NASA map reveals how much water Earth's rivers hold

While this may seem a minuscule amount in the grand scheme of things, the Earth's rivers provide a lifeblood to many communities, and have done since the earliest civilizations were alive, NASA reports.

The estimates have been presented in a Nature Geoscience study, lead by researchers at NASA's Jet Propulsion Laboratory (JPL) in Southern California. The study also calculates the rates at which the water feeds into the world's oceans.

South America's Amazon basin and the Orange River basin in Southern Africa, have also been flagged as regions at risk from heavy human water use.

The Amazon had the most river water storage in total, at around 204 cubic miles the study reported. This is around 38 percent of the total global estimate. The Amazon basin also releases the most water into the ocean.

To reach their findings, the researchers used steam-gauge measurements and computer models to calculate the segments of 3 million rivers around the globe.

Co-author of the study Cédric David at JPL, said in a statement that although there have been previous estimates over the years, the amount of water held in the globe's rivers remains relatively unknown. It is similar to using a bank account, he said, when one does not know how much money it holds.

"We don't know how much water is in the account, and population growth and climate change are further complicating matters," David said in a statement. "There are many things we can do to manage how we're using it and make sure there is enough water for everyone, but the first question is: How much water is there? That's fundamental to everything else."

Knowing how much water is available is becoming more vital as climate change threatens world's rivers.

The Colorado River is just one example of how prolonged drought conditions caused by a warming climate, is affecting river flows. Not long ago, the Colorado River had the lowest flows seen in a century. This was affecting integral reservoirs like Lake Mead and Lake Powell, both of which provide essential water to the region.

The researchers note that there were several cases where less water emerged from rivers then went in. The Colorado, Amazon and Orange river basins all had these "negative flows" which indicated heavy human use.

Lead author of the study and doctoral student at North Carolina State University in Raleigh, Elyssa Collins, said these locations showed "fingerprints of water management."

This study provides some much needed insight into the world's freshwater cycles.

For many years, the total amounts of river water were estimated from a figure from 1974, NASA reports. Yet there has been no updated estimates on water flows that have changed over time.

The findings of this study could be used from data gathered by the Surface Water and Ocean Topography (SWOT) satellite, the researchers note. These new estimates, paired with the satellite data, could drastically improve water measurements over the world and insight into how humans are impacting it.

Do you have a tip on a science story that Newsweek should be covering? Do you have a question about the world's rivers? Let us know via science@newsweek.com.

Uncommon Knowledge

Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.

Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.

");jQuery(this).remove()}) jQuery('.start-slider').owlCarousel({loop:!1,margin:10,nav:!0,items:1}).on('changed.owl.carousel',function(event){var currentItem=event.item.index;var totalItems=event.item.count;if(currentItem===0){jQuery('.owl-prev').addClass('disabled')}else{jQuery('.owl-prev').removeClass('disabled')} if(currentItem===totalItems-1){jQuery('.owl-next').addClass('disabled')}else{jQuery('.owl-next').removeClass('disabled')}})}})})