River processes and River Features.
Key terms on River Processes and River Features
- Created by: tybeany88
- Created on: 26-09-13 17:13
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- River processes
- Erosion
- Abrasion
- Rocks: Carried along river - wear down banks and beds
- Works when river has lots of energy.
- Large particles produce: rapid erosion. Smaller: smooth surfaces
- Hydraulic Action
- When water wears riverbank
- Moving water - frictional drag - dislodges particles
- Faster on the outside of a meander, undercuts riverbank - creates river cliff
- Attrition
- Rocks carried along the river smash into each other - becoming smaller and smoother
- Solution
- Some river water can be slightly acidic
- Particles that have dissolved in the water
- Effective on carbonated rocks - limestone
- Abrasion
- Transportation
- Solution
- Particles and minerals dissolved in water
- Suspension
- Fine light material carried along river - SUSPENDED LOAD (largest proportion of rivers total load)
- Saltation
- Small stones picked up and dropped, bounce along river bed - becoming smaller
- Traction
- Boulders and large rocks - rolled along riverbed
- Influences on a rivers load
- Capacity - total load a rver is capable of carrying
- Increases with discharge, measured by vol, mass, or weight
- Competence: maximum load - increases downstream - velocity and discharge increase
- Hjulstorm graphs
- Capacity - total load a rver is capable of carrying
- Deposition
- Occurs when a river loses energy and can no longer transport material
- River enters shallow water
- Volume of water decreases
- Velocity is reduced
- Load is increased
- Solution
- Deposition
- Occurs when a river loses energy and can no longer transport material
- River enters shallow water
- Volume of water decreases
- Velocity is reduced
- Load is increased
- River Features
- Caused by Erosion
- V-Shaped Valleys
- Weathering and Erosion attacks the valley forcing it to retreat
- Interlocking Spurs
- Areas of hard rock that the river did not erode
- Potholes
- active corrasion in areas with turbulent and high velocity flow
- Waterfalls
- resistant rock overlies soft rock in steep areas - undercut of soft rock. resistant rock on top becomes too heavy and collapses
- Rapids
- Bedrock more resistant to erosion
- V-Shaped Valleys
- Caused by EROSION and DEPOSITION
- Meanders
- Oxbow Lakes
- One meander catches up with the next. Cutting off the meander - causing river to become straight.
- Meander abandoned.
- Large bends in river channel. high volume of water.
- More velocity on outside bend, erodes river bank. undercutting.
- Inside bend, velocity is reduced. Deposition of material that the river eroded earlier on
- Oxbow Lakes
- Meanders
- Caused by Deposition
- Braiding
- network of small channels separated by small islands
- Main channel - straight; Sediment load is high and made of gravel and coarse sand.
- Frequent variable and rapid discharge
- Levees
- Banks of silt where rivers keep flooding. - builds up over time
- Flood Plains
- areas surrounding river - flat and fertile good for agriculture
- Deltas
- Bird's Foot
- Mississippi river: USA
- Splits, river extends like the foot of a bird.
- Cuspate
- Land sticks out of the sea like an arrow.
- Ebro in Spain
- Arcurate
- Creates a fan effect. River splits many times. Curving shoreline.
- Nile in Egypt
- Mouth of the river; many distributaries
- River meets sea; sea is calm; river carrying a large load; material deposited faster than sea can remove it
- Bird's Foot
- Braiding
- Caused by Erosion
- Erosion
- Erosion
- Abrasion
- Rocks: Carried along river - wear down banks and beds
- Works when river has lots of energy.
- Large particles produce: rapid erosion. Smaller: smooth surfaces
- Hydraulic Action
- When water wears riverbank
- Moving water - frictional drag - dislodges particles
- Faster on the outside of a meander, undercuts riverbank - creates river cliff
- Attrition
- Rocks carried along the river smash into each other - becoming smaller and smoother
- Solution
- Some river water can be slightly acidic
- Particles that have dissolved in the water
- Effective on carbonated rocks - limestone
- Abrasion
- Capacity - total load a rver is capable of carrying
- Increases with discharge, measured by vol, mass, or weight
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