Moisture from groundwater sources supports one of the world’s oldest and most biologically diverse deserts

The ocean is not the only source of the fog that sustains the life of many plants and animals living in the coastal Namib Desert of Africa. The fog also comes from groundwater and other sources, report ecohydrologists supported by the National Science Foundation (NSF) and affiliated with Indiana University-Purdue University Indianapolis (IUPUI).

Scientists conducted the research in one of the oldest and most biologically diverse deserts in the world. Their results are published today in the journal Science Advances.

Today, on World Water Day – and indeed every day – water sources are an important consideration for society. To develop ecological models of arid environments, scientists say they need to deepen their understanding of water sources. This knowledge can help them assess the functioning of plants and animals in current and future climates.

Fog and, to a lesser extent, dew are crucial sources of moisture in the Namib Desert. Fog is made up of tiny droplets of water suspended in the air; dew is water that forms on the surface of plants, soil, and other ground objects.

“Knowing exactly where the fog and dew are coming from will help us predict the availability of non-rainwater in the future, both in Namib and elsewhere,” said Lixin Wang, ecohydrologist at IUPUI who led the study. “With this knowledge, we may be able to determine ways to harvest new water sources for potential use in water scarcity situations.”

Surprisingly, non-oceanic fog accounted for more than half of the total fog in the Namib during the study period.

Groundwater was the most important generator of non-ocean fog, serving as the source of more than a quarter of the fog in the desert. Soil water, which comes from precipitation and is located below the surface but higher than groundwater, was also an unexpected source of moisture.

With environmental change, more and more areas in the United States and around the world are becoming drier and more desert-like. Drylands – which include deserts and arid and non-desert areas such as parts of the Great Plains and the southwestern United States – cover about 40% of the earth’s surface and are home to about 2.5 billion people, have discovered researchers.

“Dryland ecosystems have some of the lowest amounts of annual precipitation on Earth,” said Tom Torgersen, hydrologist and program manager in NSF’s Division of Earth Sciences. “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 essential for keeping the environment alive and functioning. “

Like other dryland ecosystems around the world, Namib’s hydrologic cycle is likely to change over the coming decades. Given the importance of fog and dew in this desert, Wang said, the Namib is a great place to study non-rainy water.

The Namib’s temperature ranges from less than 32 to 140 degrees Fahrenheit (zero to 60 degrees Celsius) and is almost completely devoid of surface water. Many parts of the desert receive virtually no rain. Some years are without rain; others may only see an inch or two of rain on average, although some places can receive up to four inches.

But the Namib is home to a range of specially adapted organisms, such as fog-gathering beetles. To survive during periods without rain, most plants and animals in Namib probably draw moisture from fog or dew, Wang said. His future research will focus on the mechanisms by which groundwater and soil water turn into fog and dew.

The long-term goal, he said, is to expand this ecohydrological research beyond the Namib on a global scale.

IUPUI’s Kudzai Farai Kaseke and Mary Seely, desert ecologist and former director of the Gobabeb Research and Training Center in Namibia, co-authored the article with Wang.

About the National Science Foundation (NSF)
The National Science Foundation (NSF) is an independent federal agency that supports basic research and education in all areas of science and engineering. In fiscal year (FY) 2016, its budget is $ 7.5 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, the NSF receives more than 48,000 competitive funding proposals and awards approximately 12,000 new grants. NSF also awards approximately $ 626 million in professional and service contracts each year. For more information, visit https://www.nsf.gov.