Satellite technology continues to prove indispensable in furthering our knowledge of global environmental systems, particularly of the world’s water cycle. According to a press release from Ohio State University, researchers there have applied remote sensing techniques to deriving the first accurate measure of just how much water is represented by the annual variation in the flow of the Amazon River.
It may sound like just so much arcane eco-geekery, but the innovation offers hope that we may get a decent handle on the world’s changing freshwater picture.
As rivers flow, their levels rise and fall within their banks and floodplains in cycles that may be measured in hours or by the season. The volume of water represented by this flux can offer very important clues that point to regional precipitation, and to any changes that may be taking place in patterns of water distribution as a result of climate change. As important as this information can be, its precise measurement has also been elusive. Especially in some of the world’s major river systems that flow through very remote locations, putting people and monitoring devices on the ground to obtain usable data can be difficult or altogether impossible.
The Ohio State team, led by earth sciences professor Douglas Alsdorf, has successfully sidestepped the problem of spotty data from ground measurements by incorporating information taken from four satellites (three of NASA‘s, and one belonging to Japan Aerospace Exploration Agency) to provide the first accurate measure of water in the Amazon River’s floodplain as well as of its annual variation.
The team calculates the annual volume represented by this rise-and-fall in the floodplain to clock in at 285 billion metric tons. This no doubt sounds at first to be a whole lot of water, and it is. For comparison purposes, it’s approximately half the volume of Lake Erie, but it represents only about five percent of the total annual flow through the Amazon basin, a volume of water that can still only be estimated as an exact measurement remains unknown.
“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,” Alsdorf explains. He adds: “Nobody knows exactly how much water there is on the planet. 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.”
The successful ability to calculate volume variability in major river systems will undoubtedly be of continued value as environmental and climate scientists continue to ask and answer questions about global fresh water distribution, and particularly about the extent to which climate change may alter patterns of that distribution.
Alsdorf already has his eyes keenly focused on the next generation of tools that will further the cause, as he has been selected to serve a leading advisory role on NASA’s Surface Water and Ocean Topography (SWOT) mission. Scheduled for launch in 2020, SWOT has the lofty mission to monitor and measure the world’s fresh and marine waters in total.
Photo by NASA via Wikimedia Commons