A billabong is an Australian term describing a small body of water, usually permanent. It is most often defined as an oxbow lake, caused by a change in course by a river channel; however, other types of small lakes, ponds, or waterholes are also described as billabongs in various Australian sources. The term most likely derives from an Aboriginal Australian language of New South Wales, the Wiradjuri language.
A billabong along Scrubby Creek at Berrinba Wetlands, Queensland, 2014
Billabong, Northern Territory
An oxbow lake is a U-shaped lake or pool that forms when a wide meander of a river is cut off, creating a free-standing body of water. The word "oxbow" can also refer to a U-shaped bend in a river or stream, whether or not it is cut off from the main stream.
This picture of the Nowitna River in Alaska shows two oxbow lakes – a short one at the bottom of the picture and a longer, more curved one at the middle-right. The picture also shows that a third oxbow lake is probably in the making: the isthmus or bank in the centre of the most prominent meander is very narrow – much narrower than the width of the river; eventually, the two sections of river on either side of an isthmus like that tend to break through and create a new, straighter course; a new river bank then starts to accumulate, sealing off the meander and leaving another oxbow lake.
A Horseshoe or oxbow lake near Hughes, Arkansas. The bulges in the border reflect changes in the course of the river; when the river shifted its course and cut off the former channel, the border remained unchanged.
Oxbow lakes on New Zealand's Taieri River have been converted into water meadows.
The Oxbow, on the Connecticut River, Thomas Cole
