Transcript River processes

Key words - Transportation.
• Traction – where large rocks and boulders are
rolled along the river bed.
• Saltation – where smaller stones are bounced
along the river bed in a leap frogging motion
• Suspension – where very small grains of sand or
silt are carried along with the water
• Solution – where some material is dissolved (like
sugar in a cup of tea) and is carried downstream.
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0 50 100 150 200 250
Height above sea level in meters.
Long Profile
Source.
Gradient/slope decreasing
Velocity/flow increasing
Upland stream.
Cumecs/discharge increasing
Energy increases
Lowland river.
Mouth.
35
30
25
20
15
10
Distance from sea in Kms.
5
0
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Traction
Heavy rocks and boulders are rolled
along the river bed. Happens most
in times of flood, when the current
is strongest.
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Saltation.
Small stones and pebbles
are ‘bounced’ along the river
bed. Saltation can take
place when the river flow is
less than that needed for
‘Traction’ to take place.
4
Suspension
Very small particles of sand or
clay that are ‘suspended’ in the
water. These particles will ‘settle’
if kept in a jar of water overnight
and the water will look clear.
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Solution.
Takes place when material is dissolved in the
water, it is invisible and does not colour the
water. Occurs often in limestone landscapes
where the water if very acidic. Some
pollutants like weedkiller are also held in
solution in the water
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Methods of transport
Copy this picture into your books and add the
title above and labels for each type of transport
Shows the rate of flow needed
Traction
Saltation
Suspension
Solution
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Key Words - Erosion.
• Attrition – where material is moved along the bed
of a river, collides with other material, and breaks
up into smaller and smaller pieces.
• Corrasion – fine material rubs against the river
bank. The bank is worn away, by a sort of
sandpapering action called abrasion.
• Corrosion – some rocks forming the banks and
bed of a river are dissolved by acids in the water
• Hydraulic action – the sheer force of water
hitting the banks of the river.
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