Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Earth sinks three inches under weight of flooded Amazon

05.10.2005


As the Amazon River floods every year, a sizeable portion of South America sinks several inches because of the extra weight – and then rises again as the waters recede, a study has found.



This annual rise and fall of earth’s crust is the largest ever detected, and it may one day help scientists tally the total amount of water on Earth.

“What would you do if you knew how much water was on the planet?” asked Douglas Alsdorf, assistant professor of geological sciences at Ohio State University. “That’s a really exciting question, because nobody knows for sure how much water there is.”


Having an estimate of Earth’s entire fresh water cache – from hidden groundwater, to the world’s rivers and wetlands, to mountaintop glaciers – would greatly improve our ability to predict drought, flooding and climate change.

The study appears in the journal Geophysical Research Letters.

The study began in 2004 after Michael Bevis, now an Ohio Eminent Scholar and professor of civil and environmental engineering and geodetic science at Ohio State, detected an up-and-down motion at a global positioning system (GPS) station he’d placed in the ground near a lake in the Andes. He concluded that as the water level in the lake rose and fell, the ground nearby moved in response. At the time, he was a professor at the University of Hawaii.

Bevis began to look for similar oscillations in data recorded by other GPS stations around South America. Other scientists had already reported detecting such changes up to half an inch in other parts of the globe, but they suspected that the greatest motion would occur beneath the Amazon River Basin, the largest river system in the world. In late 2004, one group used satellite data to predict that the bedrock beneath the Amazon would rise and fall about one inch every year.

But when Bevis looked at the data from a GPS station in Manaus, Brazil – near the center of the river basin – he saw not a one-inch change, but three inches.

He recruited Alsdorf to help him couple his data to a computer model of water flow through the basin. They used a very simple approach colloquially called a “bathtub model,” which assumed that the water level rose and fell uniformly across the Amazon, like running water in a bathtub.

They used a simple model because scientists know relatively little about the Amazon River Basin, Alsdorf explained. Its sheer size – approximately equal to the continental United States, with a flood area the size of Texas – hinders detailed study.

Like many researchers, they suspect that the amount of water that flows through the Amazon into the Atlantic Ocean every year is about ten times larger than that carried by the Mississippi River into the Gulf of Mexico.

“The old joke is, we know the discharge of the Amazon, give or take the Mississippi,” Alsdorf said.

With colleagues in the United States and Brazil, Bevis and Alsdorf merged the water model and the GPS data to show that between 1995 and 2003 the bedrock around Manaus rose and fell in a regular pattern that coincided with the basin’s annual flood. The bedrock sank slowly as the floodwaters gathered, then rose back up as the waters receded. The average change in height was about three inches.

Alsdorf was quick to point out caveats of the study. The researchers have data for only one GPS station, and the “bathtub model” is greatly simplified compared to the natural variability in water level throughout the Amazon. What’s more, scientists aren’t exactly sure of the composition of the bedrock beneath the basin.

Despite the uncertainties of the study, the three-inch oscillation is the most dramatic measured to date, and it’s the first known recording of a land mass oscillating in response to the flow of a river.

It also raises the possibility that scientists could one day calculate the amount of water in the Amazon – that is, they could “weigh” the river system based on how much it makes the earth sink.

Similar techniques could be used to calculate the amount water on the planet, but much more data would be needed from all over the globe, Alsdorf said.

As a first step, he and his colleagues want to install more GPS stations around Manaus and the rest of the Amazon to see if the sinking varies by location. He suspects that similar effects could also be detected in the Congo River system in Africa.

But to monitor water flow worldwide would require a satellite, and Alsdorf leads the American portion of an international team that is proposing a new satellite to do just that. The Water Elevation Recovery (WatER) mission would use radar to measure global water levels every eight days.

Data from WatER would give scientists a better estimate of fresh water storage and river discharge, and improve models of the global water cycle and climate change, he said.

Coauthors on the Geophysical Research Letters paper included Eric Kendrick, senior research associate in the Department of Civil and Environmental Engineering and Geodetic Science at Ohio State; Luiz Paulo Fortes of the Institute Brasilieiro de Geographia e Estatística in Brazil; Bruce Forsberg of the Instituto Nacional de Pesquisas da Amazonas in Brazil; Robert Smalley Jr. of the University of Memphis; and Janet Becker of the University of Hawaii.

Douglas Alsdorf | EurekAlert!
Further information:
http://www.osu.edu

More articles from Earth Sciences:

nachricht How much biomass grows in the savannah?
16.02.2017 | Friedrich-Schiller-Universität Jena

nachricht Canadian glaciers now major contributor to sea level change, UCI study shows
15.02.2017 | University of California - Irvine

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Biocompatible 3-D tracking system has potential to improve robot-assisted surgery

17.02.2017 | Medical Engineering

Real-time MRI analysis powered by supercomputers

17.02.2017 | Medical Engineering

Antibiotic effective against drug-resistant bacteria in pediatric skin infections

17.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>