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Slide 1

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Potholes are holes drilled into the river bed by turbulent high-velocity water loaded
with pebbles. They can be just a few centimetres or metres as the one below.
Bourke's luck, Sabie, south Africa…read more

Slide 2

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How are they formed:
Pebbles become trapped in slight hollows
and vertical eddies in the water are strong
enough to allow sediment to rind a hole in
the rock by abrasion.
Attrition rounds and smoothes the pebbles
caught in the hole helps to reduce size of
bed load.…read more

Slide 3

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They are generally found in the upper
curse or early middle course of a river.
This is where the valley lies well above
base level, giving more potential energy
for down cutting, and where the river bed
is more likely to be rocky in nature.…read more

Slide 4

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Braided Channels
Braided channels are when the river is forced to split into several channels
separated by islands.
Braided reach of Lillooet River, south-western British Columbia.…read more

Slide 5

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Braided channels
Are a feature of rivers that carry a large
amount of sand and gravel.
Banks formed from sand and gravel are
generally unstable and easily eroded.
As a result the channel becomes a lot
wider in comparison to its depth…read more

Slide 6

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Braided channels
They also occur when the discharges are
rapidly fluctuating for example...
Semi- arid areas of low relief that receive
rivers from mountainous areas
Glacial streams with variable annual
discharge. Meltwater causes discharge to
increase and more particles can be
transported. As the temperature drops the
load is deposited as islands.…read more


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