oxbow

An oxbow is a crescent-shaped body of water formed when a wide meander of a river is cut off from the main channel, creating what is commonly called an oxbow lake. The term derives from the U-shaped yoke used for oxen, which resembles the shape of the feature.

Formation occurs in stages. In a meandering river, erosion wears away the outer banks of bends while sediment is deposited on the inner banks. During a flood, the neck of a loop may be breached, providing a shorter route for the river. The main channel then abandons the loop, leaving the cut-off bend isolated from the current flow. Over time, sediment and vegetation can fill the lake, turning it into a marsh or wetland, though some oxbow lakes remain as open water.

Oxbow lakes are typically found in river floodplains and other settings with strong lateral migration of a river. They contribute to landscape diversity and create specialized habitats that support a variety of aquatic plants, fish, amphibians, birds, and other wildlife. Their hydrology can influence groundwater recharge and sedimentation patterns in the surrounding floodplain.

In many river systems worldwide, oxbow lakes persist as remnants of former channels. While they may gradually infill, they often remain recognizable features that illustrate the dynamic nature of river channels and the historical course changes of rivers.