UK: Scientists have used satellite technology to provide the first detailed measurements of water flow between the Amazon River and its floodplains. Four satellites were used to study the floodplain, looking at water level changes during the wet and dry seasons. The measurements were taken using a satellite called GRACE which measures changes in the planet’s gravity field and records the weight (and hence the volume) of water resting on the Earth’s surface.
The study was conducted by a team of experts from the Universities of Ohio, Baltimore, Bristol and California, and is reported online in the journal Remote Sensing of Environment.
Prof Paul Bates, from Bristol’s School of Geographical Sciences, said, “This is the first time we have been able to actually measure the amount of water that flows every year from the Amazon River channel to its floodplain and back again.” Further, Prof Bates added, “The work is important as we currently don’t know how much water flows from the Amazon into the ocean, or the route that water takes to get there. These new measurements tell us more about both of these things and provide a baseline from which we can look for future changes in the Amazon flood wave.”
The combined data from the satellites reveals how the Amazon landscape has changed as a result of highland rains creating an overflow into the lowland jungle. 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.
Every year, 285 billion metric tons, or 285 cubic kilometres of water by volume, rises and falls in the Amazon floodplain, accounting for just five per cent of the total water flow into the ocean. Until now, the sheer size of the area and the difficulties of access meant that researchers had to rely on data taken from sporadic field visits, leading them to believe that the water flow was as much as 30 per cent. The findings will be of critical importance to scientific efforts to understand climate change, and will impact significantly on future predictions and analyses of flood levels.
Source: Bristol University