
Scientists have created the most detailed map yet of Earth’s extensive river systems, revealing these bodies of water cover much more of the surface than previously thought.

The Global River Widths map was created using NASA satellite images and statistical techniques to measure the length and width of rivers and streams all around the world.

The new study suggests scientists may previously have underestimated the role of rivers in controlling atmospheric greenhouse gases.

Scientists have created the most detailed map yet of Earth’s extensive river systems, revealing these bodies of water cover much more of the surface than previously thought. The Global River Widths map was created using NASA satellite images and statistical techniques. A close up view of South American rivers is shown on bottom

‘We were able to measure over two million kilometers of rivers that were wider than 30 meters,’ said George Allen, assistant professor of geography in the College of Geosciences at Texas A&M.

‘There are many more narrow rivers than wide rivers, and we found that the relationship between river length and width is actually pretty predictable.’

Not all of the rivers were wide enough to be measured from the images in the Landsat Database, though.

When this was the case, the researchers used a statistical technique, relying on the fractal characteristics of river networks.

‘We added up all the rivers and streams around the world and got an area larger than the size of Texas,’ Allen said. ‘The estimate was significantly larger than the previous best estimate, particularly in the Arctic.’

While the overall area may have been larger than expected, there were some surprises on the opposite end of the spectrum too.

According to the researchers, the surface area of rivers and streams in more developed parts of the world fell short of expectations.

This is likely due to human activity.

‘We think that there is less river water in these areas because humans are modifying the river system,’ Allen said.

While the overall area may have been larger than expected, there were some surprises on the opposite end of the spectrum too. According to the researchers, the surface area of rivers and streams in more developed parts of the world fell short of expectations

‘Water withdrawal and leveeing might be causing rivers to be narrower and more scarce than they would be otherwise.’

As rivers and streams are known to release greenhouse gases into the atmosphere, researchers say the new estimates must be taken into consideration.

‘A greater global total surface area implies that rivers and streams contribute more gasses to the atmosphere like carbon dioxide and methane than currently represented by carbon cycling models,’ Allen said.

In addition to understanding greenhouse gases, the database could also help improve flood models and classify different types of water bodies.

‘We think of this database as a first step to a lot more work,’ Allen said.