Rivers frequently alter their path, but they do not do it progressively. River avulsions are similar to earthquakes in that they occur suddenly and can be catastrophic. Scientists have discovered that these abrupt course shifts occur when silt accumulates in a river, reducing the amount of water it can carry. Eventually, the river’s resistance to flow becomes so great that it breaks its banks in quest of a more direct route to the sea. This is a life-threatening dilemma for the adjacent towns, where they rely on the river’s sedimentation for their fertile farming. Scientists, however, are beginning to grasp the physics of avulsions through the use of small-scale models, providing optimism that they may be predicted or even avoided entirely in the future.
