Water researchers lap up the Namib desert

26 March 2017 - 18:27 By Dave Chambers
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As one of the driest places on the planet‚ the Namib desert may not seem the obvious place to study the world’s water future.

But it is exactly the right place for academics from the US and 77-year-old Wits University desert ecologist Mary Seely‚ who has studied the Namib for more than half a century.

The Namib’s fog and dew are the desert’s twin lifelines‚ and “understanding (them) is key to understanding how plants and animals sustain themselves and function under current or future climates”‚ ecohydrologists from Indiana write in the journal Science Advances.

The Namib‚ which means “vast place” in Nama‚ stretches for more than 2‚000km along the Atlantic coast between the Olifants River in the Western Cape and the Carunjamba River in Angola.

Annual rainfall ranges between 2mm and 200mm‚ and coastal regions are enveloped in thick fog for more than half the year.

The new study‚ however‚ finds that the ocean is not the desert’s only source of moisture.

Non-ocean derived fog accounted for more than half of the fog during the year that Lixin Wang and colleagues from Purdue University spent working with Seely in the Namib. Groundwater was the source of more than a quarter of the desert’s fog‚ and “soil water” — derived from rain stored below the surface but located higher than groundwater — was an unexpected source of moisture.

Said Wang: “Knowing exactly where the fog and dew come from will help us to predict the availability of non-rainfall water in the future‚ both in the Namib and elsewhere.

“With this knowledge‚ we may be able to determine ways to harvest novel water sources for potential use in water-scarcity situations.”

Tom Torgesen‚ of the US National Science Foundation‚ said so-called drylands covered 40% of the Earth’s surface.

“To survive‚ these ecosystems recycle water in the form of fog and dew. In the driest places on the planet‚ even seemingly minor components of the water cycle‚ such as fog and dew‚ become major and are critical to keeping the environment alive and functioning.”

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