The Amazon River basin, by far the largest river basin in the world, is responsible for 20 percent of the world's discharge of freshwater into the oceans. Seasonal floods cover an area as large as 140,000 square miles every year. If these floods weren't considered a natural seasonal pattern — that is, if the banks of the river in the dry season were highly developed — they would be responsible for incredible devastation. This is one major reason that massive deforestation, damming and development in the Amazon could be so dangerous: the Amazon River and its many tributaries are virtually uncontainable.
The largest recorded flood along the Amazon occurred in 1953. It was the largest meteorological flood (that is, caused by rainfall) in recorded history, with a peak discharge of 370,000 square meters per second.