Erosion, transport and deposition.

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  • Created by: hamishc
  • Created on: 24-04-16 13:42
What is transport?
When loose eroded material is carried by the river as its load.
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What is suspension?
Smaller finer particles ,such as silt and clay, are carried as suspended load, occurs most during times of flood, makes up most of the transported material.
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What is saltation?
Larger particles, such as sand and gravel, are transported in a series of 'hops' as the saltated load, material is picked up for a short time before being dropped when the current falls.
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What is traction?
Pebbles and stones are rolled along the river bed as the 'bed' or 'tracted load', larger boulders may only move during times of flood.
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What is solution?
In areas of calcareous rock, chemical reactions occur, the material is dissolved and carried as the solution load.
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What is river capacity?
The total load the stream can carry.
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What is river competence?
The maximum particle size the stream can carry.
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What is sediment yield?
The amount of material carried by the water.
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What causes a high sediment yield?
Erodable sediments, high releif, techtonic activity, erosive storms, limited vegitation cover, intense human activity (such as removing vegetation and exposing ground surfaces.
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What are the features of the Hjulstrom curve?
Smallest and largest particles require high velocities to lift them. Higher velocities are required for entrainment than transport. When velocity falls below a certain level, those particles are deposited.
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What is abrasion?
The wearing away of the bed and bank by the load carried by the river.
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What is attrition?
The wearing away of the load carried by a river, creating smaller, rounder particles.
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What is hydraulic action?
When water and air is forced into the sides of the river and cracks, pressure builds up and blasts away material, occurs most in waterfalls where water crashes onto and erodes the rocks below.
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What is solution?
When a chemical reaction occurs between the river and the calcium in the bank, occurs especially when the bank is made of chalk and limestone.
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What are the factors affecting rates of erosion?
Load (the heavier and shaper), velocity, gradient, geology (weaker and unconsolidated rocks), pH level, human impact (human obstacles interfere with natural flow)
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When does deposition occur?
When a river looses its energy (due to: a shallowing gradient, a decrease in water volume, an increase in friction, human obstructions such as dams).
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Other cards in this set

Card 2

Front

What is suspension?

Back

Smaller finer particles ,such as silt and clay, are carried as suspended load, occurs most during times of flood, makes up most of the transported material.

Card 3

Front

What is saltation?

Back

Preview of the front of card 3

Card 4

Front

What is traction?

Back

Preview of the front of card 4

Card 5

Front

What is solution?

Back

Preview of the front of card 5
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