Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

First satellite measurement of water volume in Amazon floodplain

06.08.2010
For the first time, scientists have been able to measure the amount of water that rises and falls annually in the Amazon River floodplain.

The result -- 285 billion metric tons, or 285 cubic kilometers of water by volume -- sounds like a lot. That amount is over half the volume of Lake Erie, which is the world’s 15th largest lake.

But it accounts for only 5 percent of the water flowing through the Amazon River every year, and it is a much smaller amount than researchers were expecting to find in the largest drainage basin in the world.

Doug Alsdorf, associate professor of earth sciences at Ohio State University, and his colleagues report their study online in the journal Remote Sensing of Environment, in a paper to appear in a future print edition.

Until now, researchers could only estimate the amount of water in the Amazon floodplain using a few sporadic field studies and crude assumptions about water flow. In fact, water volumes on any floodplain are poorly known, if at all. Yet this information is critical to predicting the floods and droughts that could accompany global climate change, explained Alsdorf.

Much of Earth’s available fresh water resides in remote rivers, lakes and wetlands, and also underground.

“Nobody knows exactly how much water there is on the planet,” he said. “We need to understand how our water supply will change as the climate changes, and the first step is getting a handle on how much water we actually have.”

Alsdorf and his team have made it their mission to find ways to measure water from space.

“Satellite observations are the only reliable option for places like the Amazon and especially the Congo Basin, where in-person measurements are near-impossible. Just getting there is a serious challenge,” he said.

For this study, the researchers were interested only in the amount of water that flowed into and out of the floodplain -- that is, the amount of water that spilled onto land when the Amazon River overflowed its banks during the rainy season.

Alsdorf and his team used four satellites -- three NASA satellites and one from the Japan Aerospace Exploration Agency -- to get the first direct measure of water in the floodplain.

They combined data from the Gravity Recovery and Climate Experiment, the Global Precipitation Climatology Project, the Shuttle Radar Topography Mission, and the Japanese Earth Resources Satellite. They focused on measuring water level changes during the wet and dry seasons between 2003 and 2006.

Taken together, these satellites gave a picture of how the Amazon landscape changed as highland rains surged through the river’s many tributaries and the resulting overflow spilled into the lowland jungle. After the water receded, they calculated the change in volume along the floodplain.

These calculations haven’t been made before, in part due to the immense difficulty of combining different kinds of data in a reliable way. The researchers had to meld gravity readings -- a measure of the flood water’s mass -- with radar and optical measurements of the water level and extent of the floodplain.

The measurements added up to an average of 285 cubic kilometers (285 billion metric tons) of water stored and emptied from the floodplain in a year.

At the height of the rainy season, water flowed into various locations on the Amazon floodplain at a rate of 5,500 cubic meters (5,500 metric tons) per second, and during the dry season, it drained away into the Amazon River -- and, ultimately, into the Atlantic Ocean – at a rate of 7,500 cubic meters (7,500 metric tons) per second.

The floodplain total, however large, represents only 5 percent of the amount that scientists believe is emptying from the Amazon River into the ocean every year.

To Alsdorf, the finding begs the question of exactly how much water is flowing through the Amazon system, and it underscores the many unknowns that scientists must confront as they work to understand climate change.

The Amazon, however grand in size, is just one river basin among countless basins around the planet -- each vital to the soil quality and water quality of its surroundings, he said.

Future measurements should be easier with the Surface Water and Ocean Topography (SWOT) mission, which aims to take stock of all the world’s water. Alsdorf co-leads the science team for the SWOT satellite, which NASA has set to launch in 2020.

Contact: Doug Alsdorf, (614) 247-6908; Alsdorf.1@osu.edu
Written by Pam Frost Gorder, (614) 292-9475; Gorder.1@osu.edu

Pam Frost Gorder | EurekAlert!
Further information:
http://www.osu.edu

More articles from Earth Sciences:

nachricht Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center

nachricht NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Metal too 'gummy' to cut? Draw on it with a Sharpie or glue stick, science says

19.07.2018 | Materials Sciences

NSF-supported researchers to present new results on hurricanes and other extreme events

19.07.2018 | Earth Sciences

Scientists uncover the role of a protein in production & survival of myelin-forming cells

19.07.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>