The Paraná River is South America’s second largest, and the river and its tributaries are important transportation routes for landlocked cities in Argentina, Paraguay, Bolivia, and Brazil. This astronaut photograph shows a 29-kilometer (18 mile) stretch of the Paraná, downstream of the small city of Goya, Argentina (just off the top left of the image).
The Paraná River ranges up to 3 kilometers wide along the reach illustrated in this image. The main channel is deep enough to allow smaller ocean-going ships to pass north to the capital city of Asunción, Paraguay, fully 1,200 kilometers (745 miles) inland and well out of the image.
The river’s dark brown shading indicates a heavy load of muddy sediment; smaller side channels also carry this mud. Numerous lakes are typical on active floodplains, and appear here as irregular bodies of water. Some appear brown, indicating that they probably have been refilled during recent rises and floods of the active channels.
The Paraná floodplain occupies the entire image; it is so wide—18 kilometers (11 miles) in this view—that its banks are not visible. Numerous curved, meandering channels are the most prominent characteristic of the floodplain, indicating prior positions of the river and its channels. As riverbeds move laterally by natural processes, they leave remnants of their channels, which appear as lakes and finally fill with mud. This is an excellent image for illustrating these meander forms.
From a geological standpoint, it is interesting that almost all of the old channels are similar in curvature to today’s side channels. However, almost none of them seem to show prior positions of the main, wide Paraná channel.
Other astronaut photographs show examples of meandering—on the Rio Negro of southern Argentina, the Mamore River of Bolivia, and the Amazon River of western Brazil.
Astronaut photograph ISS027-E-11058 was acquired on April 9, 2011, with a Nikon D2Xs digital camera using a 400 mm lens, and is provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center. The image was taken by the Expedition 27 crew. The image has been cropped and enhanced to improve contrast. Lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by M. Justin Wilkinson, NASA-JSC.