River processes of erosion
fter heavy rain a river will begin to erode its channel and Valley. there are four processes
A
of erosion:
➢
H ydraulic action: the force of fast-moving water hitting the river bed and banks
➢ Abrasion: sand pebbles and boulders carried by the river, scrape against the river
bed and banks dislodging particles
➢ Solution: mildly acidic water erodes the river bed/banks of a channel made of
chalk
➢ Attrition: bedload (Stones) bang into each other on the river bed becoming smaller
and rounder
hen erosion makes the channel wider it is called lateral erosion
W
When erosion makes the channel deeper it is called vertical erosion #
River processes of transportation
Material transported by a river is called it's load there are four types of transportation:
➢ T raction: boulders and pebbles are rolled along the river bed. This happens in high
energy rivers eg. after rainfall.
➢ Saltation: load bounces along the river
➢ Suspension: small load eg. sand and clay particles are carried within the river flow
➢ Soulution: the load is dissolved from the chalk banks and beds and carried
downstream
hen a river is flowing slowly it does not have enough energy to transport much load so
W
the river water looks clear. But after a rainstorm the water levels increase and so does its
velocity, this gives the river more energy to transport load and results in a murky/muddy
river
Deposition
eposition is when a river deposits its load, this happens because it slows down due to
D
friction and loses energy. When and where does this happen?
➢ O nce river levels have fallen after a rainstorm the boulders in the upper course can
no longer be transported by traction and they will be deposited
➢ On the inside of a meander (bend) the flow is slow due to friction this reduces its
energy levels and so the river deposits its load
➢ At the river's mouth the river interact with tides, greatly reducing its velocity,
consequently its energy levels fall and it deposits its load
fter heavy rain a river will begin to erode its channel and Valley. there are four processes
A
of erosion:
➢
H ydraulic action: the force of fast-moving water hitting the river bed and banks
➢ Abrasion: sand pebbles and boulders carried by the river, scrape against the river
bed and banks dislodging particles
➢ Solution: mildly acidic water erodes the river bed/banks of a channel made of
chalk
➢ Attrition: bedload (Stones) bang into each other on the river bed becoming smaller
and rounder
hen erosion makes the channel wider it is called lateral erosion
W
When erosion makes the channel deeper it is called vertical erosion #
River processes of transportation
Material transported by a river is called it's load there are four types of transportation:
➢ T raction: boulders and pebbles are rolled along the river bed. This happens in high
energy rivers eg. after rainfall.
➢ Saltation: load bounces along the river
➢ Suspension: small load eg. sand and clay particles are carried within the river flow
➢ Soulution: the load is dissolved from the chalk banks and beds and carried
downstream
hen a river is flowing slowly it does not have enough energy to transport much load so
W
the river water looks clear. But after a rainstorm the water levels increase and so does its
velocity, this gives the river more energy to transport load and results in a murky/muddy
river
Deposition
eposition is when a river deposits its load, this happens because it slows down due to
D
friction and loses energy. When and where does this happen?
➢ O nce river levels have fallen after a rainstorm the boulders in the upper course can
no longer be transported by traction and they will be deposited
➢ On the inside of a meander (bend) the flow is slow due to friction this reduces its
energy levels and so the river deposits its load
➢ At the river's mouth the river interact with tides, greatly reducing its velocity,
consequently its energy levels fall and it deposits its load
