{"id":380364,"date":"2026-03-05T02:12:55","date_gmt":"2026-03-04T16:12:55","guid":{"rendered":"https:\/\/www.nasa.gov\/?p=970155"},"modified":"2026-03-05T02:12:55","modified_gmt":"2026-03-04T16:12:55","slug":"us-french-satellite-takes-stock-of-worlds-river-water","status":"publish","type":"post","link":"https:\/\/www.vibewire.com.au\/?p=380364","title":{"rendered":"US-French Satellite Takes Stock of World\u2019s River Water"},"content":{"rendered":"
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5 min read<\/p>\n

Preparations for Next Moonwalk Simulations Underway (and Underwater)<\/h1>\n<\/div>\n<\/div>\n<\/div>\n
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\"An<\/a><\/figure>
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Sunlight glints off one of the solar panels of the SWOT satellite in this artist\u2019s concept. The antennas of the mission\u2019s key instrument \u2014 the Ka-band Radar Interferometer (KaRIn) \u2014 collect data along a swath 30 miles (50 kilometers) wide on either side of the satellite.<\/div>\n
CNES<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\n

Rivers rise and fall throughout the year, but by how much? Perhaps less than previously thought, according to new data from the SWOT mission. Hidden riverbed contours are also emerging.<\/em><\/p>\n

In a first, a space mission led by NASA and France has tracked Earth\u2019s rivers swelling and shrinking from month to month over the course of a year and found significantly less of a swing than previous model-based estimates. A record drought in the Amazon likely influenced the tally made by the Surface Water and Ocean Topography (SWOT) satellite. The findings also reveal new details about the underwater topography of the world\u2019s river channels.<\/p>\n

Launched in 2022, SWOT<\/a> is a collaboration between NASA and the French space agency CNES (Centre National d\u2019\u00c9tudes Spatiales). It is the first satellite capable of surveying not only the ocean, but also nearly all the world\u2019s lakes and rivers with ultraprecision. While SWOT does not measure the absolute volume of rivers, it can track their width, surface height, and slope changing over time.<\/p>\n

Traditionally, hydrologists have relied on models to calculate river storage changes, or they multiplied altimeter estimates of height by optical or radar estimates of width. In contrast, SWOT measures both dimensions, height and width, at the same time using its sensitive Ka-band Radar Interferometer<\/a> (KaRIn) instrument to bounce microwaves off the water\u2019s surface and time how long the signal takes to return. The new study, published<\/a> Wednesday in Nature, analyzed nearly 1.6 million such observations.<\/p>\n

The analysis paints a picture of some 127,000 river segments rising and falling between October 2023 and September 2024. In aggregate, river volumes varied by almost 83 trillion gallons (313 cubic kilometers). That\u2019s about 28% less of a swing than the lowest previous estimates, a result likely skewed by extremely dry conditions during that period in the Amazon, home to Earth\u2019s largest river by volume.<\/p>\n

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