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Slide 1

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The Formation Of Meanders
· Meanders are curves found in the middle and lower course of a river caused by
erosion and deposition and the change in speed of water causes the meanders.
· They form when alternating pools (deep areas of water) and riffles (shallow
water) develop at equal spaces along a river.
· The river channel are deeper in pools so they are more efficient so has greater
energy and erosive power. Energy is lost as the river travels over a riffle as there'
s friction.
· The distance between the riffles and pools mean the rivers flow is uneven and
maximum flow is concentrated on one side of the river.
· Turbulence increases in and around pools as the water speeds up so the water
begins to twist and coil.
· This can cause a corkscrew like current in the water which spiral from bank to
bank between pools.
· The flow causes more erosion and deepening of the pools and the eroded
material is then deposited on the inside of the next bend and the river will lose
energy.
· Combination of the erosion and deposition helps expand the size of the
meander. Eventually this can lead to the formation of an oxbow lake.…read more

Slide 2

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The meanders are found in the lower part of
the course as all rivers flow down a slope
River flow Pool Riffle towards the sea and will take the easiest route
movement available. However, the geology of the land
means a river will rarely flow in a straight path
so this is why it will meander. The rates of
Erosion on outside
Deposition on inside deposition and lateral erosion are highest at
this part of the river and also contribute to
meanders occurring due to little potential
energy but lots of kinetic energy allowing it to
flow faster forming a meander.
Inside bend
Lateral erosion
is dominant
As the
meanders have
migrated Slip off slope Corkscrew like
downstream, created on currents
meander size inside bend
Lateral erosion
has increased by abrasion and
Inside bend has
hydraulic action
shallow water forms river cliff
and slower Deep water and
flow faster flow on
outside bend
Outside bend (river cliff
can be created)…read more

Slide 3

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The formation of an Oxbow Lake
·In the lower course of the river meanders can
become so pronounced that they can form ox-bow
lakes.
On the inside of the loop, ·In the lower course the lateral erosion cuts into
the river travels more slowly
leading to deposition of silt, the neck of the meander, narrowing it considerably.
while water on the outside ·Eventually the force of the river breaks through
edges tends to flow faster,
the neck, and as this is the easiest way for the water
eroding the outside banks.
to go, the old meander is left without any significant
amount of water flowing through it.
·Quickly the river deposits material along the side
of its new course, which completely block off the
old meander, creating an ox-bow lake.
Over time the loop of the Eventually the
meander widens until the bend becomes
neck vanishes altogether isolated from
as the gap has been the river's path
narrowed by erosion. and an ox-bow
lake is formed.
The oxbow lakes occur in the lower course as this is where meanders occur and the river is able to take a quicker route by
discarding the meanders curve. They are more dominant in the lower course than the middle as meanders are larger so
there is more reason to reduce the amount of energy used by finding a quicker route.…read more

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