GCSE Geography Revision aid - Rivers

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Rivers
Methods of Erosion
· Attrition ­ material (load) carried by the river bump into each other resulting into smoother,
smaller particles.
· Abrasion ­ This is the process which the bed and banks of the river are worn down by the
river load.
· Corrosion ­ This is the chemical action of river water. The acids in water slowly dissolve the
bed and banks (limestone).
· Hydraulic action ­ This process involves the force of the water action against the river bed
and the banks.
Methods of Transportation
· Saltation ­ Sand sized particles bounce along the river bed.
· Solution ­ Some minerals dissolve in the water of the river.
· Suspension ­ Silt and clay particles are carried within the water.
· Traction ­ Rolling stones along the river bed.
Features of erosion
· Meander ­ The current is fastest on the outside of the bend because the river
channel is deeper so there's less friction meaning the water isn't as slow as it is on
the inside of the bend. Therefore more erosion takes place on the outside of the
bend forming river cliffs . Eroded material is deposited on the inside of the bend
forming slip off slopes.

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Oxbow Lakes ­ erosion causes the outsides of the bends to get closer until there's
only a small bit of land left between the bends, this is called the neck. The river
breaks through the land more than likely during a flood. The river flows along the
shortest course, deposition eventually cuts off the meander forming an oxbow lake.…read more

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Over time the deposited material builds up, creating levees along
the edges of the channel.
· Deltas ­ Rivers are forced to slow down when they meet the sea, this causes them
to deposit the material, the material builds up and the channel gets blocked, this
forces the channel to split up into lots of smaller rivers called distributaries.…read more

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Confluence - The confluence is the point at which two rivers or streams meet.
· Tributary - A tributary is a smaller stream or river which joins to a bigger stream or
river.
· Source - The start of the river.
· Mouth - The point where the river meets the sea or the end of the river.
· Long profile - The long profile of a river shows you how the gradient changes over
different courses.…read more

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A hydrograph shows the following;
-Peak rainfall: Peak rainfall is the highest amount of rain/precipitation that takes place.
- Peak discharge: The highest amount of discharge in the time period you are observing.
- Lag time: The lag time is the delay between peak rainfall and peak discharge.
- Rising limb: The rising limb is increase in river discharge as rainwater flows into the river.
- Falling/Recession limb: The decrease in river discharge as the river returns to its normal
level.…read more

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The area of the storage basin: Large basins recieve more precipitation than a smaller basin,
it also takes longer for the water to get to a river or watersource therefore resulting in a
longer lag time.
- The shape of the drainage basin: An elongated basin with flat slopes will cause the lag time
to increase as there is less surface runoff meaning water reaches the river in a slower time.…read more

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· Urbanisation - Many impermeable materials are in an urban area, buildings, roads and paths
are made of materials such as concrete and tarmac, these impermeable surfaces increase
runoff. The drains also take water to the river incrasing the likelihood of a flood.
Flood management strategies
· Dams and reservoirs - Dams are huge walls which are built across rivers mainly in the upper
course leaving a reservoir behind.…read more

Comments

Mr A Gibson

In terms of the theory and concepts this document has everything you need no matter which exam board you are studying. Print this off and get it in your revision folder. Even better, do a second copy and annotate some examples onto it in the relevant place.

Abdul2906

This is really helpful. Thankyou

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