Dear nature lovers,
Greetings from oikos !
The curves and bends of a river, while flowing over gentle slopes, are called meanders. Rivers usually put up a brilliant meandering display on plains, in the middle and lower course of their journey to the ocean.
Meandering is an important process of the river as it stimulates transportation of silt and organic matter. When water changes its course in the meander, there is the inevitable erosion and deposition of sediment. Water flow strikes outer part of meandering bank, so erosion takes place along the outer bank and is called the ‘cut bank’. Further downstream, inner parts of a meander experience deposition of sediment, called ‘point bars’. Sediments are also deposited within river channel to form successive pools and riffles. At certain places large islands are created due to excessive sedimentation. Erosion of the outer part makes the river deeper towards the outer curve, and water flows faster here. The inner part stays shallower and has a slower flow.
The incessant erosion and deposition causes meanders to grow over time. When meanders grow so big that the two bends can connect with each other bypassing the bend, isolated meander channel becomes an Oxbow lake. The river cuts off the flow to the Oxbow lake and over time, the lake fills up with sediment and may disappear leaving a scar
The space in between successive meanders inundate during each flood to form fertile floodplain.
A meander is an extremely important element of the river, which controls the velocity and flow of water. This influences the formation of habitats. Meanders are responsible for maintaining the biological rhythm of a river. It is vital to preserve the meanders in a natural state. Any kind of straightening or channelizing the river must be prohibited.
Ketaki & Manasi
With Team oikos !
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