SonTek’s Amazon Adventure RiverSurveyor M9 Tackles the World’s Largest Discharge

The Amazon River is a system so massive it nearly defies description. Draining a watershed bigger than Western Europe, the Amazon carries 52.2 million gallons per second to the Atlantic. That’s 209,000 cubic meters per second. It’s 7.38 million cfs. Nearly 16 times the average discharge of the Mississippi River. Enough to fill Lake Erie in less than a month. More fresh water flow than anywhere on earth. To a hydrologist, every aspect of measuring the Amazon is a challenge of the highest magnitude.

“Everything is big,” says SonTek Application Specialist David Velasco. “Everything is far away. Everything takes longer. And there’s no Radio Shack on the margin you can run to

” It’s not just the fact that the Amazon carries 15 percent of the world’s fresh water that makes it so challenging to analyse. There are logistics to consider. There are no bridges spanning the river to provide a stable platform for instruments. It’s hard to cross: a
current of more than 3.5 meters per second (11.5 fps) sweeps small boats off track and challenges the skills and nerve of the pilots of larger craft. It’s even hard to hold still as the current drags anchors across the muddy
bottom.

There’s also the challenging bathymetry of the system. A single crossing can pass over a flat, level bottom in one area and mega-ripples in another. Broad shallows give way to channels that plunge 100 meters (330 feet) deep. The muddy bottom is in nearly constant motion – which hydrologists call a “moving bed” – creating enormous challenges for accurately measuring velocity and properly positioning vessels at a known location.