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The swampy remains of an oxbow lake are evident in the jungle surrounding the Ramu River in Papua New Guinea.
Photograph by James P. Blair
Billabong
In Australia, oxbow lakes are called billabongs. A billabong is the setting for the unofficial national anthem of Australia, Waltzing Matilda.An oxbow lake starts out as a curve, or meander, in a river. A lake forms as the river finds a different, shorter, course. The meander becomes an oxbow lake along the side of the river.
Oxbow lakes usually form in flat, low-lying plains close to where the river empties into another body of water. On these plains, rivers often have wide meanders.
Meanders that form oxbow lakes have two sets of curves: one curving away from the straight path of the river and one curving back. The corners of the curves closest to each other are called concave banks. The concave banks erode over time. The force of the rivers flowing water wears away the land on the meanders concave banks.
The banks opposite the concave banks are called convex banks. The opposite of erosion happens here. Silt and sediment build up on convex banks. This build-up is called deposition.
Erosion and deposition eventually cause a new channel to be cut through the small piece of land at the narrow end of the meander. The river makes a shortcut. Oxbow lakes are the remains of the bend in the river.
Oxbow lakes are stillwater lakes. This means that water does not flow into or out of them. There is no stream or spring feeding the lake, and it doesnt have a natural outlet. Oxbow lakes often become swamps or bogs, and they often dry up as their water evaporates.
Oxbow lakes can be rich wildlife habitats. Along the Amazon River in South America, oxbow lakes are common and their still waters provide a unique habitat for plants and wildlife. Giant river otters frequently live in the Amazons oxbow lakes, and feed on about 5 kilograms (11 pounds) of fish per day.
People often create oxbow lakes. The Mississippi River is shorter now than it was in the 19th century, for instance, because engineers have cut off hundreds of meanders. This created hundreds of oxbow lakes. These lakes eventually dried up to create acres of land for farming, housing, and industry.
An oxbow lake gets its name from the U-shaped collar placed around an oxs neck to which a plow is attached. It can also be called a horseshoe lake, a loop lake, or a cutoff lake. -
Term Part of Speech Definition Encyclopedic Entry billabong Noun Australian name for an oxbow lake.
bog Noun wetland of soft ground made mostly of decaying plant matter.
channel Noun waterway between two relatively close land masses.
Encyclopedic Entry: channel concave bank Noun the outside bank of a rounded bend in a river.
convex bank Noun inside bank of a rounded bend in a river.
deposition Noun process of silt and sediment building up in an area.
engineer Noun person who plans the building of things, such as structures (construction engineer) or substances (chemical engineer).
erode Verb to wear away.
evaporate Verb to change from a liquid to a gas or vapor.
farming Noun the art, science, and business of cultivating the land for growing crops.
fish Noun aquatic animals with gills, and usually fins and scales.
giant river otter Noun aquatic otter up to six feet long, native to the Amazon, Orinoco, and La Plata rivers of South America.
habitat Noun environment where an organism lives throughout the year or for shorter periods of time.
Encyclopedic Entry: habitat housing Noun shelters where people live.
industry Noun activity that produces goods and services.
lake Noun body of water surrounded by land.
Encyclopedic Entry: lake meander Noun large curve in a lake or stream.
ox Noun large bovine often used for hauling heavy loads.
oxbow lake Noun lake formed from an abandoned bend in a river.
Encyclopedic Entry: oxbow lake plain Noun flat, smooth area at a low elevation.
Encyclopedic Entry: plain plow noun, verb tool used for cutting, lifting, and turning the soil in preparation for planting.
river Noun large stream of flowing fresh water.
Encyclopedic Entry: river sediment Noun solid material transported and deposited by water, ice, and wind.
Encyclopedic Entry: sediment silt Noun small sediment particles.
Encyclopedic Entry: silt spring Noun small flow of water flowing naturally from an underground water source.
still-water lake Noun body of water with no streams or springs flowing into or out of it.
stream Noun body of flowing water.
Encyclopedic Entry: stream swamp Noun land permanently saturated with water and sometimes covered with it.
Encyclopedic Entry: swamp