The ANASA map has unveiled the Earth's rivers' water capacity, which is critical data as the globe grapples with climate change effects.
Researchers have identified areas of concern, such as the severely depleted water flows in the Colorado River Basin.
"There are numerous approaches we can employ to manage our water usage and ensure there's enough for everyone," says one of the study's authors, stressing the fundamental importance of knowing the total water volume.
Between 1980 and 2009, the world's rivers held an average total volume of 539 cubic miles, approximately half the volume of Lake Michigan, according to NASA. Despite appearing small in the grand scheme, rivers play a crucial role in many communities since ancient times.
This information stems from a Nature Geoscience study led by researchers at NASA's Jet Propulsion Laboratory (JPL) in Southern California. The study also calculates the rates at which water flows into the oceans.
The Amazon basin in South America and the Orange River basin in Southern Africa are also at risk due to heavy human water use.
The Amazon basin holds the most river water storage, around 204 cubic miles, which is about 38 percent of the global total. It also releases the most water into the ocean. Researchers used stream-gauge measurements and computer models to estimate the volumes of 3 million rivers worldwide.
Cédric David, a co-author at JPL, stated that while there have been previous estimates, the total water in the world's rivers remains relatively unknown, likening it to an unknown bank account balance. Population growth and climate change further complicate the situation.
Understanding the available water is increasingly important as climate change affects the world's rivers. For example, the Colorado River recently experienced its lowest flows in a century due to prolonged drought conditions from a warming climate, impacting crucial reservoirs like Lake Mead and Lake Powell.
There were instances where less water was discharged from rivers than entered, termed "negative flows," indicating intense human use. Lead author Elyssa Collins noted these locations showed "fingerprints of water management."
This study sheds light on the world's freshwater cycles, providing insights not available from the 1974 estimates previously relied upon. The findings, along with data from the Surface Water and Ocean Topography (SWOT) satellite, could significantly improve global water measurements and our understanding of human impacts.