A popular but poorly explained feature of rivers is the meander, so we will feature it here, but you should learn more than one feature!
Formation of a meander
Water never flows in a straight line even in an apparently straight river channel. Water twists and turns around stones and other obstructions resulting in areas of slower and faster water movement. Slower areas are found in deeper parts of the river filled with fine sediments and are called pools. Faster areas are found in shallower parts of the river around larger stones and are called riffles.
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| How a River Changes Shape |
The river starts to flow from side to side in a winding course but still in a relatively straight channel. The pools tend to move to opposite sides of the channel over time and this is where a meander will develop.
Water moving faster has more energy to erode. This occurs on the outside of the pool.
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| Cross-Section of a River Channel |
Water moving slowly tends to deposit material as it has little energy left to erode or transport material. This occurs on the inside of the pool.
Meanders migrate downstream and change shape over time. The neck of land between the loops also gets narrower. At the next flood, the river may cut through this to find a faster course. It then deposits material at the entrance to the old meander, cutting off the flow of water and creating an ox-bow lake.
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| The Changing Shape of a Meander |
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What landforms can be created along the course of a river?
UPPER COURSE - Meanders
Meanders are found throughout the middle and lower courses of many rivers. A meander is the geographical term for a bend in the course of a river. They form when the fastest flowing water erodes one side of the river, this causes one bank to erode more rapidly than the other. On the opposite side the water is flowing much slower so material is deposited. This creates a bend in river. Over time this meander will become larger and more exaggerated.
Eventually the meander will become so large that during a flood the river will attempt to take the shortest route possible. This will result in the river breaking through the neck of a meander, cutting off the meander itself. This results in the creation of an Ox-bow Lake.
Eventually the meander will become so large that during a flood the river will attempt to take the shortest route possible. This will result in the river breaking through the neck of a meander, cutting off the meander itself. This results in the creation of an Ox-bow Lake.
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