Uk landscape River Flashcards
upper course -valley is steep sided
What does vertical erosion do ?
Where is it dominant ?
deepens the river valley making it v shaped
dominant in the upper course
high turbulence causing rough, angular particles to be scraped along river bed calling downwards erosion
What is lateral erosion?
widens the river valley during the formation of meanders
dominant in middle and lower coarse
Upper course
the source is an area of hard resistant rock
steep-sided due to vertical erosion
the river channel is narrower and shallower (discharge is low )
velocity is low due to friction from rough channel sea bed
carries large angular stones
Middle course
soft,less resistant ,easily eroded rock
river becomes wider because of lateral erosion
gradient of channel is less steep
sediment load is made up of smaller rounder rocks
lower course
very wide and flat
high velocity ,very little friction ,very large discharge
river channel is very wide and deep
Material carried is well rounded
water gets into rocks that have cracks ,when it freezes it expands .Putting pressure on the rock
When the water thaws it contracts releasing pressure on rock
repeated thawing causes the rock to break.
What are the four types of erosion processes
solution ,attrition,abrasion ,hyrdaulic action
Hydraulic action -the force of water breaks rock particles away from the river channel
solution-river water dissolves some types of rocks.
abrasion-eroded rock rub against channel wearing it away .
attrition -eroded rocks hit against each other
What is a floodplain?
What happens when a river floods onto the floodplain ?
Does flood plain higher or lower?
Where is it found ?
wide valley floor on either side of a river that occasionally gets flooded
when a river floods onto a floodplain water slows down and deposits eroded materials that its transporting building up the floodplain higher
in lower course
What are levees?
How are they created ?
When are they created ?
levees are natural embankments along the edges of a river channel
during a flood eroded material is deposited over the whole floodplain .
Heaviest material is deposited closest to river channel
over time deposited materials creayes levess along the edges
What are rivers forced to do when they meet the mouth?
How are deltas formed ?
rivers are forced to slow down when they meet the sea or the lake causing them to deposit the material they are carrying
if the sea dosen’t washes away the material it builds up and the channel gets blocked.
causing the channel to split up into smaller rivers called distributaries
overtime forms deltas
What are the three physical factors that shape the physical landscape and sediment load?
geology, climate, and slope process.
Climate
What do rivers in wetter climates have?
The rate of what is increased?
What three thing is climate responsible for ?
rivers in wetter climates have higher discharges as there is more water entering the river channel
therefore increasing rate of erosion as there is a higher volume of water
climate is what causes vertical erosion in upper course and lateral erosion in lower course
transportion increases when there is more water
weathering increases rivers sediment load
hydrographs show the change in river discharge.
river discharge -volume of water that glows per second
