但在干旱地区，地下水也可能完全保留在干涸河床的表面之下。

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In particularly wet years, short stretches of an otherwise dry stream-bed may have flowing water because the water table rises to intersect the land surface.

在气候特别湿润的年月里，平常干涸的河床下游可能会有水流动，因为地下水在那里位抬升到了地表以上。

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In the centre of Tafraoute, sheep make their way up a dry stream bed.

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Lisbon, Portugal, which is located in the path of the Gulf Stream, averages the most daily hours of sunlight year-round thanks to its dry air and stable climate (much like southern California in the U.S.).

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