finally including the marine waters of the Río Pará bay in its entire length. According to an earlier article on the webpage of the National Geographic, the Amazon's length was calculated as by a Brazilian scientist. In June 2007, Guido Gelli, director of science at the Brazilian Institute of Geography and Statistics (IBGE), told London's Telegraph Newspaper that it could be considered that the Amazon was the longest river in the world. However, according to the above sources, none of the two results was published, and questions were raised about the researchers' methodology. In 2009, a peer-reviewed article, was published, concluding that the Nile is longer than the Amazon by stating a length of for the Nile and for the Amazon, measured by using a combination of satellite image analysis and field investigations to the source regions. According to the Encyclopædia Britannica, the final length of the Amazon remains open to interpretation and continued debate. Watershed The Amazon basin, the largest in the world, covers about 40% of South America, an area of approximately . It drains from west to east, from Iquitos in Peru, across Brazil to the Atlantic. It gathers its waters from 5 degrees north latitude to 20 degrees south latitude. Its most remote sources are found on the inter-Andean plateau, just a short distance from the Pacific Ocean. The Amazon River and its tributaries are characterised by extensive forested areas that become flooded every rainy season. Every year, the river rises more than , flooding the surrounding forests, known as várzea ("flooded forests"). The Amazon's flooded forests are the most extensive example of this habitat type in the world. In an average dry season, of land are water-covered, while in the wet season, the flooded area of the Amazon basin rises to . The quantity of water released by the Amazon to the Atlantic Ocean is enormous: up to in the rainy season, with an average of from 1973 to 1990. The Amazon is responsible for about 20% of the Earth's fresh water entering the ocean. The river pushes a vast plume of fresh water into the ocean. The plume is about long and between wide. The fresh water, being lighter, flows on top of the seawater, diluting the salinity and altering the colour of the ocean surface over an area up to in extent. For centuries ships have reported fresh water near the Amazon's mouth