Transcript Forced Migration Case Study: Zimbabwe to South Africa

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Hydrosphere
Past Question: Erosion,
transportation and deposition
change down the river – choose
one of these processes then
describe and explain this change?
The Upper Course
Areas with steep gradients
will have an increased velocity
and so the potential for erosion is
higher, especially vertical erosion. The river also has the ability at
this point to transport and break up larger pieces of rock. The
main type of erosion here is hydraulic action which is caused
when water traps air into the river banks, forcing them to expand
and crack. Abrasion will often occur on the river bed, often
resulting in potholes. Erosion is highest under flood conditions.
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Middle course
The main areas of erosion will occur on the outside bends of
the river through hydraulic action and abrasion (load being
knocked against the bank and bed of the river and wearing it
away). The main direction of the erosion is lateral.
Lower course
Erosion at this point is minimal but may be found in meanders.
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The Upper Course
[Date]
Today I will:
- Know the formation of a waterfall
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Characteristics of the Upper Course
- River channel is rocky.
- Covered with various shapes and sizes
of boulder.
- Discharge is low.
- Under flood conditions rivers energy is
expended on ‘vertical erosion’ with
hydraulic action and corrosion processes
at work.
-Valley sides are steep and form a ‘V’
shaped cross section.
-Interlocking spurs.
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V- Shaped Valley
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The tallest waterfall in the world is Angel Falls
in Venezuela which drops 979m.
Niagara Falls, on the other hand, is only
51m high!
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Largest Waterfall in
the UK – High Force
in England.
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When waterfalls retreat they leave behind a
gorge.