The unusual and large fluctuation of the bedrock in the Amazon basin comes from the sheer weight of the water that drains from the river system annually. Conceivably, the data and techniques used in the study could lead to an accurate estimate of how much water there is on the planet, a figure scientists don't accurately know today.
The study began in 2004, after OSU professor Michael Bevis began to notice fluctuations in data from a Global Positioning System device near a lake in the Andes mountains. Bevis concluded that the changes were caused by the lake's fluctuating water level.
He then began to examine GPS data from other parts of the world and found variations of about half an inch. However, GPS data near Manaus, Brazil, a major city at the heart of the Amazon, showed fluctuations of three inches. This sizable oscillation, geologically speaking, occurs because of the massive amount of water that drains from the Amazon. Many believe that 10 times as much water comes out of the river than drains from the Mississippi every year.
Bevis and Douglas Alsdorf, another professor at OSU, then created a computer model of the basin and compared it to GPS data from 1995 to 2003.
The computer model is a simplified version of what occurs in reality, but the two found that the land mass fluctuated regularly with the cycle of flooding in the basin.
Collecting data on the fluctuation of land masses could, in turn, allow researchers to calculate the weight, and hence the volume, of water in different parts of the world.