Rivers - flood defenses, mass movement, weathering, 4 processes o erosion, long profile, transportations
- Created by: katieglanville
- Created on: 21-06-21 18:12
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- Rivers Katie Glanville
- long profile
- middle course
- wider and depper
- transportation accor
- load size becomes smaller
- deposition becomes more obvious
- more vertical and lateral erosion
- upper cource
- load size very small
- erosion processed accor
- deposition of large material
- vertical erosion
- lower course
- load size very small
- less erosion
- deepest and widest
- deposits fine materail
- vertical erosion = this deepens the river valley making it a V-shaped. it's dominant in the upper course of the river
- lateral erosion = widens the river valley. dominant in the middle and lower cource
- middle course
- transportation
- suspension
- small particles are carried within the water by turbulent flow
- saltation
- sand sized particles may be bounced along the bad if the river
- traction
- heaviest material is rolled along the river bed
- suspension
- 4 processes of erosion
- hydraulic action
- the force of the water breaks rock particles away from the river channel
- abrasion
- eroded rocks picked up by the river scrape and rub against the channel, wearing it away
- attrition
- eroded rocks picked up by the river smash into smaller fragments. Their edges also get rounded off as they rub together
- solution
- river water dissolves some types of rock, e.g. chalk and limestone
- hydraulic action
- mass movement
- slumping
- valley sides are eroded by the river making the slides steep and increasing the downward movement of materials. heavy rainfall can trigger this movement
- soil creep
- partials of soil slowly moves down the sides of the valley under the influence of gravity
- slumping
- weathering
- chamical
- rainwater is slightly acidic and can dissolve some rock, especially limestone and chalk
- freeze-thaw weathering
- water goes into cracks in rocks, when winter or a cold period accors the water freezes and expands causing the crack to expand, then the process repeats until the rock is split
- biological
- tree roots can penetrate cracks in the rocks and split them apart
- chamical
- flood defences
- soft engineering
- do nothing
- land-use zoning
- soil embankment
- preparation
- hard engineering
- flood walls and gates
- channel straightening
- concrete embankments
- dam
- disad = expensive, ugly, floods
- ad = hydroelectric, lasts a long time
- soft engineering
- long profile
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