An oxbow lake is a crescent-shaped body of water that forms when a meandering river or stream erodes its banks over time.
The process typically unfolds as follows:
- Meandering River: In a meandering river, the water flows in a sinuous, winding pattern as it travels downstream. The outer bank of a meander curve experiences greater erosion due to the higher velocity of water, while the inner bank experiences deposition.
- Neck Formation: Over time, erosion causes the outer bank of a meander to migrate and approach the inner bank. As the erosion continues, the distance between the two banks decreases, forming a narrow neck of land.
- Cutoff: Eventually, the river’s flow can become more direct across the neck of land due to increased erosion. During periods of high water flow, such as flooding, the river may breach through the neck, creating a new channel.
- Oxbow Formation: Once a new channel is established, the water flow in the old meander is reduced. Sediments start to accumulate in the abandoned meander, and the loop of the meander becomes isolated from the main river channel. This isolated loop, which retains water, forms the oxbow lake.
- Lake Evolution: Oxbow lakes gradually fill with sediment and organic matter over time. They may become shallower and develop wetland vegetation around their edges. The size, shape, and ecology of an oxbow lake can change as sedimentation and vegetation continue to influence the area.
Oxbow lakes are common features in floodplains and are created as a result of the natural evolution of meandering rivers. They serve as important ecological habitats, providing shelter and food for various aquatic and terrestrial organisms. Oxbow lakes also offer insight into the historical patterns of river meandering and landscape changes over time.
Q. What is an oxbow lake?
(a) A lake formed by a volcanic eruption
(b) A small pond in a desert
(c) A crescent-shaped body of water formed by a meandering river
(d) A lake created by a glacier
Ans: (c) A crescent-shaped body of water formed by a meandering river.
Explanation: An oxbow lake is a curved or crescent-shaped body of water that forms when a meandering river or stream erodes its banks and creates a cutoff.