The Earth has many more rivers and streams than we thought, according to a new satellite study

According to a new study published in Science rivers and streams cover a much larger part of the planet than geologists previously thought. In total, this new estimate shows that, with the exception of glacier-covered lands, the Earth is covered by just under 773,000 square kilometers of rivers and streams. It's more square than the state of Texas, and it's 44 percent higher than previous accounts.

The discovery has implications for the study of climate change, because rivers exchange greenhouse gases with the atmosphere. "It was assumed until 2006 that rivers and lakes were just a simple pipeline carrying carbon to the ocean," said John Downing, limnologist and biogeochemist to Gizmodo. at the University of Minnesota Duluth. "But rivers emit gases into the atmosphere."

When pollutants like fertilizers and sewage seep into the water, gases, including methane, carbon and nitrous oxide, fall back into the atmosphere. More river cover could mean that we are sending more greenhouse gases in the air than current calculations warrant.

"Here's another reason not to spoil the water," said Downing. "If you pollute it, you spoil fishing and swimming, but you also spoil the atmosphere."

To map the rivers and streams of the planet, George Allen and Tamlin Pavelsky, hydrologists of the 39 University of North Carolina, analyzed thousands of images. Satellite. Using software developed by Pavelsky, the duo ended up with 58 million river measurements that they then used to calculate the total coverage of rivers and streams on Earth.

And they did not blindly trust their software. To make sure the program was reliable, the researchers used what Allen called "a small army of students" to vigilantly monitor if the program measured the rivers, not the roads, and did not know what to do. he avoided other mistakes along the way. "They were so excited," Pavelsky said. "They did such a good job."

In addition to their Texas estimate, the researchers also found that the rivers were narrower and more scattered in the areas developed by the US. man, which surprised them. This could be due to people siphoning water for agriculture, draining swamps and licking rivers, but further research will have to be done to be safe.

Other scientists have made estimates of water course coverage. Downing, for example, used the distinct way that rivers connect and the amount of water they move to estimate their overall coverage. Others have used the data of elevation and flow of water to do it. The researchers said, "If you look around the world, the rivers look different from one place to another," Allen, who recently started a professorship. at Texas A & M University, told Gizmodo. "They could be braided, or winding, or meandering, and for the most part, the current technology does not take into account the actual morphology of the rivers." This dataset is the first of its kind to do so at this time. High resolution global scale. "

Downing was impressed by the number of data points that Allen and Pavelsky took into account, especially because the duo's estimate" "I think that C & D Is absolutely great, "said Downing." They have put tremendous effort and confirmed the numbers we had already created from basic physical principles. "

Have a map of the morphology of the The Earth River can prove extremely useful in predicting floods, how rivers will behave in the future as the Earth warms, and now that this river measurement technique has a reliable record, says that he could be useful to see how river flows change from season to season – another good set of data to protect communities from flooding

"Rivers are so wonderful, but they can be dangerous too," said Downing . "The water goes where it wants to go, so it is good to know where it is going and what area it covers."

[Science]